Why do countries give importance for the development of non-conventional energy sources?

Non Conventional Energy sources: Those energy sources which are renewable and ecologically safe. such as solar energy, wind energy, biomass energy, ocean energy (tidal energy, wave energy, ocean thermal energy), geothermal energy, nuclear energy etc.

Serious environmental problems are caused by increasing use of fossil fuels. Hence, the need to use renewable energy sources like solar energy, wind, tide, biomass andenergy from waste material, has shown its importance.