Tom Shelley reports on the growing move across the Atlantic running diesel cars and pickup trucks on vegetable oils and petrol cars on alcoho
With mineral oil prices high and likely to stay up, it should
come as no surprise that in the land of free enterprise, more and
more diesel car and light truck owners are converting their
vehicles to run on vegetable oils.
The favourite fuel stock at present is waste frying fat from restaurants, but other sources of supply are being looked at. The main technical challenge at present is to overcome the higher viscosity but in the long term, if the idea catches on, there is a potential conflict between demands for fuel and food for a still increasing world population.
Sticking to waste vegetable oil, however, is truly 'green' since otherwise, it presents a disposal problem, and there are other mineral oil substitute feed stocks which are totally organic waste derived, which are well worth looking at commercially and industrially.
We first heard about the move to "Veggie vehicles", from Walter Darnell of the SMC Corporation of America when we met him over lunch at a SolidWorks World event.
Walter told us about his friend, who had converted a 2000 VW Jetta TDI to run on conventional diesel oil until it got hot, upon which it could be switched to vegetable oil without clogging up the injectors. Overall mineral diesel oil fuel efficiency was reported to us as being around 200 to 300 miles per US gallon, which is significantly smaller than the British Imperial variety. The next stage, is apparently, to install a pre-heater to avoid the need for any mineral diesel oil to be used at all.
Dr Rudolf Diesel developed the world's very first diesel engine to run on vegetable oil in 1895, and when it was demonstrated at the World Exhibition in Paris in 1900, it was fuelled by peanut oil.
Complete kits for the two fuel approach are available from Greasecar, based in Florence, Massachusetts and Frybrid based in Seattle. Parts for those wishing to devise their own conversions in the UK are available from C G Engine Services in Reading.
Frybrid points out that the not only must the oil be heated to at least 70 deg C before it is injected in order to get through the holes, but the engine must also be hot to avoid oil polymerisation on metal surfaces leading to carbon build up. The fuel system also needs to be purged with diesel oil immediately prior to shutdown.
Elements of he Jetta conversion
The Frybrid System has a vegetable oil fuel tank with a built-in heat exchanger. Heat is supplied from engine coolant which is normally at least 82 deg C. It also employs heated fuel lines, a heated fuel filter and a final fuel heat exchanger. Microprocessor controlled solenoid valves automatically switch to vegetable oil when the proper temperatures have been reached. Pressing a "Purge" button a few seconds before shut down flushes all vegetable oil from the system and replaces it with diesel. When complete, the "Puge mode" indicator goes out and the "Diesel mode" indicator lit. An alarm sounds if the engine is shut down while running in vegetable oil mode and keeps sounding until the engine is re-started unless the purge cycle is completed before shut down. The purge cycle is also automatically initiated if the fuel level goes too low in the vegetable oil tank.
Veggie fuel gauge and purge button on the Jetta
Greasecar says that vegetable oil has superior lubrication and detergent values over conventional diesel fuel. Examination of engines is said to show dramatic reductions in carbon build-up. They also point out that there is no sulphur in vegetable oil and some studies have shown NOX reductions. Massachusetts gets quite cold in Winter and Greasecar reports customers using vehicles daily in temperatures down to -34 deg C. The company recommends avoiding sources that rinse their fryers with water. Asian food restaurants are apparently good because they use pure canola or soy oil, which has a lower gell point and higher quality restaurants use higher quality oils than fast food outlets.
These technologies are not to be confused with use of biodiesel, which is made by reacting fat or oil with an alcohol, typically methanol, in the presence of a catalyst to produce glycerine and methyl esters, which form the biodiesel. The methanol is charged in excess to ensure quick conversion and recovered for re-use. The catalyst is usually sodium or potassium hydroxide.
The other fuel source being looked at with great interest is wheat and rice straw, which with the help of suitable enzymes, may be turned into sugars that can be fermented to alcohol. Not surprisingly, one of the companies most interested in this possibility is Shell, which has partnered with the Ottawa, Canada based company Iogen, and has made it clear that it intends to stay in the fuel and energy business regardless of what happens to petroleum supplies.
One of the automotive majors committed to bio derived fuels is Ford. Their Escape Hybrid E85 research vehicle is capable of running on a hybrid-electric battery, petrol, or a blend of 85 per cent ethanol and 15 per cent petrol. Ford has already put more than 1.5 million bioethanol capable vehicles on the road across the world and will produce 250,000 more this year. Bioethanol did not go on public sale in the UK until March 16th this year, but can now be found at ten Morrisons supermarkets, priced cheaper than unleaded petrol from 84.9 p a litre. Five of the forecourts selling bioethanol are in Somerset where Ford has sold the most Focus FFVs (Flexible Fuel Vehicles), which can run on 100 per cent ethanol or 100 per cent petrol or any mix of the of the two in the same tank.
The remaining bioethanol outlets are in East Anglia, three in Norfolk and two in Suffolk. Andy Taylor, Ford's European sustainability director, said: "This is an important breakthrough for the Ford Focus FFV and the biofuel industry. Ford has been working with partners such as Morrisons for a year to make bioethanol publicly available. Together we have taken a vital next step towards encouraging more customers to consider buying Ford's biofuel cars."
The 1.8-litre Ford Focus FFV costs from £14,095 - in between the petrol-only 1.6 and 2.0-litre Focus models.
It is incidentally, perfectly legal to run your car on vegetable oil, alcohol or almost anything else in the UK, provided you pay the fuel tax duty.
C G Engine Services
* Diesel engines run perfectly well on waste vegetable oil provided fuel and engines are sufficiently pre-heated to get over viscosity and polymerisation problems
* Bioethanol is now on public sale in the UK
* Almost any fuel is legal to use in vehicles in the UK provided fuel tax is paid.
For more technical developments see www.eurekamagazine.co.uk
Back to list of stories