How to Convert Vegetable Oil Into Heating Fuel

Written by david roberts
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How to Convert Vegetable Oil Into Heating Fuel
A steel barrel is used to store used vegetable oil to prevent rodents from chewing through the sides to get to the oil. (green barrel image by Tammy Mobley from

Using vegetable oil for fuel is not a new idea. Peanut oil was used in the first diesel engine. With crude oil prices so high, heating oil prices are rising as well. The alternative to use vegetable oil for home heating requires converting the vegetable oil to biodiesel fuel. While there are some fuel companies that sell biodiesel, often the price per gallon is more than the price per gallon of the fossil fuel alternative. The answer to that problem is to convert used vegetable oil you obtain yourself into biodiesel.

Skill level:

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Things you need

  • 2 50-gallon steel drums
  • Pump and hose
  • Micron filters, #1
  • Goggles
  • Gloves
  • Apron
  • Lye
  • Sulphuric acid
  • Methanol
  • Drum heater
  • Drum mixer
  • Immersible heating coil
  • Aquarium stone
  • Air pump

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  1. 1

    Contact local restaurant owners and ask if you can remove their used oil from their premises. Many restaurant owners are being charged for waste oil removal and if you can reliably pick up the used oil you may end up getting it for free. Provide a couple of 50-gallon steel drums and you will have an endless supply of used oil for heating oil conversion.

  2. 2

    Filter the used cooking oil through the Micron 1 filter. Place the filter at the top of an empty steel barrel. The filter can be secured into place by stretching it over the top of the empty barrel and using the lid clamp to hold it in. Pour the oil slowly through the filter screen. If the container with the used oil is equipped with a spigot on the bottom, open it up and allow the oil to drain through the filter into the empty barrel.

  3. 3

    Heat the filtered oil to 60 degrees C and maintain that temperature for 15 minutes. Use the barrel heater to do so. This will help settle the water content of the oil out of the mixture. Pour the filtered, now heated, oil into a settling tank. Let the contents settle for at least 24 hours.

  4. 4

    Remove the oil from the settling tank by pumping the oil out from the top of the tank. Whatever water and sediment happens to still be in the mixture will remain at the bottom. Do not pump the tank dry, allow at least 10 per cent of the mixture to remain as waste.

  5. 5

    Check the processed oil for solid fats that may be still in there. If you see the solid fats, heat the oil to 35 degrees C to melt the solid portions.

  6. 6

    Pour mixture into barrel mixer. Add 32 pints of methanol to the oil mixture. Mix for about five minutes. Put on your goggles and gloves and preferably an apron. Add 1/2 gallon of sulphuric acid for a 50-gallon container.

  7. 7

    Mix slowly and keep mixture at least 25 degrees Celsius. Use the immersible heating element for this by inserting the heating rod and plugging the heater in.

  8. 8

    Turn off heat and mix for another hour, then let the mixture settle overnight.

  9. 9

    Measure out 1 gallon of sodium methoxide into another container. Add 709gr of lye to the sodium methoxide and stir until the lye is completely dissolved. Wear the goggles and gloves when working with these chemicals. Let this mixture settle overnight as well.

  10. 10

    Add half of the methoxide into the oil and mix for five minutes. Heat the mixture to about 130 degrees and maintain that temperature. Add the second half of the sodium methoxide to the mixture and continue mixing.

  11. 11

    Pour contents into a container with a spigot on the bottom. Wait about two hours for it to settle. The thick brown gel that will settle is glycerine. Turn off the heat and drain off the glycerine. Use about a quarter of the glycerine and mix with a half gallon of 10 per cent phosphoric acid. Pour the glycerine back into the oil and stir for 20 minutes. Allow the oil to settle for about six hours and then drain all the glycerine from the container.

  12. 12

    Wash the biodiesel fuel. Pour a ratio of 1/3 water to 1 part oil mixture into another container, with a spigot at the bottom. Add a half gallon of 10 per cent phosphoric acid to the water. Insert the aquarium stone into the container and turn on the air pump and let it run for 24 hours. Drain the water and repeat this process two more times.

  13. 13

    Wait for about three weeks, the biodiesel fuel should now be clear and ready to use.

Tips and warnings

  • Working with lye, methanol and fuel oil mixtures is dangerous. The fluid is flammable and can be explosive. Wear your goggles and gloves.

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