Gas and Petrol

Gas (LPG/Liquefied petroleum gas/ auto gas) and petrol (gasoline) consist of hydrocarbons, and they are used as fuels in internal combustion engines of vehicles. In recent years, there has been an increased move towards gas as an alternative fuel in vehicles. Both LP gas and petrol are obtained from petroleum, so both are fossil fuels.

Gas

Gas (LPG) is used as a fuel in vehicles as well as in domestic appliances. Gas, which is used in vehicles, is mainly a mixture of propane and butane. It can be liquefied under pressure, hence stored as a compressed liquid, and it is burnt as a dry vapour in the engine. Gas is non- corrosive, free from lead and has a high octane rating. In order to use gas in vehicles, they have to be converted to either dual fuel or dedicated gas operation. In dual fuels, vehicle can operate by petrol or gas alternatively. A separate gas tank should be installed in the vehicle along with the petrol tank. LPG and petrol have slightly different burning characteristics but, the engines can be set up to use both fuels alternatively without a problem. Dedicated gas vehicles don’t have a petrol fuel system, therefore operate using gas only. This conversion is costly, but in the long run, it saves money, because the gas price is much lower than petrol. All the vehicles cannot be converted to gas, and for the installation of the gas tank, a considerable space is needed which are some of the drawbacks.

Petrol

Petrol is a liquid form of hydrocarbon fuel. Hydrocarbons are like isooctane or benzene, and toluene is added to petrol, to increase its octane rating. It is volatile and has a higher density than LPG.

Difference between Gas and Petrol

When operating vehicles with gas, fuel consumption is higher than that of petrol. Also, the energy output is lower in gas compared to petrol. However, gas is lot cheaper than petrol, and that offsets its high consumption. Petrol combustion is partial, resulting lot of carbon dioxide and other particulate matter in the emissions. Comparatively gas is cleaner, and emissions are less than petrol. Therefore, gas is more environmental friendly and economical to use in vehicles than petrol. However, lot of people are still into using petrol for their vehicles; gas is less available than petrol in filling stations. Although, the gas is expected to be more efficient than petrol, this may not be observed unless the engine design is optimized for LPG fuel.