Biodiesl

To make biodiesel fuel efficiently from used vegetable oils and animal fats we have to avoid one major problem: soap formation. Soap is formed during base-catalyzed transesterification (using lye) when sodium ions combine with free fatty acids present in used (and some virgin) vegetable oils and animal fats. The soaps diminish the yield because they bond the methyl esters to water. The bondedesters get washed out at the washing stage but make water separation more difficult and increase water consumption. This process takes care of the free fatty acids.

In one early test I used a mixture of 50% heavily used cooking oil and 50% pork lard. The result was a pure product with absolutely no trace of soap! The biodiesel looked nice, and smelt nice, as if made from virgin oil.

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This is a simple procedure. The first-stage process is not transesterification, but pure and simple ESTERIFICATION. Esterification is followed by transesterification, but under acid conditions it's much slower than under caustic conditions and it won't do a complete oil-to-methyl ester conversion as the reaction is much more equilibrium-sensitive. Without methanol recovery, thealcohol overdose required would make the price of your fuel jump, and even with recovery it would still be much more expensive. Hence the second base-stage.

For the first stage you'll form a compound out of an acid and an alcohol. The alcohol is still methanol, but instead of using lye (sodium hydroxide), the CATALYST in this reaction is sulphuric acid ("battery acid"). It needs 95% sulphuric acid(battery acid is around 50%). Sulphuric acid is one of the commonest chemicals on Earth, just like lye. More concentrated sulphuric acid -- 98% and above -- costs more, but 95% works just fine if you follow these directions. Other acids won't work: it must be sulphuric acid. You can buy sulphuric acid online from Duda's Alternative Energy Store: http://dudadiesel.com/

The second stage uses lye,as usual -- but it only uses about half as much as other methods.

The sulfate ion in the sulphuric acid combines with the sodium ion in the lye during the second-stage reaction to form sodium sulphate, which is a water-soluble salt and is removed in the wash. No sulphur remains in the biodiesel fuel product.
Equipment
You don't need a special processor for the Foolproof method. Generally, abottom-drained reactor vessel is best, closed on top. Tall, narrow containers work better than wide, shallow ones. Use a circulating pump for mixing rather than a mechanical stirrer. The pump should take the mixture from near the bottom of the reactor and return it via the top, to splash down on the surface. For a 35-litre reactor, a 100-W washing-machine pump will do, along with a 1.5kWwashing-machine immersion heater to heat the mixture (get a heater that's coated with stainless steel). You could use a thermostat to control the temperature, but they're expensive: just use a thermometer and switch on the heater as required.

Ordinary iron and steel implements and containers will eventually corrode because of the acid used in this process. However, you can still use the usual 55-gal(200-litre) drum. The proportion of acid used in this process is very low -- you should be able to use an uncoated drum for a year or more before the rust gets out of control. I use a polypropylene plastic reaction vessel. Any plastic that won't deform at 100 deg C (212 deg F) or a bit more is fine. Stainless steel is also fine. Use an immersion heater with plastic containers. With steel containers youcan use propane heaters to heat the oil, then switch to an immersion heater before adding the methanol.
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Test batches
Whenever you're trying a new method, it's always a good idea to make small test batches of a litre or less first to familiarize yourself with the process before moving on to bigger batches. Most people use kitchen blenders for this --...