"As fuel prices continue to rise, more and more backyard inventors will tinker with ideas to discover low-cost alternatives to gasoline and petroleum-based diesel. On product that has some market potential is 'biodiesel,' a motor vehicle fuel created from one or more organic products such as soy, corn, grasses, or animal fats. The home operation in the photograph used recycled cooking oil from a fast food restaurant to make biodiesel. While the finished product may resemble a Class IIIB combustible liquid, the manufacturing process itself may involve significantly more hazardous materials. To make biodiesel, an alcohol (Class IB) and base are required. Generally, ethanol or methanol are mixed in a sodium hydroxide solution. If not mixed properly under strictly con¬trolled conditions, an exothermic reaction may cause a small deflagration."
Coffee Break Training - Hot Coffee Series No. HC-2008-0502
United States Fire Administration: http://www.usfa.fema.gov/