Making Biodiesel from Waste Vegetable Oil

It’s time for spring cleaning even if the snow keeps falling. I found a stack of fliers in my office from the 2008 AG Sustainability Fair. For all of you do-it-your-self-ers out there, here is one “recipe for disaster” you could consider trying: Make your own biodiesel from your waste vegetable oil. If you do not get around to that, check out the National Sustainable Agriculture Information Service website. I bet you will click that link before you cook some biodiesel.

Recipe provided by ATTRA, National Sustainable Agriculture Information Service Website.

Making a Small Batch (of Biodiesel) Using Waste Vegetable Oil


One bottle of isopropyl alcohol. (In the U.S., Iso-HEET ? Premium Fuel System Dryer & Antifreeze, 12 fl. oz., in the red bottle, is available at auto parts stores and is about 100% isopropyl alcohol. Isopropyl alcohol is also available at pharmacies.

One bottle of phenol red from the hot tub store.

One liter of 0.1% sodium hydroxide in distilled water"?which is another way of saying 1 gram sodium hydroxide (lye) dissolved in 1 liter of distilled water.

Since you might not have particularly accurate scales, one way of achieving this is to measure out 10 grams of lye and dissolve it into 1 liter of distilled water. Now take 100 milliliters of this water and mix it with 900 milliliters distilled water. You now have pretty close to the 1 gram of lye in 1 liter of distilled water. You can also go to your local pharmacist or high school science department and ask them to do the measuring for you.


One one-cup jelly jar.

Two glass 1 milliliter eyedroppers with graduations marked on the side. Note that you will use one for oil, one for the lye-water mixture. Always use the same eyedropper for the same chemical; do not mix them up.

The procedure

  1. Pour 10 milliliters of room-temperature isopropyl alcohol into the one-cup jelly jar.

  2. Add 2 or 3 drops of phenol red to the alcohol.

  3. Using one of the eyedroppers, slowly, drop by drop, add the 0.1% lye solution until the alcohol just starts to turn red. Stir the alcohol while dropping in the 0.1% lye solution.

  4. Using the other eyedropper, add exactly 1 milliliter of the oil to be titrated.

  5. Now, filling the eyedropper with exactly 1 milliliter of 0.1% lye solution, start dripping this solution into the medicine measure while stirring.

  6. Keep track of how many milliliters of 0.1% lye solution are needed for the liquid to turn and stay red.

The number of milliliters of 0.1% lye solution needed is equal to the number of extra grams of pure sodium hydroxide catalyst needed to produce the proper reactions to make biodiesel. For example, if it takes 3 milliliters of 0.1% lye solution to turn the oil and isopropyl alcohol solution to a base, you will need to add 3 grams of sodium hydroxide to the 3.5 grams for new oil, or 6.5 grams total per liter of waste oil.