मराठी विश्वकोश प्रथमावृत्ती

सौर ऊर्जा : ही सूर्याकडून प्रेषित होणारी विद्युत् चुंबकीय प्रारणाच्या (तरंगांच्या) रूपातील ऊर्जा आहे. सूर्याकडून उत्सर्जित होणारे विद्युत् चुंबकीय प्रारण आणि इलेक्ट्रॉन, प्रोटॉन व अधिक विरल जड अणुकेंद्रे म्हणजे सौर प्रारण होय. हे प्रारण उष्णतानिर्मिती करणारे, रासायनिक विक्रिया घडविणारे किंवा विद्युत् (वीज) निर्माण करणारे आहे. सूर्य हा अतिशय शक्तिशाली ऊर्जास्रोत आहे आणि सौर प्रारण हा पृथ्वीवर येणारा सर्वांत मोठा ऊर्जास्रोत आहे. तथापि, प्रत्यक्षात त्याची पृथ्वीच्या  पृष्ठभागावरील तीव्रता पुष्कळच कमी असते. पृथ्वीकडे येणार्‍या एकूण सूर्यप्रकाशापैकी सु. ५४ टक्क्यांपर्यंतचा प्रकाश वातावरण, त्यातील ढग व धूलिकण यांच्याकडून शोषला जातो वा प्रकिर्णित होतो (विखुरला जातो). सूर्यप्रकाशाची भूपृष्ठावरील तीव्रता कमी होण्याचे हे एक प्रमुख कारण आहे. असे असले, तरी विसाव्या शतकाच्या उत्तरार्धानंतर ऊर्जास्रोत म्हणून सौर ऊर्जा वाढत्या प्रमाणात आकर्षक ठरली. कारण तिचा पुरवठा न संपणारा आहे आणि या ऊर्जेने प्रदूषण होत नाही. याचा अर्थ दगडी कोळसा, खनिज तेल, नैसर्गिक वायू यांसारख्या प्रचलित इंधनांच्या तुलनेत सौर ऊर्जा अधिक सुरक्षित व खात्रीशीर ऊर्जा आहे.

पृथ्वीच्या वातावरणाच्या वरच्या भागाला दरवर्षी सौर प्रारणाची सु. १.५ X १०२१ वॉट-तास (औष्णिक) ऊर्जा मिळते. ही ऊर्जा पृथ्वीवर माणसे वापरत असलेल्या एकूण ऊर्जेच्या तुलनेत अगदी प्रचंड म्हणजे २३,००० पटींहून जास्त आहे. सूर्यापासून एकूण सु. ३.९ X १०२०  मेवॉ. ऊर्जा उत्सर्जित होते व तिच्यापैकी केवळ दोन अब्जांश भागाएवढी ऊर्जा पृथ्वीच्या वातावरणाच्या वरच्या भागात पोहोचते.

पृथ्वीच्या वातावरणाच्या लगेचच बाहेर व संपूर्ण सौर वर्णपटातील मोजलेल्या सौर प्रारणाच्या शक्ति-घनतेला सौरांक म्हणतात. म्हणजे पृथ्वी व सूर्य यांच्यात सरासरी (माध्य) अंतर असताना वातावरणाच्या माथ्यावरील  प्रारणाच्या आपतनाला लंब दिशेत असलेल्या पृष्ठभागावर सूर्याकडून येऊन पोहोचणार्‍या ऊर्जेच्या त्वरेला सौरांक म्हणतात व तो दर चौ. सेंमी.ला ०.१४० वॉ. असतो. जागतिक वातावरणवैज्ञानिक संघटनेनुसार १९८१ मध्ये सौर स्थिरांकाचे सर्वांत विश्वासार्ह मूल्य दर चौ. मी.ला १,३७० ± ६ वॉ. एवढे होते. या सौर शक्तीपैकी ८% शक्ती वर्णपटातील जंबुपार तरंगलांब्यांची, ४७% ऊर्जा दृश्य वर्णपटाची आणि ४५% ऊर्जा अवरक्त तरंगलांब्यांची असते. सौर स्थिरांक हा वस्तुतः यथार्थ वा खरा स्थिरांक नाही. कारण पृथ्वीच्या सूर्याभोवतीच्या कक्षेच्या लंबगोल आकारामुळे त्यात सतत लहानलहान बदल होत असतात. ५ जुलैच्या सुमारास पृथ्वी सूर्यापासून कमाल अंतरावर असताना सौर स्थिरांकाचे सरासरी मूल्य ३.३% कमी होते तर ३ जानेवारीच्या सुमारास पृथ्वी सूर्याच्या सर्वांत जवळ असताना सौर स्थिरांकाच्या सरासरी मूल्यात सु. ३.४% वाढ होते.

essay on renewable energy in marathi

सौर प्रारण भूपृष्ठावर पोहोचण्याआधी वातावरणामुळे त्याचे क्षीणन होते. म्हणजे परावर्तन, प्रकीर्णन व शोषण (हवा गरम होणे) या वातावरणातील क्रियांमुळे आपाती सौर ऊर्जेचा काही भाग काढून टाकला जातो वा बदलला जातो. विशेषतः जवळजवळ सर्व जंबुपार प्रारण आणि अवरक्त विभागातील विशिष्ट तरंगलांब्यांचे प्रारण काढून टाकले जाते वा स्थलांतरित होते. तथापि, दरवर्षी भूपृष्ठावर येऊन पडणारे सौर प्रारण हे जगाच्या ऊर्जेच्या वापराच्या दहा हजारपटींहून जास्त असते. वायूंचे रेणू, पाण्याची वाफ किंवा धूलिकण यांच्यावर आदळणार्‍या प्रारणाचे प्रकीर्णन होते. त्याला विसरित प्रारण म्हणतात. विशेषतः ढगांमुळे सौर प्रारणाचे मोठ्या प्रमाणात प्रकीर्णन व परावर्तन होते. त्यांच्यामुळे थेटपणे येणार्‍या प्रारणामध्ये ८०–९०% एवढी मोठी घट होऊ शकते. अर्थात ढगांचे प्रकार व त्यांची होणारी वाटणी यांच्यात पुष्कळ बदल होऊ शकत असल्याने त्यांच्यामुळे प्रारणात होऊ शकणार्‍या घटीचे भाकीत करणे अतिशय अवघड असते.सूर्याकडून भूपृष्ठावर थेटपणे येणार्‍या प्रारणाला शलाका किंवा थेट प्रारण म्हणतात. भूपृष्ठावर येऊन पडणार्‍या सर्व सौर प्रारणाला जागतिक प्रारण म्हणतात आणि त्यात थेटपणे येणारे विसरित प्रारण असते.

ज्या प्रभावी अंतरातून सौर प्रारण प्रवास करीत असते त्याच्यावर सौर प्रारणाचे वातावरणातील शोषण व प्रकीर्णन यांचे प्रमाण अवलंबून असते. कारण प्रभावी अंतर हे वातावरणाची जाडी व त्यातील घटक यांच्यावर अवलंबून असते. पृष्ठभागाला अनुसरून किंवा पृष्ठभागावरून वाहणार्‍या प्रारणिक शक्तीच्या दर एकक क्षेत्रफळामागील प्रमाणाला प्रारणिक स्रोत घनता म्हणतात. तरंगलांबीच्या दर एकक पृष्ठभागावर आपतन होणार्‍या घनतेला वर्णपटीय किरणीयन म्हणतात व ते हवेच्या द्रव्यमानाच्या प्रमाणात असते. हवेच्या ज्या शून्य द्रव्यमानातून सूर्याचे किरण गेले पाहिजेत, त्याला हवा द्रव्यमान शून्य ही संज्ञा वापरतात (ही पृथ्वीच्या वातावरणाबाहेरील सौर तीव्रता आहे). वातावरणाच्या सीमेवर हवा नसते व तेथे पोहोचणार्‍या प्रारणाच्या संदर्भात भूपृष्ठावर येणारे प्रारण मोजता येऊ शकते. सूर्य थेट डोक्यावर म्हणजे शिखर बिंदूवर असताना किंवा त्याचा उन्नतांश ९० ० असताना सूर्यप्रकाश समुद्रसपाटीवर असलेल्या हवा द्रव्यमान १ यामधून जातो असे म्हणतात व त्यामुळे सरासरी शिखर तीव्रता दर चौ. मी.ला १ किवॉ. असते. सूर्याची क्रांती (पृथ्वी-सूर्य रेषा व पृथ्वीची विषुववृत्तीय पातळी यांमधील कोन) पृथ्वी सूर्याभोवती फिरते तशी बदलते आणि याचा भूपृष्ठावर पोहोचणार्‍या सौर प्रारणावर परिणाम होतो. सूर्य जसजसा क्षितिजसमीप येतो तशी किरणांची तीव्रता कमी होते. कारण सूर्यकिरण वातावरणाची अधिक जाडी भेदून जातात. समुद्रसपाटीला क्षितिजसमांतर पृष्ठभागावर पडणारे सौर प्रारणाचे प्रमाण दिवसाला दर चौ. मी.ला ७ किवॉ.-तास पर्यंत असते. ३५ ० उत्तर व ३५ ० दक्षिण या अक्षांशांदरम्यानच्या प्रदेशावर दरवर्षी २,२००—३,५०० तास सूर्यप्रकाश पडतो. यापेक्षा अधिक अक्षांश असलेल्या प्रदेशात कमी काळ सूर्यप्रकाश मिळतो. [⟶ विद्युत् चुंबकीय तरंग सौरतापन ].

कमी घनतेची सौर ऊर्जा हस्तगत करण्याचे (मिळविण्याचे) सर्वांत कार्यक्षम मार्ग शोधणे आणि उपयुक्त कामांसाठी त्या ऊर्जेचे परिवर्तन करणार्‍या पद्धती विकसित करणे, हे सौर संशोधन व तंत्रविद्येचा विकास याचे उद्दिष्ट आहे. वारा, बायोमास (जैव द्रव्यमान), जलविद्युत् आणि उष्ण कटिबंधातील महासागराचे पृष्ठभाग हे अप्रत्यक्ष सौर ऊर्जेचे संभाव्य स्रोत म्हणून महत्त्वाचे आहेत. जलविद्युत् हा अपवाद वगळता इतर ऊर्जास्रोतांचा अगदी थोड्याच प्रमाणात उपयोग करून घेतला जात आहे.

सौर ऊर्जेचा वापर करणार्‍या पाच प्रमुख तंत्रविद्या विकसित होत आहेत : (१) इमारतीमधील वायुवीजनाकरिता मध्यम तापमान निर्माण करण्यासाठी सौर प्रारणातील उष्णता वापरणे मध्यम व उच्च तापमानाची उष्णता औद्योगिक प्रक्रियांसाठी वापरणे आणि उच्च तापमानाची उष्णता वीजनिर्मितीसाठी वापरणे. (२) प्रकाशविद्युत् चालक प्रणालीद्वारे सौर ऊर्जेचे थेट विजेत परिवर्तन करणे. (३) बायोमास तंत्रविद्यांमार्फत ⇨ प्र काशसंश्लेषणा तून निर्माण झालेल्या रासायनिक ऊर्जेचा उपयोग करून घेणे (प्रकाशसंश्लेषणाला सौर प्रारणातून ऊर्जा मिळते). (४) पवन ऊर्जा प्रणालीने यांत्रिक ऊर्जा निर्माण करतात व तिचे मुख्यत्वे विजेत परिवर्तन करतात. (५) अखेरीस महासागरापासून मिळणार्‍या ऊर्जेच्या अनेक अनुप्रयुक्तींचा (व्यावहारिक उपयोगांचा) पाठपुरावा करण्यात येत आहे. यांपैकी महासागर औष्णिक ऊर्जा परिवर्तन ही सर्वांत प्रगत अनुप्रयुक्ती  आहे. सदर अनुप्रयुक्तीत महासागराच्या पृष्ठावरील गरम पाणी आणि अधिक खोलीवरचे अधिक थंड पाणी यांच्या तापमानांमधील फरकाचा वीजनिर्मिती-साठी उपयोग करून घेतला जातो.

इमारतींमधील सौर ऊर्जा प्रणाली : याचे अक्रियाशील प्रणाली व क्रियाशील प्रणाली असे दोन वर्ग करतात.

अक्रियाशील प्रणाली : याच्यामध्ये ऊर्जा बचत प्रणाली म्हणून खुद्द इमारतीचा सौर ऊर्जेबरोबर उपयोग करतात. अशा अक्रियाशील प्रणालीत इमारतीचा परिसर, तिच्या स्थानाची वैशिष्ट्ये (घटक गुण), तिचे बांधकाम व वापरलेले बांधकाम साहित्य यांचा उपयोग करून घेतात. त्यामुळे तिला इंधनापासून मिळणारी ऊर्जा पुष्कळच कमी लागते. अक्रियाशील प्रकाशनाला बहुधा दिवसाचे प्रकाशन म्हणतात. विद्युत् प्रकाशनाला पर्याय व पूरक म्हणून दिवसाच्या प्रकाशनाद्वारे इमारतीचे अंतर्गत प्रकाशन साध्य होते.

तापन प्रणाली : बहुतेक सौर औष्णिक प्रणालींमध्ये उष्णता संकलक, संग्राहक (साठवण) व वाटप प्रणाली असे तीन मूलभूत भाग असतात. अक्रियाशील सौर तापन प्रणालीमध्ये बहुधा खुद्द इमारतच संकलक असते. थेट (प्रत्यक्ष) पद्धतीत बहुधा खिडक्यांमधून सूर्यकिरण इमारतीत प्रवेश करतात आणि थेट सूर्यप्रकाशात खोली किंवा अवकाश (मोकळी जागा) तापतात. जादा उष्णता बाहेर काढून टाकता येते किंवा नंतरच्या वापरासाठी भिंती व जमीन यांसारख्या इमारतीच्या द्रव्यमानात (वास्तविक द्रव्यात) साठविता येते. प्रविष्ट होणार्‍या सौर ऊर्जेचे वाटप पुढील दोन प्रकारे होते. एक म्हणजे इमारतीच्या द्रव्यमानाकडून तिचे पुन्हा प्रारण (उत्सर्जन व प्रसारण) होते आणि दुसरे म्हणजे खोल्यांदरम्यान उष्ण हवेचे नैसर्गिक रीतीने अभिसरण होते. अप्रत्यक्ष तापन प्रणालीत एक वा अधिक खोल्यांचा उष्णता संकलक म्हणून उपयोग होतो. या संकलकाचा त्या खोलीला उरलेल्या इमारतीपासून अलग करणार्‍या संग्राहक द्रव्यमानाबरोबर संयुक्तपणे उपयोग होतो. सदर संग्राहक द्रव्यातून आरपार गेल्यावर सूर्याच्या ऊर्जेचे इमारतीत परत प्रारण व परिवर्तन होते. संग्राहक द्रव्यमान रात्रीच्या वापरासाठीची उष्णता दिवसा साठवून ठेवू शकते. पादपगृहे ही अक्रियाशील तापन प्रणालींची लोकप्रिय उदाहरणे आहेत.

शीतलीकरण प्रणाली : अक्रियाशील तापन प्रणालीत प्रस्थापित झालेले चक्र उलट दिशेत कार्य करू लागले की, अक्रियाशील सौर शीतलीकरण घडते. यामुळे रात्रीच्या वेळी इमारत आकाशाकडे उष्णता प्रारित करू शकते. इमारतीतील द्रव्यमान थंड झाले की, इमारतीच्या आतील तापमान कमी होते. मग दिवसाच्या काळात थंड द्रव्यमानाची उन्हाळ्यामध्ये वायुवीजनाविना सुखावह परिस्थिती निर्माण करण्यास मदत होते. कधीकधी प्रारणशील शीतलीकरण प्रक्रियेला पाण्याच्या पिशव्यांसारखे उष्णता संग्राहक द्रव्यमान इमारतीच्या माथ्यावर (छपरावर) ठेवून मदत केली जाते. उष्णता संग्राहक द्रव्यमानावर आच्छादन घालतात. त्यामुळे दिवसा तापनाला प्रतिबंध होतो परंतु रात्री हे द्रव्यमान आकाशाला उघडे ठेवतात.

नैसर्गिक वायुवीजन हा अक्रियाशील शीतलीकरणाचा दुसरा प्रकार आहे. हे वायुवीजन उघड्या दाराखिडक्यांतून वाहणार्‍या हवेच्या प्रवाहांद्वारे घडते. तापलेली हलकी हवा छतापर्यंत वर गेल्याने हे वायुवीजन होते. खोलीच्या छतालगत व जमिनीच्या पातळीशी हवेसाठी छिद्रे वा प्रवेशमार्ग ठेवल्यास उष्ण हवा वर जाऊन छतालगतच्या छिद्रांमधून बाहेर पडते आणि खालील छिद्रांमधून अधिक थंड हवा आत खेचली जाते.

उन्हाळ्यात इमारतीभोवती सावली निर्माण केल्यासही नैसर्गिक शीतली- करण होते. सावलीसाठी पानझडी वृक्ष लावल्यास त्यांची पाने हिवाळ्यात गळून पडल्याने अक्रियाशील तापन प्रणालीत व्यत्यय येत नाही. विस्तारित भिंती व पुढे आलेले बांधकाम यांच्यामुळे घराची स्वतःचीच सावली निर्माण होते.

दिवसातील प्रकाशन प्रणाली : व्यापारी, औद्योगिक आणि संस्था यांच्या इमारतींमध्ये विद्युत् प्रकाशनासाठी सर्वाधिक ऊर्जा वापरली जाते. अशा ज्या इमारतींमध्ये मुख्यतः दिवसा काम चालते, तेथे दिवसातील उजेडाद्वारे होणारे प्रकाशन हे विद्युत् प्रकाशनाला पर्याय किंवा पूरक म्हणून वापरता येते. खिडक्यांतून व इतर प्रकारच्या उघड्या भागांतून प्रकाश आत येऊ शकतो. दिवसाचा हा प्रकाश पुरेसा असतो तेव्हा विद्युत् प्रकाशन खास प्रकारच्या नियामक प्रणालीने बंद होते. इतर अक्रियाशील प्रणालीपेक्षा दिवसाचे प्रकाशन ढगाळ वातावरणातही वेगळ्या प्रकारे आपले कार्य करते. कारण इमारतीमधील दिवसाचा प्रकाश सूर्याच्या थेट किरणांच्या वापरावर अवलंबून नसतो.

अक्रियाशील सौर कार्यमानावर (कार्यावर) परिणाम करण्यासाठी विविध द्रव्ये वापरणे शक्य आहे. उदा., खिडक्यांच्या तावदानावरील परावर्तन प्रतिबंधक लेप, खिडक्यांवरील उष्णतानिरोधक आडोसा (छाया) व पडदे किंवा उष्णता नियमनकारक पाण्याच्या भिंती वगैरे. खिडक्यांच्या तावदानां-वरील काही लेपांतून विद्युत् प्रवाह वाहतो. तो हवामानाच्या परिस्थितीला प्रतिसाद म्हणून खिडक्यांतून होणारे पारगमन बदलू शकतो. शिवाय खिडकीच्या संग्राहक किंवा निरोधक क्षमता वाढविण्यासाठी खिडकीच्या काचेत किंवा तावदानांदरम्यान घालता येण्यासारखी अनेक रासायनिक संयुगे आहेत.

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क्रियाशील अवकाश अनुकूलन आणि गरम पाणी प्रणाली : इमारती गरम वा थंड करणे आणि घरगुती वा व्यापारी उपयोगांसाठी पाणी गरम करणे यांसाठी या प्रणालींमध्ये यांत्रिक साधने वापरतात. संकलकांचा सर्वांत लहान रचनाव्यूह, सर्वांत साधा अभिकल्प (आराखडा) व किमान खर्च ही सर्वसाधारणपणे पाणी तापविणे या सर्वांत साध्या प्रणालीची गुणवैशिष्ट्ये आहेत. उलट मोठा संकलक रचनाव्यूह, कमाल उष्णता संग्राहक व सापेक्षतः जास्त खर्च ही अवकाश तापनाची गुणवैशिष्ट्ये होत. अवकाश तापन व शीतलीकरण ही क्रियाशील सौर प्रणालींपैकी सर्वांत जटिल (गुंतागुंतीची) प्रणाली आहे. तिच्यासाठी सर्वांत मोठा संकलक रचनाव्यूह, सर्वोच्च तापमान आणि जटिल यांत्रिक प्रक्रिया यांची गरज असते. क्रियाशील प्रणालीमध्ये सर्वसाधारणपणे संकलन (यात संग्र्रह येतो), परिवर्तन, वाटप आणि नियंत्रण हे चार भाग असतात.

संकलन : संकलक सपाट फलकांचे, निर्वात नलिकांचे किंवा केंद्री-भवन करणारे असतात. बहुतेक क्रियाशील प्रणालींत सपाट फलकांचे संकलक एका वा अधिक स्वयंघटकांच्या किंवा रचनापरिमाणांच्या रूपात वापरतात. संकलकाने सौर प्रारण शोषले जाऊन त्याचे द्रवरूप (पाणी वा ग्लायकॉल) किंवा वायुरूप (हवा) उष्णता संक्रमण माध्यमात उष्णतेमध्ये परिवर्तन होते. लगेच वापरण्यासाठी वा नंतरच्या उपयोगाकरिता संग्रहित करण्यासाठी ही उष्णता पंपांनी वा पंख्यांनी परिवर्तन व वाटप प्रणालीकडे वाहून नेतात. द्रवरूप प्रणालीमध्ये थंड हवामानात उष्णता संक्रमण माध्यम (बहुधा पाणी) गोठण्यापासून सुरक्षित ठेवावे लागते. यासाठी पाण्यात गोठणप्रतिबंधक द्रव्य घालता येते किंवा जेव्हा बाहेरील तापमान गोठणबिंदूलगत येते, तेव्हा संकलकातून द्रवाचा निचरा करता येतो. गोठण प्रतिबंधक द्रव्य घातल्यास संकलकातील पाणी इमारतीअंतर्गत पाण्यापासून अलग करण्यासाठी उष्णता विनिमयक वापरतात.

परिवर्तन : अवकाश तापन व शीतलीकरण आणि घरगुती गरम पाणी या दोन्हीसाठी औष्णिक ऊर्जेचे उपयुक्त उष्णतेत परिवर्तन करणार्‍या परिवर्तन प्रणालीची गरज असते. औष्णिक ऊर्जेचे यांत्रिक कार्यातही रूपांतर करता येते. नंतर या यांत्रिक कार्याद्वारे प्रचलित दाब संपीडन शीतलीकरण सामग्री चालविता येते. औष्णिक ऊर्जा थेटपणेही (उदा., अवकाश शीतलीकरणासाठी शोषण-गोठण क्रियेमार्फत) वापरता येते.

वायुवीजनासाठी आर्द्रताशोषक शीतलीकरणामध्ये इमारतींसाठीची थंड व सुखकर हवा तयार करण्यासाठी पुन्हा अभिसरण केलेली निरार्द्रीकरण केलेली हवा, तसेच बाष्पन-शीतलीकरण वापरतात. जेव्हा सौर तापनाद्वारे गरम केलेल्या हवेने पाणी बाहेर काढले जाते, तेव्हा आर्द्रताशोषक द्रव्य पुन्हा निर्माण करतात व वापरतात.

वाटप : परिवर्तन प्रणालीतील गरम वा थंड द्रायू (द्रव किंवा वायू ) वाटप प्रणालीद्वारे इमारतीमधील वापरावयाच्या ठिकाणी वाहून नेला जातो. सर्वसाधारणपणे द्विरुक्ती टाळण्यासाठी सौर प्रणाली व पूरक (बॅकअप) प्रणाली या दोन्हीसाठी एकच वाटप प्रणाली असते.

नियंत्रण : इमारतीमधील व बाहेरील तापमानविषयक माहिती नियंत्रक प्रणाली गोळा करते, त्या माहितीवर संस्करण करते आणि परिस्थितीच्या मागणीनुसार (गरजेनुसार) आदेश देते. तापमान संवेदक अभिचालित्रांच्या जाळ्याला अथवा सूक्ष्मप्रक्रियकाच्या जाळ्याला प्रदत्त (माहिती) पुरवितो. अभिचालित्र किंवा सूक्ष्मप्रक्रियक या प्रदत्तावर संस्करण करतो आणि संकलन, परिवर्तन किंवा वाटप प्रणाली चालू करण्यासाठी आदेश पाठवितो.

संशोधनामध्ये संकलकांसाठी लागणारा खर्च कमी करण्याचे प्रयत्न करतात. यामध्ये सपाट पृष्ठाच्या कमी वजनाच्या संकलकांची चाचणी घेतात व त्यांसाठी प्रचलित धातु-काच या द्रव्यांऐवजी पातळ प्लॅस्टिक पटले वापरतात. तसेच आर्द्रताशोषक व शीतलीकरणाच्या इतर द्रव्यांचा शोध घेऊन आणि क्रियाशील सौर प्रणालीचे कार्यमान, विश्वासार्हता व टिकाऊपणा यांच्याविषयीची माहिती इमारतीच्या स्थानांविषयीच्या जालकातून गोळा करून खर्च कमी करता येतो का ते पाहतात.

