Natural gas is a mixture of hydrocarbons, mainly methane. It can be produced either from gas wells or in conjunction with crude oil production.
Natural gas is a clean burning, domestically produced fuel that generates significantly less carbon monoxide, carbon dioxide, particulate matter, and nitrous oxide compared to similar fossil fuel vehicles. It is used in vehicles as compressed natural gas (CNG) or liquefied natural gas (LNG).
There are about 100,000 natural gas vehicles in the United States. Nearly one of every five new transit buses in the United States runs on natural gas.