Biodiesel is a fuel similar to ordinary diesel, but instead of being made from fossil fuel – oil – it’s produced from either vegetable oils or animal fat. The main source of biodiesel is presently waste cooking oil, which is collected from restaurants and fast food outlets. Pure oil is too expensive to turn into biodiesel, but used oil can be collected very cheaply – in fact some restaurants even pay to have it taken away!
You can run a diesel engine on vegetable oil alone, but it’s not recommended. It will quickly choke up the engine, leading to failure. To overcome this the oil is turned into diesel by a process called transesterification. This involves mixing methanol (industrial alcohol) with caustic soda then adding the vegetable oil. Glycerin and biodiesel are the end result. The glycerin can be used in cosmetics and the biodiesel goes in your car.
Home biodiesel production is quite a cottage industry, thanks to rocketing fuel prices and the desire to cut down on greenhouse gas emissions. There are plenty of plans for home biodiesel reactors on the web, and you can go on courses which teach you how to build one. All you need are basic DIY skills.
The production process is actually quite straightforward. You’ll need some space to build your biodiesel reactor – ideally an outhouse or shed – a ready supply of used vegetable oil (make friends with your local fast food outlet manager) and somewhere to store your biodiesel.
Once you’ve sorted the logistics of raw material and storage, it’s time for the fun part – making the fuel. You’ll need to get hold of a reaction vessel to mix your ingredients. It’s going to have to be as big as you can fit in your shed – it’s not worth making a few pints of fuel, you want to be producing gallons. Aim for a 55-gallon container if possible. Plastic can be used (some people use water butts), but make sure it’s polypropylene, not PVC. For more durability go for mild steel, or even better, stainless steel. Look on eBay or Freecycle, you never know what you might find.
The mixture needs to be heated to around 60 deg Centigrade so you’ll need a heating element. If you’re using a plastic container, don’t put the element in the container. Instead, use an inline heater to warm the mixture before it goes into the reaction vessel.
Once the vegetable oil, methanol and caustic soda are mixed and heated, a chemical reaction occurs which leaves glycerin and biodiesel. The biodiesel has to be washed with water then separated, leaving you pure biodiesel which goes straight into your car. You can use the glycerin to make soap to clean your hands after all your hard work! -MARKLEE