India's renewable energy research and policies to phase down coal: Success after Paris agreement and possibilities post-Glasgow Climate Pact

In Paris Climate Agreement (COP 21) in December 2015, India committed to cut its carbon (C) emissions by 30-35% of its GDP (gross domestic product) and attain 40% of installed energy from renewables by 2030. In the Glasgow Climate Pact (COP 26), an agreement developed at COP26 of UNFCCC in November 2021, India committed to enhancing its renewable energy (RE) capacity to 500 GW and installing 50% of its power from renewable resources by 2030. It is projected that this will help India to reduce its C emissions by 1Bt, reduce emission intensity to the economy by 45% by 2030, and meet the goal of C neutral economy by 2070. Realization of these highly ambitious commitments made at COP26 can be determined by the nation's growth in REs after COP21. Therefore, this article reviews the overall development of renewable energies - solar, wind, biomass, hydrogen, and hydro - in India after COP21 by the end of December 2021. This review provides detailed information on various policies and roadmaps for each energy sector commitments. It identifies major technical and social challenges associated with the sustainability of these sectors. This review offers insights into how realistically ambitious plans India has for 'phasing down' the use of coal by 2050 and being a carbon-neutral economy by 2070. India achieved massive success through solar energy after COP21 and 80% of future investments are for solar energy. Comparatively, there has been the least investment in other REs such as bio-energy, water, and wind.