As the 20th century passes the sources of energy were became lesser than the past time. As a need of more energy, the scientists have invented the other source of energy called the ‘’renewable energy’’. In the past and in current times as well the sources which we are using is not useable again even after one time using, but the renewable sources are which that can be used again and again even after used once. As you know there is a large amount of crude oil is used during all these centuries and in latest there is always a hike of crude oil prices so world need the another source of energy which is renewable. Renewable sources are that energy source which produced from natural energy sources like sunlight, rain, etc… that are replenished. Renewable sources are such sources that it built at a higher cost but after that the fuel will be always free forever.