सौर औष्णिक तंत्रविद्या : सौर ऊर्जा उपयुक्त कामांमध्ये किंवा उष्णतेत परिवर्तित करण्यासाठी वापरता येते. यासाठी संकलकात सौर प्रारण शोषले जाते. त्यामुळे सूर्याच्या प्रारण ऊर्जेचे उष्णतेत परिवर्तन होते. ही उष्णता घरातील, औद्योगिक व कृषिविषयक कामे करण्यासाठी थेट वापरता येते. तिचे यांत्रिक किंवा विद्युत् शक्तीत परिवर्तन होऊ शकते अथवा इंधने व रसायने निर्माण करण्यासाठी ती रासायनिक विक्रियांमध्ये वापरता येते.

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संकलक प्रणाली : या प्रणालीत सूर्यप्रकाशाचे केंद्रीकरण करणारा केंद्रीकरणकारक व ग्रहण करणारा ग्राही हे दोन घटक असतात. आरसे व भिंगे यांच्यामार्फत केंद्रीकरणकारकाने सूर्यप्रकाशाला पुन्हा दिशा दिली जाऊन तो ग्राहीवर केंद्रीभूत केला जातो. ग्राहीवर सौर प्रारण शोषले जाऊन त्याचे उष्णतेत परिवर्तन होते. केंद्रीकरण करणारे व न करणारे हे सौर संकलकांचे दोन मूलभूत वर्ग आहेत. केंद्रीकरणकारक प्रकाशकीय गुणधर्म आणि ग्राहीवर मिळविता येणारे तापमान यांच्या आधारे संकलकांचे आणखी भिन्न प्रकार करतात. उदा., मध्यवर्ती ग्राही, बिंदु-केंद्रित, रेखा-केंद्रित, निर्वात नलिका, सपाट फलकाचा, सौर पल्वल इत्यादी.

केंद्रीकरण न करणारे संकलक : हे सामान्यपणे पक्के बसविलेले व पुष्कळदा सूर्यानुगामी म्हणजे सूर्यानुसार फिरणारे असतात. सौर पल्वल ( वा खाचर ) व निर्वात नलिका संकलक हे याचे दोन प्रकार आहेत.

लवण-प्रवणतायुक्त सौर पल्वल प्रकारचा संकलक व्यापकपणे वापरता येण्यासारखा आहे (आ.३) यामध्ये कमी लवणता असलेल्या वा गोड्या पाण्याचा पातळ थर अधिक खोलीवर असलेल्या थरावर आच्छादलेला असतो. या खालील थरात लवणता-प्रवणता निर्माण केलेली असते म्हणजे त्यात खोलीनुसार लवणाची संहती (प्रमाण) वाढत जाते. तळाचा थर बहुधा लवण-संपृक्त वा त्याजवळची संपृक्तता असलेला असतो. पाण्यातून जाणारा सूर्यप्रकाश पाण्यात शोषला जाऊन तळाचा थर तापतो. अधिक खोलीवरील पाण्यातील लवणामुळे त्याची घनता वाढते व त्याद्वारे नैसर्गिक अभिसरणाला प्रतिबंध होतो. अन्यथा या अभिसरणामुळे सामान्यपणे पाण्याचे खालचे गरम थर आणि वरील थंड थर हे दोन्ही एकमेकांत मिसळले गेले असते. अशा प्रकारे उष्णता सापळ्यात पकडली जाऊन साचते. ही उष्णता वापरण्यासाठी गरम पाणी वर काढता येते, असे पाणी काढून  घेताना थरांचे स्थैर्य बिघडणार नाही याची काळजी घेतात. वार्‍याचा पृष्ठभागाशी परिणाम होऊन थरांचे मिश्रण होण्याची शक्यता असल्याने तिचा सौर पल्वलाच्या कार्यमानावर विपरित परिणाम होऊ शकतो. तसेच पाण्यावर तरंगणार्‍या वा निलंबित डबरीमुळे पाण्याची पारदर्शकता कमी होते. जगभर अशी अनेक सौर पल्वले कार्यरत आहेत. तळाच्या गरम पाण्याच्या थरातील ही कमी तापमानाची ( तापमान सु. ८२ ० से.) मिठवणी अनेक औद्योगिक उपयोगांसाठी थेटपणे वा उष्णता-विनिमयकामार्फत वापरता येते. तिच्याद्वारे अवकाश गरम होते किंवा तिच्यापासून वीजनिर्मिती करता येते.

निर्वात नलिका संकलकात १५० ० से.पर्यंत तापमान निर्माण होऊ शकते. एवढे तापमान कमी प्रतीच्या औद्योगिक प्रक्रियेसाठी लागणार्‍या वाफेची निर्मिती करण्याकरिता आवश्यक असते. कधीकधी अधिक सौर केंद्रीकरण होण्यासाठी या संकलकात परावर्तनकारी साहाय्यक सामग्री अंतर्भूत करतात.

केंद्रीकरणकारक संकलक : हा संकलकांचा एक प्रमुख गट आहे. यात विभागणी केलेली ग्राही प्रणाली व बिंदूमध्ये केंद्रीकरण करणारी मध्यवर्ती ग्राही प्रणाली असतात.

रेषेमध्ये केंद्रीकरण करणारी ( रेखा-केंद्रित उदा., अन्वस्तीय द्रोणी ) व केंद्रामध्ये केंद्रीकरण करणारी ( उदा., अन्वस्तीय तबकडी ) यांसारख्या विभागणी केलेल्या ग्राही प्रणाल्या सामान्यपणे पुढील उपयोगांच्या संदर्भात विचारात घेतात. उदा., दूरवर्ती लोकसमूहासाठी वीज प्रणाली, लष्करी उपयोग, कारखाना किंवा व्यापारी निवास प्रणाली किंवा कृषिविषयक उपयोग. हे संकलक नेहमी सूर्याकडे रोखलेले असावेत आणि त्यांच्यात प्रकीर्णित वा परावर्तित प्रकाशाचा उपयोग होऊ शकत नाही. कारण अशा प्रकाशामुळे सपाट फलक संकलकांत ५ ० –१० ० से. तापमान वाढू शकते.

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(१) रेखा-केंद्रित संकलकात केंद्रीकरण करणारा व आरसे लावलेला परावर्तक सूर्याच्या गतीनुसार फिरतो. तो पूर्व-पश्चिम अथवा उत्तर-दक्षिण या एका अक्षावर फिरतो. सौर प्रारण शोषक नलिकेवर ( ग्राहीवर ) परावर्तित होते. अन्वस्तीय द्रोणी संकलक ( आ. ४ ) हा रेखा-केंद्रित संकलकांचा सर्वांत सामान्य प्रकार आहे. याद्वारे कार्यकारी तापमानाचा व्यापक पल्ला (७० ० –३२० ० से.) उपलब्ध होतो. म्हणून हा संकलक १०० ० से.पेक्षा कमी तापमानाला पाणी तापविण्यासाठी, १०० ० –३२० ० से. दरम्यानच्या तापमानाला वाफनिर्मितीसाठी आणि उष्णता संक्रमण वेटोळी वापरून ३२० ० से.पर्यंत वीजनिर्मितीसाठी वापरतात.

(२) बिंदु-केंद्रित संकलकाचे प्रकाशकीय व औष्णिक कार्यमान सर्वाधिक आहे. कारण सूर्याचा त्याच्या पूर्ण दैनिक गतीच्या पल्ल्यात मागोवा घेण्याची क्षमता यात आहे आणि ग्राही घटकांमध्ये वापरलेल्या शोषकाचे क्षेत्रफळ सापेक्षतः लहान असते. अन्वस्तीय तबकडीच्या आकाराचा संकलक थेट येणारे सौर प्रारण अन्वस्तांच्या केंद्राच्या बिंदूत केंद्रीभूत करतो. अशी प्रत्येक तबकडी परिपूर्ण वीजनिर्मिती घटक असते ( आ. ५ ) ती स्वतंत्र प्रणाली म्हणून आपले कार्य करू शकते अथवा अधिक मोठी प्रणाली निर्माण करण्यासाठी जोडलेल्या स्वयंघटकांच्या गटाचा एक भाग म्हणून कार्य करू शकते. एक अन्वस्तीय तबकडी स्वयंघटक द्रायूचे तापमान ३०० ० –१,४०० ० से.पर्यंत मिळवू शकतो आणि तो द्रायू २५ किवॉ.पर्यंत वीज कार्यक्षम रीतीने निर्माण करू शकतो.

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केंद्रीकरणकारक ही अन्वस्तीय तबकडी स्वयंघटकाची सर्वांत मोठी उपप्रणाली आहे. या उथळ तबकडीचा परावर्तक पृष्ठभाग सूर्यप्रकाश ग्राहीवर केंद्रित करण्यासाठी सूर्याला अनुसरून फिरत असतो. दोन अक्षांना अनुसरून सूर्याचा मागोवा घेतल्याने दिवसभरात कमाल सौर ऊर्जा संकलनाची खातरजमा होते. केंद्रीभूत सौर प्रारण ग्राही १,४०० ० से.पर्यंतच्या अतिउच्च तापमानाला शोषतो. त्यामुळे ही प्रणाली उच्च तापमान रासायनिक विक्रियांसाठी अथवा वाफ, वीज किंवा इंधन, रसायने यांच्या निर्मितीसाठी वापरता येऊ शकते. या प्रणालीच्या अनेक अभिकल्पांमध्ये औष्णिक ऊर्जेचे यांत्रिक ऊर्जेत परिवर्तन करणारे एंजिन ग्राहीबरोबर केंद्रापाशी बसविलेले असते.

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(३) मध्यवर्ती ग्राही प्रणालीमध्ये थेटपणे येणारे सौर प्रारण मनोर्‍यावर बसविलेल्या ग्राहीवर परावर्तित करण्यासाठी सपाट किंवा किंचित वक्र आरसे दोन अक्षांभोवती परिभ्रमण करतात. शोषक पृष्ठभाग हा दंडगोल ( बाह्य ग्राही ) किंवा पोकळीतील सपाट पृष्ठभाग ( पोकळी ग्राही ) असू शकतो. ग्राहीवर १,४०० ० से. किंवा अधिक तापमान व ७ मेगॅपास्कल दाब निर्माण होऊ शकतो. या मध्यवर्ती ग्राही संकलक संकल्पनेद्वारे  १–१०० MWe ( मेगॅवॉट इलेक्ट्रिक ) क्षमतांपर्यंतची सौर औष्णिक विद्युत् शक्ती निर्माण होऊ शकेल, असे वाटते. आ. ६ मध्ये प्रचलित वाफ तंत्रविद्या वापरून वीजनिर्मितीसाठीची नमुनेदार बिंदु-केंद्रित मध्यवर्ती ग्राही प्रणालीची कार्यपद्धती दाखविली आहे.

परिवर्तन प्रणाली : सौर औष्णिक उष्णतेचे सरळ विजेत परिवर्तन करता येते. ती प्रथम यांत्रिक ऊर्जेत व नंतर विद्युत् शक्तीत परिवर्तित होऊ शकते अथवा योग्य ऊष्मागतिकीय एंजिन चक्रामार्फत रसायने व इंधने यांच्या निर्मितीत ती वापरता येते. औष्णिक ऊर्जेचे यांत्रिक ऊर्जेत परिवर्तन करण्यासाठी तीन ऊष्मागतिकीय चक्रे विचारात घेतात. [⟶ ऊष्मागतिकी ].

संग्राहक : ( साठवण ). सौर ऊर्जा प्रणाली दिवसातून सामान्यपणे ६ ते १० तास उपयुक्त उष्णता देऊ शकेल, अशा रीतीने तिचा अभिकल्प तयार केलेला असतो. अर्थात हा कालावधी हंगाम व हवामान यांवर अवलंबून असतो. सौर औष्णिक प्रणालीतील संग्राहक क्षमता हा संयंत्राची कार्यकारी क्षमता वाढविण्याचा एक मार्ग आहे.

सौर औष्णिक ऊर्जा साठविण्याचे पुढील चार प्रमुख मार्ग आहेत :  (१) संवेद्य उष्णता संग्राहक प्रणालीमध्ये उष्णता धारणेचे चांगले गुण असलेल्या द्रव्यांमध्ये औष्णिक ऊर्जा साठवितात. (२) सुप्त उष्णता संग्राहक प्रणालीत अवस्थांतर करणार्‍या विशिष्ट द्रव्यांच्या द्रवीभवनाच्या व बाष्पीभवनाच्या सुप्त उष्णतेच्या रूपात सौर औष्णिक ऊर्जा साठवितात. (३) रासायनिक ऊर्जा संग्राहक प्रणालीत सौर औष्णिक ऊर्जा साठविण्यासाठी व्युत्क्रमी ( उलट सुलट दिशेत होणार्‍या ) विक्रियेचा उपयोग करतात ( उदा., सल्फ्यूरिक अम्ल आणि पाणी यांच्यातील संगमन व विगमन विक्रिया ). (४) विद्युतीय किंवा यांत्रिक संग्राहक प्रणालीत विशेषतः संचायक विद्युत् घटमाला ( विद्युतीय ) व संपीडित ( दाब दिलेली ) हवा यांच्या वापराद्वारे सौर औष्णिक ऊर्जा साठवितात.

उपयोग : विद्युत् शक्ती ( विजेच्या ) उपयोगांमध्ये वापरल्या जात असलेल्या सौर औष्णिक प्रणाली पुढीलप्रमाणे आहेत. विशेषतः १,००० kWe ( किलोवॉट इलेक्ट्रिक ) किंवा कमी क्षमतेच्या लहान वितरित शक्ती प्रणाल्या आणि १,००० kWe वा अधिक क्षमतेच्या मोठ्या मध्यवर्ती शक्ती प्रणाल्या. या सौर औष्णिक प्रणाल्या विद्युत् शक्ती उपयोगांमध्ये वापरल्या जातात. लहान शक्ती प्रणाल्या दूरवर राहणारे लोकसमूह, लष्करी उपयोग, कारखाना, व्यापारी इमारती व शेतीची कामे यांसाठी वापरतात. या उपयोगांसाठी वितरित ग्राही शक्ती प्रणाल्या सर्वांत सामान्यपणे वापरतात. उपयोगिता जाळ्यामार्फत वितरणासाठी किंवा इंधने व रसायने निर्माण करण्यासाठी वीजनिर्मिती करण्याच्या दृष्टीने मध्यवर्ती ग्राही शक्ती प्रणाली आणि अन्वस्तीय तबकडी प्रणाली या सर्वांत योग्य आहेत.

औद्योगिक प्रक्रिया उष्णता ही औष्णिक ऊर्जा असून ती द्रव्ये आणि उद्योगात उत्पादित झालेल्या वस्तू यांच्या प्राप्तीसाठी व संस्करणासाठी थेटपणे वापरतात. निर्वात नलिका प्रकारच्या संकलकांमधील शोषक नलिकांत किंवा रेषीय केंद्रीभवनकारक संकलकांमधील शोषक नलिकांत थेटपणे तापविलेले ५० ० व १०० ० से. तापमानाचे पाणी पुरविता येऊ शकते. सुमारे १८० ० से.पेक्षा कमी तापमानाच्या औद्योगिक शुष्कन कामांसाठी लागणारी गरम हवा संकलक प्रणालींमार्फत पुरविणे शक्य आहे. अभिसरण करणारा द्रायू म्हणून हाताळण्यासाठी किंवा हवा-द्रव उष्णता-विनिमयकारकामधून पंप केलेल्या द्रायूचे अभिसरण करण्यासाठी या संकलक प्रणाल्या तयार केलेल्या असतात. वितरित व केंद्रीकृत या दोन्ही प्रकारच्या केंद्रीकरणकारक सौर औष्णिक संकलक प्रणालींचा विचार १५० ० –४०० ० से. तापमानांना वाफनिर्मितीसाठी सामान्यपणे करतात. ही वाफ विविध उत्पादक उद्योगांमध्ये थेट उष्णता म्हणून वापरतात. मोठ्या खतनिर्मिती संयंत्रांतील अमोनियाचे उत्पादन आणि खनिज तेलाची वाढीव पुनर्प्राप्ती यांसाठी भावी काळात सौर औष्णिक तंत्रविद्या वापरता येऊ शकेल.

प्रकाशविद्युत् चालकशास्त्र : ( फोटोव्होल्टॅइक्स ). प्रकाशविद्युत् चालक प्रणालींमध्ये प्रकाशाच्या ऊर्जेचे थेट विद्युत् ऊर्जेत परिवर्तन होते. यांतून मिलीवॉटपासून ते मेगॅवॉटपर्यंतच्या विजेच्या गरजा भागविता येऊ शकतात. मनगटी घड्याळासारख्या छोट्या अनुप्रयुक्तींपासून ते संपूर्ण लोकसमूहासाठीच्या मोठ्या अनुप्रयुक्तींना वीज पुरविण्यासाठी या प्रणालींचा   उपयोग होऊ शकतो. शक्तिसंयंत्रातील विद्युत् जनित्रासारख्या केंद्रीकृत प्रणालींत किंवा उपयुक्त विद्युत् मार्गांचे जाळे जेथे सहजपणे उपलब्ध नसते, अशा दूरवरच्या क्षेत्रांत विखुरलेल्या अनुप्रयुक्तींच्या ठिकाणी या प्रणालींचा उपयोग होऊ शकतो.

जेथे प्रचलित मार्गांनी वीज उपलब्ध नव्हती किंवा खूप महाग पडत होती, अशा ठिकाणी प्रकाश विद्युत् चालक प्रणाल्या प्रथम वापरण्यात आल्या. कृत्रिम उपग्रहाचा वीजपुरवठा, दूरवर असलेली घरे व दालने, संदेशवहन केंद्रे , वेधशाळा, पाण्याचे पंप, फिरते लष्करी उपयोग किंवा संपूर्ण खेडे तसेच घड्याळे, गणक यंत्रे, सुवाह्य दूरचित्रवाणी संचइत्यादींसाठी प्रकाशविद्युत् चालक प्रणाली वापरतात. यांच्यामुळे जगातील काही दुर्गम भागांत वीज उपलब्ध झाली आणि इंधन व देखभालीची गरज असलेल्या डीझेलवरील विद्युत् जनित्रांच्या जागी या प्रणाल्या वापरात आल्या.

प्रकाशविद्युत् चालक प्रणालीतील घटक : मुख्यतः अर्धसंवाहक द्रव्याचा बनलेला ⇨ सौर विद्युत् घट हा प्रकाशविद्युत् चालक प्रणालीतील मूलभूत घटक असतो. सौर विद्युत् घटांसाठी अनेक द्रव्ये व संरचना यांचे अनुसंधान ( बारकाईने संशोधन ) झाले आहे. मात्र बहुतेक व्यापारी सौर विद्युत् घटांमध्ये शुद्ध एकस्फटिकी सिलिकॉन वेफर वापरतात. हे वेफर अपद्रव्यभरित p – प्रकारचे असते. म्हणजे वेफरमध्ये योग्य प्रकारची अशुद्धी थोड्या प्रमाणात घातलेली असते. यामुळे त्यात जादा रिक्त ( संपूर्ण न केलेले ) बंध किंवा धनभारित बिंदू (होल) ही असतात. वेफरच्या माथ्याकडील उथळ भागात दुसरी अशुद्धी विखरून अंतर्भूत करतात. त्यामुळे विनाबंध जादा इलेक्ट्रॉन उपलब्ध होतात. त्यामुळे तो भाग n – प्रकारचा होतो. विद्युतीय दृष्टीने भिन्न असलेल्या अर्धसंवाहक थरांच्या प्रस्थानकापाशी ( संधीपाशी ) वर्चस् रोध किंवा विद्युत् क्षेत्र निर्माण होते. प्रोटॉन विद्युत् घटावर आदळल्यावर आयनांच्या ( ऋण विद्युत् भारित इलेक्ट्रॉन व धन विद्युत् भारित बिंदू यांच्या ) जोड्या निर्माण होतात. पुन्हा संयोग होईपर्यंत हे विद्युत् भार सिलिकॉन अणुजालक संरचनेभोवती फिरतात अथवा प्रस्थानक ओलांडत प्रकाशविद्युत् चालक प्रक्रियेत वापरले जातात. वर्चस् रोधामुळे आयन जोड्या विद्युत् घटाच्या विरुद्ध टोकांशी अलग होतात. अलग झालेल्या या विद्युत् भारांमुळे विद्युत् वर्चस् निर्माण होते. त्याचा विद्युत् प्रवाह वहनासाठी उपयोग होतो. हा विद्युत् प्रवाह प्रकाशामुळे निर्माण झालेल्या इलेक्ट्रॉनांचा बनलेला असतो आणि विद्युत् घटाच्या दोन्ही फलकांना जोडलेल्या विद्युतीय स्पर्शकांमधून व बाहेरच्या विद्युत् मंडलामधून वाहतो ( आ. ७ ).

essay on renewable energy in marathi

नमुनेदार एकस्फटिकी सिलिकॉन घट वैशिष्ट्यपूर्ण खंडित ( अपूर्ण ) मंडलात सु. ०.५ व्होल्ट विद्युत् दाबाचा एकदिश ( एकाच दिशेत वाहणारा ) विद्युत् प्रवाह निर्माण करतो. घटाची कार्यक्षमता त्याचे क्षेत्रफळ व आपाती सूर्यप्रकाश यांच्यावर अवलंबून असते. १० सेंमी. व्यासाच्या नमुनेदार घटामुळे आकाश स्वच्छ असताना व सूर्य थेट माथ्यावर असताना सु. १ वॉट वीज निर्माण होऊ शकते. यापेक्षा मोठ्या विद्युत् प्रवाहासाठी वा विद्युत् दाबासाठी सौर प्रकाशविद्युतीय स्वयंघटक ( मोड्यूल ) वा रचना-परिमाण तयार करतात. त्यामध्ये एका दृढ फलकावर अनेक घटांचा एक गट एकत्र बसवितात आणि त्या घटांची एकसरीत किंवा अनेकसरीत अथवा संयुक्तपणे जोडणी करतात. एकसरीतील मालिकारूप जोडणीमुळे विद्युत् दाब आणि अनेकसरीतील जोडणीमुळे विद्युत् प्रवाह वाढतो. विद्युत् प्रवाह किंवा विद्युत् दाब आणखी वाढविण्यासाठी स्वयंघटकांची एकसरीत किंवा अनेकसरीत आंतरजोडणी करून प्रकाशविद्युतीय रचना-व्यूह किंवा समुच्चय तयार करतात. समुच्चयांच्या आंतरजोडणीतून समुच्चय क्षेत्र निर्माण होते. विद्युत् घटांप्रमाणेच एकसरीतील समुच्चय जोडल्याने विद्युत् दाब तर अनेकसरीतील समुच्चय जोडल्याने विद्युत्प्रवाह वाढतो. ( आ. ८).

essay on renewable energy in marathi

बहुतेक व्यापारी सौर प्रकाशविद्युत् स्वयंघटक आणि समुच्चय सपाट फलक संकलकावर बसविलेले असतात. ते खिडक्यांप्रमाणे दिसतात आणि त्यांत घट मागे दिसतात. ते थेटपणे पडलेला व विसरित प्रकाश प्रभावीपणे वापरू शकतात. ते छपरासारख्या स्थिर पृष्ठभागावर बसविता येतात आणि उत्तर गोलार्धात ते दक्षिणेस योग्य कोनात रोखलेले असतात. केंद्रीकरण प्रणालीत प्रत्येक घटावर सूर्यप्रकाश केंद्रित करण्यासाठी आरसे व भिंगे वापरतात. केंद्रीकरणामुळे प्रत्येक घटाकडून निर्माण होणार्‍या विजेत वाढ होते. यासाठी थेट सूर्यप्रकाश गरजेचा असल्याने त्यांच्यासाठी सूर्यानुगामी यंत्रणा वापरावी लागते. शिवाय त्यातून उष्णता काढून टाकण्याची तरतूद करावी लागते, कारण उच्च तापमानामुळे घटातून वीजनिर्मिती कमी होते.

विजेच्या अनेक उपकरणांसाठी प्रत्यावर्ती ( उलटसुलट दिशेत वाहणार्‍या ) विद्युत् प्रवाहाची आवश्यकता असते. त्यामुळे या घटाने निर्माण झालेल्या एकदिश विद्युत् प्रवाहाचे प्रत्यावर्ती विद्युत् प्रवाहात परिवर्तन करावे लागते व त्यासाठी शक्तिअभिसंधान प्रणालीची आवश्यकता असते. त्या प्रणालीत तसा परिवर्तक असतो. तसेच हानिकारक व अनिष्ट संकेत काढून टाकणारे छानक मंडल व प्रकाशविद्युतीय प्रणालीच्या उघड-मिट चक्राचे नियमन करण्यासाठी तार्किक उपप्रणाली असते. विद्युतीय शक्तीमध्ये भंग झाल्यास एकदिश विद्युत् स्रोत हा प्रत्यावर्ती विद्युत् तारांपासून अलग करण्यासाठी एक एकदिश विद्युत् स्पर्शक असतो. एकदिश विद्युत् स्रोत विद्युत् दाब हा प्रत्यावर्ती विद्युत् तारा विद्युत् दाबापासून अलग करण्यासाठी अलगीकरण करणारे ⇨ रोहित्र असते.

