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
Compressed natural gas the end user. CNG is being experimentally stored at lower pressure in a form known as an ANG (adsorbed natural gas) tank, where it is adsorbed at 35 bar (500 psi, the pressure of gas in natural gas pipelines) in various sponge like materials, such as activated carbon and MOFs (metal-organic frameworks). The fuel is stored at similar or greater energy density than CNG. This means that vehicles can be refueled from the natural gas network without extra gas compression, the fuel tanks can be slimmed down and made of lighter, weaker materials. Compressed natural gas is sometimes mixed with