Biodiesel History and Facts

Fall 2003

Drawing by Toki Oshima
Toki Oshima drawing

By Ralph Turner, P.E.

The benefits of biodiesel have generated considerable interest in Maine, especially in the environmental and agricultural communities. Biodiesel is chemically converted from vegetable and animal fats to be similar to diesel, but with lower regulated emissions and better health effects in most respects.

Maine recently adopted a definition for biodiesel that will help to protect consumers as well as those who may choose to try to make their own. This new definition is, in many ways, like the standards that MOFGA developed over many years to define what “organic” means. In this article, this definition will be discussed with some background information to help put it into perspective. References for those interested in learning more are provided at the end of this article and on our Web site,

All transportation fuels must meet the Clean Air Act and national standards for quality, because burning fuels lacking quality, even fuels called biodiesel, will damage diesel engines and emit more air pollutants. If you purchase biodiesel from a reputable dealer, such as the Solar Market in Arundel or Frontier Energy in South China, you can be sure that your biodiesel is safe to use, because it is registered with the EPA and is subject to quality controls by the manufacturer.

Making your own is more complicated. Under the Clean Air Act, you are allowed to make small quantities for personal use but not to sell or for any commercial use on roads without EPA registration or a special exemption. This means that even homemade biodiesel must be registered with the EPA if it will be used in any on-road commercial activity. The only exemptions to this rule are for legitimate, limited scientific studies and for schools to make small batches for demonstration purposes. The Clean Air Act governs on-road fuels only, so registration is not required for biodiesel made for off-road use in farming, construction, heating or marine activities.

Hazards of the Trade

Although biodiesel made at home for off-road use need not be registered, you should still follow the many health, safety, environmental, quality and tax regulations and standards to protect yourself, the environment, your business and employees, and your equipment. Extremely hazardous materials, such as methanol, ethanol, sodium hydroxide, sulfuric acid and others, are used to make biodiesel. When purchasing these materials, obtain the Material Safety Data Sheets (MSDS), study them carefully, and take all the listed precautions.

Long-term health problems and serious injury can result from improper use of these materials. Alcohol can present a serious fire or explosion risk due to its flammability. Handling and storage of these materials are regulated by OSHA, EPA, DEP and the state fire marshal. Hazardous air emissions will, and hazardous waste may, result from homemade biodiesel. The DEP and EPA regulate these emissions and wastes. Any facility that stores more than 1300 gallons of any petroleum oil, vegetable or animal oil, or biodiesel is required by the EPA to have a Spill Prevention Control and Countermeasures (SPCC) Plan in place. This includes farms and greenhouses, whether for profit or not.

The Maine Revenue Services and the IRS both tax biodiesel. Homemade biodiesel is not exempt from these taxes or from the rules for dyeing fuel intended for off-road use. Off-road fuels are not subject to the same taxes as fuels intended for transportation and are dyed to ensure that they are not used in on-road vehicles without taxes being paid. Although these are not important considerations for anyone purchasing biodiesel from a reputable dealer, anyone who makes homemade biodiesel must be aware of and follow these rules, just as we would expect any responsible business to do.

Maine’s Definition

Maine’s new biodiesel definition came from an amendment to a bill that the Transportation Committee heard in April. The bill, LD 441, “An Act To Establish a Definition for Biodiesel Fuels,” was signed by the governor on May 23, 2003. According to this new law, “‘Biodiesel fuel’ means renewable fuel composed of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats that is registered with the United States Environmental Protection Agency as a fuel and a fuel additive under the federal Clean Air Act, … and as otherwise specified in the American Society for Testing Materials Standard D6751-02a or its subsequent Standard Specification for ‘Biodiesel Fuel (B100) Blend Stock for Distillate Fuels.’”

To understand the origin of Maine’s definition, consider the history of what we now call biodiesel. During the energy crisis of the 1970s, researchers began reevaluating a process called esterification that was discovered in 1846, and in the 1880s, the products of esterification were first demonstrated as a motor fuel by Rudolf Diesel. Esterification is the process that converts the fatty acids in vegetable and animal fats to the esters that are biodiesel. While consumers were facing fuel shortages, soy farmers were being paid not to grow soy, because the surpluses at that time made the markets unstable. The soy farmers understood esterification and the fact that producing soy for fuel made more sense than being paid not to grow the crop. This occurred at the same time that the Clean Air Act first passed Congress.

Those interested in biodiesel commercialization then identified two requirements for successful commercialization in the United States: first, acceptance by engine manufacturers considering engine performance and longevity; and second, acceptance by the EPA under the Clean Air Act. The private National Biodiesel Board (NBB) (4) was established to coordinate activities toward these goals, with development of a national technical standard as the focal point for both goals.

For more than 20 years, many companies and universities researched the effects on many types of diesel engines of biodiesel that was made from different “recipes.” Engines were run on biodiesel, then taken apart and studied. The starting point was unconverted vegetable oil that caused engines to fail after only a few hours. From this, researchers found what concentrations of which impurities damaged diesel engines, and which concentrations were safe. The American Society for Testing Materials (ASTM) (5) is the recognized authority in the United States for defining specifications for product quality and for the test methods used to confirm the specifications. An ASTM committee was formed in 1994 that consisted of engine manufacturers, fuel manufacturers, government representatives and independent researchers. The committee adopted a preliminary ASTM biodiesel specification in 1999 to specify acceptable characteristics and explain why each is important.

