Biodiesel Process Description

While one commonly followed version of the biodiesel process is presented here, there are a multitude of alternative methods through which small producers successfully transform feedstock oils into quality biodiesel. New practices for safe and efficient processing are constantly being devised by the small-scale production community.

Simplified Overview of Processing Steps

1. Collect feedstock: waste oil from restaurants, pressed oil from oilseed crops, render animal fats, trap grease, etc.

2. Check oil for water content (see Biodiesel Quality Test Methods) and de-water oil if necessary. (Settling collected oils in large bulk tanks/drums, then drawing oil for processing from the top of the tank/drum may be sufficient in warmer weather.)

3. Filter oil to remove food particles and debris.

4. Fill processing equipment with oil and begin heating.

5. Test oil for free-fatty acid content via titration to determine the amount of catalyst (NaOH lye or KOH) to be used per liter of oil (see Biodiesel Quality Test Methods).

6. Make a mini batch with the heated oil (500 mL or 1 liter) to test the accuracy of the recipe being used before proceeding to a large batch. Mason jars make cheap and effective test batch vessels, provided they have tight-fitting lids.

7. When oil has reached the reaction temperature of 120 to 130 degrees Fahrenheit (50 to 55 degrees Celsius), proceed to mix the large batch using the recipe from a successful test batch. Carefully mix lye with methanol, add chemicals to oil, mix for up to two hours, and then allow glycerol by-product to settle.

8. Make accurate records of all variables in each batch of fuel: oil source, mixing time, temperature, quantities of reactants, any other processing variables.

9. Drain glycerol by-product and label for further processing, temporary storage, or disposal. The glycerol will contain significant methanol and should be handled as such (flammable and toxic).

10. Recover excess methanol from raw biodiesel. If methanol is not recovered from biodiesel, the raw fuel should be treated as if it were methanol (flammable and toxic).

11. Pump biodiesel to wash tanks and wash.

12. Allow water to settle out over several days or dry biodiesel via “active drying.”

13. Pump through a filter to fuel storage barrels.

14. Test fuel for quality parameters and compare with processing records.

15. Recover methanol from glycerol once sufficient quantities are on hand.

16. Dispose of gycerol and wash water in a safe and responsible manner