Please Note: This website is out of date. The Steward Community Woodland sustainable living project ended in 2018 for legal and planning permission reasons. The contents have been left here as a historical archive.


- a renewable fuel made from plant oils -

Biodiesel is produced from vegetable oil (including used cooking oil) and while its physical and chemical properties are similar to those of petroleum diesel, it burns up to 75% cleaner. Its use cuts by upto 100%, the net emissions of CO2 (which contributes to 50% of the Greenhouse Effect). Further more biodiesel is apparently as biodegradable as sugar and less toxic than salt.

Using vegetable oil as a fuel is nothing new. The inventor who developed the diesel engine designed it to run on a variety of fuels, including vegetable oil. When he demonstrated the engine at the World Exhibition in Paris in 1900, he used peanut oil. He stated "The diesel engine can be fed with vegetable oils and would help considerably in the development of agriculture of the countries which use it". He also predicted that "such oils may become in course of time as important as petroleum".

Vegetable oil will react very similarly to petroleum diesel fuel when inside a diesel engine. Some diesel engines can cope fine using unprocessed vegetable oil but many (especially modern designs) can not. The oil may slowly congeal and hardens inside the engine and fuel injectors, leading to expensive rebuilds.

There are modifcations that can be made to prevent an engine from coking up. Better still, the fatty acids that cause the problem can be removed from the oil so that it can be used in any unmodified diesel engine.

The fatty acids (glycerides) are removed in a process called transesterification which is less complex than it sounds. Alcohol is mixed with lye to make sodium methoxide. This caustic liquid is then mixed with heated vegetable oil. The mixture settles out leaving Glycerin on the bottom and Biodiesel at the top.

Easy. Almost anyone could make biodiesel ;-) and there are an increasing number of commercial suppliers of biodiesel.

When bio-diesel is used as a fuel on public roads HM Customs and Excise require duty to be paid thanks to the HYDROCARBON OIL DUTIES ACT 1979. Until July 2002, this duty was the same for biodiesel as for petroleum diesel. However the rate has been cut by 20 pence which makes it around 25 pence per liter. If you make your own bio-diesel then you would need to register with Customs and Excise in order to pay the duty. If you buy bio-diesel from a tax registered producer then you don't have to worry about this as they will pay the tax and pass the cost onto you. Do remember to keep your reciepts as you may need to show customs at some point that you have paid the tax and are not simply using un-taxed vegetable oil straight off the supermarket shelves.

There have been a few stories in the media about people using straight veg oil and it does work fine in many diesel cars. Some people find they can use 100% vegetable oil, others use a blend of petroleum diesel and veg oil to make sure the oil is thin enough. Using veg oil in this way is not illegal as long as you pay the tax. Unfortunately there is no way easy way of doing this apart from registering as a fuel producer or buying tax paid veg oil from an existing tax registered producer.

It is currently extrememly difficult to purchase biodiesel unless you are lucky enough to live near one of the few suppliers or have a good contacts. Biodiesel suppliers are swamped with the demand and there is no way they can supply everyone who currently wants it. Despite this, their prices are generally no greater than the price of petroleum diesel.

At Steward Wood we have failed to locate a supplier close to us so we took advantage of a friends trip to North Wales to purchase several hundred liters of bio-diesel from Goat Industries. We have also purchased e-diesel from Ebony Solutions via a biodisel buyers co-operative. We would like to find a regular supplier and possible start a biodiesel buyers co-operative in our area.

While biodiesel is cleaner burning than petroleum, and a renewable resource, it must be remembered that even if everyone stopped burning fossil fuels in vehicals, it would not solve all the problems associated with car-culture and our energy dependent society. We must reduce our need to travel, provide local services and build a society that is not dependent on imported goods.

How to make diesel from vegetable oil

You can read more about Biodiesel elsewhere on the web:

Goat Industries

Last updated: 2009-04-22

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