सूर्य तळपत नसताना, रात्रीच्या वेळी किंवा प्रतिकूल हवामानात प्रकाशविद्युत् चालक संकलकाकडून वीजनिर्मिती होत नाही. शिवाय या प्रणालीची उघड-मिट सुरळीतपणे होण्यासाठी आणि वापरणार्‍याची गरज भागविण्यासाठी पूरक प्रणाली व संचायक प्रणाली पुष्कळदा आवश्यक ठरते. यासाठी विविध पर्यायी व्यवस्था करता येतात.

कार्यक्षमता : आदर्श स्थितीत एका एकस्फटिकी सिलिकॉन सौर विद्युत् घटाची सैद्धांतिक कमाल कार्यक्षमता सु. २५%, तर व्यवहारात  कमाल कार्यक्षमता सु. २२% असते. अनेक घटकांमुळे या कार्यक्षमतेवर मर्यादा येतात. त्यांपैकी भौतिकीतील अंगभूत अशा घटकांचा संयुक्तपणे परिणाम होतो. आपाती फोटॉन ( प्रकाशकण ) व सिलिकॉन सौर विद्युत् घट यांच्यातील आंतरक्रिया हा असा सर्वांत महत्त्वाचा घटक आहे. आपाती फोटॉन प्रारणातील पुष्कळ प्रोटॉन हे पुरेसे ऊर्जावान नसल्याने ते घटाकडून शोषले जात नाहीत व त्यामुळे इलेक्ट्रॉन-धन विद्युत् भारित बिंदू जोड्या कमी प्रमाणात निर्माण होतात. याहून अधिक टक्के प्रोटॉन प्रारण जास्त ऊर्जावान असून त्याची जादा फोटॉन ऊर्जा परिवर्तन प्रक्रियेत वापरली जात नाही.

एकस्फटिकी सिलिकॉनापासून बनविलेल्या नमुनेदार व्यापारी विद्युत् घटाची कार्यक्षमता १९८४ पर्यंत जवळजवळ दुपटीने वाढली. आपाती प्रारण ऊर्जेच्या १३—१५% ऊर्जेचे विजेत परिवर्तन करणारे व्यापारी विद्युत् घट उपलब्ध झाले (२५ ० से. आणि आपाती प्रारण दर चौ. मी.ला १ किवॉ. ). १९% कार्यक्षमतेचे विद्युत् घट प्रयोगशाळेत तयार करण्यात आले व त्यात सुधारणा होऊ शकेल असे वाटले होते. समुच्चय व स्वयंघटक यांची कार्यक्षमता वाढविण्यासाठी प्रयत्न करण्यात आले. त्यासाठी घटांतर्गत जोडणीचे विद्युत् रोध कमी केले व अल्प शक्ती वापरणारी संरक्षक मंडल योजना वापरली. यामुळे समुच्चयाची कार्यक्षमता १२% झाली. ही कार्यक्षमता प्रचलित ऊर्जा स्रोतांच्या कार्यक्षमतांशी स्पर्धा करू शकेल, अशी असल्याचे काही तज्ञांना वाटते.

शक्ति-अवलंबीकरण उपप्रणालींत सुधारणा झाली आहे. या उपप्रणाल्या प्रकाशविद्युत् चालक प्रणालीमधील शक्तिहानीला कारणीभूत असणारा दुसरा स्रोत आहे. १९८०—९० या दशकादरम्यान उपलब्ध व्यापारी परिवर्तकांची कार्यक्षमता सु. ८०% होती. २००७ पर्यंत त्यांची प्रायोगिक कार्यक्षमता ९५% झाली होती.

इतर प्रकाशविद्युत् चालक द्रव्यांच्या ऊर्जा सौर वर्णपटाशी अधिक चांगल्या जुळतात व अशा प्रकारे सौर वर्णपटाचा अधिक कार्यक्षम रीतीने उपयोग करून घेतात. उदा., एकस्फटिकी गॅलियम आर्सेनाइड हे एक-स्फटिकी सिलिकॉनापेक्षा उच्च कार्यक्षमता व स्थिरता असलेले आहे व ते उच्चतर कार्यकारी तापमानाला टिकून राहते. याच्या विद्युत् घटाची कमाल सैद्धांतिक कार्यक्षमता २७ % असून प्रयोगशाळेत त्याची कार्यक्षमता २२ टक्क्यांपर्यंत आढळते. सूर्यप्रकाश १५० पट केंद्रित केल्यास त्याची प्रयोगशाळेतील कार्यक्षमता २४ टक्क्यांपर्यंत वाढलेली आढळली आहे.

याहून अधिक कार्यक्षमतेसाठी बहुप्रस्थानक प्रयुक्ती उपलब्ध आहे. या जटिल प्रयुक्तीमध्ये निरनिराळी अनेक अर्धसंवाहक द्रव्ये वापरतात. प्रत्येक थराला असलेले प्रस्थानक सौर प्रारण वर्णपटातील भिन्न भागाला संवेदनशील असते. यामुळे सर्व आपाती प्रारणाचा पर्याप्त वापर होतो. उदा., तीन घट व गॅलियम ॲल्युमिनियम आर्सेनाइड, गॅलियम आर्सेनाइड व सिलिकॉन ही तीन प्रस्थानके वापरणार्‍या मांडणीची सैद्धांतिक कमाल कार्यक्षमता ४० टक्क्यांहून अधिक आहे. [⟶ सौर विद्युत् घट ].

बायोमास : ( जैव द्रव्यमान म्हणजे जीवद्रव्याचे शुष्क वजन ). हे वनस्पतिज व प्राणिज द्रव्य असून त्यात साठविलेली सौर ऊर्जा म्हणजे बायोमास ऊर्जा होय. वनस्पतींमधील प्रकाशसंश्लेषणात हवा, पाणी वमृदा यांच्यातील साध्या मूलद्रव्यांचे सौर ऊर्जेच्या साहाय्याने जटिल कार्बोहायड्रेटांत रूपांतर होते. ही कार्बोहायड्रेटे सरळ इंधन म्हणून ( उदा., सरपण, लाकूडफाटा इ. ) वापरता येतात किंवा त्यांच्यावर प्रक्रिया करून द्रव किंवा वायू ( उदा., एथेनॉल व मिथेन ) तयार करतात. उपयुक्त ऊर्जेत  परिवर्तित करता येऊ शकणारे बायोमासचे स्रोत पुढीलप्रमाणे आहेत : शेतातील पिके, अपशिष्टे ( टाकाऊ पदार्थ ) व अवशिष्ट पदार्थ वनातील लाकूड आणि टाकाऊ व अवशिष्ट पदार्थ प्राण्यांचे अवशेष नगरपालिके-कडील काही अपशिष्टे जलवासी ( जलीय ) व वाळवंटातील वनस्पती. तसेच सूक्ष्मजंतू व शैवले इ. बायोमासमधील नवीनीकरण करता येऊ शकणारे ऊर्जा स्रोत आहेत. कारण हंगामानुसार त्यांचे परत पीक घेता येते व त्यांचे इंधनांत परिवर्तन होऊ शकते.

उष्णतेत व इंधनात परिवर्तन : कच्च्या बायोमासच्या वाहतुकीपेक्षा द्रवरूप व वायुरूप इंधनाची वाहतूक करणे बहुधा अधिक सोपे व कार्य-क्षमतेने होणारे काम आहे. द्रवात वा वायूत परिवर्तन करण्यासाठी बायोमासवर ऊष्मीय, रासायनिक व जैव प्रक्रिया करावी लागते. थेट ज्वलन करणे ही बायोमास परिवर्तनाची सर्वांत जुनी व साधी पद्धत आहे. तथापि, इंधन तेल, नैसर्गिक वायू किंवा दगडी कोळसा यांच्यापेक्षा इंधन म्हणून लाकूड १५–५०% कमी कार्यक्षम आहे. सुकलेल्या लाकडापासून मिळणार्‍या ज्योतीचे तापमान देखील कमी असून त्याच्यासाठी विशिष्ट प्रकारच्या अधिक मोठ्या भट्ट्या ( फायरबॉक्सेस ) व उष्णतासंक्रमण पृष्ठभाग यांची आवश्यकता असते. मोठ्या बाष्पित्रांमधील बायोमासचे उष्णता ऊर्जेत परिवर्तन करण्याची कार्यक्षमता ७०—७५% असते तर घरातील चुलीत जाळण्यात येणार्‍या लाकडाची कार्यक्षमता ५०–७०% असते.

प्रकाशसंश्लेषी सूक्ष्मजीव : सूक्ष्म शैवलांचे काही प्रकार व सूक्ष्मजंतू यांच्या अंगी प्रकाशसंश्लेषणाच्या रीतीने ऊर्जासमृद्ध द्रव्यांचे उत्पादन करण्याची क्षमता असते. उदा., योग्य परिस्थितीमध्ये काही सूक्ष्म शैवले वाढत्या प्रमाणात तेले व लिपिडे निर्माण करतात आणि ती थेटपणे इंधन म्हणून वापरता येतात. काही सूक्ष्मजंतू हायड्रोजन वायू उत्सर्जित करतात आणि तोही इंधन म्हणून सरळ वापरता येऊ शकतो. जननिक अभियांत्रिकी, कृत्रिम रीतीने चालू ठेवलेल्या उत्पादन प्रणाल्या आणि प्रकाश-संश्लेषणाचे मूलभूत रसायनशास्त्र व भौतिकी या विषयांवर आता संशोधकांनी लक्ष केंद्रित केले आहे. [⟶ प्रकाशसंश्लेषण ].

पवन ऊर्जा परिवर्तन प्रणाली : जहाजे चालविणे, धान्य दळणे व पाणी चढविणे या कामांसाठी पवन ( वार्‍याची ) ऊर्जा शेकडो वर्षां-पासून वापरली जात आहे. पवनचक्कीमार्फत म्हणजे पवन टरबाइनमार्फत पवन ऊर्जा यांत्रिक कामांसाठी व वीजनिर्मितीसाठीही वापरतात.पवन ऊर्जा साधारणपणे १९३० पासून वीजनिर्मितीसाठी वापरली जाऊ लागली. [⟶ पवनचक्की].

वारा ही नैसर्गिक साधनसंपत्ती : वारा हा ऊर्जेचा नैसर्गिक स्रोत आहे. सौर ऊर्जेमुळे भूपृष्ठ असमान तापते व मुख्यतः यामुळे वारा निर्माण होतो. स्थानिक भूमिरूपे व वार्‍याची गती बदलत असल्याने तसेच बदलणारे ऋतू व दिवस यांच्यामुळे वार्‍याची गती बदलते. वार्‍याची वार्षिक सरासरी गती तसेच महिना, दिवस व तास यांच्यानुसार असलेली वार्‍याच्या गतीची वाटणी हेही मुद्दे पवन ऊर्जेचा विचार करताना महत्त्वाचे ठरतात. भूपृष्ठालगतच्या पातळीपेक्षा वरच्या पातळीत सर्वसाधारणपणे वार्‍याची गती जास्त असते. कारण वार्‍याच्या भूपृष्ठाशी होणार्‍या घर्षणाने त्याची गती कमी होते.

महासागर औष्णिक ऊर्जा परिवर्तन : या परिवर्तनात सौर ऊर्जेने  तापलेले पृष्ठभागावरील पाणी आणि पंपाने खेचून वर आणलेले ६००–९०० मी. खोलीवरचे थंड पाणी यांच्या तापमानांमधील फरकाचा वापर करतात. उष्णता एंजिनामागील संकल्पना वापरून तापमानांतील या फरकाचा उपयोग करून वीजनिर्मिती करणे शक्य होते. दीर्घ काळात तापमानात थोडाच फरक होत असणारी व प्रचंड सौर ऊर्जा साठविणारी सुविधा या रूपात महासागराचे कार्य चालते. त्यामुळे या परिवर्तनाने २४ तास वीज पुरविणे शक्य आहे. इतर पुनर्निर्मितिक्षम ऊर्जा तंत्रविद्यांमध्ये हे साध्य होत नाही. शिवाय या परिवर्तनासाठी संयंत्रे किनार्‍यावर खंड-फळीवर किंवा तरंगत्या फलाटावर उभारता येतात. या फलाटांचे विविध आकार असतात.

ऊर्जेचा साठा व वीज : १० ० से. एवढा तापमानातील फरक असलेल्या महासागराच्या हिमरहित, मिश्र थरातील गणिताने अंदाजे काढलेली औष्णिक ऊर्जा सु. ७५ X १०२३ जूल एवढी असते. अशा रीतीने महासागरातील औष्णिक ऊर्जेची नैसर्गिक साधनसंपत्ती प्रचंड आहे; परंतु ऊर्जा परिवर्तनाच्या सुविधांच्या दृष्टीने योग्य असा यांपैकी थोडाच साठा उपयुक्त आहे तरी तोही प्रचंड स्रोत आहे. सर्वसाधारणपणे यादृष्टीने योग्य असलेली ठिकाणे विषुववृत्तापासून ३० ० उत्तर व २५ ० दक्षिण या अक्षांशांदरम्यानच्या पट्ट्यातच सीमित आहेत. पृष्ठभागावरील व १,५०० मी.पर्यंत खोलीवरच्या पाण्याच्या तापमानांतील वार्षिक सरासरी २० ० से. वा अधिक एवढा फरक उपलब्ध तंत्रविद्येने महासागर औष्णिक ऊर्जा परिवर्तन संयंत्र अखंडपणे व कार्यक्षम रीतीने चालू ठेवण्यासाठी आवश्यक असतो. शिवाय सर्वांत थंड महिन्यांच्या काळात माध्य तापमानातील फरक १७ ० से.पेक्षा जास्त असावा लागतो. प्रणालीची कार्यक्षमता सुधारल्यास आवश्यक असलेला तापमानांतील फरक कमी असेल आणि महासागर औष्णिक ऊर्जा परिवर्तनाच्या उपयोगासाठी महासागराचे अधिक मोठे क्षेत्रफळ योग्य ठरेल.

महासागराने विषुववृत्तालगत संकलित केलेल्या व साठविलेल्या ऊर्जेपासून वीजनिर्मिती करण्याची शक्यता सर्वप्रथम जे. ए. दैं आरसांव्हाल यांनी १८८१ मध्ये सुचविली होती. १९३० मध्ये जी. क्लॉड यांनी क्यूबा लगतच्या मांटाझास उपसागरात वीज संयंत्र उभारले. त्यात १४ ० से.चा तापमानांतील फरक वापरून महासागर औष्णिक ऊर्जेचे विजेत परिवर्तन केले. पृष्ठभागावरील व ७०० मी. खोलीवरच्या पाण्याच्या तापमानांतील हा फरक वीजनिर्मितीसाठी वापरून २२ किवॉ. वीजनिर्मिती करण्यात आली. १९७९ मध्ये एका लहान संवृत (बंदिस्त) चक्राच्या चाचणी संयंत्रात ५० किवॉ. वीज निर्माण केली. १९८० मध्ये अमेरिकेच्या नाविक दलाच्या परिवर्तित केलेल्या तेलवाहू जहाजावर उष्णताविनिमयकाची चाचणी घेण्यासाठी १,००० किवॉ. चाचणी बैठे संयंत्र बसविण्यात आले. नाऊरू या बेटावरील प्रजासत्ताकासाठी जपानी लोकांनी किनार्‍यावरील १०० किवॉ. संयंत्राची चाचणी १९८१ मध्ये घेतली. क्यूशू इलेक्ट्रिक कंपनीने १९८३ मध्ये टोकुनोशियामधील ५० किवॉ. चाचणी संयंत्र चालवायला सुरुवात केली. त्यात डीझेल एंजिनातून वाया जाणारी उष्णता गरम सागरी पाण्याचे तापमान वाढविण्यासाठी वापरतात.

परिवर्तन प्रणाली : संवृत रँकिन-चक्र ( क्लॉड-चक्र ), विवृत ( खुले ) रँकिन-चक्र आणि झाकळ किंवा फेन-उत्थापक-चक्र या महासागर औष्णिक ऊर्जेसाठीच्या तीन प्रमुख परिवर्तन प्रणाल्या आहेत. फेन-उत्थापक-चक्र ही तंत्रविद्येच्या संदर्भात सर्वांत कमी विकसित झालेली व सिद्धांततः संभाव्य कार्यक्षमता सर्वांत अधिक असलेली प्रणाली आहे.

भारत : प्रखर ऊन पडणार्‍या प्रदेशाच्या पट्ट्यात भारताचा अंतर्भाव होतो. दरवर्षी भारताला सु. ५,००० X १०१२ किवॉ.-तास या ऊर्जेशी तुल्य एवढी सौर ऊर्जा प्राप्त होत असते. दररोज दर चौ. मी. भूपृष्ठावर पडणारी ( आपाती होणारी ) सरासरी सौर ऊर्जा स्थानानुसार ४–७ किवॉ. -तास ऊर्जेशी तुल्य अशी भिन्न असते. क्षितिजसमांतर पृष्ठभागावर पडणारे वार्षिक सरासरी जागतिक सौर प्रारण दर दिवशी दर चौ. मी. क्षेत्रफळामागे सु. ५.५ किवॉ.-तास ऊर्जेशी तुल्य एवढे असते. भारताच्या बहुतेक भागांत वर्षातील सु. ३०० दिवस कडक ऊन पडते. लडाख, पश्चिम राजस्थान व गुजरात राज्याचा काही भाग येथे वर्षातील सर्वाधिक सौर प्रारण मिळते तर ईशान्य भारतात सापेक्षतः याहून कमी प्रमाणात वार्षिक सौर प्रारण पडते. भारतात वापरल्या जाणार्‍या सौर ऊर्जेपेक्षा उपलब्ध सौर ऊर्जा खूप जास्त आहे. तथापि, भारतात सौर ऊर्जाविषयक प्रगती मंद आहे.

प्रकाश व उष्णता या रूपांतील सौर ऊर्जा भारतात पुढील दोन मार्गांनी वापरतात. तिचे थेट विजेत परिवर्तन करणारा सौर प्रकाशविद्युत् चालक व थेट उष्णतेत परिवर्तन करणारी सौर औष्णिक प्रयुक्ती हे ते दोन मार्ग आहेत. पाणी वा अवकाश गरम करणे, अन्न शिजविणे, शुष्कन, पाण्याचे निर्लवणीकरण, औद्योगिक प्रक्रिया, वीजनिर्मिती ( शक्तिनिर्मिती ) यांसाठी वाफ निर्माण करणे, शीतलीकरण प्रणाली चालविणे इत्यादींसाठी भारतात सौर औष्णिक प्रयुक्त्या वापरतात. १०० ० –३०० ० से. या कमी तापमानाच्या सौर औष्णिक प्रयुक्त्या ( उदा., सौर जलतापक, हवातापक, सौर कूकर, सौर शुष्कक इ. ) भारतात तयार करून वापरल्या जातात व काहींची निर्यात करतात. दररोज ५०–२०,००० लि. क्षमतेचे सौर जल-तापक भारतात घरगुती, व्यापारी व औद्योगिक उपयोगांसाठी उभारले आहेत. अशा प्रकारे भारतात सु. २३ लाख चौ. मी.पेक्षा अधिक मोठ्या संकलक क्षेत्रावर सौर जलतापक उभारले आहेत. यासाठी मुख्यतः सपाट फलकाचे व निर्वात नलिकांचे संकलक उभारले आहेत.

भारतात सु. ६.३४ लाख सौर कूकर वापरले जात असून वाफ निर्मितीसाठी सौर केंद्रीकरणकारक संकलक उभारले आहेत. तबकडीच्या रूपातील १० माणसांसाठीचे सौर कूकर खेड्यात वापरण्याची योजना आहे. तिरुमल ( आंध्र प्रदेश ) येथे सौर वाफेवर अन्न शिजविण्याची जगातील सर्वांत मोठी प्रणाली उभारली असून तिच्या मदतीने दररोज सु. १५,००० लोकांसाठी अन्न शिजवितात.

सूर्यप्रकाशाचे थेट विजेत रूपांतर करणार्‍या प्रकाशविद्युत् चालक प्रणाल्या या विकेंद्रित वीजनिर्मितीसाठी पर्यायी ऊर्जास्रोत म्हणून वाढत्या प्रमाणात आकर्षक ठरत आहेत. या प्रणाल्या दूरवरच्या व ऊर्जेची टंचाई असलेल्या भागांत अधिक उपयुक्त ठरत आहेत. प्रकाशन, पंपाने पाणी उपसणे तसेच प्राथमिक आरोग्य केंद्रे, सामूहिक केंद्रे, शाळा व यांसारख्या आवश्यक ठिकाणी वीज पुरविणे यांसाठीही या प्रणाल्या ऊर्जास्रोत म्हणून चांगल्या ठरल्या आहेत. दूरचित्रवाणी प्रेषक, विद्युत् घटमालेचे विद्युत् भारण इत्यादींकरिता माणसाची उपस्थिती नसलेल्या ठिकाणी या प्रणाल्या वीज पुरविण्याचा एक विश्वासार्ह स्रोत ठरला आहे.

भारतात सौर प्रकाशविद्युत् प्रणालींचे उत्पादन करणारे १३० पेक्षा अधिक उद्योग असून सौर प्रकाशविद्युत् स्वयंघटक ( मोड्यूल ) तयार करणारे २१ पेक्षा अधिक उद्योग आहेत. २००७-०८ मध्ये सु. ८० मेवॉ. क्षमतेचे सौर प्रकाशविद्युत् स्वयंघटक देशात तयार झाले व त्यांपैकी ५५ मेवॉ. क्षमतेच्या स्वयंघटकांची निर्यात करण्यात आली. ३१ मार्च २००८ रोजी देशातील सौर प्रकाशविद्युत् स्वयंघटकांचे संकलित उत्पादन ४६० मेवॉ.पेक्षा अधिक क्षमतेचे होते आणि त्यापैकी ३२५ मेवॉ. क्षमतेची उत्पादने यूरोप, अमेरिका व इतर विविध देशांत निर्यात करण्यात आली.

सौर जलतापक प्रणाली विकसित करण्याच्या व वापरण्याच्या कार्य-क्रमाला देशात गती देण्यात आली आहे. त्यानुसार देशात १५ लाख चौ. मी. संकलक क्षेत्र उभारण्यात आले असून त्यांपैकी सु. ४ लाख चौ. मी. क्षेत्र २००५-०६ मध्ये उभारले गेले आणि विविध  क्षमतांच्या १२ सौर वाफनिर्मिती प्रणाल्या देशात उभारल्या आहेत. सौर ( अक्रियाशील ) वास्तुशिल्पअभिकल्पाच्या ( आराखड्याच्या ) सौर इमारती बांधण्याची शिफारस शासनाने केली आहे. अशा इमारतींमध्ये उन्हाळ्यात व हिवाळ्यात राहणे आणि काम करणे सुखावह होणार आहे तसेच परंपरागत विजेची बचतही होणार आहे.

भारतातील काही सर्वांत मोठी प्रकाशविद्युत् ( चालक ) संयंत्रे पुढीलप्रमाणे आहेत : कोलार, इटनाल ( बेळगाव ) ॲझ्यूर पॉवर, जमुरिया त्यागराज क्रीडागार, शिवगंगा इ. संयंत्रांचे काम पूर्ण झाले आहे. अडानी बिट्टा संयंत्र डिसेंबर २०११ मध्ये पूर्ण झाले असून टाटा-मुळशी ( महाराष्ट्र ), ॲझ्यूर साबरकांटा ( गुजरात ), मोझर बेअर ( पाटन, गुजरात ), टाटा-मयील दुराई ( तमिळनाडू ), टाटा-पातपूर ( ओडिशा ), टाटा-उस्मानाबाद ( महाराष्ट्र ), अबेंगाव-ग्वाल-पहारी ( हरयाणा ) वगैरे संयंत्रे २०११ मध्ये सुरू होणार होती. मात्र यांतून मिळणारी वीज अजून तरी महाग पडते. उदा., एक युनिट सौर विजेसाठी १५—३० रुपये खर्च येतो तर परंपरागत औष्णिक वीज निर्मितीत एक युनिट विजेसाठी ५—८ रुपये खर्च होतो.

