Answer:
fossil fuel combustion
Step-by-step explanation:
Fossil fuel is the source of energy that drives almost all industrial processes on the surface of earth. Burning of these fuels releases energy for use in automobiles, industries, homes e.t.c. The complete combustion of these fuels in the presence of oxygen liberates carbon-dioxide and water with heat energy.
Fossil fuels are to a large extent hydrocarbon compounds and their derivatives. They form from organisms million of years ago. When organic matter is prevented from decay in an oxic or oxygen rich environment, they are able to conserve and preserve the energy in them for a vast duration in geologic time. This preserved energy is what becomes available during combustion.
Some of the fossil fuels are oil, natural gas, coal, e.t.c.