Renewable energy in the 21st century: A review

Renewable energy was the only source available for the generation of energy since the ancient time. However, after the discovery of fossil fuels (initially as coal, after that crude oil and lately gas) it has lost ground in the 19th and 20th centuries in most industrialized countries majorly for heating and transportation purposes. Renewable sources such as biomass (In wood form) for heating, cooking, and lighting; then wind energy for navigation and for driving mills; lastly hydropower, also for driving mills; were only sources of energy available prior to the introduction of fossil fuels. From the late 20th century, renewable energy has become much popular because fossil fuels are depleting and have a serious negative impact on the environment; globally new policies and measures are widely implemented now to encourage its use but still it is a difficult to find the right support mechanism for the development of renewable energy, since technologies and costs are evolving exponentially. The present investigation is aimed to study the present situation and to forecast the future of renewable energy in the various sectors such as industrial, automobile, electricity generation and also focuses on how the consumption of fossil fuels can be brought down. © 2021