भारतात मिनिस्ट्री ऑफ न्यू अँड रिन्यूएबल एनर्जी सोर्सेस ( नवीन व पुनर्नवीनीकरणयोग्य ऊर्जा स्रोत ) हा मंत्रालय विभाग नवीन व पुनर्वापर करता येतील अशा ऊर्जास्रोतांविषयीचा कारभार हाताळतो. सौर प्रकाश-विद्युत् तंत्रविद्येतील संशोधन व विकास तसेच तंत्रविद्येचा विकास यांना हा विभाग ( खाते ) ३० पेक्षा अधिक वर्षे पाठबळ देत आला आहे. हा विभाग सौर प्रकाशविद्युत् स्वयंघटकाचा खर्च कमी करण्याचे प्रयत्न करतो आणि हे उद्दिष्ट साध्य करण्यासाठी संशोधन व विकास आणि तंत्रविद्येचा विकास यांतील महत्त्वाची क्षेत्रे त्याने निश्चित केली आहेत. अकराव्या पंचवार्षिक योजनेच्या काळातील संशोधन, अभिकल्प व विकास आणि तंत्रविद्येचा विकास यांविषयीचे प्रयत्न पुढील बाबी विकसित करण्याकरिता केंद्रीत केले आहेत : बहुसिलिकॉन व इतर द्रव्ये, कार्यक्षम सिलिकॉन सौर विद्युत् घट, पातळ पटल द्रव्ये व सौर विद्युत् घट स्वयंघटक, केंद्रीकरणकारक प्रकाशविद्युत् प्रणाली व तिचे अभिकल्प यांच्या विकासावर एकवटलेल्या प्रयत्नांमधून भांडवली खर्च व परिवर्तन कार्यक्षमता यांच्यातील गुणोत्तर लक्षणीय रीतीने कमी करण्याचा हेतू आहे.

मार्च २००८ पर्यंत सौर प्रकाशविद्युत् कार्यक्रमाखाली भारतात सु. ६.७ सौर कंदिल ४.०३ लाख सौर गृह प्रकाशन प्रणाल्या ७०,५००  सौर रस्ता प्रकाशन प्रणाल्या ७,१४८ सौर पाणी पंप एकेकटी सौर वीजनिर्मिती संयंत्रे ( एकूण क्षमता २.२ मेवॉ. ) आणि राष्ट्रीय जाळ्याशी ( ग्रीडशी ) जोडता येणारी वीजनिर्मिती संयंत्रे ( एकूण क्षमता २.२ मेवॉ. ) उभारली होती. यांशिवाय दूरवरची ३,९४५ खेडी व १,१४२ पाडे यांचे विद्युतीकरण सौर प्रकाशविद्युत् वापरून केले आहे.

सदर विभागाने सौर ऊर्जा क्षेत्रातील काही मोठे प्रकल्प प्रस्तावित केले आहेत आणि थर वाळवंटातील ३५,००० चौ. किमी. क्षेत्र सौर वीज प्रकल्पांसाठी वेगळे काढून ठेवले आहे. एवढे क्षेत्र ७००–२,१०० गिगॅवॉट वीजनिर्मितीसाठी पुरेसे आहे. २०२० पर्यंत २० गिगॅवॉट वीजनिर्मितीची अपेक्षा असलेल्या एका प्रकल्पाचे भारतात जुलै २००९ मध्ये उद्घाटन झाले आहे. या योजनेनुसार शासकीय इमारती, रुग्णालये व हॉटेले या ठिकाणी सौर विजेवर चालणारी सामग्री व अनुप्रयुक्ती वापरणे बंधनकारक केले आहे. जलवायुमानातील बदलाविषयीच्या राष्ट्रीय कृती योजनेखाली जवाहरलाल नेहरू राष्ट्रीय सौर मोहीम ( नॅशनल सोलर मिशन ) सुरू करण्यास सज्ज असल्याचे १८ नोव्हेंबर २००९ रोजी जाहीर करण्यात आले.या मोहिमेसाठी सदर विभागाने १० अब्ज रुपयांची तरतूद केली होती.

सौर ऊर्जा तंत्रविद्यांचा विकास व प्रसार करण्यासाठी सदर विभागाने आपले सौर ऊर्जा केंद्र १९८२ मध्ये सुरू केले.या केंद्राचे संशोधन व विकास यांसाठीचे आवार दिल्ली शहरालगत आहे. या केंद्रात परीक्षा-विषयक सुविधा, प्रयोगशाळा, कार्यशाळा, प्रात्यक्षिक विभाग, चर्चासत्र दालन, सभागृह, ग्रंथालय, अतिथिगृह वगैरे सोयी आहेत हे केंद्र पुढील मुख्य उद्दिष्टे समोर ठेवून उभारले आहे : (१) सौर ऊर्जेसाठी लागणारी द्रव्ये, घटक आणि प्रणाली यांची परीक्षा व प्रमाणीकरण यांविषयीचे राष्ट्रीय केंद्र म्हणून कार्य करणे. (२) उद्योग व शैक्षणिक संस्था यांच्याबरोबर सहकार्य करून सौर ऊर्जाविषयक संशोधन आणि विकास यांचा पाठपुरावा करणे. (३) नवीन तंत्रविद्यांचे मूल्यमापन करणे. (४) सल्लागारी व विचारविनिमयविषयक सेवा पुरविणे (५) मानवी साधनसंपत्तीचा विकास व माहितीचा प्रसार यांविषयी काम करणे.

शासन, संस्था, उद्योग आणि सौर ऊर्जेचा वापर करणार्‍या संघटना यांच्यातील दुवा म्हणून हे केंद्र काम करते.स्थापनेपासून देशात सौर ऊर्जा तंत्रविद्यांच्या पुरस्काराचे महत्त्वाचे काम सदर केंद्र करते. सौरतंत्रविद्याविषयक अनेक मानके या केंद्राने तयार केली आहेत.मोठ्या आकारमानाच्या (२०० x २०० सेंमी.) सौर प्रकाशविद्युत् स्वयंघटकांची (क्षमता ६०० वॉ.) परीक्षा व मूल्यमापन करण्यासाठी या केंद्रात मोठ्या क्षेत्राचे सूर्य सादृशित्र उभारले आहे. प्रकाशविद्युत् केंद्रीकरणकारक स्वयंघटक परीक्षा स्तर सुविधा ही प्रगत सुविधा तेथे आहे. तेथे स्वयंचलित हवामान स्थानक व हँडबुक सुरू करण्याची योजना अंमलात येत आहे. विशेषतः पुनर्नवीनीकरण करता येण्याजोग्या ऊर्जांच्या बाबतीत जनजागृती व प्रसार करण्यासाठी दरवर्षी २० ऑगस्ट रोजी राजीव गांधी अक्षय ऊर्जा दिवस साजरा करतात. तसेच या ऊर्जांसाठीच्या प्रणाल्या किंवा प्रयुक्त्या उपलब्ध करून देणे, त्यांची दुरुस्ती व देखभाल करणे इ. कामांसाठी देशभर अक्षय ऊर्जा केंद्रे उभारण्यात येत आहेत.

इतिहास : प्राचीन काळात भारत, चीन, ईजिप्त, फिनिशिया, ग्रीस व इटली ( रोम ) येथील लोक समुद्राच्या खार्‍या पाण्यापासून मीठ तयार करण्यासाठी तसेच अन्नधान्य, वैरण, मासळी इ. सुकविण्यासाठी सौर ऊर्जा वापरीत. उत्तर चिलीतील वाळवंटात लास सालीनास येथे खार्‍या पाण्यापासून गोडे पाणी मिळविण्यासाठी सौर ऊर्जा ऊर्ध्वपातन यंत्र उभारले होते. त्याचे क्षेत्रफळ ४,००० चौ. मी.पेक्षा अधिक होते. येथे उथळ पात्रात खारे पाणी असे व त्याच्यावर काचेचे तिरपे आच्छादन होते. हे यंत्र सु. ४० वर्षे कार्यरत होते व तेथे दररोज २२,८०० लि. गोडे पाणी तयार होत असे. हे पाणी तेथील नायट्रेटाच्या खाणींतील लोक व प्राणी यांच्यासाठी वापरीत. या खाणीचे काम थांबल्यावर या यंत्राचे कामही थांबले. १८९८ मध्ये पॅरिसमधील प्रदर्शनात बाष्पित्रावर सूर्यप्रकाश केंद्रित करून वाफ तयार होई. या वाफेवर चालणार्‍या एंजिनाचा उपयोग छापखान्यातील कामांसाठी केला जाई. या आधी ⇨ आंत्वान लॉरां लव्हायझर या फ्रेंच रसायनशास्त्रज्ञांनी काचेचे मोठे भिंग असलेली सौर भट्टी वापरून उच्चतर तापमानाला रसायनशास्त्राचा अभ्यास केला. ईजिप्तमध्ये १,२३३ चौ. मी. अन्वस्ताकार संकलकाने नाईल नदीतील पाणी उपसण्यासाठी असलेल्या पंपाला वाफ पुरविली जाई (१९१३). हे पाणी शेतीच्या सिंचनासाठी वापरले जाई. याच सुमारास न्यू मेक्सिको ( अमेरिका ) येथे सौर ऊर्जेद्वारे निर्माण केलेली वीज साठविण्याचा प्रयत्न करण्यात आला. त्यासाठी सूर्यप्रकाश एका बाष्पित्रावर केंद्रित केला व त्यातून निर्माण झालेल्या वाफेवर एंजिन चालत असे. हे एंजिन पंपाद्वारे ६ मी. उंचीवर असलेल्या १९,००० लि. क्षमतेच्या टाकीत पाणी चढवीत असे. तेथून हे पाणी  खाली असलेल्या जल टरबाइनातून जात असे व त्याद्वारे विद्युत् जनित्र (डायनामो ) चालविले जाई. अशा रीतीने तयार होणार्‍या विजेचा उपयोग लहान खाणीतील दिवे लावण्यासाठी करीत असत.

सौर ऊर्जेने तापन होणारे पहिले घर मॅसॅचूसेट्स इन्स्टिट्यूट ऑफ टेक्नॉलॉजी या संस्थेने केंब्रिज ( मॅसॅचूसेट्स ) येथे १९३९ मध्ये उभारले. अशा प्रायोगिक सौर गृहांच्या मालिकेतील हे पहिले घर होते. जपान व इझ्राएल यांसारख्या देशांत लहान प्रमाणावरील जलतापन व गृहतापन यांसाठी सौर ऊर्जा कार्यक्षम रीतीने वापरली जात आहे. त्यामुळे प्रचलित विजेच्या एकूण खपात १०–१५% बचत होत असल्याचा अंदाज आहे.

पहा : ऊर्जा; नैसर्गिक साधनसंपत्ति; शक्ति-उद्गम; सूर्य; सूर्यप्रकाश; सौरतापन; सौर विद्युत् घट.

संदर्भ : 1. Anderson, B. Solar Building Architecture , 1990.

2. Anderson, B. Wells, M. Passive Solar Energy : The Homeowner’s Guide to Natural Heating and Cooling , 1993.

3. Duffie, J. A. Beckman, W. A. Solar Engineering of Thermal Processes , 1991.

4. Green, M. A. Third  Generation  Photo – voltaics Advanced Solar Energy Conversion , 2003.

5. Halacy, D. Understanding Passive Cooling  Systems , 1987.

6. Norton, B. Solar Energy Technology , 1991.

7. Tiwarik, G. N. Solar Energy Fundamentals, Design, Modelling and Applications ,  2002.

8. Wieder, S. An Introduction  to Solar Energy  for Scientists and Engineers , 1990.

ठाकूर, अ. ना.

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Renewable energy for sustainable development in India: current status, future prospects, challenges, employment, and investment opportunities

  • Charles Rajesh Kumar. J   ORCID: orcid.org/0000-0003-2354-6463 1 &
  • M. A. Majid 1  

Energy, Sustainability and Society volume  10 , Article number:  2 ( 2020 ) Cite this article

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The primary objective for deploying renewable energy in India is to advance economic development, improve energy security, improve access to energy, and mitigate climate change. Sustainable development is possible by use of sustainable energy and by ensuring access to affordable, reliable, sustainable, and modern energy for citizens. Strong government support and the increasingly opportune economic situation have pushed India to be one of the top leaders in the world’s most attractive renewable energy markets. The government has designed policies, programs, and a liberal environment to attract foreign investments to ramp up the country in the renewable energy market at a rapid rate. It is anticipated that the renewable energy sector can create a large number of domestic jobs over the following years. This paper aims to present significant achievements, prospects, projections, generation of electricity, as well as challenges and investment and employment opportunities due to the development of renewable energy in India. In this review, we have identified the various obstacles faced by the renewable sector. The recommendations based on the review outcomes will provide useful information for policymakers, innovators, project developers, investors, industries, associated stakeholders and departments, researchers, and scientists.

Introduction

The sources of electricity production such as coal, oil, and natural gas have contributed to one-third of global greenhouse gas emissions. It is essential to raise the standard of living by providing cleaner and more reliable electricity [ 1 ]. India has an increasing energy demand to fulfill the economic development plans that are being implemented. The provision of increasing quanta of energy is a vital pre-requisite for the economic growth of a country [ 2 ]. The National Electricity Plan [NEP] [ 3 ] framed by the Ministry of Power (MoP) has developed a 10-year detailed action plan with the objective to provide electricity across the country, and has prepared a further plan to ensure that power is supplied to the citizens efficiently and at a reasonable cost. According to the World Resource Institute Report 2017 [ 4 , 5 ], India is responsible for nearly 6.65% of total global carbon emissions, ranked fourth next to China (26.83%), the USA (14.36%), and the EU (9.66%). Climate change might also change the ecological balance in the world. Intended Nationally Determined Contributions (INDCs) have been submitted to the United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement. The latter has hoped to achieve the goal of limiting the rise in global temperature to well below 2 °C [ 6 , 7 ]. According to a World Energy Council [ 8 ] prediction, global electricity demand will peak in 2030. India is one of the largest coal consumers in the world and imports costly fossil fuel [ 8 ]. Close to 74% of the energy demand is supplied by coal and oil. According to a report from the Center for monitoring Indian economy, the country imported 171 million tons of coal in 2013–2014, 215 million tons in 2014–2015, 207 million tons in 2015–2016, 195 million tons in 2016–2017, and 213 million tons in 2017–2018 [ 9 ]. Therefore, there is an urgent need to find alternate sources for generating electricity.

In this way, the country will have a rapid and global transition to renewable energy technologies to achieve sustainable growth and avoid catastrophic climate change. Renewable energy sources play a vital role in securing sustainable energy with lower emissions [ 10 ]. It is already accepted that renewable energy technologies might significantly cover the electricity demand and reduce emissions. In recent years, the country has developed a sustainable path for its energy supply. Awareness of saving energy has been promoted among citizens to increase the use of solar, wind, biomass, waste, and hydropower energies. It is evident that clean energy is less harmful and often cheaper. India is aiming to attain 175 GW of renewable energy which would consist of 100 GW from solar energy, 10 GW from bio-power, 60 GW from wind power, and 5 GW from small hydropower plants by the year 2022 [ 11 ]. Investors have promised to achieve more than 270 GW, which is significantly above the ambitious targets. The promises are as follows: 58 GW by foreign companies, 191 GW by private companies, 18 GW by private sectors, and 5 GW by the Indian Railways [ 12 ]. Recent estimates show that in 2047, solar potential will be more than 750 GW and wind potential will be 410 GW [ 13 , 14 ]. To reach the ambitious targets of generating 175 GW of renewable energy by 2022, it is essential that the government creates 330,000 new jobs and livelihood opportunities [ 15 , 16 ].

A mixture of push policies and pull mechanisms, accompanied by particular strategies should promote the development of renewable energy technologies. Advancement in technology, proper regulatory policies [ 17 ], tax deduction, and attempts in efficiency enhancement due to research and development (R&D) [ 18 ] are some of the pathways to conservation of energy and environment that should guarantee that renewable resource bases are used in a cost-effective and quick manner. Hence, strategies to promote investment opportunities in the renewable energy sector along with jobs for the unskilled workers, technicians, and contractors are discussed. This article also manifests technological and financial initiatives [ 19 ], policy and regulatory framework, as well as training and educational initiatives [ 20 , 21 ] launched by the government for the growth and development of renewable energy sources. The development of renewable technology has encountered explicit obstacles, and thus, there is a need to discuss these barriers. Additionally, it is also vital to discover possible solutions to overcome these barriers, and hence, proper recommendations have been suggested for the steady growth of renewable power [ 22 , 23 , 24 ]. Given the enormous potential of renewables in the country, coherent policy measures and an investor-friendly administration might be the key drivers for India to become a global leader in clean and green energy.

Projection of global primary energy consumption

An energy source is a necessary element of socio-economic development. The increasing economic growth of developing nations in the last decades has caused an accelerated increase in energy consumption. This trend is anticipated to grow [ 25 ]. A prediction of future power consumption is essential for the investigation of adequate environmental and economic policies [ 26 ]. Likewise, an outlook to future power consumption helps to determine future investments in renewable energy. Energy supply and security have not only increased the essential issues for the development of human society but also for their global political and economic patterns [ 27 ]. Hence, international comparisons are helpful to identify past, present, and future power consumption.

Table 1 shows the primary energy consumption of the world, based on the BP Energy Outlook 2018 reports. In 2016, India’s overall energy consumption was 724 million tons of oil equivalent (Mtoe) and is expected to rise to 1921 Mtoe by 2040 with an average growth rate of 4.2% per annum. Energy consumption of various major countries comprises commercially traded fuels and modern renewables used to produce power. In 2016, India was the fourth largest energy consumer in the world after China, the USA, and the Organization for economic co-operation and development (OECD) in Europe [ 29 ].

The projected estimation of global energy consumption demonstrates that energy consumption in India is continuously increasing and retains its position even in 2035/2040 [ 28 ]. The increase in India’s energy consumption will push the country’s share of global energy demand to 11% by 2040 from 5% in 2016. Emerging economies such as China, India, or Brazil have experienced a process of rapid industrialization, have increased their share in the global economy, and are exporting enormous volumes of manufactured products to developed countries. This shift of economic activities among nations has also had consequences concerning the country’s energy use [ 30 ].

Projected primary energy consumption in India

The size and growth of a country’s population significantly affects the demand for energy. With 1.368 billion citizens, India is ranked second, of the most populous countries as of January 2019 [ 31 ]. The yearly growth rate is 1.18% and represents almost 17.74% of the world’s population. The country is expected to have more than 1.383 billion, 1.512 billion, 1.605 billion, 1.658 billion people by the end of 2020, 2030, 2040, and 2050, respectively. Each year, India adds a higher number of people to the world than any other nation and the specific population of some of the states in India is equal to the population of many countries.

The growth of India’s energy consumption will be the fastest among all significant economies by 2040, with coal meeting most of this demand followed by renewable energy. Renewables became the second most significant source of domestic power production, overtaking gas and then oil, by 2020. The demand for renewables in India will have a tremendous growth of 256 Mtoe in 2040 from 17 Mtoe in 2016, with an annual increase of 12%, as shown in Table 2 .

Table 3 shows the primary energy consumption of renewables for the BRIC countries (Brazil, Russia, India, and China) from 2016 to 2040. India consumed around 17 Mtoe of renewable energy in 2016, and this will be 256 Mtoe in 2040. It is probable that India’s energy consumption will grow fastest among all major economies by 2040, with coal contributing most in meeting this demand followed by renewables. The percentage share of renewable consumption in 2016 was 2% and is predicted to increase by 13% by 2040.

How renewable energy sources contribute to the energy demand in India

Even though India has achieved a fast and remarkable economic growth, energy is still scarce. Strong economic growth in India is escalating the demand for energy, and more energy sources are required to cover this demand. At the same time, due to the increasing population and environmental deterioration, the country faces the challenge of sustainable development. The gap between demand and supply of power is expected to rise in the future [ 32 ]. Table 4 presents the power supply status of the country from 2009–2010 to 2018–2019 (until October 2018). In 2018, the energy demand was 1,212,134 GWh, and the availability was 1,203,567 GWh, i.e., a deficit of − 0.7% [ 33 ].

According to the Load generation and Balance Report (2016–2017) of the Central Electricity Authority of India (CEA), the electrical energy demand for 2021–2022 is anticipated to be at least 1915 terawatt hours (TWh), with a peak electric demand of 298 GW [ 34 ]. Increasing urbanization and rising income levels are responsible for an increased demand for electrical appliances, i.e., an increased demand for electricity in the residential sector. The increased demand in materials for buildings, transportation, capital goods, and infrastructure is driving the industrial demand for electricity. An increased mechanization and the shift to groundwater irrigation across the country is pushing the pumping and tractor demand in the agriculture sector, and hence the large diesel and electricity demand. The penetration of electric vehicles and the fuel switch to electric and induction cook stoves will drive the electricity demand in the other sectors shown in Table 5 .

According to the International Renewable Energy Agency (IRENA), a quarter of India’s energy demand can be met with renewable energy. The country could potentially increase its share of renewable power generation to over one-third by 2030 [ 35 ].

Table 6 presents the estimated contribution of renewable energy sources to the total energy demand. MoP along with CEA in its draft national electricity plan for 2016 anticipated that with 175 GW of installed capacity of renewable power by 2022, the expected electricity generation would be 327 billion units (BUs), which would contribute to 1611 BU energy requirements. This indicates that 20.3% of the energy requirements would be fulfilled by renewable energy by 2022 and 24.2% by 2027 [ 36 ]. Figure 1 shows the ambitious new target for the share of renewable energy in India’s electricity consumption set by MoP. As per the order of revised RPO (Renewable Purchase Obligations, legal act of June 2018), the country has a target of a 21% share of renewable energy in its total electricity consumption by March 2022. In 2014, the same goal was at 15% and increased to 21% by 2018. It is India’s goal to reach 40% renewable sources by 2030.

figure 1

Target share of renewable energy in India’s power consumption

Estimated renewable energy potential in India

The estimated potential of wind power in the country during 1995 [ 37 ] was found to be 20,000 MW (20 GW), solar energy was 5 × 10 15 kWh/pa, bioenergy was 17,000 MW, bagasse cogeneration was 8000 MW, and small hydropower was 10,000 MW. For 2006, the renewable potential was estimated as 85,000 MW with wind 4500 MW, solar 35 MW, biomass/bioenergy 25,000 MW, and small hydropower of 15,000 MW [ 38 ]. According to the annual report of the Ministry of New and Renewable Energy (MNRE) for 2017–2018, the estimated potential of wind power was 302.251 GW (at 100-m mast height), of small hydropower 19.749 GW, biomass power 17.536 GW, bagasse cogeneration 5 GW, waste to energy (WTE) 2.554 GW, and solar 748.990 GW. The estimated total renewable potential amounted to 1096.080 GW [ 39 ] assuming 3% wasteland, which is shown in Table 7 . India is a tropical country and receives significant radiation, and hence the solar potential is very high [ 40 , 41 , 42 ].

Gross installed capacity of renewable energy in India

As of June 2018 reports, the country intends to reach 225 GW of renewable power capacity by 2022 exceeding the target of 175 GW pledged during the Paris Agreement. The sector is the fourth most attractive renewable energy market in the world. As in October 2018, India ranked fifth in installed renewable energy capacity [ 43 ].

Gross installed capacity of renewable energy—according to region

Table 8 lists the cumulative installed capacity of both conventional and renewable energy sources. The cumulative installed capacity of renewable sources as on the 31 st of December 2018 was 74081.66 MW. Renewable energy (small hydropower, wind, biomass, WTE, solar) accounted for an approximate 21% share of the cumulative installed power capacity, and the remaining 78.791% originated from other conventional sources (coal, gas diesel, nuclear, and large hydropower) [ 44 ]. The best regions for renewable energy are the southern states that have the highest solar irradiance and wind in the country. When renewable energy alone is considered for analysis, the Southern region covers 49.121% of the cumulative installed renewable capacity, followed by the Western region (29.742%), the Northern region (18.890%), the Eastern region (1.836%), the North-Easter region 0.394%, and the Islands (0.017%). As far as conventional energy is concerned, the Western region with 33.452% ranks first and is followed by the Northern region with 28.484%, the Southern region (24.967%), the Eastern region (11.716%), the Northern-Eastern (1.366%), and the Islands (0.015%).

Gross installed capacity of renewable energy—according to ownership

State government, central government, and private players drive the Indian energy sector. The private sector leads the way in renewable energy investment. Table 9 shows the installed gross renewable energy and conventional energy capacity (percentage)—ownership wise. It is evident from Fig. 2 that 95% of the installed renewable capacity derives from private companies, 2% from the central government, and 3% from the state government. The top private companies in the field of non-conventional energy generation are Tata Power Solar, Suzlon, and ReNew Power. Tata Power Solar System Limited are the most significant integrated solar power players in the country, Suzlon realizes wind energy projects, and ReNew Power Ventures operate with solar and wind power.

figure 2

Gross renewable energy installed capacity (percentage)—Ownership wise as per the 31.12.2018 [ 43 ]

Gross installed capacity of renewable energy—state wise

Table 10 shows the installed capacity of cumulative renewable energy (state wise), out of the total installed capacity of 74,081.66 MW, where Karnataka ranks first with 12,953.24 MW (17.485%), Tamilnadu second with 11,934.38 MW (16%), Maharashtra third with 9283.78 MW (12.532%), Gujarat fourth with 10.641 MW (10.641%), and Rajasthan fifth with 7573.86 MW (10.224%). These five states cover almost 66.991% of the installed capacity of total renewable. Other prominent states are Andhra Pradesh (9.829%), Madhya Pradesh (5.819%), Telangana (5.137%), and Uttar Pradesh (3.879%). These nine states cover almost 91.655%.

