Today, fossil fuel industries drill or mine for these energy sources, burn them to produce electricity, or refine them for use as fuel for heating or transportation. Coal was the first fuel exploited by humans for energy on a large scale, it is a black or brownish-black carbonaceous rock formed from dead trees and other plant animals. Coal is classified into four main types: anthracite, bituminous, sub-bituminous, and lignite. In 2016, the U.S. accounted for 10 percent of the total coal production worldwide.
Crude oil and gas were formed from dead marine organisms. After crude oil is removed from the ground, it is sent to a refinery where different parts of the crude oil are separated into various petroleum products. According to a governmental forecast, U.S. refineries will produce a total of approximately 20.53 quadrillion Btu of crude oil by 2050. Crude oil is often used to fabricate liquid-fuel products like gasoline, diesel fuel, and heating oil, among its many uses.
The use of many fossil fuel sources such as coal, natural gas and oil/petroleum are still necessary to help meet the energy and electricity demands of many countries. The energy demand in the U.S. is largely covered by fossil fuels, although, the capacity of renewables has increased in the last decade. About 85% of the electricity generated was from fossil fuels and nuclear resources. However, the overconsumption of fossil fuels can lead to serious environmental issues such as air pollution.