Liquefied natural gas gasoline and diesel auto-ignite at temperatures and pressures relevant to engine design. An important part of traditional engine design is designing the cylinders, compression ratios, and fuel injectors such that pre-ignition is avoided, but at the same time as much fuel as possible can be injected, become well mixed, and still have time to complete the combustion process during the power stroke. Natural gas does not auto-ignite at pressures and temperatures relevant to traditional gasoline and diesel engine design, thus providing more flexibility in the design of a natural gas engine. Methane, the main component of natural gas, has an
Natural gas prices import gas based on the Henry Hub index, which was, until very recently, the most widely used reference for US natural gas prices. Depending on the marketplace, the price of natural gas is expressed in US dollars (or other currency) per 1 million British thermal units (MMBtu), thousand cubic feet (Mcf), or 1,000 cubic meters. Note that, for natural gas price comparisons, $ per MMBtu multiplied by 1.025 = $ per Mcf of pipeline-quality gas, which is what is delivered to consumers. For rough comparisons, one million Btu is approximately equal to a thousand cubic feet of natural gas. Pipeline-quality