Domestic production of biodiesel - health and safety warning

Biodiesel is a relatively new synthetic fuel made chemical treatment of vegetable oils. It is produced commercially and can be bought from some petrol stations. However, there are 'recipes' available on the Internet for domestic production of biodiesel. These usually involve mixing methanol with sodium hydroxide (also known as caustic soda or lye), then pouring the resulting mixture into vegetable oil.

Home production raises health and safety concerns. Making biodiesel is a potentially hazardous process as it involves hazardous chemicals and the risk of fire and explosion. It should only be carried out in controlled conditions by people with the proper training and experience.

The main hazards are described below.

Hazardous chemicals

The individual chemicals needed for the process are hazardous.

Sodium hydroxide is extremely corrosive. It can cause burning to unprotected skin and is particularly damaging to the eyes. Stirring the liquid can often produce a fine mist of liquid droplets. If this mist is inhaled, severe irritation of the respiratory tract and breathlessness can occur. Accidental swallowing can cause major damage to the throat lining and digestive system.

Methanol is a toxic chemical. It can enter the body through breathing in the vapour, direct skin contact or by accidental swallowing. It can cause nausea, dizziness and visual disturbances that can result in blindness. Swallowing small quantities could pose a significant health threat to the central nervous system and could also affect other vital organs. It is a cumulative poison and repeated exposure to relatively low concentrations could cause harm in the longer term.

Risk of fire and explosion

There is a serious risk of fire and explosion because methanol is highly flammable and there are many potential sources of ignition in most homes such as:

• normal electrical equipment, for example kitchen appliances, plugs and switches;
• open flames, for example gas burners; and
• smoking materials.

It is also possible that a violent chemical reaction could occur by

• making a mistake with the recipe, for example getting the quantities wrong or adding the chemicals in the wrong order;
• poor mixing; or
• making too much at once.

Any of these could result in the mixture splashing or boiling over, causing serious burns.

HSE advises against home production

While HSE does not enforce health and safety in domestic premises, because of these serious health and safety risks, HSE advises against the home manufacture of biodiesel using domestic or other unsuitable facilities and by people who are not trained in handling dangerous substances.

Further information

• Free leaflet - Controlling fire and explosion risks in the workplace (INDG370)
  ISBN 978 0 7176 6485 6
• Available from HSE Books - The safe use and handling of flammable liquids (HSG140)
  More detailed guidance on flammable liquids (ISBN 0 7176 0967 7)
• Designing and operating safe chemical reaction processes (HSG143)

HSE publications are obtainable from HSE Books, telephone +44 (0)333 202 5070

Although HSE's prime concern is with health and safety, we are also obliged to point out that duty must be paid on any biodiesel fuel if production for personal use is over 2500 litres a year or if it is sold.