Biodiesel is an alternative fuel similar to conventional diesel.

Biodiesel can be produced from straight vegetable oil, animal oil/fats, tallow and waste cooking oil. The largest possible source of suitable oil comes from oil crops such as rapeseed, palm or soybean.

In the UK rapeseed represents the greatest potential for biodiesel production. Most biodiesel produced at present is produced from waste vegetable oil sourced from restaurants, chip shops, industrial food producers.

Though oil straight from the agricultural industry represents the greatest potential source it is not being produced commercially simply because the raw oil is too expensive. After the cost of converting it to biodiesel has been added on it is simply too expensive to compete with fossil diesel.

Waste vegetable oil can often be sourced for free or sourced already treated for a small price. (The waste oil must be treated before conversion to biodiesel to remove impurities).

The result is Biodiesel produced from waste vegetable oil can compete with fossil diesel.

What benefits does Biodiesel have?

Biodiesel has many environmentally beneficial properties.

The main benefit of biodiesel is that it can be described as ‘carbon neutral’. This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2).

This effect occurs because when the oil crop grows, it absorbs the same amount of CO2 as is released when the fuel is combusted.

Biodiesel is rapidly biodegradable and completely non-toxic, meaning spillages represent far less of a risk than fossil diesel spillages.

Biodiesel has a higher flash point than fossil diesel and so is safer in the event of a crash.

What are the disadvantages of biodiesel fuel?

Biodiesel is currently about one and a half times more expensive than petroleum diesel fuel.

Part of this cost is because the most common source of oil is the soybean, which only is only 20% oil.

However, the costs of biodiesel can be reduced by making biodiesel from recycled cooking oils rather than from new soy beans, or by making it from plant matter with higher oil content.

It takes energy to produce biodiesel fuel from soy crops, including the energy of sowing, fertilizing and harvesting.

Biodiesel fuel can damage rubber hoses in some engines, particularly in cars built before 1994.

You should check with the manufacturer before using biodiesel to see if you need to replace any hoses or rubber seals.

Can I use Biodiesel in my car?

Biodiesel, in theory, can go into all diesel engines as the diesel engine itself was designed to run on plant oil.

However it is the parts attached to the diesel engine which could potentially cause problems – although the vast majority of diesels on the road are fine running on 100% biodiesel.

In reality, the rule of thumb is you can use 100% biodiesel in any diesel built between 1990 -2004, but be aware that a one-off fuel filter change will be needed after you first make the transition (and any mix of biodiesel and fossil diesel is OK too).

I would recommend that cars built after 2004 should run on a 50% blend not 100%. Be aware too that biodiesel made from waste cooking oil will freeze in winter and so from November to April one should blend that kind of Biodiesel at 50% as well.

However, Biodiesel made from a Rapeseed crop (RME) will not freeze and can be used at 100% all year round in the UK.

Please note that it is advisable to purchase biodiesel with EN14214 specification, which gives you some guarantee of quality. In short – to be safe, use RME Biodiesel at EN14214 in a car built between 1990 and 2004 and then you can be carbon neutral all year without problems!


In terms of official compatibility, despite the majority of diesel vehicles on the road being fine on 100%, only a handful of companies will officially approve their vehicles for 100% use.

The companies that have approved 100% biodiesel are VW, Audi, SEAT and Skoda. They have approved all their cars built between 1996 and 2004 on 100% use of “RME” Biodiesel (Biodiesel made from Rapeseed) providing it meets the specification DIN41606 (which was later replaced by EN14214).