Renewable Energy is energy derived from resources that are regenerative or for all practical purposes cannot be depleted. Sources such the sun and the wind, can never be exhausted and therefore called renewable. They cause fewer emissions and are available locally. Their use can, to a large extent, reduce chemical, radioactive and thermal pollution. They are a viable source of clean and limitless energy. These are the non-conventional sources of energy. Most of the renewable sources of energy are fairly non-polluting and considered clean except for biomass, a renewable source, is a major polluter indoors.
Sources of renewable energy or non-conventional energy are the sun, wind, agricultural residue, firewood and animal dung. Energy generated from the sun is known as solar energy. Energy derived from water is called hydroelectricity. Biomass is firewood, animal dung, biodegradable waste from cities and crop residue.
It becomes a source of energy when it is burnt. Geothermal energy is energy derived from hot, dry rocks, magma, hot water springs and natural geysers. Ocean thermal is energy derived from waves and tidal waves.