What is biofuel?

Wondering what biofuels are and whether they are cleaner than fossil fuels? Wonder no more

The word ‘bios’ means ‘life’ in Greek, and it is from this that biology, biography, bioluminescence, and numerous other words take their root.

Biofuel is no different – the prefix ‘bio’ indicates that some form of life is involved in the production of the bio-petrol and biodiesel, and indeed there is – but don’t think that this means they’re not vegan friendly.

Enough with the English lesson – what is biofuel?

Assuming you don’t have an electric or a hydrogen vehicle and you live in the UK, the fuel you fill your car up with is a biofuel.

That’s because the standard grade of unleaded petrol here is called E10, which means at least 90% of it is made from fossil fuels, and up to 10% is made from ethanol. E5, by comparison, is up to 5% ethanol; our super unleaded is E5.

Ethanol is a form of alcohol, and the ethanol used in our petrol comes from fermented plants – hence the ‘bio’ bit.

The standard grade of diesel, meanwhile, is B7, which means it must have 7% biodiesel.

The 7% of biofuel in our diesel also comes from plants, although it is mainly composed of fatty acid methyl esters. These are generally obtained from vegetable oils.

How are biofuels made?

Bioethanol for E10 petrol is made by breaking down crops such as maize and corn; these ferment, producing alcohol, which then gets refined to a point where it can be combined with conventional fossil-fuel petrol. Biodiesel, meanwhile, is made by combining vegetable oils with alcohol.

Why are biofuels used?

Biofuels don’t produce fewer emissions than fossil fuels when they are burned, but because plants like maize absorb carbon dioxide (CO2) as they grow, using biofuels actually reduces CO2 emissions in comparison to conventional fuels.

The UK switched from using E5 as the standard grade of unleaded to using E10 in 2011, and the official line is that by making this change, national CO2 emissions were reduced by an amount equivalent to removing 350,000 cars from the road.

Biofuels aren’t perfect, though: they take up land that could be otherwise used to grow food crops, while cultivating and transporting those crops has a CO2 cost in and of itself.

Can my car run on biofuel?

Probably, although not necessarily. The extra alcohol in the bioethanol used in E10 unleaded petrol is relatively tough on rubber, and some older cars may not be able to run on it as they risk damage to their fuel systems, and other components that use rubber.

All petrol cars made from 2011 must legally be compatible E10, though, while cars from much earlier will also be able to use the fuel – though it’s worth using the Government’s checker to find out if you’re at all unsure.

You can use E5 super-unleaded or pop a fuel additive into your tank if your car isn’t compatible with E10; our guide to the fuel has more details.

The same consideration does not apply to diesel vehicles – almost all of these are compatible with the B7 biodiesel we use as our standard grade.

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