Fuel properties of hydrogen, liquefied petroleum gas (LPG), and compressed natural gas (CNG) for transportation

Hydrogen has been suggested as a convenient, clean-burning fuel. Hydrogen gas may be stored as a compressed gas or as a liquid. Hydrogen has good properties as a fuel for internal combustion engines in automobiles. Worldwide-liquefied petroleum gas (LPG) production is limited to about 10% of total gasoline and diesel fuel consumption and is used to a great extent for domestic and industrial purposes. Since LPG burns cleaner with less carbon build-up and oil contamination, engine wear is reduced and the life of some components such as rings and bearings is much longer than with gasoline. The high octane of LPG also minimizes wear from engine knock. Natural gas is widely available. CO2 emission of natural gas is lower than both diesel fuel and gasoline, which makes natural gas engines favorable also in terms of the greenhouse effect. Positive contribution of compressed natural gas (CNG) on environmental pollution must also be considered in economical aspects.