Gross installed capacity of renewable energy—according to source

Under union budget of India 2018–2019, INR 3762 crore (USD 581.09 million), was allotted for grid-interactive renewable power schemes and projects. As per the 31.12.2018, the installed capacity of total renewable power (excluding large hydropower) in the country amounted to 74.08166 GW. Around 9.363 GW of solar energy, 1.766 GW of wind, 0.105 GW of small hydropower (SHP), and biomass power of 8.7 GW capacity were added in 2017–2018. Table 11 shows the installed capacity of renewable energy over the last 10 years until the 31.12.2018. Wind energy continues to dominate the countries renewable energy industry, accounting for over 47% of cumulative installed renewable capacity (35,138.15 MW), followed by solar power of 34% (25,212.26 MW), biomass power/cogeneration of 12% (9075.5 MW), and small hydropower of 6% (4517.45 MW). In the renewable energy country attractiveness index (RECAI) of 2018, India ranked in fourth position. The installed renewable energy production capacity has grown at an accelerated pace over the preceding few years, posting a CAGR of 19.78% between 2014 and 2018 [ 45 ] .

Estimation of the installed capacity of renewable energy

Table 12 gives the share of installed cumulative renewable energy capacity, in comparison with the installed conventional energy capacity. In 2022 and 2032, the installed renewable energy capacity will account for 32% and 35%, respectively [ 46 , 47 ]. The most significant renewable capacity expansion program in the world is being taken up by India. The government is preparing to boost the percentage of clean energy through a tremendous push in renewables, as discussed in the subsequent sections.

Gross electricity generation from renewable energy in India

The overall generation (including the generation from grid-connected renewable sources) in the country has grown exponentially. Between 2014–2015 and 2015–2016, it achieved 1110.458 BU and 1173.603 BU, respectively. The same was recorded with 1241.689 BU and 1306.614 BU during 2015–2016 and 1306.614 BU from 2016–2017 and 2017–2018, respectively. Figure 3 indicates that the annual renewable power production increased faster than the conventional power production. The rise accounted for 6.47% in 2015–2016 and 24.88% in 2017–2018, respectively. Table 13 compares the energy generation from traditional sources with that from renewable sources. Remarkably, the energy generation from conventional sources reached 811.143 BU and from renewable sources 9.860 BU in 2010 compared to 1.206.306 BU and 88.945 BU in 2017, respectively [ 48 ]. It is observed that the price of electricity production using renewable technologies is higher than that for conventional generation technologies, but is likely to fall with increasing experience in the techniques involved [ 49 ].

figure 3

The annual growth in power generation as per the 30th of November 2018

Gross electricity generation from renewable energy—according to regions

Table 14 shows the gross electricity generation from renewable energy-region wise. It is noted that the highest renewable energy generation derives from the southern region, followed by the western part. As of November 2018, 50.33% of energy generation was obtained from the southern area and 29.37%, 18.05%, 2%, and 0.24% from Western, Northern, North-Eastern Areas, and the Island, respectively.

Gross electricity generation from renewable energy—according to states

Table 15 shows the gross electricity generation from renewable energy—region-wise. It is observed that the highest renewable energy generation was achieved from Karnataka (16.57%), Tamilnadu (15.82%), Andhra Pradesh (11.92%), and Gujarat (10.87%) as per November 2018. While adding four years from 2015–2016 to 2018–2019 Tamilnadu [ 50 ] remains in the first position followed by Karnataka, Maharashtra, Gujarat and Andhra Pradesh.

Gross electricity generation from renewable energy—according to sources

Table 16 shows the gross electricity generation from renewable energy—source-wise. It can be concluded from the table that the wind-based energy generation as per 2017–2018 is most prominent with 51.71%, followed by solar energy (25.40%), Bagasse (11.63%), small hydropower (7.55%), biomass (3.34%), and WTE (0.35%). There has been a constant increase in the generation of all renewable sources from 2014–2015 to date. Wind energy, as always, was the highest contributor to the total renewable power production. The percentage of solar energy produced in the overall renewable power production comes next to wind and is typically reduced during the monsoon months. The definite improvement in wind energy production can be associated with a “good” monsoon. Cyclonic action during these months also facilitates high-speed winds. Monsoon winds play a significant part in the uptick in wind power production, especially in the southern states of the country.

Estimation of gross electricity generation from renewable energy

Table 17 shows an estimation of gross electricity generation from renewable energy based on the 2015 report of the National Institution for Transforming India (NITI Aayog) [ 51 ]. It is predicted that the share of renewable power will be 10.2% by 2022, but renewable power technologies contributed a record of 13.4% to the cumulative power production in India as of the 31st of August 2018. The power ministry report shows that India generated 122.10 TWh and out of the total electricity produced, renewables generated 16.30 TWh as on the 31st of August 2018. According to the India Brand Equity Foundation report, it is anticipated that by the year 2040, around 49% of total electricity will be produced using renewable energy.

Current achievements in renewable energy 2017–2018

India cares for the planet and has taken a groundbreaking journey in renewable energy through the last 4 years [ 52 , 53 ]. A dedicated ministry along with financial and technical institutions have helped India in the promotion of renewable energy and diversification of its energy mix. The country is engaged in expanding the use of clean energy sources and has already undertaken several large-scale sustainable energy projects to ensure a massive growth of green energy.

1. India doubled its renewable power capacity in the last 4 years. The cumulative renewable power capacity in 2013–2014 reached 35,500 MW and rose to 70,000 MW in 2017–2018.

2. India stands in the fourth and sixth position regarding the cumulative installed capacity in the wind and solar sector, respectively. Furthermore, its cumulative installed renewable capacity stands in fifth position globally as of the 31st of December 2018.

3. As said above, the cumulative renewable energy capacity target for 2022 is given as 175 GW. For 2017–2018, the cumulative installed capacity amounted to 70 GW, the capacity under implementation is 15 GW and the tendered capacity was 25 GW. The target, the installed capacity, the capacity under implementation, and the tendered capacity are shown in Fig. 4 .

4. There is tremendous growth in solar power. The cumulative installed solar capacity increased by more than eight times in the last 4 years from 2.630 GW (2013–2014) to 22 GW (2017–2018). As of the 31st of December 2018, the installed capacity amounted to 25.2122 GW.

5. The renewable electricity generated in 2017–2018 was 101839 BUs.

6. The country published competitive bidding guidelines for the production of renewable power. It also discovered the lowest tariff and transparent bidding method and resulted in a notable decrease in per unit cost of renewable energy.

7. In 21 states, there are 41 solar parks with a cumulative capacity of more than 26,144 MW that have already been approved by the MNRE. The Kurnool solar park was set up with 1000 MW; and with 2000 MW the largest solar park of Pavagada (Karnataka) is currently under installation.

8. The target for solar power (ground mounted) for 2018–2019 is given as 10 GW, and solar power (Rooftop) as 1 GW.

9. MNRE doubled the target for solar parks (projects of 500 MW or more) from 20 to 40 GW.

10. The cumulative installed capacity of wind power increased by 1.6 times in the last 4 years. In 2013–2014, it amounted to 21 GW, from 2017 to 2018 it amounted to 34 GW, and as of 31st of December 2018, it reached 35.138 GW. This shows that achievements were completed in wind power use.

11. An offshore wind policy was announced. Thirty-four companies (most significant global and domestic wind power players) competed in the “expression of interest” (EoI) floated on the plan to set up India’s first mega offshore wind farm with a capacity of 1 GW.

12. 682 MW small hydropower projects were installed during the last 4 years along with 600 watermills (mechanical applications) and 132 projects still under development.

13. MNRE is implementing green energy corridors to expand the transmission system. 9400 km of green energy corridors are completed or under implementation. The cost spent on it was INR 10141 crore (101,410 Million INR = 1425.01 USD). Furthermore, the total capacity of 19,000 MVA substations is now planned to be complete by March 2020.

14. MNRE is setting up solar pumps (off-grid application), where 90% of pumps have been set up as of today and between 2014–2015 and 2017–2018. Solar street lights were more than doubled. Solar home lighting systems have been improved by around 1.5 times. More than 2,575,000 solar lamps have been distributed to students. The details are illustrated in Fig. 5 .

15. From 2014–2015 to 2017–2018, more than 2.5 lakh (0.25 million) biogas plants were set up for cooking in rural homes to enable families by providing them access to clean fuel.

16. New policy initiatives revised the tariff policy mandating purchase and generation obligations (RPO and RGO). Four wind and solar inter-state transmission were waived; charges were planned, the RPO trajectory for 2022 and renewable energy policy was finalized.

17. Expressions of interest (EoI) were invited for installing solar photovoltaic manufacturing capacities associated with the guaranteed off-take of 20 GW. EoI indicated 10 GW floating solar energy plants.

18. Policy for the solar-wind hybrid was announced. Tender for setting up 2 GW solar-wind hybrid systems in existing projects was invited.

19. To facilitate R&D in renewable power technology, a National lab policy on testing, standardization, and certification was announced by the MNRE.

20. The Surya Mitra program was conducted to train college graduates in the installation, commissioning, operations, and management of solar panels. The International Solar Alliance (ISA) headquarters in India (Gurgaon) will be a new commencement for solar energy improvement in India.

21. The renewable sector has become considerably more attractive for foreign and domestic investors, and the country expects to attract up to USD 80 billion in the next 4 years from 2018–2019 to 2021–2022.

22. The solar power capacity expanded by more than eight times from 2.63 GW in 2013–2014 to 22 GW in 2017–2018.

23. A bidding for 115 GW renewable energy projects up to March 2020 was announced.

24. The Bureau of Indian Standards (BIS) acting for system/components of solar PV was established.

25. To recognize and encourage innovative ideas in renewable energy sectors, the Government provides prizes and awards. Creative ideas/concepts should lead to prototype development. The Name of the award is “Abhinav Soch-Nayi Sambhawanaye,” which means Innovative ideas—New possibilities.

figure 4

Renewable energy target, installed capacity, under implementation and tendered [ 52 ]

figure 5

Off-grid solar applications [ 52 ]

Solar energy

Under the National Solar Mission, the MNRE has updated the objective of grid-connected solar power projects from 20 GW by the year 2021–2022 to 100 GW by the year 2021–2022. In 2008–2009, it reached just 6 MW. The “Made in India” initiative to promote domestic manufacturing supported this great height in solar installation capacity. Currently, India has the fifth highest solar installed capacity worldwide. By the 31st of December 2018, solar energy had achieved 25,212.26 MW against the target of 2022, and a further 22.8 GW of capacity has been tendered out or is under current implementation. MNRE is preparing to bid out the remaining solar energy capacity every year for the periods 2018–2019 and 2019–2020 so that bidding may contribute with 100 GW capacity additions by March 2020. In this way, 2 years for the completion of projects would remain. Tariffs will be determined through the competitive bidding process (reverse e-auction) to bring down tariffs significantly. The lowest solar tariff was identified to be INR 2.44 per kWh in July 2018. In 2010, solar tariffs amounted to INR 18 per kWh. Over 100,000 lakh (10,000 million) acres of land had been classified for several planned solar parks, out of which over 75,000 acres had been obtained. As of November 2018, 47 solar parks of a total capacity of 26,694 MW were established. The aggregate capacity of 4195 MW of solar projects has been commissioned inside various solar parks (floating solar power). Table 18 shows the capacity addition compared to the target. It indicates that capacity addition increased exponentially.

Wind energy

As of the 31st of December 2018, the total installed capacity of India amounted to 35,138.15 MW compared to a target of 60 GW by 2022. India is currently in fourth position in the world for installed capacity of wind power. Moreover, around 9.4 GW capacity has been tendered out or is under current implementation. The MNRE is preparing to bid out for A 10 GW wind energy capacity every year for 2018–2019 and 2019–2020, so that bidding will allow for 60 GW capacity additions by March 2020, giving the remaining two years for the accomplishment of the projects. The gross wind energy potential of the country now reaches 302 GW at a 100 m above-ground level. The tariff administration has been changed from feed-in-tariff (FiT) to the bidding method for capacity addition. On the 8th of December 2017, the ministry published guidelines for a tariff-based competitive bidding rule for the acquisition of energy from grid-connected wind energy projects. The developed transparent process of bidding lowered the tariff for wind power to its lowest level ever. The development of the wind industry has risen in a robust ecosystem ensuring project execution abilities and a manufacturing base. State-of-the-art technologies are now available for the production of wind turbines. All the major global players in wind power have their presence in India. More than 12 different companies manufacture more than 24 various models of wind turbines in India. India exports wind turbines and components to the USA, Europe, Australia, Brazil, and other Asian countries. Around 70–80% of the domestic production has been accomplished with strong domestic manufacturing companies. Table 19 lists the capacity addition compared to the target for the capacity addition. Furthermore, electricity generation from the wind-based capacity has improved, even though there was a slowdown of new capacity in the first half of 2018–2019 and 2017–2018.

The national energy storage mission—2018

The country is working toward a National Energy Storage Mission. A draft of the National Energy Storage Mission was proposed in February 2018 and initiated to develop a comprehensive policy and regulatory framework. During the last 4 years, projects included in R&D worth INR 115.8 million (USD 1.66 million) in the domain of energy storage have been launched, and a corpus of INR 48.2 million (USD 0.7 million) has been issued. India’s energy storage mission will provide an opportunity for globally competitive battery manufacturing. By increasing the battery manufacturing expertise and scaling up its national production capacity, the country can make a substantial economic contribution in this crucial sector. The mission aims to identify the cumulative battery requirements, total market size, imports, and domestic manufacturing. Table 20 presents the economic opportunity from battery manufacturing given by the National Institution for Transforming India, also called NITI Aayog, which provides relevant technical advice to central and state governments while designing strategic and long-term policies and programs for the Indian government.

Small hydropower—3-year action agenda—2017

Hydro projects are classified as large hydro, small hydro (2 to 25 MW), micro-hydro (up to 100 kW), and mini-hydropower (100 kW to 2 MW) projects. Whereas the estimated potential of SHP is 20 GW, the 2022 target for India in SHP is 5 GW. As of the 31st of December 2018, the country has achieved 4.5 GW and this production is constantly increasing. The objective, which was planned to be accomplished through infrastructure project grants and tariff support, was included in the NITI Aayog’s 3-year action agenda (2017–2018 to 2019–2020), which was published on the 1st of August 2017. MNRE is providing central financial assistance (CFA) to set up small/micro hydro projects both in the public and private sector. For the identification of new potential locations, surveys and comprehensive project reports are elaborated, and financial support for the renovation and modernization of old projects is provided. The Ministry has established a dedicated completely automatic supervisory control and data acquisition (SCADA)—based on a hydraulic turbine R&D laboratory at the Alternate Hydro Energy Center (AHEC) at IIT Roorkee. The establishment cost for the lab was INR 40 crore (400 million INR, 95.62 Million USD), and the laboratory will serve as a design and validation facility. It investigates hydro turbines and other hydro-mechanical devices adhering to national and international standards [ 54 , 55 ]. Table 21 shows the target and achievements from 2007–2008 to 2018–2019.

National policy regarding biofuels—2018

Modernization has generated an opportunity for a stable change in the use of bioenergy in India. MNRE amended the current policy for biomass in May 2018. The policy presents CFA for projects using biomass such as agriculture-based industrial residues, wood produced through energy plantations, bagasse, crop residues, wood waste generated from industrial operations, and weeds. Under the policy, CFA will be provided to the projects at the rate of INR 2.5 million (USD 35,477.7) per MW for bagasse cogeneration and INR 5 million (USD 70,955.5) per MW for non-bagasse cogeneration. The MNRE also announced a memorandum in November 2018 considering the continuation of the concessional customs duty certificate (CCDC) to set up projects for the production of energy using non-conventional materials such as bio-waste, agricultural, forestry, poultry litter, agro-industrial, industrial, municipal, and urban wastes. The government recently established the National policy on biofuels in August 2018. The MNRE invited an expression of interest (EOI) to estimate the potential of biomass energy and bagasse cogeneration in the country. A program to encourage the promotion of biomass-based cogeneration in sugar mills and other industries was also launched in May 2018. Table 22 shows how the biomass power target and achievements are expected to reach 10 GW of the target of 2022 before the end of 2019.

The new national biogas and organic manure program (NNBOMP)—2018

The National biogas and manure management programme (NBMMP) was launched in 2012–2013. The primary objective was to provide clean gaseous fuel for cooking, where the remaining slurry was organic bio-manure which is rich in nitrogen, phosphorus, and potassium. Further, 47.5 lakh (4.75 million) cumulative biogas plants were completed in 2014, and increased to 49.8 lakh (4.98 million). During 2017–2018, the target was to establish 1.10 lakh biogas plants (1.10 million), but resulted in 0.15 lakh (0.015 million). In this way, the cost of refilling the gas cylinders with liquefied petroleum gas (LPG) was greatly reduced. Likewise, tons of wood/trees were protected from being axed, as wood is traditionally used as a fuel in rural and semi-urban households. Biogas is a viable alternative to traditional cooking fuels. The scheme generated employment for almost 300 skilled laborers for setting up the biogas plants. By 30th of May 2018, the Ministry had issued guidelines for the implementation of the NNBOMP during the period 2017–2018 to 2019–2020 [ 56 ].

The off-grid and decentralized solar photovoltaic application program—2018

The program deals with the energy demand through the deployment of solar lanterns, solar streetlights, solar home lights, and solar pumps. The plan intended to reach 118 MWp of off-grid PV capacity by 2020. The sanctioning target proposed outlay was 50 MWp by 2017–2018 and 68 MWp by 2019–2020. The total estimated cost amounted to INR 1895 crore (18950 Million INR, 265.547 million USD), and the ministry wanted to support 637 crores (6370 million INR, 89.263 million USD) by its central finance assistance. Solar power plants with a 25 KWp size were promoted in those areas where grid power does not reach households or is not reliable. Public service institutions, schools, panchayats, hostels, as well as police stations will benefit from this scheme. Solar study lamps were also included as a component in the program. Thirty percent of financial assistance was provided to solar power plants. Every student should bear 15% of the lamp cost, and the ministry wanted to support the remaining 85%. As of October 2018, lantern and lamps of more than 40 Lakhs (4 million), home lights of 16.72 lakhs (1.672 million) number, street lights of 6.40 lakhs (0.64 million), solar pumps of 1.96 lakhs (0.196 million), and 187.99 MWp stand-alone devices had been installed [ 57 , 58 ].

Major government initiatives for renewable energy

Technological initiatives.

The Technology Development and Innovation Policy (TDIP) released on the 6th of October 2017 was endeavored to promote research, development, and demonstration (RD&D) in the renewable energy sector [ 59 ]. RD&D intended to evaluate resources, progress in technology, commercialization, and the presentation of renewable energy technologies across the country. It aimed to produce renewable power devices and systems domestically. The evaluation of standards and resources, processes, materials, components, products, services, and sub-systems was carried out through RD&D. A development of the market, efficiency improvements, cost reductions, and a promotion of commercialization (scalability and bankability) were achieved through RD&D. Likewise, the percentage of renewable energy in the total electricity mix made it self-sustainable, industrially competitive, and profitable through RD&D. RD&D also supported technology development and demonstration in wind, solar, wind-solar hybrid, biofuel, biogas, hydrogen fuel cells, and geothermal energies. RD&D supported the R&D units of educational institutions, industries, and non-government organizations (NGOs). Sharing expertise, information, as well as institutional mechanisms for collaboration was realized by use of the technology development program (TDP). The various people involved in this program were policymakers, industrial innovators, associated stakeholders and departments, researchers, and scientists. Renowned R&D centers in India are the National Institute of Solar Energy (NISE), Gurgaon, the National Institute of Bio-Energy (NIBE), Kapurthala, and the National Institute of Wind Energy (NIWE), Chennai. The TDP strategy encouraged the exploration of innovative approaches and possibilities to obtain long-term targets. Likewise, it efficiently supported the transformation of knowledge into technology through a well-established monitoring system for the development of renewable technology that meets the electricity needs of India. The research center of excellence approved the TDI projects, which were funded to strengthen R&D. Funds were provided for conducting training and workshops. The MNRE is now preparing a database of R&D accomplishments in the renewable energy sector.

The Impacting Research Innovation and Technology (IMPRINT) program seeks to develop engineering and technology (prototype/process development) on a national scale. IMPRINT is steered by the Indian Institute of Technologies (IITs) and Indian Institute of science (IISCs). The expansion covers all areas of engineering and technology including renewable technology. The ministry of human resource development (MHRD) finances up to 50% of the total cost of the project. The remaining costs of the project are financed by the ministry (MNRE) via the RD&D program for renewable projects. Currently (2018–2019), five projects are under implementation in the area of solar thermal systems, storage for SPV, biofuel, and hydrogen and fuel cells which are funded by the MNRE (36.9 million INR, 0.518426 Million USD) and IMPRINT. Development of domestic technology and quality control are promoted through lab policies that were published on the 7th of December 2017. Lab policies were implemented to test, standardize, and certify renewable energy products and projects. They supported the improvement of the reliability and quality of the projects. Furthermore, Indian test labs are strengthened in line with international standards and practices through well-established lab policies. From 2015, the MNRE has provided “The New and Renewable Energy Young Scientist’s Award” to researchers/scientists who demonstrate exceptional accomplishments in renewable R&D.

Financial initiatives

One hundred percent financial assistance is granted by the MNRE to the government and NGOs and 50% financial support to the industry. The policy framework was developed to guide the identification of the project, the formulation, monitoring appraisal, approval, and financing. Between 2012 and 2017, a 4467.8 million INR, 62.52 Million USD) support was granted by the MNRE. The MNRE wanted to double the budget for technology development efforts in renewable energy for the current three-year plan period. Table 23 shows that the government is spending more and more for the development of the renewable energy sector. Financial support was provided to R&D projects. Exceptional consideration was given to projects that worked under extreme and hazardous conditions. Furthermore, financial support was applied to organizing awareness programs, demonstrations, training, workshops, surveys, assessment studies, etc. Innovative approaches will be rewarded with cash prizes. The winners will be presented with a support mechanism for transforming their ideas and prototypes into marketable commodities such as start-ups for entrepreneur development. Innovative projects will be financed via start-up support mechanisms, which will include an investment contract with investors. The MNRE provides funds to proposals for investigating policies and performance analyses related to renewable energy.

Technology validation and demonstration projects and other innovative projects with regard to renewables received a financial assistance of 50% of the project cost. The CFA applied to partnerships with industry and private institutions including engineering colleges. Private academic institutions, accredited by a government accreditation body, were also eligible to receive a 50% support. The concerned industries and institutions should meet the remaining 50% expenditure. The MNRE allocated an INR 3762.50 crore (INR 37625 million, 528.634 million USD) for the grid interactive renewable sources and an INR 1036.50 crore (INR 10365 million, 145.629 million USD) for off-grid/distributed and decentralized renewable power for the year 2018–2019 [ 60 ]. The MNRE asked the Reserve Bank of India (RBI), attempting to build renewable power projects under “priority sector lending” (priority lending should be done for renewable energy projects and without any limit) and to eliminate the obstacles in the financing of renewable energy projects. In July 2018, the Ministry of Finance announced that it would impose a 25% safeguard duty on solar panels and modules imported from China and Malaysia for 1 year. The quantum of tax might be reduced to 20% for the next 6 months, and 15% for the following 6 months.

Policy and regulatory framework initiatives

The regulatory interventions for the development of renewable energy sources are (a) tariff determination, (b) defining RPO, (c) promoting grid connectivity, and (d) promoting the expansion of the market.

Tariff policy amendments—2018

On the 30th of May 2018, the MoP released draft amendments to the tariff policy. The objective of these policies was to promote electricity generation from renewables. MoP in consultation with MNRE announced the long-term trajectory for RPO, which is represented in Table 24 . The State Electricity Regulatory Commission (SERC) achieved a favorable and neutral/off-putting effect in the growth of the renewable power sector through their RPO regulations in consultation with the MNRE. On the 25th of May 2018, the MNRE created an RPO compliance cell to reach India’s solar and wind power goals. Due to the absence of implementation of RPO regulations, several states in India did not meet their specified RPO objectives. The cell will operate along with the Central Electricity Regulatory Commission (CERC) and SERCs to obtain monthly statements on RPO compliance. It will also take up non-compliance associated concerns with the relevant officials.

Repowering policy—2016

On the 09th of August 2016, India announced a “repowering policy” for wind energy projects. An about 27 GW turnaround was possible according to the policy. This policy supports the replacing of aging wind turbines with more modern and powerful units (fewer, larger, taller) to raise the level of electricity generation. This policy seeks to create a simplified framework and to promote an optimized use of wind power resources. It is mandatory because the up to the year 2000 installed wind turbines were below 500 kW in sites where high wind potential might be achieved. It will be possible to obtain 3000 MW from the same location once replacements are in place. The policy was initially applied for the one MW installed capacity of wind turbines, and the MNRE will extend the repowering policy to other projects in the future based on experience. Repowering projects were implemented by the respective state nodal agencies/organizations that were involved in wind energy promotion in their states. The policy provided an exception from the Power Purchase Agreement (PPA) for wind farms/turbines undergoing repowering because they could not fulfill the requirements according to the PPA during repowering. The repowering projects may avail accelerated depreciation (AD) benefit or generation-based incentive (GBI) due to the conditions appropriate to new wind energy projects [ 61 ].

