How to Make Used Oil Into Diesel Fuel
Used cooking oil can be used as a component in a biodiesel mix in cars with a diesel engine. The terms waste vegetable oil (WVO) or used vegetable oil (UVO) are used interchangeably and refer to any excess oil remaining after cooking. Biodiesel is a combination of oil, a lye catalyst, and alcohol (methanol or ethanol).
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Things You'll Need
- Filter (optional)
- Processor
- Used cooking oil
- Alcohol (methanol or ethanol)
- Lye (sodium hydroxide)
- Balance or something to weigh ingredients
- Barrels
- Pump
Instructions
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1
Find used cooking oil. In the past, restaurants would gladly hand over used oil. That time is gone in many areas. Establish a relationship with a local restaurant and arrange to pick up the excess oil they used to fry food. If you establish a schedule for pick up, keep to it; there may be others in line to take your spot.
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Ask the restaurant owner what kind of oil they use. Straight used vegetable oil is easier to work with than a mixture of oil with grease or animal fats. Know what you have before you start processing the biodiesel.
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3
Settle or filter the oil. Many people filter the used oil, but filtering will not remove any water that is mixed in with the oil. Allow the oil to sit in a container until the water and any particles separate. This is a long process--up to 2 weeks--so plan ahead and have a batch settling while you are processing a new batch. A drain about 6 inches from the bottom will allow you to pour out the oil without the solid material (from the bottom) or the water (from the top).
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Find your other ingredients. Methanol can be bought from bulk food distributors, paint companies and some car racing shops. Lye, also known as sodium hydroxide, can be found at some hardware stores, chemical suppliers or plumbing stores. As biodiesel becomes more popular there may be companies that specialize in providing these ingredients.
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Create a recipe for biodiesel. The ratio of chemicals is the most important part of any biodiesel recipe. Methanol and lye together can be a volatile product, so care and caution are necessary. In general, the amount of methanol should be 20% of the volume of used or waste oil, and 6 to 7 grams of lye should be used for every liter of used oil. Do a small test batch (e.g., 1 liter) to make sure the proportions work before making a large batch. As with any recipe, test until you get it right.
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Mix the ingredients. Heat the vegetable oil to 100 degrees Fahrenheit. Mix the methanol and sodium hydroxide together to create methoxide. Do not move on until the lye has completely dissolved, which may take several hours. Add the oil to the methoxide mix.
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Process or blend the mixture. An industrial mixer or paint mixer works as well as a purchased processor if used correctly.
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Let the biodiesel settle at least 12 hours. Skim the top layer off before pumping into your diesel car.
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Tips & Warnings
Waste oil can be used straight (after settling or filtering) if your car has a conversion kit or double tank. In that case there is no need to convert the oil to biodiesel.
In cold weather consider adding a winterized diesel solution to the biodiesel.
Use protective gloves and a respirator.
People who steal used cooking oil are known as biodiesel pirates; make sure you have permission to take used oil.
Only use biodiesel in a car with a diesel engine.
