How to make Biodiesel, Part 1

Welcome to the next post in our Biodiesel series!


In this post we will describe the best way to prepare your raw materials by performing a titration test before starting the process of making biodiesel.

Biodiesel can be produced using either clean, straight vegetable oil (SVO) or waste vegetable oil (WVO).  If you are using SVO, you do not need to perform a titration test before starting the process of making biodiesel. If you intend to use WVO to make your fuel, firstly you will need to filter it thoroughly to remove any food particles. Secondly you need to perform a titration test to determine the levels of free fatty acids (FFAs) in the oil. The higher the level of FFAs, the more catalyst is required. This test must be performed using the catalyst you have chosen to use for your biodiesel – either Sodium Hydroxide or Potassium Hydroxide.

Step-by-step Titration Test

1. Once filtered down to 5-10 microns, heat your WVO to 120°C to remove any water. If water is present the oil will spit (perhaps violently) so care should be taken. Once the oil is still, allow the temperature to reduce to 60°C.
2. In a glass container, dissolve 1g of your chosen catalyst in 1 litre of distilled water. This is your tester solution.
3. Using an eye dropper, drop tester into the oil mixture 1ml at a time. After each drop, test the mixture with pH paper. Keep going until the pH is at level 8-9. Count how many millilitres of tester solution you have added.
4. Repeat testing until you have obtained the same results a few times to check accuracy.
5. For every ml of tester solution you added, you need to add 1g extra catalyst to your methanol. If more than 4ml was added, it is advisable not to use that oil.

Here is a handy formula to help you work out how much catalyst to use:

If using Sodium Hydroxide:          # litres of oil x (5g + test results) = total g NaOH required

If using Potassium Hydroxide:      # litres of oil x (7g + test results) = total g KOH required

In our next post, we will go through the process involved in making biodiesel.


Please ensure you have read and understood the guidelines provided by HMRC if you intend to produce biodiesel, or if you intend to sell it.
Producing biodiesel involves working with potentially dangerous chemicals, and you should always wear appropriate protective clothing, including gloves, goggles and overalls. Please see the Health and Safety guidelines from HSE.