Do it right, and DIY biodiesel can cost as little as $1 per gallon to manufacture. The scale is up to you: Brew enough to make your homestead fuel-independent, or join forces with neighbors to produce fuel for your collective households.
At minimum, the equipment you’ll need for home biodiesel production is a stainless steel reactor tank, a wash station to remove the coproducts, and containers for storing the resulting fuel. You can rig up an electric water heater as a biodiesel reactor for less than $1,000, or spend about the same amount on a kit. If you’d rather opt for a ready-made, automated system, expect to pay $10,000 or more.
The Chemistry of Making Biodiesel
Biodiesel production is dependent on two chemical reactions. The first is commonly called the methoxide reaction. It happens when you mix methanol with a catalyst, which can be either potassium hydroxide or sodium hydroxide.
The methoxide reaction is “exothermic,” meaning it gives off heat. Don’t use plastic vessels when creating methoxide. They don’t hold up well to heat and have a tendency to explode or dissolve because plastic can store a static electrical charge. Always opt for stainless steel equipment when making biodiesel.
Sodium hydroxide is commercially produced lye; both sodium hydroxide and potassium hydroxide are available online from suppliers of soap-making equipment. Procure methanol at your local chemical distributor or race car shop (race car drivers often blend methanol into their fuel supplies). After you’ve achieved a successful methoxide reaction, the second required process is the biodiesel reaction. This occurs when you mix methoxide with oil and agitate the molecules. The product of the biodiesel reaction will be a mix of about 80 percent biodiesel and a 20 percent cocktail of coproducts. You can either drain the coproducts off the bottom of your tank, or decant the biodiesel from the top of the tank.
Planning a Home Biodiesel Plant
Step one: Find a reliable source of feedstock. Try sourcing used cooking oil from restaurants, makeup manufacturers or nutraceutical companies. If you’re planning to sell your biodiesel, begin by analyzing the available feedstock supply, and make plans to size your operation accordingly.
You can easily make your own fuel for $1 per gallon by collecting free or cheap cooking oil after it’s served its useful life in a restaurant’s deep fryer. A gallon of oil will yield about a gallon of biodiesel.
Step two: Build your plant, sized to your feedstock supply. A small homebrewing operation can fit in the corner of a garage, within the footprint of a single parking space. Allow enough space for a water heater, a tank for storing your incoming feedstock, and a tank for washing your fuel.If you’re collecting used cooking oil from restaurants, expect that 20 percent of the material you gather will be water and bits of fried food. Water is not your friend when making biodiesel, so you’ll need to remove it by heating the oil and allowing the contaminants to settle to the bottom before you pour the oil off the top. You’ll have to devise a plan for disposing of the greasy wastewater. Pigs love it, and it improves their coats.
Designing a DIY Biodiesel Plant
Backyard biodiesel plants tend to be as diverse as the people who create them. Water heater tanks recycled into biodiesel reactors are common: Imagine an electric water heater, with a pipe plumbed to its outlet at the bottom, attached to a mixing pump that sends liquids to the top of the tank and back around again.
Books on Home Biodiesel Production
Suppliers of Biofuel Plant Equipment