Refining waste cooking oil...then burning

[Kareem Shihab]

A previous thread talks about the changes needed to a diesel engine if you want to burn waste cooking oil directly. I read somwhere about a guy that was taking the waste cooking oil refining it then burning it. He said he filters it to get chunks of fries and what not out of it first, then adds Lye and Methanol. Does anyone have more detail on this relating to ingredient proportions, other ingredient alternatives, sources of lye and methanol, and if other engine modifications are necessary.
........ I always seem to be asking the questions, someday ill be giving the answers. -K

[Frank Flynn]

"Dirty Jobs" a TV show on the Discovery Channel did a segment on this, converting used cooking oil into bio-diesel. I don't remember the exact process but it did impress me a fairly straight forward; perhaps no more difficult than balancing the chemicals in your pool. That is after you collected all the used oil - which was a bit of work. One thing I took away from seeing it was the space it takes. It took over this fellows whole garage for all the tanks and hardware. While I suppose you could do this in a 5 gallon bucket, you'd wind up with something less than 5 gallons of fuel when done. Not really enough to get you through the week. So he had a couple of hundred gallon tanks and pumps and hoses - his garage looked a lot like a refinery.

[Roy Lent]

Kareem,

Vegetable oil can be used for fuel in a diesel motor, in two forms: straight vegetable oil and after converting it to biodiesel. In the first case, the motor must be converted to burn vegetable oil directly, especially in cold zones, as the oil tends to solidify. In the tropics vegetable oil is sometimes burned directly in simple one cyclinder Lister engines since maintainence is so simple on these.

To make biodiesel, an alcohol must be used. Normally methanol is used but absolute ethanol and some other alcohols can be used. Methanol has a big disadvantage. It is commercially made from methane in natural gas, a fossil fuel. Ethanol can be used but must be absolute, that is with no water contained. Removing the last 4% of water from 96% distilled ethanol can be expensive but I understand that this can be done using corn meal (reusable).

[Stewart Corman]

I recently met our cousin who has two "converted" diesel vehicles that burn WVO directly.

One is an old Mercedes, the other is a F350 truck. It cost $1500 and $3000 respectively for the professional conversions. Each requires a separate tank and the diesel fuel is used just to start the engine when cold and to preheat the WVO at first

BTW, there was no "Fench Fry" odor coming out the exhaust ( at this time?)

He uses the truck to fill a 55gal drum with a 12v electric pump, then it must be filtered with a 1um throw away filter by gravity feed ..takes him about 1 1/2hrs to filter.
Me personally would figure an inline filter that would work with the pump and only take ten minutes unattended.

There is no other processing and the conversion has a two year payback.

He is considering a WVO oil boiler to heat his house, since he has the supply of WVO and the means to get it in multiple 55gal quantities ...the boiler unit costs about $2K more than a conventional oil furnace. If he can run a line from garage down to basement ..he could store in 275gal oil tank and use the pressure head from truck bed/basement level to aid in auto filtering


As far as biodiesel ...I have looked at the process and it has reasonable expenses ...I am a chemical engineer and I wouldn't touch it! Lye is sodium hydroxide and any residual could kill an engine ..this is something for a large commercial venture with real controls on the process ..not to do in the garage!

Note: when commercial processors start to pay restaurants for their WVO OR many individuals compete for the supply....the whole game is up ...for now it is viable

Stew Corman from sunny Endicott

[Roy Lent]

Stew,

Yes, lye is tricky in making biodiesel. However it mostly comes out in the glycerine and sludge, not in the biodiesel. Besides, the pH of the biodiesel should be checked, no? In a good operation the lye should be recovered as it can be used again and again.

[Stewart Corman]

Is anyone on this forum into DIY WVO furnaces?
I specifically an looking for heating a house or garage with a low electric consumption
fuel burner. Converting a Beckett to syphon nozzle which runs at 700 watts and/or needing a Babington requiring a compressor full time to provide air pressure isn't in this paradigm.

Stew Corman from sunny Endicott

[Penny Walters]

Why not all the governments recycle cooking oil?

[Dave Turpin]

Governments could give a crap. If the government of the US cared about making renewable fuel, simply revoking the Fallow Fields Act would go a good part of the way. Did you know that almost 40% of the fuel consumption in the US is for converting fuel into nitrate fertilizer?

People, though, are smart and will do whatever it takes to save a buck.

Back when WVO was free for the taking, there were a few select people cashing in on it. It didn't take long, however, for there to be enough demand for businesses to discover that they could SELL their used oil.

Now you can buy Biodiesel at the pump in some cities (including Seattle)

On a chemical engineering standpoint, Biodiesel is easy to make. Basically Biodiesel is just vegetable oil with the Glycerin and water removed. You need a strong base chemical to get the Glycerin to precipitate. Lye is the easiest to procure. The Lye cannot be recovered, though, and you are left with a high-Ph glycerin sludge that has to be disposed of as HazMat. (Most DIYers ignore this requirement and just throw it away in the trash) Or you could nuetralize it Hydrochloric Acid.

Burning unrefined WVO is also possible, but the Glycerin gums up the works, and this is where the additional expense of converting the engine comes into play. You need to replace the injector assemblies and modify or replace the governor. Refined Biodiesel, on the other hand, can be burned in any Diesel engine as long as the climate allows the Biodiesel to remain liquid.