Make your own biodiesel: Journey to Forever Part 4

Make your own biodiesel: Journey to Forever
Detailed description of methods of creating biodiesel and its related issues.

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The process
Vegetable oils and animal fats are triglycerides, containing glycerine. The biodiesel process turns the oils and fats into esters, separating out the glycerine. The glycerine sinks to the bottom and the biodiesel floats on top and can be syphoned off.

The process is called transesterification, which substitutes alcohol for the glycerine in a chemical reaction, using lye as a catalyst. See How the process works

Chemicals needed

The alcohol used can be either methanol, which makes methyl esters, or ethanol (ethyl esters). Most methanol comes from fossil fuels (though it can also be made from biomass, such as wood), while most ethanol is plant-based (though it is also made from petroleum) and you can distill it yourself. There is as yet no "backyard" method of producing methanol. But the biodiesel process using ethanol is more difficult than with methanol, it's not for beginners. (See Ethyl esters.)

Ethanol (or ethyl alcohol, grain alcohol -- EtOH, C2H5OH) also goes by various other well-known names, such as whisky, vodka, gin, and so on, but methanol is a poison. Actually they're both poisons, it's just a matter of degree, methanol is more poisonous. But don't be put off -- methanol is not dangerous if you're careful, it's easy to do this safely. Safety is built-in to everything you'll read here. See Safety. See More about methanol.

Methanol is also called methyl alcohol, wood alcohol, wood naphtha, wood spirits, methyl hydrate (or "stove fuel"), carbinol, colonial spirits, Columbian spirits, Manhattan spirits, methylol, methyl hydroxide, hydroxymethane, monohydroxymethane, pyroxylic spirit, or MeOH (CH3OH or CH4O) -- all the same thing. (But, confusingly, "methylcarbinol" or "methyl carbinol" is used for both methanol and ethanol.)

You can usually get methanol from bulk liquid fuels distributors; in the US try getting it at race tracks. With a bit of patience, most people in most countries manage to track down a source of methanol for about US$2-3 per US gallon.

For small amounts, you can use "DriGas" fuel antifreeze, one type is methanol (eg "HEET" in the yellow container), another is isopropyl alcohol (isopropanol, rubbing alcohol), make sure to get the methanol one.

Methanol is also sold in supermarkets and chain stores as "stove fuel" for barbecues and fondues, but check the contents -- not all "stove fuel" is methanol, it could also be "white gas", basically gasoline. It must be pure methanol or it won't work for making biodiesel. See Methanol suppliers

Methylated spirits (denatured ethanol) doesn't work; isopropanol also doesn't work.

The lye catalyst can be either potassium hydroxide (KOH) or sodium hydroxide (caustic soda, NaOH).

NaOH is often easier to get and it's cheaper to use.

KOH is easier to use, and it does a better job. Experienced biodieselers making top-quality fuel usually use KOH, and so do the commercial producers. (KOH can also provide potash fertiliser as a by-product of the biodiesel process.)

With KOH, the process is the same, but you need to use 1.4 times as much (1.4025). (See More about lye.)

You can get both KOH and NaOH from soapmakers' suppliers and from chemicals suppliers.

NaOH is used as drain-cleaner and you can get it from hardware stores. It has to be pure NaOH. Shake the container to check it hasn't absorbed moisture and coagulated into a useless mass, and make sure to keep it airtight.

The Red Devil-brand NaOH lye drain-cleaner previously sold in the US is no longer made. Don't use Drano or ZEP drain-cleaners or equivalents with blue or purple granules or any-coloured granules, it's only about half NaOH and it contains aluminium -- it won't work for biodiesel.

CAUTION:
Lye (both NaOH and KOH) is dangerous -- don't get it on your skin or in your eyes, don't breathe any fumes, keep the whole process away from food, and right away from children. Lye reacts with aluminium, tin and zinc. Use HDPE (High-Density Polyethylene), glass, enamel or stainless steel containers for methoxide. (See Identifying plastics.) See Safety

See also Making lye from wood ash.

Chemicals for WVO

Isopropanol for titration is available from chemicals suppliers. Some people have used the other kind of Dri-Gas, which is isopropanol, but they found that it's unreliable. Best get 99% pure isopropanol from a chemicals supplier. 70% pure isopropanol is also said to work, but we found it didn't give satisfactory results.

Contrary to rumour, "phenol red", sold by pool supply stores and used for checking water, won't work for titrating WVO, its pH range isn't broad enough. Use phenolphthalein indicator, specifically 1% phenolphthalein solution (1.0w/v%) with 95% ethanol. Phenolphthalein lasts about a year. It's sensitive to light, store it in a cool, dark place. You can get it from chemicals suppliers. See: Phenolphthalein

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