The wind-solar hybrid policy—2018

On the 14th of May 2018, the MNRE announced a national wind-solar hybrid policy. This policy supported new projects (large grid-connected wind-solar photovoltaic hybrid systems) and the hybridization of the already available projects. These projects tried to achieve an optimal and efficient use of transmission infrastructure and land. Better grid stability was achieved and the variability in renewable power generation was reduced. The best part of the policy intervention was that which supported the hybridization of existing plants. The tariff-based transparent bidding process was included in the policy. Regulatory authorities should formulate the necessary standards and regulations for hybrid systems. The policy also highlighted a battery storage in hybrid projects for output optimization and variability reduction [ 62 ].

The national offshore wind energy policy—2015

The National Offshore Wind Policy was released in October 2015. On the 19th of June 2018, the MNRE announced a medium-term target of 5 GW by 2022 and a long-term target of 30 GW by 2030. The MNRE called expressions of Interest (EoI) for the first 1 GW of offshore wind (the last date was 08.06.2018). The EoI site is located in Pipavav port at the Gulf of Khambhat at a distance of 23 km facilitating offshore wind (FOWIND) where the consortium deployed light detection and ranging (LiDAR) in November 2017). Pipavav port is situated off the coast of Gujarat. The MNRE had planned to install more such equipment in the states of Tamil Nadu and Gujarat. On the 14 th of December 2018, the MNRE, through the National Institute of Wind Energy (NIWE), called tender for offshore environmental impact assessment studies at intended LIDAR points at the Gulf of Mannar, off the coast of Tamil Nadu for offshore wind measurement. The timeline for initiatives was to firstly add 500 MW by 2022, 2 to 2.5 GW by 2027, and eventually reaching 5 GW between 2028 and 2032. Even though the installation of large wind power turbines in open seas is a challenging task, the government has endeavored to promote this offshore sector. Offshore wind energy would add its contribution to the already existing renewable energy mix for India [ 63 ] .

The feed-in tariff policy—2018

On the 28th of January 2016, the revised tariff policy was notified following the Electricity Act. On the 30th May 2018, the amendment in tariff policy was released. The intentions of this tariff policy are (a) an inexpensive and competitive electricity rate for the consumers; (b) to attract investment and financial viability; (c) to ensure that the perceptions of regulatory risks decrease through predictability, consistency, and transparency of policy measures; (d) development in quality of supply, increased operational efficiency, and improved competition; (e) increase the production of electricity from wind, solar, biomass, and small hydro; (f) peaking reserves that are acceptable in quantity or consistently good in quality or performance of grid operation where variable renewable energy source integration is provided through the promotion of hydroelectric power generation, including pumped storage projects (PSP); (g) to achieve better consumer services through efficient and reliable electricity infrastructure; (h) to supply sufficient and uninterrupted electricity to every level of consumers; and (i) to create adequate capacity, reserves in the production, transmission, and distribution that is sufficient for the reliability of supply of power to customers [ 64 ].

Training and educational initiatives

The MHRD has developed strong renewable energy education and training systems. The National Council for Vocational Training (NCVT) develops course modules, and a Modular Employable Skilling program (MES) in its regular 2-year syllabus to include SPV lighting systems, solar thermal systems, SHP, and provides the certificate for seven trades after the completion of a 2-year course. The seven trades are plumber, fitter, carpenter, welder, machinist, and electrician. The Ministry of Skill Development and Entrepreneurship (MSDE) worked out a national skill development policy in 2015. They provide regular training programs to create various job roles in renewable energy along with the MNRE support through a skill council for green jobs (SCGJ), the National Occupational Standards (NOS), and the Qualification Pack (QP). The SCGJ is promoted by the Confederation of Indian Industry (CII) and the MNRE. The industry partner for the SCGJ is ReNew Power [ 65 , 66 ].

The global status of India in renewable energy

Table 25 shows the RECAI (Renewable Energy Country Attractiveness Index) report of 40 countries. This report is based on the attractiveness of renewable energy investment and deployment opportunities. RECAI is based on macro vitals such as economic stability, investment climate, energy imperatives such as security and supply, clean energy gap, and affordability. It also includes policy enablement such as political stability and support for renewables. Its emphasis lies on project delivery parameters such as energy market access, infrastructure, and distributed generation, finance, cost and availability, and transaction liquidity. Technology potentials such as natural resources, power take-off attractiveness, potential support, technology maturity, and forecast growth are taken into consideration for ranking. India has moved to the fourth position of the RECAI-2018. Indian solar installations (new large-scale and rooftop solar capacities) in the calendar year 2017 increased exponentially with the addition of 9629 MW, whereas in 2016 it was 4313 MW. The warning of solar import tariffs and conflicts between developers and distribution firms are growing investor concerns [ 67 ]. Figure 6 shows the details of the installed capacity of global renewable energy in 2016 and 2017. Globally, 2017 GW renewable energy was installed in 2016, and in 2017, it increased to 2195 GW. Table 26 shows the total capacity addition of top countries until 2017. The country ranked fifth in renewable power capacity (including hydro energy), renewable power capacity (not including hydro energy) in fourth position, concentrating solar thermal power (CSP) and wind power were also in fourth position [ 68 ].

figure 6

Globally installed capacity of renewable energy in 2017—Global 2018 status report with regard to renewables [ 68 ]

The investment opportunities in renewable energy in India

The investments into renewable energy in India increased by 22% in the first half of 2018 compared to 2017, while the investments in China dropped by 15% during the same period, according to a statement by the Bloomberg New Energy Finance (BNEF), which is shown in Table 27 [ 69 , 70 ]. At this rate, India is expected to overtake China and become the most significant growth market for renewable energy by the end of 2020. The country is eyeing pole position for transformation in renewable energy by reaching 175 GW by 2020. To achieve this target, it is quickly ramping up investments in this sector. The country added more renewable capacity than conventional capacity in 2018 when compared to 2017. India hosted the ISA first official summit on the 11.03.2018 for 121 countries. This will provide a standard platform to work toward the ambitious targets for renewable energy. The summit will emphasize India’s dedication to meet global engagements in a time-bound method. The country is also constructing many sizeable solar power parks comparable to, but larger than, those in China. Half of the earth’s ten biggest solar parks under development are in India.

In 2014, the world largest solar park was the Topaz solar farm in California with a 550 MW facility. In 2015, another operator in California, Solar Star, edged its capacity up to 579 MW. By 2016, India’s Kamuthi Solar Power Project in Tamil Nadu was on top with 648 MW of capacity (set up by the Adani Green Energy, part of the Adani Group, in Tamil Nadu). As of February 2017, the Longyangxia Dam Solar Park in China was the new leader, with 850 MW of capacity [ 71 ]. Currently, there are 600 MW operating units and 1400 MW units under construction. The Shakti Sthala solar park was inaugurated on 01.03.2018 in Pavagada (Karnataka, India) which is expected to become the globe’s most significant solar park when it accomplishes its full potential of 2 GW. Another large solar park with 1.5 GW is scheduled to be built in the Kadappa region [ 72 ]. The progress in solar power is remarkable and demonstrates real clean energy development on the ground.

The Kurnool ultra-mega solar park generated 800 million units (MU) of energy in October 2018 and saved over 700,000 tons of CO 2 . Rainwater was harvested using a reservoir that helps in cleaning solar panels and supplying water. The country is making remarkable progress in solar energy. The Kamuthi solar farm is cleaned each day by a robotic system. As the Indian economy expands, electricity consumption is forecasted to reach 15,280 TWh in 2040. With the government’s intent, green energy objectives, i.e., the renewable sector, grow considerably in an attractive manner with both foreign and domestic investors. It is anticipated to attract investments of up to USD 80 billion in the subsequent 4 years. The government of India has raised its 175 GW target to 225 GW of renewable energy capacity by 2022. The competitive benefit is that the country has sun exposure possible throughout the year and has an enormous hydropower potential. India was also listed fourth in the EY renewable energy country attractive index 2018. Sixty solar cities will be built in India as a section of MNRE’s “Solar cities” program.

In a regular auction, reduction in tariffs cost of the projects are the competitive benefits in the country. India accounts for about 4% of the total global electricity generation capacity and has the fourth highest installed capacity of wind energy and the third highest installed capacity of CSP. The solar installation in India erected during 2015–2016, 2016–2017, 2017–2018, and 2018–2019 was 3.01 GW, 5.52 GW, 9.36 GW, and 6.53 GW, respectively. The country aims to add 8.5 GW during 2019–2020. Due to its advantageous location in the solar belt (400 South to 400 North), the country is one of the largest beneficiaries of solar energy with relatively ample availability. An increase in the installed capacity of solar power is anticipated to exceed the installed capacity of wind energy, approaching 100 GW by 2022 from its current levels of 25.21226 GW as of December 2018. Fast falling prices have made Solar PV the biggest market for new investments. Under the Union Budget 2018–2019, a zero import tax on parts used in manufacturing solar panels was launched to provide an advantage to domestic solar panel companies [ 73 ].

Foreign direct investment (FDI) inflows in the renewable energy sector of India between April 2000 and June 2018 amounted to USD 6.84 billion according to the report of the department of industrial policy and promotion (DIPP). The DIPP was renamed (gazette notification 27.01.2019) the Department for the Promotion of Industry and Internal Trade (DPIIT). It is responsible for the development of domestic trade, retail trade, trader’s welfare including their employees as well as concerns associated with activities in facilitating and supporting business and startups. Since 2014, more than 42 billion USD have been invested in India’s renewable power sector. India reached US$ 7.4 billion in investments in the first half of 2018. Between April 2015 and June 2018, the country received USD 3.2 billion FDI in the renewable sector. The year-wise inflows expanded from USD 776 million in 2015–2016 to USD 783 million in 2016–2017 and USD 1204 million in 2017–2018. Between January to March of 2018, the INR 452 crore (4520 Million INR, 63.3389 million USD) of the FDI had already come in. The country is contributing with financial and promotional incentives that include a capital subsidy, accelerated depreciation (AD), waiver of inter-state transmission charges and losses, viability gap funding (VGF), and FDI up to 100% under the automated track.

The DIPP/DPIIT compiles and manages the data of the FDI equity inflow received in India [ 74 ]. The FDI equity inflow between April 2015 and June 2018 in the renewable sector is illustrated in Fig. 7 . It shows that the 2018–2019 3 months’ FDI equity inflow is half of that of the entire one of 2017–2018. It is evident from the figure that India has well-established FDI equity inflows. The significant FDI investments in the renewable energy sectors are shown in Table 28 . The collaboration between the Asian development bank and Renew Power Ventures private limited with 44.69 million USD ranked first followed by AIRRO Singapore with Diligent power with FDI equity inflow of 44.69 USD million.

figure 7

The FDI equity inflow received between April 2015 and June 2018 in the renewable energy sector [ 73 ]

Strategies to promote investments

Strategies to promote investments (including FDI) by investors in the renewable sector:

Decrease constraints on FDI; provide open, transparent, and dependable conditions for foreign and domestic firms; and include ease of doing business, access to imports, comparatively flexible labor markets, and safeguard of intellectual property rights.

Establish an investment promotion agency (IPA) that targets suitable foreign investors and connects them as a catalyst with the domestic economy. Assist the IPA to present top-notch infrastructure and immediate access to skilled workers, technicians, engineers, and managers that might be needed to attract such investors. Furthermore, it should involve an after-investment care, recognizing the demonstration effects from satisfied investors, the potential for reinvestments, and the potential for cluster-development due to follow-up investments.

It is essential to consider the targeted sector (wind, solar, SPH or biomass, respectively) for which investments are required.

Establish the infrastructure needed for a quality investor, including adequate close-by transport facilities (airport, ports), a sufficient and steady supply of energy, a provision of a sufficiently skilled workforce, the facilities for the vocational training of specialized operators, ideally designed in collaboration with the investor.

Policy and other support mechanisms such as Power Purchase Agreements (PPA) play an influential role in underpinning returns and restricting uncertainties for project developers, indirectly supporting the availability of investment. Investors in renewable energy projects have historically relied on government policies to give them confidence about the costs necessary for electricity produced—and therefore for project revenues. Reassurance of future power costs for project developers is secured by signing a PPA with either a utility or an essential corporate buyer of electricity.

FiT have been the most conventional approach around the globe over the last decade to stimulate investments in renewable power projects. Set by the government concerned, they lay down an electricity tariff that developers of qualifying new projects might anticipate to receive for the resulting electricity over a long interval (15–20 years). These present investors in the tax equity of renewable power projects with a credit that they can manage to offset the tax burden outside in their businesses.

Table 29 presents the 2018 renewable energy investment report, source-wise, by the significant players in renewables according to the report of the Bloomberg New Energy Finance Report 2018. As per this report, global investment in renewable energy was USD of 279.8 billion in 2017. The top ten in the total global investments are China (126.1 $BN), the USA (40.5 $BN), Japan (13.4 $BN), India (10.9 $BN), Germany (10.4 $BN), Australia (8.5 $BN), UK (7.6 $BN), Brazil (6.0 $BN), Mexico (6.0 $BN), and Sweden (3.7 $BN) [ 75 ]. This achievement was possible since those countries have well-established strategies for promoting investments [ 76 , 77 ].

The appropriate objectives for renewable power expansion and investments are closely related to the Nationally Determined Contributions (NDCs) objectives, the implementation of the NDC, on the road to achieving Paris promises, policy competence, policy reliability, market absorption capacity, and nationwide investment circumstances that are the real purposes for renewable power expansion, which is a significant factor for the investment strategies, as is shown in Table 30 .

The demand for investments for building a Paris-compatible and climate-resilient energy support remains high, particularly in emerging nations. Future investments in energy grids and energy flexibility are of particular significance. The strategies and the comparison chart between China, India, and the USA are presented in Table 31 .

Table 32 shows France in the first place due to overall favorable conditions for renewables, heading the G20 in investment attractiveness of renewables. Germany drops back one spot due to a decline in the quality of the global policy environment for renewables and some insufficiencies in the policy design, as does the UK. Overall, with four European countries on top of the list, Europe, however, directs the way in providing attractive conditions for investing in renewables. Despite high scores for various nations, no single government is yet close to growing a role model. All countries still have significant room for increasing investment demands to deploy renewables at the scale required to reach the Paris objectives. The table shown is based on the Paris compatible long-term vision, the policy environment for renewable energy, the conditions for system integration, the market absorption capacity, and general investment conditions. India moved from the 11th position to the 9th position in overall investments between 2017 and 2018.

A Paris compatible long-term vision includes a de-carbonization plan for the power system, the renewable power ambition, the coal and oil decrease, and the reliability of renewables policies. Direct support policies include medium-term certainty of policy signals, streamlined administrative procedures, ensuring project realization, facilitating the use of produced electricity. Conditions for system integration include system integration-grid codes, system integration-storage promotion, and demand-side management policies. A market absorption capacity includes a prior experience with renewable technologies, a current activity with renewable installations, and a presence of major renewable energy companies. General investment conditions include non-financial determinants, depth of the financial sector as well, as an inflation forecast.

Employment opportunities for citizens in renewable energy in India

Global employment scenario.

According to the 2018 Annual review of the IRENA [ 78 ], global renewable energy employment touched 10.3 million jobs in 2017, an improvement of 5.3% compared with the quantity published in 2016. Many socio-economic advantages derive from renewable power, but employment continues to be exceptionally centralized in a handful of countries, with China, Brazil, the USA, India, Germany, and Japan in the lead. In solar PV employment (3.4 million jobs), China is the leader (65% of PV Jobs) which is followed by Japan, USA, India, Bangladesh, Malaysia, Germany, Philippines, and Turkey. In biofuels employment (1.9 million jobs), Brazil is the leader (41% of PV Jobs) followed by the USA, Colombia, Indonesia, Thailand, Malaysia, China, and India. In wind employment (1.1 million jobs), China is the leader (44% of PV Jobs) followed by Germany, USA, India, UK, Brazil, Denmark, Netherlands, France, and Spain.

Table 33 shows global renewable energy employment in the corresponding technology branches. As in past years, China maintained the most notable number of people employed (3880 million jobs) estimating for 43% of the globe’s total which is shown in Fig. 8 . In India, new solar installations touched a record of 9.6 GW in 2017, efficiently increasing the total installed capacity. The employment in solar PV improved by 36% and reached 164,400 jobs, of which 92,400 represented on-grid use. IRENA determines that the building and installation covered 46% of these jobs, with operations and maintenance (O&M) representing 35% and 19%, individually. India does not produce solar PV because it could be imported from China, which is inexpensive. The market share of domestic companies (Indian supplier to renewable projects) declined from 13% in 2014–2015 to 7% in 2017–2018. If India starts the manufacturing base, more citizens will get jobs in the manufacturing field. India had the world’s fifth most significant additions of 4.1 GW to wind capacity in 2017 and the fourth largest cumulative capacity in 2018. IRENA predicts that jobs in the wind sector stood at 60,500.

figure 8

Renewable energy employment in selected countries [ 79 ]

The jobs in renewables are categorized into technological development, installation/de-installation, operation, and maintenance. Tables 34 , 35 , 36 , and 37 show the wind industry, solar energy, biomass, and small hydro-related jobs in project development, component manufacturing, construction, operations, and education, training, and research. As technology quickly evolves, workers in all areas need to update their skills through continuing training/education or job training, and in several cases could benefit from professional certification. The advantages of moving to renewable energy are evident, and for this reason, the governments are responding positively toward the transformation to clean energy. Renewable energy can be described as the country’s next employment boom. Renewable energy job opportunities can transform rural economy [ 79 , 80 ]. The renewable energy sector might help to reduce poverty by creating better employment. For example, wind power is looking for specialists in manufacturing, project development, and construction and turbine installation as well as financial services, transportation and logistics, and maintenance and operations.

The government is building more renewable energy power plants that will require a workforce. The increasing investments in the renewable energy sector have the potential to provide more jobs than any other fossil fuel industry. Local businesses and renewable sectors will benefit from this change, as income will increase significantly. Many jobs in this sector will contribute to fixed salaries, healthcare benefits, and skill-building opportunities for unskilled and semi-skilled workers. A range of skilled and unskilled jobs are included in all renewable energy technologies, even though most of the positions in the renewable energy industry demand a skilled workforce. The renewable sector employs semi-skilled and unskilled labor in the construction, operations, and maintenance after proper training. Unskilled labor is employed as truck drivers, guards, cleaning, and maintenance. Semi-skilled labor is used to take regular readings from displays. A lack of consistent data on the potential employment impact of renewables expansion makes it particularly hard to assess the quantity of skilled, semi-skilled, and unskilled personnel that might be needed.

Key findings in renewable energy employment

The findings comprise (a) that the majority of employment in the renewable sector is contract based, and that employees do not benefit from permanent jobs or security. (b) Continuous work in the industry has the potential to decrease poverty. (c) Most poor citizens encounter obstacles to entry-level training and the employment market due to lack of awareness about the jobs and the requirements. (d) Few renewable programs incorporate developing ownership opportunities for the citizens and the incorporation of women in the sector. (e) The inadequacy of data makes it challenging to build relationships between employment in renewable energy and poverty mitigation.

Recommendations for renewable energy employment

When building the capacity, focus on poor people and individuals to empower them with training in operation and maintenance.

Develop and offer training programs for citizens with minimal education and training, who do not fit current programs, which restrict them from working in renewable areas.

Include women in the renewable workforce by providing localized training.

Establish connections between training institutes and renewable power companies to guarantee that (a) trained workers are placed in appropriate positions during and after the completion of the training program and (b) training programs match the requirements of the renewable sector.

Poverty impact assessments might be embedded in program design to know how programs motivate poverty reduction, whether and how they influence the community.

Allow people to have a sense of ownership in renewable projects because this could contribute to the growth of the sector.

The details of the job being offered (part time, full time, contract-based), the levels of required skills for the job (skilled, semi-skilled and unskilled), the socio-economic status of the employee data need to be collected for further analysis.

Conduct investigations, assisted by field surveys, to learn about the influence of renewable energy jobs on poverty mitigation and differences in the standard of living.

Challenges faced by renewable energy in India

The MNRE has been taking dedicated measures for improving the renewable sector, and its efforts have been satisfactory in recognizing various obstacles.

Policy and regulatory obstacles

A comprehensive policy statement (regulatory framework) is not available in the renewable sector. When there is a requirement to promote the growth of particular renewable energy technologies, policies might be declared that do not match with the plans for the development of renewable energy.

The regulatory framework and procedures are different for every state because they define the respective RPOs (Renewable Purchase Obligations) and this creates a higher risk of investments in this sector. Additionally, the policies are applicable for just 5 years, and the generated risk for investments in this sector is apparent. The biomass sector does not have an established framework.

Incentive accelerated depreciation (AD) is provided to wind developers and is evident in developing India’s wind-producing capacity. Wind projects installed more than 10 years ago show that they are not optimally maintained. Many owners of the asset have built with little motivation for tax benefits only. The policy framework does not require the maintenance of the wind projects after the tax advantages have been claimed. There is no control over the equipment suppliers because they undertake all wind power plant development activities such as commissioning, operation, and maintenance. Suppliers make the buyers pay a premium and increase the equipment cost, which brings burden to the buyer.

Furthermore, ready-made projects are sold to buyers. The buyers are susceptible to this trap to save income tax. Foreign investors hesitate to invest because they are exempted from the income tax.

Every state has different regulatory policy and framework definitions of an RPO. The RPO percentage specified in the regulatory framework for various renewable sources is not precise.

RPO allows the SERCs and certain private firms to procure only a part of their power demands from renewable sources.

RPO is not imposed on open access (OA) and captive consumers in all states except three.

RPO targets and obligations are not clear, and the RPO compliance cell has just started on 22.05.2018 to collect the monthly reports on compliance and deal with non-compliance issues with appropriate authorities.

Penalty mechanisms are not specified and only two states in India (Maharashtra and Rajasthan) have some form of penalty mechanisms.

The parameter to determine the tariff is not transparent in the regulatory framework and many SRECs have established a tariff for limited periods. The FiT is valid for only 5 years, and this affects the bankability of the project.

Many SERCs have not decided on adopting the CERC tariff that is mentioned in CERCs regulations that deal with terms and conditions for tariff determinations. The SERCs have considered the plant load factor (PLF) because it varies across regions and locations as well as particular technology. The current framework does not fit to these issues.

Third party sale (TPS) is not allowed because renewable generators are not allowed to sell power to commercial consumers. They have to sell only to industrial consumers. The industrial consumers have a low tariff and commercial consumers have a high tariff, and SRCS do not allow OA. This stops the profit for the developers and investors.

Institutional obstacles

Institutes, agencies stakeholders who work under the conditions of the MNRE show poor inter-institutional coordination. The progress in renewable energy development is limited by this lack of cooperation, coordination, and delays. The delay in implementing policies due to poor coordination, decrease the interest of investors to invest in this sector.

The single window project approval and clearance system is not very useful and not stable because it delays the receiving of clearances for the projects ends in the levy of a penalty on the project developer.

Pre-feasibility reports prepared by concerned states have some deficiency, and this may affect the small developers, i.e., the local developers, who are willing to execute renewable projects.

The workforce in institutes, agencies, and ministries is not sufficient in numbers.

Proper or well-established research centers are not available for the development of renewable infrastructure.

Customer care centers to guide developers regarding renewable projects are not available.

Standards and quality control orders have been issued recently in 2018 and 2019 only, and there are insufficient institutions and laboratories to give standards/certification and validate the quality and suitability of using renewable technology.

Financial and fiscal obstacles

There are a few budgetary constraints such as fund allocation, and budgets that are not released on time to fulfill the requirement of developing the renewable sector.

The initial unit capital costs of renewable projects are very high compared to fossil fuels, and this leads to financing challenges and initial burden.

There are uncertainties related to the assessment of resources, lack of technology awareness, and high-risk perceptions which lead to financial barriers for the developers.

The subsidies and incentives are not transparent, and the ministry might reconsider subsidies for renewable energy because there was a sharp fall in tariffs in 2018.

Power purchase agreements (PPA) signed between the power purchaser and power generators on pre-determined fixed tariffs are higher than the current bids (Economic survey 2017–2018 and union budget on the 01.02.2019). For example, solar power tariff dropped to 2.44 INR (0. 04 USD) per unit in May 2017, wind power INR 3.46 per unit in February 2017, and 2.64 INR per unit in October 2017.

Investors feel that there is a risk in the renewable sector as this sector has lower gross returns even though these returns are relatively high within the market standards.

