The most common fuel concept is petroleum-powered cars, and generally these are the cheapest to buy. Unfortunately however, they are predominantly the biggest pollutants emitting carbon dioxide into the atmosphere and burning non-renewable energy sources. Of course, some of these cars are greener than others and it is still possible to find these vehicles with relatively low CO2 emissions and good kilometers per liter â€“ generally these will be small cars.
Sales are on the rise for diesel cars as we become more environmentally. Diesels do release less carbon dioxide than petroleum cars but be aware that they contain other compounds such as particulate matter and nitrous oxides which can be harmful. Generally though, they are more efficient with fewer emissions.
Actually one of the oldest green concepts around, dating back to the 1800s, electric cars have struggled to explode in popularity due to their limited range and low top speeds. However, in recent times technology has advanced and they are now capable of speeds up to 45mph and a range of around 100 miles. They are zero-emission vehicles though some emissions will be produced during electricity generation.
A Hybrid is a combination of two power sources â€“ usually an electric motor and a petrol or diesel engine. The petroleum/diesel engine powers the car at higher speeds while the electric motor works at low speeds, particularly for city driving. This makes hybrids more clean and efficient than petrol and diesel cars as there are no emissions when the electric motor is used.
Biofuels are constantly growing and developing technology. Known for courting controversy, biofuelsÂ can beÂ generated from many sources. Currently first and second generation fuel sources such asÂ food crops like wheat and other grain types. Sometimes the oil from these plants is used directly (such as with biodiesel),Â other times it is used to generate ethanol to make up fuels (a mixture of 85 per cent ethanol and 15 petroleum). OtherÂ sources of biofuels include algae, non-food plants (such as Jatropha), waste chip fat, biomass (waste products), such as manure.
Liquefied petroleum gas (LPG) is made of propane and butane and uses less CO2 than petroleum and fewer particulates and oxides than diesel. Engines can be modified for LPG through a process called LPG conversion. LPG is on the increase and is now offered at a vast number of fuelling stations.
Compressed natural gas
A fossil fuel from beneath the Earthâ€™s surface â€“ it has low CO2 emissions but is still a greenhouse gas. It works in a similar way to LPG in the sense that an engine conversion will be required so the car can switch between it and petroleum.
Hydrogen fuel cells
A developing concept with only a handful currently in use â€“ the most predominant of which use hydrogen â€“ fuel cells rely on electrochemical energy conversion devices which produce energy from an electro-chemical reaction. In the long term, it may be a strong green car alternative but for now its availability is limited and prices are high due to inefficient hydrogen production methods.