Coal: plant debris more than 200 million year old!
There are three sources of fossil energy: coal, oil and gas. These are natural reserves that can be found buried beneath our feet. Formed from organic deposits (plants or microscopic animal matter), all of these sources of energy take several million years to form, and this under very specific conditions. In general, crude oil and natural gas are created from the similar deposits, most often residue of marine plankton, whereas coal finds its origins in plant debris deposited in marshy areas.
Heat can be obtained by burning these sources of energy. They are rich in carbon and so are much used for heating purposes. Oil is also used a great deal for transport, as well as for manufacturing substances such as plastic. In addition, approximately 66% of the world's electricity is generated from fossil energy. This is done in thermal power stations where water is heated by burning a source of fossil energy. The steam produced drives turbines which, in turn, generate electricity.
Asside from the fact that natural reserves of oil and gas are running out because they cannot be renewed, the main problem associated with sources of fossil energy is the CO2 they produce when they combust. This particular greenhouse gas blends with the other greenhouse gases found naturally in the air, thereby contributing further to climate change.