There are not many developers who are interested in renewable projects. While newly established developers (small and local developers) do not have much of an institutional track record or financial input, which are needed to develop the project (high capital cost). Even moneylenders consider it risky and are not ready to provide funding. Moneylenders look exclusively for contractors who have much experience in construction, well-established suppliers with proven equipment and operators who have more experience.

If the performance of renewable projects, which show low-performance, faces financial obstacles, they risks the lack of funding of renewable projects.

Financial institutions such as government banks or private banks do not have much understanding or expertise in renewable energy projects, and this imposes financial barriers to the projects.

Delay in payment by the SERCs to the developers imposes debt burden on the small and local developers because moneylenders always work with credit enhancement mechanisms or guarantee bonds signed between moneylenders and the developers.

Market obstacles

Subsidies are adequately provided to conventional fossil fuels, sending the wrong impression that power from conventional fuels is of a higher priority than that from renewables (unfair structure of subsidies)

There are four renewable markets in India, the government market (providing budgetary support to projects and purchase the output of the project), the government-driven market (provide budgetary support or fiscal incentives to promote renewable energy), the loan market (taking loan to finance renewable based applications), and the cash market (buying renewable-based applications to meet personal energy needs by individuals). There is an inadequacy in promoting the loan market and cash market in India.

The biomass market is facing a demand-supply gap which results in a continuous and dramatic increase in biomass prices because the biomass supply is unreliable (and, as there is no organized market for fuel), and the price fluctuations are very high. The type of biomass is not the same in all the states of India, and therefore demand and price elasticity is high for biomass.

Renewable power was calculated based on cost-plus methods (adding direct material cost, direct labor cost, and product overhead cost). This does not include environmental cost and shields the ecological benefits of clean and green energy.

There is an inadequate evacuation infrastructure and insufficient integration of the grid, which affects the renewable projects. SERCs are not able to use all generated power to meet the needs because of the non-availability of a proper evacuation infrastructure. This has an impact on the project, and the SERCs are forced to buy expensive power from neighbor states to fulfill needs.

Extending transmission lines is not possible/not economical for small size projects, and the seasonality of generation from such projects affect the market.

There are few limitations in overall transmission plans, distribution CapEx plans, and distribution licenses for renewable power. Power evacuation infrastructure for renewable energy is not included in the plans.

Even though there is an increase in capacity for the commercially deployed renewable energy technology, there is no decline in capital cost. This cost of power also remains high. The capital cost quoted by the developers and providers of equipment is too high due to exports of machinery, inadequate built up capacity, and cartelization of equipment suppliers (suppliers join together to control prices and limit competition).

There is no adequate supply of land, for wind, solar, and solar thermal power plants, which lead to poor capacity addition in many states.

Technological obstacles

Every installation of a renewable project contributes to complex risk challenges from environmental uncertainties, natural disasters, planning, equipment failure, and profit loss.

MNRE issued the standardization of renewable energy projects policy on the 11th of December 2017 (testing, standardization, and certification). They are still at an elementary level as compared to international practices. Quality assurance processes are still under starting conditions. Each success in renewable energy is based on concrete action plans for standards, testing and certification of performance.

The quality and reliability of manufactured components, imported equipment, and subsystems is essential, and hence quality infrastructure should be established. There is no clear document related to testing laboratories, referral institutes, review mechanism, inspection, and monitoring.

There are not many R&D centers for renewables. Methods to reduce the subsidies and invest in R&D lagging; manufacturing facilities are just replicating the already available technologies. The country is dependent on international suppliers for equipment and technology. Spare parts are not manufactured locally and hence they are scarce.

Awareness, education, and training obstacles

There is an unavailability of appropriately skilled human resources in the renewable energy sector. Furthermore, it faces an acute workforce shortage.

After installation of renewable project/applications by the suppliers, there is no proper follow-up or assistance for the workers in the project to perform maintenance. Likewise, there are not enough trained and skilled persons for demonstrating, training, operation, and maintenance of the plant.

There is inadequate knowledge in renewables, and no awareness programs are available to the general public. The lack of awareness about the technologies is a significant obstacle in acquiring vast land for constructing the renewable plant. Moreover, people using agriculture lands are not prepared to give their land to construct power plants because most Indians cultivate plants.

The renewable sector depends on the climate, and this varying climate also imposes less popularity of renewables among the people.

The per capita income is low, and the people consider that the cost of renewables might be high and they might not be able to use renewables.

The storage system increases the cost of renewables, and people believe it too costly and are not ready to use them.

The environmental benefits of renewable technologies are not clearly understood by the people and negative perceptions are making renewable technologies less prevalent among them.

Environmental obstacles

A single wind turbine does not occupy much space, but many turbines are placed five to ten rotor diameters from each other, and this occupies more area, which include roads and transmission lines.

In the field of offshore wind, the turbines and blades are bigger than onshore wind turbines, and they require a substantial amount of space. Offshore installations affect ocean activities (fishing, sand extraction, gravel extraction, oil extraction, gas extraction, aquaculture, and navigation). Furthermore, they affect fish and other marine wildlife.

Wind turbines influence wildlife (birds and bats) because of the collisions with them and due to air pressure changes caused by wind turbines and habitat disruption. Making wind turbines motionless during times of low wind can protect birds and bats but is not practiced.

Sound (aerodynamic, mechanical) and visual impacts are associated with wind turbines. There is poor practice by the wind turbine developers regarding public concerns. Furthermore, there are imperfections in surfaces and sound—absorbent material which decrease the noise from turbines. The shadow flicker effect is not taken as severe environmental impact by the developers.

Sometimes wind turbine material production, transportation of materials, on-site construction, assembling, operation, maintenance, dismantlement, and decommissioning may be associated with global warming, and there is a lag in this consideration.

Large utility-scale solar plants require vast lands that increase the risk of land degradation and loss of habitat.

The PV cell manufacturing process includes hazardous chemicals such as 1-1-1 Trichloroethene, HCL, H 2 SO 4 , N 2 , NF, and acetone. Workers face risks resulting from inhaling silicon dust. The manufacturing wastes are not disposed of properly. Proper precautions during usage of thin-film PV cells, which contain cadmium—telluride, gallium arsenide, and copper-indium-gallium-diselenide are missing. These materials create severe public health threats and environmental threats.

Hydroelectric power turbine blades kill aquatic ecosystems (fish and other organisms). Moreover, algae and other aquatic weeds are not controlled through manual harvesting or by introducing fish that can eat these plants.

Discussion and recommendations based on the research

Policy and regulation advancements.

The MNRE should provide a comprehensive action plan or policy for the promotion of the renewable sector in its regulatory framework for renewables energy. The action plan can be prepared in consultation with SERCs of the country within a fixed timeframe and execution of the policy/action plan.

The central and state government should include a “Must run status” in their policy and follow it strictly to make use of renewable power.

A national merit order list for renewable electricity generation will reduce power cost for the consumers. Such a merit order list will help in ranking sources of renewable energy in an ascending order of price and will provide power at a lower cost to each distribution company (DISCOM). The MNRE should include that principle in its framework and ensure that SERCs includes it in their regulatory framework as well.

SERCs might be allowed to remove policies and regulatory uncertainty surrounding renewable energy. SERCs might be allowed to identify the thrust areas of their renewable energy development.

There should be strong initiatives from municipality (local level) approvals for renewable energy-based projects.

Higher market penetration is conceivable only if their suitable codes and standards are adopted and implemented. MNRE should guide minimum performance standards, which incorporate reliability, durability, and performance.

A well-established renewable energy certificates (REC) policy might contribute to an efficient funding mechanism for renewable energy projects. It is necessary for the government to look at developing the REC ecosystem.

The regulatory administration around the RPO needs to be upgraded with a more efficient “carrot and stick” mechanism for obligated entities. A regulatory mechanism that both remunerations compliance and penalizes for non-compliance may likely produce better results.

RECs in India should only be traded on exchange. Over-the-counter (OTC) or off-exchange trading will potentially allow greater participation in the market. A REC forward curve will provide further price determination to the market participants.

The policymakers should look at developing and building the REC market.

Most states have defined RPO targets. Still, due to the absence of implemented RPO regulations and the inadequacy of penalties when obligations are not satisfied, several of the state DISCOMs are not complying completely with their RPO targets. It is necessary that all states adhere to the RPO targets set by respective SERCs.

The government should address the issues such as DISCOM financials, must-run status, problems of transmission and evacuation, on-time payments and payment guarantees, and deemed generation benefits.

Proper incentives should be devised to support utilities to obtain power over and above the RPO mandated by the SERC.

The tariff orders/FiTs must be consistent and not restricted for a few years.

Transmission requirements

The developers are worried that transmission facilities are not keeping pace with the power generation. Bays at the nearest substations are occupied, and transmission lines are already carrying their full capacity. This is due to the lack of coordination between MNRE and the Power Grid Corporation of India (PGCIL) and CEA. Solar Corporation of India (SECI) is holding auctions for both wind and solar projects without making sure that enough evacuation facilities are available. There is an urgent need to make evacuation plans.

The solution is to develop numerous substations and transmission lines, but the process will take considerably longer time than the currently under-construction projects take to get finished.

In 2017–2018, transmission lines were installed under the green energy corridor project by the PGCIL, with 1900 circuit km targeted in 2018–2019. The implementation of the green energy corridor project explicitly meant to connect renewable energy plants to the national grid. The budget allocation of INR 6 billion for 2018–2019 should be increased to higher values.

The mismatch between MNRE and PGCIL, which are responsible for inter-state transmission, should be rectified.

State transmission units (STUs) are responsible for the transmission inside the states, and their fund requirements to cover the evacuation and transmission infrastructure for renewable energy should be fulfilled. Moreover, STUs should be penalized if they fail to fulfill their responsibilities.

The coordination and consultation between the developers (the nodal agency responsible for the development of renewable energy) and STUs should be healthy.

Financing the renewable sector

The government should provide enough budget for the clean energy sector. China’s annual budget for renewables is 128 times higher than India’s. In 2017, China spent USD 126.6 billion (INR 9 lakh crore) compared to India’s USD 10.9 billion (INR 75500 crore). In 2018, budget allocations for grid interactive wind and solar have increased but it is not sufficient to meet the renewable target.

The government should concentrate on R&D and provide a surplus fund for R&D. In 2017, the budget allotted was an INR 445 crore, which was reduced to an INR 272.85 crore in 2016. In 2017–2018, the initial allocation was an INR 144 crore that was reduced to an INR 81 crore during the revised estimates. Even the reduced amounts could not be fully used, there is an urgent demand for regular monitoring of R&D and the budget allocation.

The Goods and Service Tax (GST) that was introduced in 2017 worsened the industry performance and has led to an increase in costs and poses a threat to the viability of the ongoing projects, ultimately hampering the target achievement. These GST issues need to be addressed.

Including the renewable sector as a priority sector would increase the availability of credit and lead to a more substantial participation by commercial banks.

Mandating the provident funds and insurance companies to invest the fixed percentage of their portfolio into the renewable energy sector.

Banks should allow an interest rebate on housing loans if the owner is installing renewable applications such as solar lights, solar water heaters, and PV panels in his house. This will encourage people to use renewable energy. Furthermore, income tax rebates also can be given to individuals if they are implementing renewable energy applications.

Improvement in manufacturing/technology

The country should move to domestic manufacturing. It imports 90% of its solar cell and module requirements from Malaysia, China, and Taiwan, so it is essential to build a robust domestic manufacturing basis.

India will provide “safeguard duty” for merely 2 years, and this is not adequate to build a strong manufacturing basis that can compete with the global market. Moreover, safeguard duty would work only if India had a larger existing domestic manufacturing base.

The government should reconsider the safeguard duty. Many foreign companies desiring to set up joint ventures in India provide only a lukewarm response because the given order in its current form presents inadequate safeguards.

There are incremental developments in technology at regular periods, which need capital, and the country should discover a way to handle these factors.

To make use of the vast estimated renewable potential in India, the R&D capability should be upgraded to solve critical problems in the clean energy sector.

A comprehensive policy for manufacturing should be established. This would support capital cost reduction and be marketed on a global scale.

The country should initiate an industry-academia partnership, which might promote innovative R&D and support leading-edge clean power solutions to protect the globe for future generations.

Encourage the transfer of ideas between industry, academia, and policymakers from around the world to develop accelerated adoption of renewable power.

Awareness about renewables

Social recognition of renewable energy is still not very promising in urban India. Awareness is the crucial factor for the uniform and broad use of renewable energy. Information about renewable technology and their environmental benefits should reach society.

The government should regularly organize awareness programs throughout the country, especially in villages and remote locations such as the islands.

The government should open more educational/research organizations, which will help in spreading knowledge of renewable technology in society.

People should regularly be trained with regard to new techniques that would be beneficial for the community.

Sufficient agencies should be available to sell renewable products and serve for technical support during installation and maintenance.

Development of the capabilities of unskilled and semiskilled workers and policy interventions are required related to employment opportunities.

An increase in the number of qualified/trained personnel might immediately support the process of installations of renewables.

Renewable energy employers prefer to train employees they recruit because they understand that education institutes fail to give the needed and appropriate skills. The training institutes should rectify this issue. Severe trained human resources shortages should be eliminated.

Upgrading the ability of the existing workforce and training of new professionals is essential to achieve the renewable goal.

Hybrid utilization of renewables

The country should focus on hybrid power projects for an effective use of transmission infrastructure and land.

India should consider battery storage in hybrid projects, which support optimizing the production and the power at competitive prices as well as a decrease of variability.

Formulate mandatory standards and regulations for hybrid systems, which are lagging in the newly announced policies (wind-solar hybrid policy on 14.05.2018).

The hybridization of two or more renewable systems along with the conventional power source battery storage can increase the performance of renewable technologies.

Issues related to sizing and storage capacity should be considered because they are key to the economic viability of the system.

Fiscal and financial incentives available for hybrid projects should be increased.

The renewable sector suffers notable obstacles. Some of them are inherent in every renewable technology; others are the outcome of a skewed regulative structure and marketplace. The absence of comprehensive policies and regulation frameworks prevent the adoption of renewable technologies. The renewable energy market requires explicit policies and legal procedures to enhance the attention of investors. There is a delay in the authorization of private sector projects because of a lack of clear policies. The country should take measures to attract private investors. Inadequate technology and the absence of infrastructure required to establish renewable technologies should be overcome by R&D. The government should allow more funds to support research and innovation activities in this sector. There are insufficiently competent personnel to train, demonstrate, maintain, and operate renewable energy structures and therefore, the institutions should be proactive in preparing the workforce. Imported equipment is costly compared to that of locally manufactured; therefore, generation of renewable energy becomes expensive and even unaffordable. Hence, to decrease the cost of renewable products, the country should become involve in the manufacturing of renewable products. Another significant infrastructural obstacle to the development of renewable energy technologies is unreliable connectivity to the grid. As a consequence, many investors lose their faith in renewable energy technologies and are not ready to invest in them for fear of failing. India should work on transmission and evacuation plans.

Inadequate servicing and maintenance of facilities and low reliability in technology decreases customer trust in some renewable energy technologies and hence prevent their selection. Adequate skills to repair/service the spare parts/equipment are required to avoid equipment failures that halt the supply of energy. Awareness of renewable energy among communities should be fostered, and a significant focus on their socio-cultural practices should be considered. Governments should support investments in the expansion of renewable energy to speed up the commercialization of such technologies. The Indian government should declare a well-established fiscal assistance plan, such as the provision of credit, deduction on loans, and tariffs. The government should improve regulations making obligations under power purchase agreements (PPAs) statutorily binding to guarantee that all power DISCOMs have PPAs to cover a hundred percent of their RPO obligation. To accomplish a reliable system, it is strongly suggested that renewables must be used in a hybrid configuration of two or more resources along with conventional source and storage devices. Regulatory authorities should formulate the necessary standards and regulations for hybrid systems. Making investments economically possible with effective policies and tax incentives will result in social benefits above and beyond the economic advantages.

Availability of data and materials

Not applicable.

Abbreviations

Accelerated depreciation

Billion units

Central Electricity Authority of India

Central electricity regulatory commission

Central financial assistance

Expression of interest

Foreign direct investment

Feed-in-tariff

Ministry of new and renewable energy

Research and development

Renewable purchase obligations

State electricity regulatory

Small hydropower

Terawatt hours

Waste to energy

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Kumar. J, C.R., Majid, M.A. Renewable energy for sustainable development in India: current status, future prospects, challenges, employment, and investment opportunities. Energ Sustain Soc 10 , 2 (2020). https://doi.org/10.1186/s13705-019-0232-1

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Introduction, 1 installed capacity and application of solar energy worldwide, 2 the role of solar energy in sustainable development, 3 the perspective of solar energy, 4 conclusions, conflict of interest statement.

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Ali O M Maka, Jamal M Alabid, Solar energy technology and its roles in sustainable development, Clean Energy , Volume 6, Issue 3, June 2022, Pages 476–483, https://doi.org/10.1093/ce/zkac023

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Solar energy is environmentally friendly technology, a great energy supply and one of the most significant renewable and green energy sources. It plays a substantial role in achieving sustainable development energy solutions. Therefore, the massive amount of solar energy attainable daily makes it a very attractive resource for generating electricity. Both technologies, applications of concentrated solar power or solar photovoltaics, are always under continuous development to fulfil our energy needs. Hence, a large installed capacity of solar energy applications worldwide, in the same context, supports the energy sector and meets the employment market to gain sufficient development. This paper highlights solar energy applications and their role in sustainable development and considers renewable energy’s overall employment potential. Thus, it provides insights and analysis on solar energy sustainability, including environmental and economic development. Furthermore, it has identified the contributions of solar energy applications in sustainable development by providing energy needs, creating jobs opportunities and enhancing environmental protection. Finally, the perspective of solar energy technology is drawn up in the application of the energy sector and affords a vision of future development in this domain.

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With reference to the recommendations of the UN, the Climate Change Conference, COP26, was held in Glasgow , UK, in 2021. They reached an agreement through the representatives of the 197 countries, where they concurred to move towards reducing dependency on coal and fossil-fuel sources. Furthermore, the conference stated ‘the various opportunities for governments to prioritize health and equity in the international climate movement and sustainable development agenda’. Also, one of the testaments is the necessity to ‘create energy systems that protect and improve climate and health’ [ 1 , 2 ].

The Paris Climate Accords is a worldwide agreement on climate change signed in 2015, which addressed the mitigation of climate change, adaptation and finance. Consequently, the representatives of 196 countries concurred to decrease their greenhouse gas emissions [ 3 ]. The Paris Agreement is essential for present and future generations to attain a more secure and stable environment. In essence, the Paris Agreement has been about safeguarding people from such an uncertain and progressively dangerous environment and ensuring everyone can have the right to live in a healthy, pollutant-free environment without the negative impacts of climate change [ 3 , 4 ].

In recent decades, there has been an increase in demand for cleaner energy resources. Based on that, decision-makers of all countries have drawn up plans that depend on renewable sources through a long-term strategy. Thus, such plans reduce the reliance of dependence on traditional energy sources and substitute traditional energy sources with alternative energy technology. As a result, the global community is starting to shift towards utilizing sustainable energy sources and reducing dependence on traditional fossil fuels as a source of energy [ 5 , 6 ].

In 2015, the UN adopted the sustainable development goals (SDGs) and recognized them as international legislation, which demands a global effort to end poverty, safeguard the environment and guarantee that by 2030, humanity lives in prosperity and peace. Consequently, progress needs to be balanced among economic, social and environmental sustainability models [ 7 ].

Many national and international regulations have been established to control the gas emissions and pollutants that impact the environment [ 8 ]. However, the negative effects of increased carbon in the atmosphere have grown in the last 10 years. Production and use of fossil fuels emit methane (CH 4 ), carbon dioxide (CO 2 ) and carbon monoxide (CO), which are the most significant contributors to environmental emissions on our planet. Additionally, coal and oil, including gasoline, coal, oil and methane, are commonly used in energy for transport or for generating electricity. Therefore, burning these fossil fuel s is deemed the largest emitter when used for electricity generation, transport, etc. However, these energy resources are considered depleted energy sources being consumed to an unsustainable degree [ 9–11 ].

Energy is an essential need for the existence and growth of human communities. Consequently, the need for energy has increased gradually as human civilization has progressed. Additionally, in the past few decades, the rapid rise of the world’s population and its reliance on technological developments have increased energy demands. Furthermore, green technology sources play an important role in sustainably providing energy supplies, especially in mitigating climate change [ 5 , 6 , 8 ].

Currently, fossil fuels remain dominant and will continue to be the primary source of large-scale energy for the foreseeable future; however, renewable energy should play a vital role in the future of global energy. The global energy system is undergoing a movement towards more sustainable sources of energy [ 12 , 13 ].

Power generation by fossil-fuel resources has peaked, whilst solar energy is predicted to be at the vanguard of energy generation in the near future. Moreover, it is predicted that by 2050, the generation of solar energy will have increased to 48% due to economic and industrial growth [ 13 , 14 ].

In recent years, it has become increasingly obvious that the globe must decrease greenhouse gas emissions by 2050, ideally towards net zero, if we are to fulfil the Paris Agreement’s goal to reduce global temperature increases [ 3 , 4 ]. The net-zero emissions complement the scenario of sustainable development assessment by 2050. According to the agreed scenario of sustainable development, many industrialized economies must achieve net-zero emissions by 2050. However, the net-zero emissions 2050 brought the first detailed International Energy Agency (IEA) modelling of what strategy will be required over the next 10 years to achieve net-zero carbon emissions worldwide by 2050 [ 15–17 ].

The global statistics of greenhouse gas emissions have been identified; in 2019, there was a 1% decrease in CO 2 emissions from the power industry; that figure dropped by 7% in 2020 due to the COVID-19 crisis, thus indicating a drop in coal-fired energy generation that is being squeezed by decreasing energy needs, growth of renewables and the shift away from fossil fuels. As a result, in 2020, the energy industry was expected to generate ~13 Gt CO 2 , representing ~40% of total world energy sector emissions related to CO 2 . The annual electricity generation stepped back to pre-crisis levels by 2021, although due to a changing ‘fuel mix’, the CO 2 emissions in the power sector will grow just a little before remaining roughly steady until 2030 [ 15 ].

Therefore, based on the information mentioned above, the advantages of solar energy technology are a renewable and clean energy source that is plentiful, cheaper costs, less maintenance and environmentally friendly, to name but a few. The significance of this paper is to highlight solar energy applications to ensure sustainable development; thus, it is vital to researchers, engineers and customers alike. The article’s primary aim is to raise public awareness and disseminate the culture of solar energy usage in daily life, since moving forward, it is the best. The scope of this paper is as follows. Section 1 represents a summary of the introduction. Section 2 represents a summary of installed capacity and the application of solar energy worldwide. Section 3 presents the role of solar energy in the sustainable development and employment of renewable energy. Section 4 represents the perspective of solar energy. Finally, Section 5 outlines the conclusions and recommendations for future work.

1.1 Installed capacity of solar energy

The history of solar energy can be traced back to the seventh century when mirrors with solar power were used. In 1893, the photovoltaic (PV) effect was discovered; after many decades, scientists developed this technology for electricity generation [ 18 ]. Based on that, after many years of research and development from scientists worldwide, solar energy technology is classified into two key applications: solar thermal and solar PV.

PV systems convert the Sun’s energy into electricity by utilizing solar panels. These PV devices have quickly become the cheapest option for new electricity generation in numerous world locations due to their ubiquitous deployment. For example, during the period from 2010 to 2018, the cost of generating electricity by solar PV plants decreased by 77%. However, solar PV installed capacity progress expanded 100-fold between 2005 and 2018. Consequently, solar PV has emerged as a key component in the low-carbon sustainable energy system required to provide access to affordable and dependable electricity, assisting in fulfilling the Paris climate agreement and in achieving the 2030 SDG targets [ 19 ].

The installed capacity of solar energy worldwide has been rapidly increased to meet energy demands. The installed capacity of PV technology from 2010 to 2020 increased from 40 334 to 709 674 MW, whereas the installed capacity of concentrated solar power (CSP) applications, which was 1266 MW in 2010, after 10 years had increased to 6479 MW. Therefore, solar PV technology has more deployed installations than CSP applications. So, the stand-alone solar PV and large-scale grid-connected PV plants are widely used worldwide and used in space applications. Fig. 1 represents the installation of solar energy worldwide.

Installation capacity of solar energy worldwide [20].

Installation capacity of solar energy worldwide [ 20 ].

1.2 Application of solar energy

Energy can be obtained directly from the Sun—so-called solar energy. Globally, there has been growth in solar energy applications, as it can be used to generate electricity, desalinate water and generate heat, etc. The taxonomy of applications of solar energy is as follows: (i) PVs and (ii) CSP. Fig. 2 details the taxonomy of solar energy applications.

The taxonomy of solar energy applications.

The taxonomy of solar energy applications.

Solar cells are devices that convert sunlight directly into electricity; typical semiconductor materials are utilized to form a PV solar cell device. These materials’ characteristics are based on atoms with four electrons in their outer orbit or shell. Semiconductor materials are from the periodic table’s group ‘IV’ or a mixture of groups ‘IV’ and ‘II’, the latter known as ‘II–VI’ semiconductors [ 21 ]. Additionally, a periodic table mixture of elements from groups ‘III’ and ‘V’ can create ‘III–V’ materials [ 22 ].

