Tuesday, 20 December 2011

How to make Biodiesel, Part 2


In the second part of our guide, we will go through the process of transesterification and the methods required to make your own biodiesel.

The following provides the guidelines to make 1 litre of biodiesel. Quantities can be increased as desired.

Chemicals/Equipment List

-         1 litre vegetable oil (SVO/WVO)
-         200ml methanol (plus more for topping up)
-         5g Sodium Hydroxide (NaOH) -OR- 7g Potassium Hydroxide (KOH)
-         Glass container with tight lid (Must be glass – plastic will not withstand heat of reaction)
-         Plastic bottles (2 litre)
-         Funnels
-         Thermometer
-         Scales


  1. After performing the titration test described in How to Make Biodiesel, Part 1, pre-heat vegetable oil to 60°C using a saucepan and thermometer.
  2. The following step requires you to work quickly. Pour 200ml of methanol into the glass container using a funnel. Add your catalyst using a clean, dry funnel and replace the lid immediately. Shake the mixture for approximately 10 minutes, until all the catalyst has dissolved. This process will generate heat. Once the catalyst is dissolved you may need to top up with methanol to 200ml to account for any evaporation. This mixture is known as sodium/potassium methoxide (depending on which catalyst you are using).
  3. Pour the warmed oil into the plastic bottle using a clean funnel, and add the methoxide, replacing the lid tightly. Shake the bottle vigorously for 30 seconds and then for 5 seconds every 15 minutes for 1 hour.
  4. The biodiesel will need to rest for a minimum of 8 hours (ideally overnight) to allow the glycerine to sink to the bottom of the bottle, with the biodiesel on top. Slowly pour off the biodiesel into a clean plastic bottle. The glycerine can be used safely in compost, or to make soap.
  5. The next step is to wash the biodiesel. Gently add 500ml of 40°C water and place the lid back on the bottle tightly. Turn the bottle slowly and carefully, end over end for about 30 seconds. The now cloudy water and biodiesel should separate fairly quickly, the water sinking to the bottom. Turn the bottle upside down and let the water out, using your thumb as a valve. You will now need to repeat this process, increasing the length of time rotating the bottle and how vigorously. By the 4th or 5th time the biodiesel can withstand a rough shaking. It will now take longer to settle. The water should now run clear. Now, all traces of water must be removed – most easily achieved by letting the biodiesel stand for at least 2 days, at which point all the water will have separated and can be drained off as before.
  6. The result is clear, dry biodiesel that is ready for use in your diesel engine.

The quantities shown here are small, to allow you to scale up as desired. To increase quantities, simply use the formula below as a scale, and use larger receptacles as required.

1 litre    +      200ml       +          5g / 7g
    veg oil           methanol          NaOH / KOH


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.

We hope that you have found these guides useful! We hope to extend our selection of Biodiesel supplies in the near future.

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