Departments and Offices

Making Biodiesel Fuel
The rising price of fuel, environmental concerns, and ominous signs of global warming have many sustainable farmers looking for alternatives to petroleum.  Biodiesel fuel is an accessible option for those who wish to get involved in creating their own energy solution right on the farm.  Biodiesel, a renewable alternative to diesel fuel, can be run in any unmodified diesel engine, including tractors, trucks, and other equipment.  Biodiesel is made from vegetable oil or animal fat through a simple chemical process, at a cost of as little as $1.00 per gallon.

There are two divergent trends in biodiesel today.  The first is industrial biodiesel, made from virgin soybean oil and funded by the soybean check off program.  This is likely the avenue through which this biofuel will become available to mainstream consumers in the coming years.  The other trend is that of small-scale home and farm-made biodiesel, which is taking place in mini-refineries all around the globe.  Biodiesel homebrewers typically make their fuel from waste vegetable oil collected for free from restaurants that use it for deep-frying.

Biodiesel use has the following benefits:            

  • Significantly lower in EPA registered emissions of carbon monoxide, soot, particulate matter, sulfur dioxide, and carcinogenic hydrocarbons
  • Smells better when it burns (like popcorn or onion rings)
  • Domestically produced energy source from farm products

Making biodiesel from used vegetable oil recycles a high-energy waste product into something useful as fuel.  In addition, because the plants that make the oil used in biodiesel get their carbon from the atmosphere, burning biofuels does not contribute significantly to global climate change linked to elevated atmospheric CO2.

It is with these benefits in mind that we began the Biodiesel project at the Fulton Center for Sustainable Living (FCSL) of Wilson College in Chambersburg, Pa.  We started in the chemistry lab making fuel a liter at a time.  As soon as we had made a few batches and tested the fuel in a diesel irrigation pump, we had caught the biodiesel bug, and the project took off.  In 2003, the FCSL was awarded a grant from the Pennsylvania Farmers’ Union and the Community Environmental Legal Defense Fund to construct a biodiesel processor and to demonstrate the process to farmers around the area.  Engineer Peter Johnson and I created our 50-gallon mobile processor from designs that we gleaned from books and the internet.  Since 2003 we have made and burned about 1250 gallons of fuel from waste fryer grease.

Making biodiesel is fairly simple, and should be well within the grasp of anyone who can make soup, soap, beer, or cheese.  Waste vegetable oil is heated, tested for presence of free fatty acids, then combined with methanol and lye by violent mixing.  Lye can be purchased from the grocery store (in the cleaning products section) and methanol is available from racing fuel distributors.  Oil can be found for free behind many restaurants.  In our processor, the steps are as follows:
  • Heat 50 gallons of oil to 120F, the best reaction temperature.
  • Test the acidity of the oil using a simple process called titration.  Each batch of oil is different depending on how “hard” it was used, and this will require slight adjustments in the amount of lye added.  Typically for 50 gallons we use about 2.5 lbs of lye, but it varies widely and must be tested.
  • Combine lye with methanol.  We use 11 gallons of methanol for a 50 gallon batch.
  • Draw the hot oil into the mixing tank using a pump, then draw the chemical mixture into the oil using the same pump and a venturi.  The oil and chemicals are allowed to mix for about an hour.
  • Settle the mixture overnight.  After a few hours, the byproduct of the reaction, a crude glycerine, will drop out, leaving the fuel floating on top.  We have had success using the glycerine to make hand soap. For every 50 gallon batch, we end up with about 11 gallons of glycerine and 50 gallons of fuel.
  • The fuel is then passed through a filter, and either used directly, or better yet, washed with water for further purification.  Washing fuel is hotly debated among biodiesel brewers, but it really seems to clean up the fuel, leading to more confidence when using it in diesel engines.  The downside is that the waste soapy water becomes an extra byproduct to deal with, which can be a challenge on an organic farm.  At Wilson College we haul the wash water to main campus to run it through the municipal water treatment system.

SAFETY NOTE!!!  Please be advised that materials used in the biodiesel process can cause personal injury or property damage.  Methanol and lye are dangerous, toxic substances and should be used with due caution.  Anytime heat is applied to vegetable oils, fire becomes a legitimate risk.  Before attempting any biodiesel projects, please read up on safety protocols for all materials.  Detailed safety information will be compiled on this page in the near future.  Wilson College does not promote untrained persons making biodiesel.  Please proceed at your own risk!!!

To date we have run our home-made fuel in unmodified Dodge trucks, Volkswagen and Mercedes cars, a John Deere tractor, and a Deutz irrigation motor.  All of these machines run fine on well-made biodiesel.  The exhaust smells great, the fuel is affordable, and there’s no feeling like putting your own fuel in your tank!  Future aspects we hope to develop include using potassium hydroxide instead of sodium lye (the byproducts are less toxic on the farm), recovering excess methanol, and running biodiesel trials in our home heating furnace. 

The things to watch with biodiesel are fairly straightforward:  Methanol will corrode rubber parts (like fuel lines and o-rings) and cause them to leak or lose their prime.  Biodiesel is also a good cleaner, and will loosen collected debris from old fuel tanks, sometimes leading to clogged fuel filters.  Both of these problems are easily mitigated by water-washing the fuel, which removes excess methanol, soaps, and other undesirables.  We carry a spare fuel filter in vehicles running on biodiesel just in case, though we have had few problems thus far.  Safety precautions when handling lye and methanol include working in a well ventilated space, avoiding any sparks, wearing gloves and goggles, and keeping chemicals away from children and pets.  These are serious chemicals and basic precautions should be followed.

Anyone who is willing to read, practice, and tinker should be able to enact their own biodiesel project.  It does require some trial and error to gain confidence with the process, but whoever can run a farm should be able to make fuel from waste grease!  Recommended reading includes the books “From the Fryer to the Fuel Tank” by Josh Tickell, and the “Biodiesel Homebrew Guide” by Maria Alovert.  Those with web access are advised to look at the following sites:

The Fulton Center for Sustainable Living will be offering more hands-on workshops in the future.  If you would like to get on the mailing list, contact Christine Mayer at cmayer@wilson.edu or (717) 264-4141 ext. 3247.  


Making Your Own Biodiesel: Biodiesel Safety Manual