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Biodiesel: Fueling Self-Sufficiency
By Cathi-Lyn and David Dyck

 It all began with a truck—a  real fuel pig, a delightful brute to drive. It was the ultimate farm family vehicle. All we needed was fuel we could actually afford. My husband Dave was fascinated with the combination of simple chemistry, financial savings, and junkyard foraging he stumbled upon. With other people’s castoffs—used frying oil, discarded hot water tanks, old piping—he began to make his own diesel.

What Is Biodiesel?

Biodiesel is distinguished from petro-diesel by its source material. It’s made from animal or vegetable fats or oils, rather than petroleum products. As such, it’s far more renewable.  

Biodiesel has some unique attributes. It’s biodegradable. It’s not classified as a dangerous good here in North America. The fumes from burning biodiesel are much less noxious, containing no sulphur. (Our truck smells like fried food!) Unlike diesel fumes, biodiesel by-products are not carcinogenic. 

In the past, diesel fuel was manufactured from whale blubber, contributing to the near-extinction of many whale species. More benign alternatives are oilseeds such as rapeseed (canola), sunflower seed, or hemp seed. 

Biodiesel is made by chemically altering triglycerides, or oil molecules. The glycerin (glycerol) is removed from the triglyceride by a catalyst of sodium hydroxide (NaOH) or potassium hydroxide (KOH). The glycerol is replaced by methanol.


How Is Biodiesel Made?

The total cost of our processing system was somewhere around fifty dollars. Dave built it from a plan called an “appleseed processor,” available online (see resource list below). Our system consists of:

  • A half-barrel into which we dump the filtered waste oil
  • An inline pump
  • A hot water tank (no water) for a mix tank
  • A small distilling loop for methanol recovery
  • A 45-gallon plastic wash tank
  • A second hot water tank (with water) for washing the fuel

 We often alternate between metric and American measures in our daily life, but for biodiesel, we use metric. The metric amounts used for these measurements are quite small and precise, and their ratios are more conveniently expressed in metric than in American measures. For instance, one millilitre (mL) is approximately one-thousandth of a U.S. quart. A gram is a very small, precise measure of weight, about 3.5 hundredths of an ounce. (Metric measurement tools are available through science supply outlets.) 

Following is a general description of how we make biodiesel. There is another process for refining biodiesel, called a “two-stage” or acid-base process. has full, detailed instructions for both methods.

Every Oil Is Different

 Normally, the amount of lye needed to make biodiesel from raw oil averages 3.5 grams for each litre of oil. But if you are using waste vegetable oil from a restaurant, its chemical structure will have changed. This oil will contain more free fatty acids than uncooked oil. These are molecules that have been ripped apart by the cooking process, becoming diglycerides, monoglycerides, and glycerol. Extra lye must be added to remove these free fatty acids. The lye will turn them into a soap emulsion that will settle to the bottom of the mixture. 

Dave adds 1 gram of lye to 1 litre of water. A 1-mL sample of oil is dissolved in 10 mL of 90% isopropyl alcohol (rubbing alcohol) and warmed. He uses a syringe with metric graduations to add the lye solution to the oil-alcohol solution drop by drop, until the pH of the mixture is 8.5. He then takes the number of millilitres of lye solution he added as equaling the number of grams of lye needed, added to the basic average of 3.5 grams, to catalyze a litre of the cooked oil. This is called “titration.”


Mixing the Fuel
The most dangerous part of the process is mixing the lye and methanol into methoxide. A gas mask and protective gear must be worn. Dave once had an accidental exposure to the fumes from the reaction. His lower face looked like it had been literally scrubbed raw.  

We put the oil into the processor by dumping it into a half-barrel that’s piped into the processing system. The system has a pump inline, which we use to transfer the oil into the hot water tank. Then Dave adds the methoxide solution. 

Once all three ingredients are in the hot water tank, the inlet valves are closed. The mixture is warmed in the tank. Then the pump is turned on again, circulating the chemical mix to ensure the reaction occurs evenly throughout.

Washing and Settling
The mixed biodiesel is transferred to a wash tank, a plastic 45-gallon drum with a hinged wooden lid. On the underside of the lid, Dave has fixed a sprinkler head that showers the biodiesel with warm water. A batch of biodiesel usually fills no more than two-thirds of the wash tank. We fill the rest with hot water, which removes glycerin, soap, lye, and free fatty acids. These would otherwise acidify the fuel, plug a motor’s injectors with goo, and cause corrosive damage to engine and fuel system parts. 

Once washed, the fuel is left to settle. It rises to the top of the tank. The water and contaminants sink and are drained off the bottom by a tap. We may wash our fuel two or three times, until it goes from a muddy brown to a clear bronze color.


Some Hints and Considerations

Use pure catalyst. Regardless of which catalyst is used, it must be of sufficient purity to react correctly. We purchase our lye and methanol from a bulk industrial chemical supply outlet. Because making biodiesel is similar to making soap, you also can check out soap makers’ supplies. We use lye (NaOH) for our catalyst, because it’s more readily available than high-grade KOH in our area.

Inform your suppliers that you’re not making drugs in the backwoods! Illegal drug manufacturers seeking to make crystal meth may buy methanol in large quantities. It’s a good idea to be forthright about why you want a large amount of methanol.

Be prepared to change fuel filters in your vehicle a couple of times. Because biodiesel is more acidic than petro-diesel, it will clean the gunk out of your gas tank and fuel lines, speaking of which, biodiesel eats rubber (including rubber coating on wires in the engine bay). Replace rubber fuel line with synthetics.

Avoid using too much lye in your mix. Just as lye breaks down the glycerol bond with the fatty acid chain, it can break down the methanol bond with the fatty acid chain, resulting in sub-par fuel full of free fatty acids.

Biodiesel gels sooner than petro-diesel. This means that in weather below freezing, your fuel will slowly turn to slush, and then lard. One possible solution to cold-weather fuel gelling is to look into acquiring a heated fuel tank. Because biodiesel’s flashpoint is well over the boiling temperature of water, a heated tank is not the fire hazard it might sound like.

• Biodiesel costs us about $1.00/U.S. gallon compared to $3.60 at the pump. Enjoy your newfound financial freedom! We do.

 Resources:—basic biodiesel fact sheet—everything you ever wanted to know about biofuels, including how to make bio-D in a 5-gallon pail. Also, check out their kids’ activities under “School and Youth Projects.”—plan for a biodiesel processor—information about oilseed crushers for producing your own raw oil—alternative energy page with information about listeroid engines for stand-alone power generators—straight vegetable oil as fuel, bio-D and hazardous chemical designations—weekly retail diesel prices in the USA—an interesting study topic

Copyright 2008, all rights reserved by author.
Originally appeared in the Spring 2008 issue of The Old Schoolhouse Magazine®,


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