Gone are the days when you had a simple choice between buying either a petrol-fuelled or a diesel car. Now the options are wide and varied thanks to the arrival of several green car concepts including electrics, hybrids, fuel cell cars and biofuels.

This guide to green car fuel types will explain each option, how they differ and how environmentally friendly they are.

Green car fuel types: petrol cars

The most common fuel concept is petrol-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 petrol cars are greener than others and it is still possible to find petrol vehicles with relatively low CO2 emissions and good miles per gallon - generally these will be small cars, such as super-minis.

Green car fuel types: diesel cars

Sales are on the rise for diesel cars as we become more environmentally conscious. Diesels do release less carbon dioxide than petrol 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.

Green car fuel types: electric cars

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.

Green car fuel types: hybrid cars

A hybrid is a combination of two power sources - usually an electric motor and a petrol or diesel engine. The petrol/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. Read on for more on hybrid cars.

Green car fuel types: biofuels

Broadly biofuels will fit into one of two categories: biodiesel or ethanol. Biodiesel takes energy from renewable sources such as rapeseed or sunflowers and can be carbon neutral as the emissions emitted are offset during the crop’s growth. In some cases they can replace diesel outright although you should be cautious and check with your manufacturer. Ethanol is grain alcohol produced by plants and is becoming increasingly popular as it too can be carbon neutral and several manufacturers have developed flexi-fuel vehicles that can run on ethanol and petrol blended together. Read on for more on biofuels.

Green car fuel types: LPG

Liquefied petroleum gas (LPG) is made of propane and butane and uses less CO2 than petrol 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 filling stations. Read on for more on LPG conversion.

Green car fuel types: compressed natural gas

A fossil fuel from beneath the Earth’s surface - 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 petrol.

Green car fuel types: fuel cells

A developing concept with only a handful currently in use - the most predominant of which use hydrogen - 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.