On converting your car to straight veggie oil

17 Mar 2005

Got questions about the environment? Ask Umbra.

Dear Umbra,

A few years ago, I bought a Prius because it was (and still is, unfortunately) the best car that's offered in our messed-up world. I'm now going to buy an old diesel Mercedes and convert it to run on used vegetable oil. I think this might be the best way to go. What are your thoughts on this? Thanks!

Jilli
Tarzana, Calif.

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Dearest Jilli,

I answered the main part of your question in my last column, and in so doing, I promised readers that a fuller exploration would be forthcoming -- so if you don't mind, I'm going to use this opportunity to explain how straight vegetable oil (SVO) conversion works. En suite, peoples, the next class in Umbra's Basic Diesel School.

Go, veggie-mobile, go!

Photo: Neoteric Biofuels Inc.

In a diesel engine, the fuel leaves the tank via tubes, enters the fuel injector, and is forcefully sprayed into the engine, where it combusts. Diesel engines were designed with fuel oils of all types in mind, including vegetable oil. You could buy a bottle of Crisco and pour it into the tank and the car would run -- but not well, and not for long. Vegetable oil is naturally more viscous than petro diesel or biodiesel, so getting it to the point where it is liquid enough to pass through the tubes to the combustion chamber requires a significant amount of heat and can be quite difficult if the engine is cold. Additionally, SVO will gum up the works if it reaches the engine but then is left to cool. Moreover, SVO that isn't hot enough burns incompletely, and thus inefficiently.

Converting an engine to run on SVO, then, means tinkering with the fuel-delivery system to warm the SVO before it passes through the tubes and, in some cases, heating it again before it enters the combustion phase. For the mechanically minded this is a thrilling challenge, and if you want to design your own conversion system, go for it. The rest of us will have to rely on commercially available systems.

These systems almost all entail installing what is basically a second fuel system: separate SVO tanks and hoses, a heating system in said tank and/or on the way to the engine, a device for routing radiator heat to said systems, and a way to switch between diesel and SVO. With these systems, the car initially starts using diesel (or biodiesel) from the original fuel tank. When the engine and the SVO have both been heated for a sufficient amount of time, the driver flips a switch and the fuel delivery system changes over to the SVO tank. At the end of the drive, the driver must reverse the process so that when the engine comes to a stop there is diesel in the tank and the fuel lines, rather than soon-to-be-gooey SVO.

SVO conversion kits are readily available and range from about $650 to $1,500 without installation. They can be found at Frybrid, Greasel, Greasecar, Neoteric, and Elsbett. (The Frybrid folks live in my area, although not quite in my basement, and I spent some time visiting with them a few weeks back. Fun.) The world of SVO conversion is filled with lively debate over which system is best, so before you proceed with your dream, spend a chunk of time on these and other websites developing your own opinion. Running biodiesel can be a passive act of consumption at this point in certain areas of the country, but the SVO-conversion technology is new enough that you need to be informed before you make the leap. You also need to have a good mechanic and the willingness to be actively involved with your car. That's my advice.

My other advice is to spend time learning what it takes to obtain and process used restaurant oil. My Frybrid friend takes all the oil produced by a nearby Japanese restaurant, heats it for six hours in an old water heater, removes the resultant water, and then filters the oil until no particles remain that are larger than five microns. He's a particular kind of fellow, and some will insist that you don't need to go that far, but again, this is something you should decide for yourself.

I hope you go ahead with your plan; good luck.

Viscously,
Umbra

Yours is to wonder why, hers is to answer (or try). Please send Umbra any nagging question pertaining to the environment -- but first check out her FAQs!

The claims made in this column may not reflect the views of this magazine. Neither the magazine nor the author guarantees that any advice contained in this column is wise or safe. Please use this column at your own risk.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

Comments: (5 comments)

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Veggie tailpipes

Some time ago, my daughter--an ardent, well-informed environmentalist who doesn't just talk--got excited about biodiesel and looked into it as a business. She was told that straight vegetable oil doesn't work well in diesels because it contains glycerine, which has to be removed. The reigning process, currently, uses lye (a harsh caustic chemical) and exposes the operator to some danger if she is not a well-trained chemist. So Cathy decided not to do it. I have since learned that a new, noncaustic and more nearly permanent catalyst (metallocellulose?) has been discovered but is not yet available.

So, what about the glycerine problem? My hunch is that SVO will work if the engine is properly tuned, but that the claimed efficiencies and lack of pollutants are not based on it but on the purified stuff. Does anyone know?

by Bob Holt at 4:43 PM on 19 Mar 2005

Let's Get Real

Only a tiny minority of people would actually even consider doing the work or spending the money that Umbra claims using vegetable oil entails. It would be far more environmentally and ecologically beneficial to get people to stop or greatly reduce their driving, and there's about as much chance of doing that as there is of getting people to spend the time, effort, and money it appears to take to run an engine on veggie oil.

BTW, I remember perusing a book about a guy who motored his way across the world's oceans about 15 years ago on straight veggie oil, and I don't remember him saying anything about the extreme makeover that Umbra described. What gives?

Jeff Hoffman

by jdhlax at 11:36 PM on 30 Mar 2005

Yellow Grease

Biodiesel just sounds so good. Just take that chicken grease and burn it in your car. Lick your lips and just drive around on the waste cooking oil.

We wish. Unfortunately you have to have an efficient collection system in place to provide a reasonable economy of scale. Then there is the problem of refining the grease and redistributing it back out to gasoline service stations. Will big oil put in another pump? Another underground tank? And as Jdhlax stated, only a small group of people would give it a try. You probably use more petro collecting the stuff than you save in using it. It is a great idea though and to the extent practicable, it should be utilized.

Anyway, I prefer plug-in hybrid electrics.

Norris McDonald

by Norris at 2:28 PM on 31 Mar 2005

The Grease smell

I was thinking of mixing a vegetable oil perfume with the SVO if I got a Frybrid can you tell if this would reduce the smell or cause damage to the engine. I have found I can get everything from Coffee vegetabel oil to strawberry vegetable oil.

by jettcracker at 4:47 PM on 05 Sep 2005

vegiol for school busses

I remember watching the TV show "Dirty Jobs" and saw that some schools that cook their food on site have grease tanks. Grosse. But the point I want to make is that if they could process the oil on site to be used for vegiol it could be used to fuel the school buses that are going to be there anyway. This eliminates the oil moguls from having to "add a pump" etc...
The fact that there is so much oil being used for our kid's meals that it has to be kept in the huge underground tanks is another issue!
This idea could be transposed to other large industries, like hospitals/ambulances or factories/eighteen wheelers, and any other that you can think of.

Just trying to add to the solution and detract from the problem.

by kgone at 10:08 PM on 27 May 2008

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Veggie Tailpipes

On converting your car to straight veggie oil