Natural gas vehicle gas has the highest energy/carbon ratio of any fossil fuel, and thus produces less carbon dioxide per unit of energy. The major difficulty in the use of natural gas is transportation. Natural gas pipelines are economical and common on land and across medium-length stretches of water (like Langeled, Interconnector and Trans-Mediterranean Pipeline), but are impractical across large oceans. Liquefied natural gas (LNG) tanker ships, railway tankers, and tank trucks are also used. CNG is typically stored in steel or composite containers at high pressure (3000 to 4000 psi, or 205 to 275 bar). These containers are not typically temperature controlled,
Natural gas reports the following emissions in million metric tons of carbon dioxide in the world for 2012: Coal-fired electric power generation emits around of carbon dioxide for every megawatt-hour (MWh) generated, which is almost double the carbon dioxide released by natural gas-fired generation. Because of this higher carbon efficiency of natural gas generation, as the fuel mix in the United States has changed to reduce coal and increase natural gas generation, carbon dioxide emissions have unexpectedly fallen. Those measured in the first quarter of 2012 were the lowest of any recorded for the first quarter of any year since 1992. Combined