Natural gas is another major source of the energy. Oil and gas fields have been found everywhere on the planet except on the continent of Antarctica. These fields always contain some gas, but this natural gas (methane) does not take nearly as long to form.
Natural gas is also found in independent deposits within the ground as well as from others sources too. Methane is a common gas found in swamps and is also the byproduct of animals digestive system.
Although Natural Gas is a fossil fuel, it is cleaner burning than gasoline, but does produce Carbon Dioxide, the main greenhouse gas. Like petrol and diesel, natural gas is also a finite source, though available in larger quantities than the former.