There are various types of gases used as fuels, commonly including natural gas (primarily composed of methane), liquefied petroleum gas (LPG, mainly containing propane and butane), hydrogen, coal gas (a mixture of carbon monoxide and hydrogen), and biogas. These gaseous fuels are considered clean energy sources due to their complete combustion and low emission pollution. In the automotive sector, the primary gaseous fuels used are compressed natural gas (CNG), liquefied natural gas (LNG), and liquefied petroleum gas (LPG). LNG is produced by cooling natural gas to -161.5°C for liquefaction and storage, offering high energy density and being suitable for long-haul commercial vehicles. CNG is natural gas stored in a compressed gaseous state, with refueling stations being relatively widespread, making it commonly used in taxis and urban buses. LPG, a byproduct of petroleum refining, is easily liquefied and stored, and is also utilized in certain light-duty vehicles. The use of these gaseous fuels contributes to reduced vehicle emissions and extended engine lifespan, garnering significant attention in the context of energy scarcity.
