CNG, as known as Compressed Natural Gas, is made by compressing natural gas (mostly methane) to less than 1% of its volume. When compressed, natural gas can be used in place of gasoline, diesel fuel, and LPG. CNG combustion produces fewer pollutants than other fossil fuels. It also poses less of a threat in the event of spill, as it is non-toxic and lighter than air and disperses quickly. In response to high fuel prices and environmental concerns, conversion from the ‘old’ fuels to CNG for trucks, buses, and trains is a steadily growing trend in the U.S.