DIY biofuel
Getting fuel from vegetables seemed like the ultimate green solution … until we realised that the profitability of biofuel plantations meant they were replacing valuable natural habitats and local food supplies. But there are truly sustainable ways to join the new power generation, and you can do it yourself with used cooking oil from your local restaurant or fish ’n’ chip shop. The process is simple, but be warned: as you might expect from anything to do with the motorcar, it can be dirty and dangerous if not done with due care and attention.
What you’ll need:
- a diesel vehicle
- 1 litre of used restaurant cooking oil
- 200ml pure methanol (warning: highly flammable; order it from www.wpl.co.nz)
- 4g of sodium hydroxide, also known as caustic soda or NaOH (get it from www.gonative.co.nz)
- thermometer
- pH paper
- glass measuring beaker
- 3 thick 2-litre plastic bottles with good lids
- accurate scales
- gloves
- safety glasses
- old long-sleeved shirt or apron
- large sheets of newspaper
- paper towels
- bucket of warm water
- stickers
- pen
- open, well-ventilated, uncluttered space to work in
1. Be safe
Cover all exposed skin. Put on gloves and safety glasses. Do not smoke! Pour 170ml of methanol into a dry beaker. Add 2.8 grams of sodium hydroxide. Cover the beaker and swirl gently for two or three minutes. Do not shake. Keep it covered and leave for five minutes for reaction to complete. Label it as dangerous and do not smell or taste it.
2. Good chemistry
Measure 800ml of vegetable oil into the 2-litre plastic bottle. Place bottle in bucket of hot water for 10 minutes until oil reaches 30–35°C. Add the contents of the beaker. Replace bottle cap and gently rock the bottle for five minutes. You will notice a milky solution forming. (If this reaction is not working, you may need to mix together and add an extra 0.5–1 gram sodium hydroxide and 30–60ml methanol.) Wipe bottle with paper towel and wash all other used equipment and your hands twice in clean running water.
3. The acid test
Tidy equipment away, apart from pH paper. Measure pH of the milky solution after a further ten minutes. It should be about 11 (alkaline). Rock the bottle again for five minutes and measure pH again. It should be reducing. Rock again for three minutes. Measure pH. It should read about 9. Allow contents of bottle to settle. You should notice a thin brownish layer at bottom of bottle. Give the bottle one last gentle rock and then leave for 14 hours to settle.
4. Got diesel?
Pour 500ml of hand-warm water in a thin gentle stream into the centre of the bottle, then close the cap and gently rock the bottle for one minute. Leave it to settle for 5–10 minutes. You should see three layers form in the bottle. The top layer is the best biodiesel. Gently pour off the top layer into another bottle.
5. Drive
In the new bottle, repeat step 4. Do this twice, with the top layer each time (it’s the best stuff we want). Test the pH; it should be around 7.
Mix the third, final layer of biodiesel in with 10 litres of normal diesel in your vehicle and take some friends to the farmers’ market.
Your vehicle will need to be weaned off conventional diesel with careful attention to the filters and jets, but should then be capable of running on 80% biodiesel without further adjustment.
If your experiment is successful, you can work on securing more ingredients, equipment and work space to make more fuel. If you’re keen to buy your own mini-processing plant, try www.biodieselprocessors.co.nz
