LNG is a natural gas cooled and compressed to a temperature and pressure at which it exists as a liquid. It is liquefied by reducing its temperature to minus 260 degrees Fahrenhiet at atmospheric pressure. It consists of a mixture of low-boiling hydrocarbons boiling between about 113 K and 190 K. It is very useful for the transportation of natural gas, since LNG takes up about one six hundredth the volume of gaseous natural gas. It does not have a specific heat value as it is made from natural gas, which is a mixture of different gases. The heat value depends on the source of gas that is used and the process that is used to liquefy the gas. It offers an energy density and produces less pollution.