PV devices, sometimes called solar cells, are electronic devices that convert sunlight into electrical power. PVs are also one of the rapidly growing renewable-energy technologies of today. It is therefore anticipated to play a significant role in the long-term world electricity-generating mixture moving forward.

Solar PV systems can be incorporated to supply electricity on a commercial level or installed in smaller clusters for mini-grids or individual usage. Utilizing PV modules to power mini-grids is a great way to offer electricity to those who do not live close to power-transmission lines, especially in developing countries with abundant solar energy resources. In the most recent decade, the cost of producing PV modules has dropped drastically, giving them not only accessibility but sometimes making them the least expensive energy form. PV arrays have a 30-year lifetime and come in various shades based on the type of material utilized in their production.

The most typical method for solar PV desalination technology that is used for desalinating sea or salty water is electrodialysis (ED). Therefore, solar PV modules are directly connected to the desalination process. This technique employs the direct-current electricity to remove salt from the sea or salty water.

The technology of PV–thermal (PV–T) comprises conventional solar PV modules coupled with a thermal collector mounted on the rear side of the PV module to pre-heat domestic hot water. Accordingly, this enables a larger portion of the incident solar energy on the collector to be converted into beneficial electrical and thermal energy.

A zero-energy building is a building that is designed for zero net energy emissions and emits no carbon dioxide. Building-integrated PV (BIPV) technology is coupled with solar energy sources and devices in buildings that are utilized to supply energy needs. Thus, building-integrated PVs utilizing thermal energy (BIPV/T) incorporate creative technologies such as solar cooling [ 23 ].

A PV water-pumping system is typically used to pump water in rural, isolated and desert areas. The system consists of PV modules to power a water pump to the location of water need. The water-pumping rate depends on many factors such as pumping head, solar intensity, etc.

A PV-powered cathodic protection (CP) system is designed to supply a CP system to control the corrosion of a metal surface. This technique is based on the impressive current acquired from PV solar energy systems and is utilized for burying pipelines, tanks, concrete structures, etc.

Concentrated PV (CPV) technology uses either the refractive or the reflective concentrators to increase sunlight to PV cells [ 24 , 25 ]. High-efficiency solar cells are usually used, consisting of many layers of semiconductor materials that stack on top of each other. This technology has an efficiency of >47%. In addition, the devices produce electricity and the heat can be used for other purposes [ 26 , 27 ].

For CSP systems, the solar rays are concentrated using mirrors in this application. These rays will heat a fluid, resulting in steam used to power a turbine and generate electricity. Large-scale power stations employ CSP to generate electricity. A field of mirrors typically redirect rays to a tall thin tower in a CSP power station. Thus, numerous large flat heliostats (mirrors) are used to track the Sun and concentrate its light onto a receiver in power tower systems, sometimes known as central receivers. The hot fluid could be utilized right away to produce steam or stored for later usage. Another of the great benefits of a CSP power station is that it may be built with molten salts to store heat and generate electricity outside of daylight hours.

Mirrored dishes are used in dish engine systems to focus and concentrate sunlight onto a receiver. The dish assembly tracks the Sun’s movement to capture as much solar energy as possible. The engine includes thin tubes that work outside the four-piston cylinders and it opens into the cylinders containing hydrogen or helium gas. The pistons are driven by the expanding gas. Finally, the pistons drive an electric generator by turning a crankshaft.

A further water-treatment technique, using reverse osmosis, depends on the solar-thermal and using solar concentrated power through the parabolic trough technique. The desalination employs CSP technology that utilizes hybrid integration and thermal storage allows continuous operation and is a cost-effective solution. Solar thermal can be used for domestic purposes such as a dryer. In some countries or societies, the so-called food dehydration is traditionally used to preserve some food materials such as meats, fruits and vegetables.

Sustainable energy development is defined as the development of the energy sector in terms of energy generating, distributing and utilizing that are based on sustainability rules [ 28 ]. Energy systems will significantly impact the environment in both developed and developing countries. Consequently, the global sustainable energy system must optimize efficiency and reduce emissions [ 29 ].

The sustainable development scenario is built based on the economic perspective. It also examines what activities will be required to meet shared long-term climate benefits, clean air and energy access targets. The short-term details are based on the IEA’s sustainable recovery strategy, which aims to promote economies and employment through developing a cleaner and more reliable energy infrastructure [ 15 ]. In addition, sustainable development includes utilizing renewable-energy applications, smart-grid technologies, energy security, and energy pricing, and having a sound energy policy [ 29 ].

The demand-side response can help meet the flexibility requirements in electricity systems by moving demand over time. As a result, the integration of renewable technologies for helping facilitate the peak demand is reduced, system stability is maintained, and total costs and CO 2 emissions are reduced. The demand-side response is currently used mostly in Europe and North America, where it is primarily aimed at huge commercial and industrial electricity customers [ 15 ].

International standards are an essential component of high-quality infrastructure. Establishing legislative convergence, increasing competition and supporting innovation will allow participants to take part in a global world PV market [ 30 ]. Numerous additional countries might benefit from more actively engaging in developing global solar PV standards. The leading countries in solar PV manufacturing and deployment have embraced global standards for PV systems and highly contributed to clean-energy development. Additional assistance and capacity-building to enhance quality infrastructure in developing economies might also help support wider implementation and compliance with international solar PV standards. Thus, support can bring legal requirements and frameworks into consistency and give additional impetus for the trade of secure and high-quality solar PV products [ 19 ].

Continuous trade-led dissemination of solar PV and other renewable technologies will strengthen the national infrastructure. For instance, off-grid solar energy alternatives, such as stand-alone systems and mini-grids, could be easily deployed to assist healthcare facilities in improving their degree of services and powering portable testing sites and vaccination coolers. In addition to helping in the immediate medical crisis, trade-led solar PV adoption could aid in the improving economy from the COVID-19 outbreak, not least by providing jobs in the renewable-energy sector, which are estimated to reach >40 million by 2050 [ 19 ].

The framework for energy sustainability development, by the application of solar energy, is one way to achieve that goal. With the large availability of solar energy resources for PV and CSP energy applications, we can move towards energy sustainability. Fig. 3 illustrates plans for solar energy sustainability.

Framework for solar energy applications in energy sustainability.

Framework for solar energy applications in energy sustainability.

The environmental consideration of such applications, including an aspect of the environmental conditions, operating conditions, etc., have been assessed. It is clean, friendly to the environment and also energy-saving. Moreover, this technology has no removable parts, low maintenance procedures and longevity.

Economic and social development are considered by offering job opportunities to the community and providing cheaper energy options. It can also improve people’s income; in turn, living standards will be enhanced. Therefore, energy is paramount, considered to be the most vital element of human life, society’s progress and economic development.

As efforts are made to increase the energy transition towards sustainable energy systems, it is anticipated that the next decade will see a continued booming of solar energy and all clean-energy technology. Scholars worldwide consider research and innovation to be substantial drivers to enhance the potency of such solar application technology.

2.1 Employment from renewable energy

The employment market has also boomed with the deployment of renewable-energy technology. Renewable-energy technology applications have created >12 million jobs worldwide. The solar PV application came as the pioneer, which created >3 million jobs. At the same time, while the solar thermal applications (solar heating and cooling) created >819 000 jobs, the CSP attained >31 000 jobs [ 20 ].

According to the reports, although top markets such as the USA, the EU and China had the highest investment in renewables jobs, other Asian countries have emerged as players in the solar PV panel manufacturers’ industry [ 31 ].

Solar energy employment has offered more employment than other renewable sources. For example, in the developing countries, there was a growth in employment chances in solar applications that powered ‘micro-enterprises’. Hence, it has been significant in eliminating poverty, which is considered the key goal of sustainable energy development. Therefore, solar energy plays a critical part in fulfilling the sustainability targets for a better plant and environment [ 31 , 32 ]. Fig. 4 illustrates distributions of world renewable-energy employment.

World renewable-energy employment [20].

World renewable-energy employment [ 20 ].

The world distribution of PV jobs is disseminated across the continents as follows. There was 70% employment in PV applications available in Asia, while 10% is available in North America, 10% available in South America and 10% availability in Europe. Table 1 details the top 10 countries that have relevant jobs in Asia, North America, South America and Europe.

List of the top 10 countries that created jobs in solar PV applications [ 19 , 33 ]

Solar energy investments can meet energy targets and environmental protection by reducing carbon emissions while having no detrimental influence on the country’s development [ 32 , 34 ]. In countries located in the ‘Sunbelt’, there is huge potential for solar energy, where there is a year-round abundance of solar global horizontal irradiation. Consequently, these countries, including the Middle East, Australia, North Africa, China, the USA and Southern Africa, to name a few, have a lot of potential for solar energy technology. The average yearly solar intensity is >2800 kWh/m 2 and the average daily solar intensity is >7.5 kWh/m 2 . Fig. 5 illustrates the optimum areas for global solar irradiation.

World global solar irradiation map [35].

World global solar irradiation map [ 35 ].

The distribution of solar radiation and its intensity are two important factors that influence the efficiency of solar PV technology and these two parameters vary among different countries. Therefore, it is essential to realize that some solar energy is wasted since it is not utilized. On the other hand, solar radiation is abundant in several countries, especially in developing ones, which makes it invaluable [ 36 , 37 ].

Worldwide, the PV industry has benefited recently from globalization, which has allowed huge improvements in economies of scale, while vertical integration has created strong value chains: as manufacturers source materials from an increasing number of suppliers, prices have dropped while quality has been maintained. Furthermore, the worldwide incorporated PV solar device market is growing fast, creating opportunities enabling solar energy firms to benefit from significant government help with underwriting, subsides, beneficial trading licences and training of a competent workforce, while the increased rivalry has reinforced the motivation to continue investing in research and development, both public and private [ 19 , 33 ].

The global outbreak of COVID-19 has impacted ‘cross-border supply chains’ and those investors working in the renewable-energy sector. As a result, more diversity of solar PV supply-chain processes may be required in the future to enhance long-term flexibility versus exogenous shocks [ 19 , 33 ].

It is vital to establish a well-functioning quality infrastructure to expand the distribution of solar PV technologies beyond borders and make it easier for new enterprises to enter solar PV value chains. In addition, a strong quality infrastructure system is a significant instrument for assisting local firms in meeting the demands of trade markets. Furthermore, high-quality infrastructure can help reduce associated risks with the worldwide PV project value chain, such as underperforming, inefficient and failing goods, limiting the development, improvement and export of these technologies. Governments worldwide are, at various levels, creating quality infrastructure, including the usage of metrology i.e. the science of measurement and its application, regulations, testing procedures, accreditation, certification and market monitoring [ 33 , 38 ].

The perspective is based on a continuous process of technological advancement and learning. Its speed is determined by its deployment, which varies depending on the scenario [ 39 , 40 ]. The expense trends support policy preferences for low-carbon energy sources, particularly in increased energy-alteration scenarios. Emerging technologies are introduced and implemented as quickly as they ever have been before in energy history [ 15 , 33 ].

The CSP stations have been in use since the early 1980s and are currently found all over the world. The CSP power stations in the USA currently produce >800 MW of electricity yearly, which is sufficient to power ~500 000 houses. New CSP heat-transfer fluids being developed can function at ~1288 o C, which is greater than existing fluids, to improve the efficiency of CSP systems and, as a result, to lower the cost of energy generated using this technology. Thus, as a result, CSP is considered to have a bright future, with the ability to offer large-scale renewable energy that can supplement and soon replace traditional electricity-production technologies [ 41 ]. The DESERTEC project has drawn out the possibility of CSP in the Sahara Desert regions. When completed, this investment project will have the world’s biggest energy-generation capacity through the CSP plant, which aims to transport energy from North Africa to Europe [ 42 , 43 ].

The costs of manufacturing materials for PV devices have recently decreased, which is predicted to compensate for the requirements and increase the globe’s electricity demand [ 44 ]. Solar energy is a renewable, clean and environmentally friendly source of energy. Therefore, solar PV application techniques should be widely utilized. Although PV technology has always been under development for a variety of purposes, the fact that PV solar cells convert the radiant energy from the Sun directly into electrical power means it can be applied in space and in terrestrial applications [ 38 , 45 ].

In one way or another, the whole renewable-energy sector has a benefit over other energy industries. A long-term energy development plan needs an energy source that is inexhaustible, virtually accessible and simple to gather. The Sun rises over the horizon every day around the globe and leaves behind ~108–1018 kWh of energy; consequently, it is more than humanity will ever require to fulfil its desire for electricity [ 46 ].

The technology that converts solar radiation into electricity is well known and utilizes PV cells, which are already in use worldwide. In addition, various solar PV technologies are available today, including hybrid solar cells, inorganic solar cells and organic solar cells. So far, solar PV devices made from silicon have led the solar market; however, these PVs have certain drawbacks, such as expenditure of material, time-consuming production, etc. It is important to mention here the operational challenges of solar energy in that it does not work at night, has less output in cloudy weather and does not work in sandstorm conditions. PV battery storage is widely used to reduce the challenges to gain high reliability. Therefore, attempts have been made to find alternative materials to address these constraints. Currently, this domination is challenged by the evolution of the emerging generation of solar PV devices based on perovskite, organic and organic/inorganic hybrid materials.

This paper highlights the significance of sustainable energy development. Solar energy would help steady energy prices and give numerous social, environmental and economic benefits. This has been indicated by solar energy’s contribution to achieving sustainable development through meeting energy demands, creating jobs and protecting the environment. Hence, a paramount critical component of long-term sustainability should be investigated. Based on the current condition of fossil-fuel resources, which are deemed to be depleting energy sources, finding an innovative technique to deploy clean-energy technology is both essential and expected. Notwithstanding, solar energy has yet to reach maturity in development, especially CSP technology. Also, with growing developments in PV systems, there has been a huge rise in demand for PV technology applications all over the globe. Further work needs to be undertaken to develop energy sustainably and consider other clean energy resources. Moreover, a comprehensive experimental and validation process for such applications is required to develop cleaner energy sources to decarbonize our planet.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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ThembeThembe Diesel Vaache…

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Kara Bachat Dieselchi

Kra bachat dieselchi hoil pragati deshachi..

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VAPAR KARA, Vaapar Kara LED Light Cha Vaapar Kara.

वापर करा, वापर करा LED Light चा वापर करा.

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essay on renewable energy in marathi

This Is the Future: Essay on Renewable Energy

essay on renewable energy in marathi

Today the world population depends on nonrenewable energy resources. With the constantly growing demand for energy, natural gas, coal, and oil get used up and cannot replenish themselves. 

Aside from limited supply, heavy reliance on fossil fuels causes planetary-scale damage. Sea levels are rising. Heat-trapping carbon dioxide increased the warming effect by 45% from 1990 to 2019. The only way to tackle the crisis is to start the transition to renewable energy now. 

What is renewable energy? It is energy that comes from replenishable natural resources like sunlight, wind, thermal energy, moving water, and organic materials. Renewable resources do not run out. They are cost-efficient and renew faster than they are consumed. How does renewable energy save money? It creates new jobs, supports economic growth, and decreases inequitable fossil fuel subsidies. 

At the current rates of production, some fossil fuels will not even last another century. This is why the future depends on reliable and eco-friendly resources. This renewable energy essay examines the types and benefits of renewable energy and its role in creating a sustainable future.

Top 5 Types of Renewable Energy: The Apollo Alliance Rankings

There are many natural resources that can provide people with clean energy. To make a list of the five most booming types of renewable energy on the market today, this energy essay uses data gathered by the Apollo Alliance. It is a project that aims to revolutionize the energy sector of the US with a focus on clean energy. 

The Apollo Alliance unites businesses, community leaders, and environmental experts to support the transition to more sustainable and efficient living. Their expert opinion helped to compile information about the most common and cost-competitive sources of renewable energy. However, if you want to get some more in-depth research, you can entrust it to an essay writer . Here’s a quick overview of renewable energy resources that have a huge potential to substitute fossil fuels. 

Solar Renewable Energy

The most abundant and practically endless resource is solar energy. It can be turned into electricity by photovoltaic systems that convert radiant energy captured from sunlight. Solar farms could generate enough energy for thousands of homes.

An endless supply is the main benefit of solar energy. The rate at which the Earth receives it is 10,000 times greater than people can consume it, as a paper writer points out based on their analysis of research findings. It can substitute fossil fuels and deliver people electricity, hot water, cooling, heat, etc. 

The upfront investment in solar systems is rather expensive. This is one of the primary limitations that prevent businesses and households from switching to this energy source at once. However, the conclusion of solar energy is still favorable. In the long run, it can significantly decrease energy costs. Besides, solar panels are gradually becoming more affordable to manufacture and adopt, even at an individual level. 

Wind Renewable Energy

Another clean energy source is wind. Wind farms use the kinetic energy of wind flow to convert it into electricity. The Appolo Alliance notes that, unlike solar farms, they can’t be placed in any location. To stay cost-competitive, wind farms should operate in windy areas. Although not all countries have the right conditions to use them on a large scale, wind farms might be introduced for some energy diversity. The technical potential for it is still tremendous. 

Wind energy is clean and safe for the environment. It does not pollute the atmosphere with any harmful products compared to nonrenewable energy resources. 

The investment in wind energy is also economically wise. If you examine the cost of this energy resource in an essay on renewable resources, you’ll see that wind farms can deliver electricity at a price lower than nonrenewable resources. Besides, since wind isn’t limited, its cost won’t be influenced by the imbalance of supply and demand.

Geothermal Renewable Energy

Natural renewable resources are all around us, even beneath the ground. Geothermal energy can be produced from the thermal energy from the Earth’s interior. Sometimes heat reaches the surface naturally, for example, in the form of geysers. But it can also be used by geothermal power plants. The Earth’s heat gets captured and converted to steam that turns a turbine. As a result, we get geothermal energy.

This source provides a significant energy supply while having low emissions and no significant footprint on land. A factsheet and essay on renewable resources state that geothermal plants will increase electricity production from 17 billion kWh in 2020 to 49.8 billion kWh in 2050.

However, this method is not without limitations. While writing a renewable resources essay, consider that geothermal energy can be accessed only in certain regions. Geological hotspots are off-limits as they are vulnerable to earthquakes. Yet, the quantity of geothermal resources is likely to grow as technology advances. 

Ocean Renewable Energy

The kinetic and thermal energy of the ocean is a robust resource. Ocean power systems rely on:

  • Changes in sea level;
  • Wave energy;
  • Water surface temperatures;
  • The energy released from seawater and freshwater mixing.

Ocean energy is more predictable compared to other resources. As estimated by EPRI, it has the potential to produce 2640 TWh/yr. However, an important point to consider in a renewable energy essay is that the kinetic energy of the ocean varies. Yet, since it is ruled by the moon’s gravity, the resource is plentiful and continues to be attractive for the energy industry. 

Wave energy systems are still developing. The Apollo energy corporation explores many prototypes. It is looking for the most reliable and robust solution that can function in the harsh ocean environment. 

Another limitation of ocean renewable energy is that it may cause disruptions to marine life. Although its emissions are minimal, the system requires large equipment to be installed in the ocean. 

Biomass Renewable Energy

Organic materials like wood and charcoal have been used for heating and lighting for centuries. There are a lot more types of biomass: from trees, cereal straws, and grass to processed waste. All of them can produce bioenergy. 

Biomass can be converted into energy through burning or using methane produced during the natural process of decomposition. In an essay on renewable sources of energy, the opponents of the method point out that biomass energy is associated with carbon dioxide emissions. Yet, the amount of released greenhouse gases is much lower compared to nonrenewable energy use. 

While biomass is a reliable source of energy, it is only suitable for limited applications. If used too extensively, it might lead to disruptions in biodiversity, a negative impact on land use, and deforestation. Still, Apollo energy includes biomass resources that become waste and decompose quickly anyway. These are organic materials like sawdust, chips from sawmills, stems, nut shells, etc. 

What Is the Apollo Alliance?

The Apollo Alliance is a coalition of business leaders, environmental organizations, labor unions, and foundations. They all unite their efforts in a single project to harness clean energy in new, innovative ways. 

Why Apollo? Similarly to President John F. Kennedy’s Apollo Project, Apollo energy is a strong visionary initiative. It is a dare, a challenge. The alliance calls for the integrity of science, research, technology, and the public to revolutionize the energy industry.

The project has a profound message. Apollo energy solutions are not only about the environment or energy. They are about building a new economy. The alliance gives hope to building a secure future for Americans. 

What is the mission of the Apollo Alliance? 

  • Achieve energy independence with efficient and limitless resources of renewable energy.
  • Pioneer innovation in the energy sector.
  • Build education campaigns and communication to inspire new perceptions of energy. 
  • Create new jobs.
  • Reduce dependence on imported fossil fuels. 
  • Build healthier and happier communities. 

The transformation of the industry will lead to planet-scale changes. The Apollo energy corporation can respond to the global environmental crisis and prevent climate change. 

Apollo renewable energy also has the potential to become a catalyst for social change. With more affordable energy and new jobs in the industry, people can bridge the inequality divide and build stronger communities. 

Why Renewable Energy Is Important for the Future

Renewable energy resources have an enormous potential to cover people’s energy needs on a global scale. Unlike fossil fuels, they are available in abundance and generate minimal to no emissions. 

The burning of fossil fuels caused a lot of environmental problems—from carbon dioxide emissions to ocean acidification. Research this issue in more detail with academic assistance from essay writer online . You can use it to write an essay on renewable sources of energy to explain the importance of change and its global impact. 

Despite all the damage people caused to the planet, there’s still hope to mitigate further repercussions. Every renewable energy essay adds to the existing body of knowledge we have today and advances research in the field. Here are the key advantages and disadvantages of alternative energy resources people should keep in mind. 

Advantage of Green Energy

The use of renewable energy resources has a number of benefits for the climate, human well-being, and economy:

  • Renewable energy resources have little to no greenhouse gas emissions. Even if we take into account the manufacturing and recycling of the technologies involved, their impact on the environment is significantly lower compared to fossil fuels. 
  • Renewable energy promotes self-sufficiency and reduces a country’s dependence on foreign fuel. According to a study, a 1% increase in the use of renewable energy increases economic growth by 0.21%. This gives socio-economic stability.
  • Due to a lack of supply of fossil fuels and quick depletion of natural resources, prices for nonrenewable energy keep increasing. In contrast, green energy is limitless and can be produced locally. In the long run, this allows decreasing the cost of energy. 
  • Unlike fossil fuels, renewable energy doesn’t emit air pollutants. This positively influences health and quality of life. 
  • The emergence of green energy plants creates new jobs. Thus, Apollo energy solutions support the growth of local communities. By 2030, the transition to renewable energy is expected to generate 10.3 million new jobs. 
  • Renewable energy allows decentralization of the industry. Communities get their independent sources of energy that are more flexible in terms of distribution. 
  • Renewable energy supports equality. It has the potential to make energy more affordable to low-income countries and expand access to energy even in remote and less fortunate neighborhoods. 

Disadvantages of Non-Conventional Energy Sources

No technology is perfect. Renewable energy resources have certain drawbacks too: 

  • The production of renewable energy depends on weather conditions. For example, wind farms could be effective only in certain locations where the weather conditions allow it. The weather also makes it so that renewable energy cannot be generated around the clock. 
  • The initial cost of renewable energy technology is expensive. Both manufacturing and installation require significant investment. This is another disadvantage of renewable resources. It makes them unaffordable to a lot of businesses and unavailable for widespread individual use. In addition, the return on investment might not be immediate.
  • Renewable energy technology takes up a lot of space. It may affect life in the communities where these clean energy farms are installed. They may also cause disruptions to wildlife in the areas. 
  • One more limitation a renewable resources essay should consider is the current state of technology. While the potential of renewable energy resources is tremendous, the technology is still in its development phase. Therefore, renewable energy might not substitute fossil fuels overnight. There’s a need for more research, investment, and time to transition to renewable energy completely. Yet, some diversity of energy resources should be introduced as soon as possible. 
  • Renewable energy resources have limited emissions, but they are not entirely pollution-free. The manufacturing process of equipment is associated with greenhouse gas emissions while, for example, the lifespan of a wind turbine is only 20 years. 

For high school seniors eyeing a future rich with innovative endeavors in renewable energy or other fields, it's crucial to seek financial support early on. Explore the top 10 scholarships for high school seniors to find the right fit that can propel you into a future where you can contribute to the renewable energy movement and beyond. Through such financial support, the road to making meaningful contributions to a sustainable future becomes a tangible reality.

Renewable energy unlocks the potential for humanity to have clean energy that is available in abundance. It leads us to economic growth, independence, and stability. With green energy, we can also reduce the impact of human activity on the environment and stop climate change before it’s too late. 

So what’s the conclusion of renewable energy? Transitioning to renewable energy resources might be challenging and expensive. However, most experts agree that the advantages of green energy outweigh any drawbacks. Besides, since technology is continuously evolving, we’ll be able to overcome most limitations in no time.

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