Liquefied petroleum gas (LPG) or Autogas is a fossil fuel that can be used in automobiles heat engines. Most LPG vehicles are bi-fuel because it uses a different fuel, usually gasoline. These cars have storage systems, fueled and injection specific for the two fuels.
Autogas is the third most popular automotive fuel in the world, with approximately 18 million passenger cars.
The main advantages of using liquefied petroleum gas for heat engines are reduced emissions and lower cost price. The disadvantages of using LPG is the need for additional storage and fuel systems on car and the higher specific consumption of the engine.
A natural gas vehicle (NGV) is another fuel automobile that works by using compressed natural gas (CNG) or liquefied natural gas (LNG) for a more clean option to other fossil fuels.
Similar with cars on LPG, the compressed natural gas (CNG) operates on two types of fuel. Natural gas is a hydrocarbon colorless, odorless and not corrosive or with carcinogenic effects. Natural gas contains about 97% methane (CH4).
Being lighter than air, natural gas is not leaking on the ground, but dissipates into the atmosphere. This is the advantage compared to gasoline because it greatly reduces the risk of fire in case of an accident.
Advantages of CNG cars are pollutant emissions with greenhouse reduced and lower cost price of natural gas.
A disadvantage of the CNG’s is lower energy density as compared to gasoline. To increase the density of energy, natural gas is compressed to 200 bar values. Even at these high pressures, the energy density is only 20% compared with the same volume of gasoline. For these reasons autonomy CNG cars is much lower compared to petrol.