Fossil fuel, any of a class of hydrocarbon-containing materials of biological origin occurring within Earth’s crust that can be used as a source of energy. All fossil fuels can be burned in air or with oxygen derived from air to provide heat. This heat may be employed directly, as in the case of home furnaces, or used to produce steam to drive generators that can supply electricity.
The twentieth century noticed a big diversification of fossil strength consumption, with coal declining from ninety-six percentage of overall production in 1900 to less than 30 percent in 2000. Today, crude oil is the biggest power supply, accounting for round 39 percentage of fossil energy, accompanied with the aid of coal and natural fuel at 33 and 28 percent, respectively.