Waste cooking oil for cars

Biodiesel can be made from used cooking oil, a useful fuel for your car which would otherwise be a total waste. Restaurants, pubs and hotels which use oil for cooking have to ensure safe disposal of their waste and an industry has grown up to turn this into biodiesel. You may be using this now without knowing because biodiesel can be blended with  diesel at up to 7% without any change in labelling. In fact the EU has a goal to achieve 10% concentration of bio fuel in transport fuel by 2020(1) even though the environmental impacts are doubtful when forest or agricultural land is turned over to growing biofuels instead (2). However the waste oil industry has a problem because thieves are stealing waste oil from their customers and turning it into biodiesel to be sold on the black market. Making legitimate biodiesel costs around £1.24/litre of which about 80p is tax but the thieves can make substandard fuel for 20p/litre. The industry estimates this could be cheating the treasury out of £25 million/year and costing them their livelihoods (3).


£25 million/year in tax suggests there must be more than 30 million litres of biodiesel being sold on the black market per year which would be 3% of the biodiesel legitimately traded in 2011. However, this is still a fraction of the total amount of diesel we use each year which is nearly 26,000 million litres (4).

So the main point I want to make is that used cooking oil may be a valuable commodity but it isn't going to make a serious dent in our demand for diesel to drive our cars.

My second concern, though, is that even if it is small the legitimate trade in biodiesel from waste oil is a good thing as it avoids organic waste going to land fill as well as reducing carbon emissions - but the illegal trade is a serious and increasing threat. The big waste handling companies like WasteCare and Oileco now believe up to 20% of their oil collections are stolen. Often they arrive to pick up a tank of oil to find someone else collected it the day before - in a similarly painted van and with similar uniforms, only the CCTV cameras reveal the difference (5). Theoretically the customer is at fault for failing to dispose of their waste safely but who can blame them?

The incentive to steal the oil would be much less if it were not for the high tax on legitimate sales.

Some other points of interest:

Most waste oil collection companies only deal with restaurants and caterers, which generate waste in bulk. Many household recycling centres accept waste cooking oil but it is too expensive for councils to collect it with your bin collection. 

Some cars can run well on high concentrations of biodiesel. However, even if you have a good quality source you do need to check with your car manufacturer in case it invalidates your warranty. Biodiesel is a mixture of fatty acid methyl esters similar in energy content to conventional diesel but not quite the same chemically.  For example biodiesel has a tendency to dissolve natural rubber fuel lines.

You are allowed to make biodiesel for your personal use, up to 2500 litres/year, without paying tax. You can get kits to do this at home but you must be careful: the process involves handling methanol which is fairly toxic in concentration. The Telegraph ran a piece on this back in 2011 - How to run a car on cooking oil (at 18p a litre). However, this right is under threat as companies in the industry are lobbying to have it abolished. They claim that the thieves are using this as a loophole and it is feeding the black market (5).

There is a nice video showing how biodiesel is made on a commercial scale here (from Proper Oils, a recycler based in London).

Filtered cooking oil can also be used as a fuel directly instead of diesel but it does not run well in a cold engine. If you don't mind a bit of DIY on your car you can get converter kits which basically involve installing a second fuel tank and a second set of fuel lines. You start your engine with conventional fuel and switch to the biodiesel tank when the engine is warm. Then before you stop the engine you need to switch back to the conventional tank. If you forget and try to start your car on biodiesel you will have problems (6).




(1) Biofuels and other renewable energy in the transport sector
(2) European biofuels target condemned by leading US scientists
(3) Cooking oil theft 'costs Treasury £25m a year in lost duty' (March 23 2013)
(4) Digest of UK Energy Statistics (DUKES) 2012
(5) Environmental Audit CommitteeWritten evidence submitted by Agri Energy
(6) Veg Oil Car