Energy is simply the capacity to do work. Energy has become one of the necessities of our modern life. Energy can have many forms like heat, electrical, chemical, nuclear, light, etc. In the pre historic era fuel wood was the major sources of energy. Conventional energy sources are the ones that have been using so far to fulfill most f our daily energy requirements of cooking, lighting, transportation etc. these are based on fossil fuels like coal, petrol, diesel, kerosene and natural gases. Fossil fuels are obtained from biologically degradable materials such as plant and animal but undergoing million years of excessive heat, pressure, chemical and biological reactions. Thus formation of these fuels takes very long time. Also they are non-renewable sources of energy.

Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlight, wind, rain, tides, waves, and geothermal heat. It is the energy which is abundant in nature. The sun is the ultimate source of energy. Almost all the energy that we use eventually comes from the Sun. The exception is the heat of radioactivity deep inside the Earth, which is ultimately responsible for processes taking place inside the Earth. As far as the crust itself is concerned, all the processes that we use eventually depend on energy from the Sun.

Biomass is the term used to describe all the organic matter that exists on the earth 's surface produced by