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Homemade Biodiesel

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To start, you can easily make a few batches of homebrew biodiesel simply by using regular 5 gallon pails and a few power tools. Give this a try and test your results out before committing to larger scale equipment.

Initially, you will need the following items to make biodiesel:

Homemade Biodiesel

Secondary ingredients: Biodiesel isn’t made from cooking oil alone. You will need two other ingredients to create it: methanol and lye (Sodium Hydroxide). Methanol, also known as wood alcohol, is used in racing applications due to the fact that it is less flammable than gasoline, although it costs about the same per gallon. Each gallon of biodiesel you make will be comprised of about 20 percent methanol, and this stuff can be bought readily from auto parts stores and racing shops, most economically in a 55 gallon drum size.

Since the vegetable oil you start with is acidic, you must add the methanol (a base) and the lye (the catalyst), to be able to start the chemical reaction (transesterification) that makes the biodiesel. Lye is also widely available from chemical supply houses and mainly used to make soap.


  • A good scale: You will need a quality scale for measuring out precise amounts of the lye. This should be a lab type balance scale, or can even be a digital scale for compactness and accuracy.
  • Small jars, flasks, or beakers for titration
  • Some isopropyl alcohol for testing
  • Rubber gloves, safety glasses, respirator
  • Fire extinguisher
  • Disposable measuring syringes
  • A large steel cooking pot
  • A propane fired camp stove
  • Thermometer capable of being immersed in oil
  • Steel bucket
  • Plastic 5 gallon bucket with lid
  • Power drill
  • Mixing bit
  • Filter material – coarse. This can be a bag type filter.
  • Funnel with a filter built in


Before you start mixing, you must test the waste vegetable oil – it needs to be tested for its chemical properties to ensure a satisfactory reaction with the methanol. If your batch doesn’t “kick off ” because you added the wrong amounts of ingredients, you’ll be left with lots of useless sludge!

In theory, if you are using virgin cooking oil that is clean and has never been used, you will need about 1% of lye by weight, compared to the oil. In practical terms, this means 3.5 grams of lye per liter of vegetable oil (which is why you need that fancy scale!). Used vegetable oil, however, contains many waste products within, and one of these is free fatty acids. These fatty acids use up the lye before it can start the chemical reaction, meaning your mixture won’t kick off. The oil must be tested to see what its properties are, which will tell you how much lye to add. The process you use to test the oil is called titration. If this sounds familiar, you probably were not asleep in high school chemistry.

Here’s what you do:

  1. Take a good sample of the oil you are about to use, about 100 ml. Ensure the oil has been thoroughly stirred before you take the sample.
  2. Take a second jar and put exactly 10 ml of isopropyl rubbing alcohol in it.
  3. Take some standard cooking turmeric (an ochre colored spice commonly available at most supermarkets) and put a couple shakes of it into the jar with the alcohol.
  4. Take 1ml of your oil sample, and add to the jar with the turmeric and alcohol.
  5. Take a clean, new syringe, and load it with 10ml of your sodium hydroxide solution (lye).
  6. Slowly squeeze the lye solution into the jar with the turmeric and oil sample, swirling the jar to mix it as it flows in.
  7. Keep adding lye until the whole solution turns evenly red.
  8. Record the amount of lye solution left in the syringe and subtract from ten – this is the amount of lye you will need to add to the oil and methanol mix to get a chemical reaction!
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