Which fuel is the cleanest burning fossil fuel?

Natural gas is a fossil energy source that is formed deep beneath the earth's surface. Natural gas contains many different compounds. The largest component of natural gas is methane, a compound with one carbon atom and four hydrogen atoms (CH4).

The combustion of natural gas produces nitrogen oxides (NOx), which are precursors to smog, and small amounts of sulfur, mercury, and particulates. With natural gas, in light of the facts, it is consequently considered the cleanest burning fossil fuel.

Chemical scientists and other experts say, "Burning natural gas for energy results in fewer emissions of nearly all types of air pollutants and carbon dioxide (CO2) than burning coal or petroleum products to produce an equal amount of energy. The global warming emissions from burning natural gas are lower than those from coal or oil, but they are still much higher than clean energy sources like wind or solar."

About 117 pounds of CO2 are produced per million British thermal units (MMBtu) equivalent of natural gas compared with more than 200 pounds of CO2 per MMBtu of coal and more than 160 pounds per MMBtu of distillate fuel oil. The clean burning properties of natural gas have contributed to increased natural gas use for electricity generation and as a transportation fuel for fleet vehicles in the United States.