Making a test batch of biodiesel or the Dr Pepper method.

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Making biodiesel from vegetable oil

Biodiesel, is processed from vegetable oil, and can be made from fresh new straight vegetable oil (SVO) or from used mixed waste vegetable oil (WVO) and it can be used in any engine which uses conventional diesel without modification, and is a lot cheaper than diesel as well as better for your engine and the planet, But the best news is that you can make it yourself and help break the grip of the multi-national oil companies. However if you make more than 2500 litres per year fuel duty is payable to HM Customs and Revenue


Making biodiesel involves the use of some chemicals which can be dangerous or harmful, particularly methanol and sodium hydroxide (caustic soda) or potassium hydroxide suitable precautions should be taken when handling these chemicals, making biodiesel is safe if you're careful and sensible so wear protective gloves, and eye protection and do not inhale any vapors, and keep water and fire extinguisher close to hand. The chemicals used are no more toxic than other household products like drain cleaner if used with care and attention.

Methanol can cause blindness and death and is highly inflammable and burns with no visible flame.

Sodium hydroxide can cause severe burns and even death.

Methanol and sodium hydroxide form what biofulers term sodium methoxide.

These are caustic and dangerous chemicals, please treat them with respect!

Basic single stage method

This basic recipe yields approx 1 litre of biodiesel.

This is a basic method for transesterifying vegetable oil into fatty acid methyl ester biodiesel, and can be scaled up for bigger batch sizes.

Ingredients: 1 litre of straight vegetable oil (SVO) or waste vegetable oil (WVO) 200ml methanol 5g sodium hydroxide (caustic soda) Water

NOTE -- If using new, straight vegetable oil (SVO) steps 1 and 2 below are skipped and the catalyst is set at 5g per litre

What you need to do

1. Waste vegetable oil feed stock is filtered to remove any food particles, dirt and contaminants.

2. A sample of the vegetable oil is tested by titration to determine how much catalyst is needed to neutralise any free fatty acids (turn them to soap) and also achieve maximum conversion of the remaining veg oil to fatty acid methyl ester biodiesel - the catalyst can be either sodium hydroxide or potassium hydroxide.

3. The catalyst is then mixed thoroughly with methanol - methanol is calculated at 20% of the total of oil to be reacted.

4. The vegetable oil is warmed to 55°C.

5. The alcohol/catalyst solution is warmed to 55°C.

6. The alcohol/catalyst solution is added to the vegetable oil and the mixture is kept at over 50°C and agitated over a period of 1 hour or more.

7. The heat is turned off and the reacted mixture is allowed to cool and then forms into two separate layers, the lighter coloured biodiesel on the top, with a darker coloured glycerol layer underneath, it is then left to allow the glycerol to settle out completely.

8. After the two layers have separated cleanly the lower glycerol layer is drained off and what you are left with is biodiesel, which will contain some residual methanol and catalyst and soap that was created as a by product which will need to be removed, this can be done various ways, water washing or demething and bubbling are the most popular.

See also