When animals and plants are rotten in the absence of air, there produces a gas called

Black painted panels which are hanged at roofs to trap heat and energy from sun, are

Earth emits heat by eruptions of

Plants utilize water, carbon dioxide and light to produce their own food by

Plants material and waste from living things are regarded as

Fossil fuels are rich in carbon and

Thousands of mirrors or curved metals are used to focus solar energy to make it very hot, in

Wind is beneficial resource of energy as it doesn't cause

Hot water or steam carrying geothermal energy often comes up to surface in

Fossils fuel is an important source of energy for