Making your own biodiesel fuel can be a fun hobby, a good way to save some money and a great way to help the environment. Biodiesel can be made from both virgin vegetable oil (such as sunflower oil) and, with an additional cleaning and filtering process, used cooking oil. It will run in any diesel engine. Making biodiesel, however, is a complex chemical process that requires some exposure to flammable and dangerous chemicals. Be sure to read the safety instructions carefully before beginning to make your own.
- Skill level:
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Things you need
- All amounts are for a preliminary test batch and can be multiplied for more usable amounts:
- 1 litre fresh sunflower oil
- 200 millilitres of methanol (99% pure or better)
- 5.3 grams of potassium hydroxide (KOH, 92% pure as a lye catalyst)
- Scale accurate to 0.1 grams
- 2 measuring beakers
- 1 ½-litre transparent high-density polythene (HDPE, #2 plastic) container
- 2 funnels
- 3 2-litre polythene terephthalate (PET, #1 plastic) containers, like large water or soda bottles
- 1 thermometer
- Duct tape
- Protective clothing and eyewear
Read and review all safety instructions carefully.
Measure out 5.3 grams of 92% pure KOH, the lye catalyst. The measurement must be done quickly, as KOH will absorb water from the air and become less effective.
Measure out 200 millilitres of 99% pure methanol and, using a funnel, pour it into the ½-litre HDPE container. Replace the lid on the methanol quickly, as the chemical will also absorb environmental water and become less pure.
Using the second funnel (keep methanol and lye funnels separate), add the KOH to the HDPE container and tightly close the lid.
Swirl (do not shake) the HDPE container several times until the KOH is completely dissolved in the methanol. This can take anywhere from 10 minutes to several hours, but make sure the KOH is completely dissolved before moving on to the next step. The resulting chemical is potassium methoxide, and the reaction will cause the temperature of the solution and container to increase.
Preheat the sunflower oil to 55 degrees Celsius and place it in the blender or mini-processor. A household blender will work for mixing biodiesel but will not last long and should not be reused for kitchen applications afterward. If you're serious about making large batches of biodiesel, you may want to invest in a home processor unit that will last longer and be safer.
Carefully pour the solution from the HDPE container into the blender, making sure all the blender seals are tightly closed. Leave the blender running on low speed for 20 to 30 minutes.
Transfer the blended solution into a PET bottle and close the lid. As the solution cools and contracts, you may have to let more air into the container.
Allow the solution to settle for 24 hours. A dark layer of glycerine byproduct will collect at the bottom of the container.
Pour out the biodiesel from the settling container into another PET bottle, making sure no glycerine makes it into the new bottle. Use an oil filter if necessary.
Tips and warnings
- Especially in the case of test batches, you may want to test the purity of your biodiesel. Several tests exist to test different properties of the biodiesel, and it's a good idea to research and implement numerous tests to improve and monitor your process.
- Washing biodiesel is also an important step for purifying the product and making sure that no chemicals accumulate in your engine. Once again, many washing methods exist, and you should research one that works with the equipment you have at hand (see Resources).
- Making biodiesel involves several dangerous, flammable and toxic chemicals. Always make sure you are preparing biodiesel in a safe and well-ventilated environment (certain fumes can be highly toxic), and follow all safety directions with each individual chemical. Mix all chemicals slowly, monitor reactions and wear protective clothing and eyewear to avoid chemical and fire risks.
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