Renewable energy resources are mostly biomass based and are available in unlimited amount in nature since these can be renewed over relatively short period of time. These include, firewood obtained from forests, petroplants, plant biomass, animal dung, solar energy, wind energy, water energy, geothermal and dendrothermal energy etc. These can reproduce themselves in nature and can be harvested continuously through a sustained proper planning and management.
Non renewable energy resources are available in limited amount and develope over a longer period of time. As a result of unlimited use, they are likely to be exhausted one day. These include coal, mineral oil, natural gas and nuclear power.