Once researchers understood a biodiesel that would not harm diesel engines, that fuel had to be tested as required by the Clean Air Act. It was subjected to the EPA’s Tier 1 health effects and Tier 2 toxicity effects testing to be certain that no adverse effects on people or the environment occurred. After several years and over $2.5 million, the EPA accepted the results. The NBB incurred the full cost of this extensive testing. The specification, ASTM D6751 (1), was adopted in December 2001. This is why you should feel confident when you purchase biodiesel from a reputable dealer.

Most automotive engine manufacturers’ warrantees, including Ford, GM, Volkswagen and Mercedes, will not cover engine repairs if biodiesel fuel is used. Some of these manufacturers were part of the ASTM committee that accepted the biodiesel specification, but they are reluctant to extend warrantees to engines running biodiesel, partly because of misinformation presented by advocates of the “homebrew” approach to biodiesel, which makes a material that will not meet the ASTM standards. Luckily for farmers, John Deere, Caterpillar, Cummins, Detroit Diesel and International will warrantee engines using biodiesel as long as it meets the ASTM standard.

Importance of the Proper Process

Manufacturers are concerned about homemade biodiesel because of the raw materials and the process used to make it. The raw material most often used in the United States is soy oil because of its relative abundance. This material has value as food oil, and the commodity price is too high to produce biodiesel that can be sold competitively with petroleum diesel. In an effort to produce cost competitive biodiesel, researchers have studied waste materials, such as used fryolator oil from restaurants called waste vegetable oil (WVO), yellow grease (YG), and rendered animal fats. Yellow grease is WVO that has been filtered to remove solids, processed to remove moisture, and has had the acid value adjusted to meet the quality specification for yellow grease. Most YG is sold for use in animal feeds, so controlling the quality of this product is important.

Unused soy oil, like other vegetable oils, consists of triglyceride molecules and typically has very low acid values. Picture a triglyceride as the capital letter E. The vertical line represents the glycerin backbone, while the three horizontal lines represent the attached fatty acids that contain the biodiesel. The acid value is an indication of how complete the triglyceride molecules are in the mixture. As oil is heated during cooking, the fatty acids break away from the glycerin backbone and become free fatty acids (FFAs). More FFAs increase the acid value of the mixture. This is important because the same process that will make biodiesel from triglycerides with low acid values, such as unused vegetable oil, will make very poor material from WVO or YG with high acid values.

The esterification process most commonly understood for biodiesel production is alkaline catalysis. Detailed descriptions of this process exist on the Internet. In this process hazardous materials such as methanol (an alcohol) and an alkaline catalyst such as sodium hydroxide (lye) are used to separate the ester portion of the fatty acids on the glycerin backbone and replace the esters with alcohol to form glycerol. The ester, or biodiesel, floats to the top, while the glycerol and most of the other impurities settle to the bottom. This separation looks much like water poured into a glass of cooking oil, where the water settles to the bottom and a distinct line shows the separation. This simple process produces a reasonable quality biodiesel fairly reliably from unused vegetable oils with multiple esterification batches and several water washes to remove the impurities.

This same process is often erroneously recommended to make biodiesel from high acid value feedstock such as WVO or yellow grease. Alkaline catalysis will make soap from FFAs, especially if the feedstock contains moisture, as is most often true with waste vegetable oil. You may be familiar with this saponification process: It’s the same one your grandmother used to make soap in the good old days. When the alkaline is used up in making soap, it is no longer available to break the esters free from the glycerin. Further, the soap will form stable emulsions of glycerin, salts, soaps, water and other impurities in the ester that will resist removal by the wash. For this reason, the material that floats to the top and looks like biodiesel actually contains large concentrations of impurities that will damage diesel engines and produce harmful exhaust emissions. Several processes (2) can overcome this problem, but all involve more steps, more hazardous materials and more cost.

To know what concentrations of impurities are in biodiesel, the biodiesel must be tested according to the ASTM standard. For example, pour point (3) is important because it defines the lowest temperature at which you can expect biodiesel to pour. Biodiesel will gel at a higher temperature than petroleum diesel, so it is less suitable for winter use in climates such as ours without taking precautions, such as heating or mixing with a winter grade of petroleum diesel. B20 is a 20% mix of biodiesel with petroleum diesel that may be suitable in cold climates. Glycerin content (3) is important because glycerin in the biodiesel indicates that the conversion process was not complete. Glycerin will clog fuel lines and injectors and will leave extremely hard carbon deposits called coke on valves, pistons and cylinder walls. Think of the sweetness of a glycerin-based herbal extract and remember the old “sugar in the gas tank” trick, and you’ll easily understand that these deposits will significantly decrease the life of a diesel engine and cause expensive repairs.

In summary, buying biodiesel from a reputable dealer can help the environment and contribute to our energy independence. On the other hand, homemade biodiesel must be carefully and correctly made and tested to be certain that it won’t harm people, the environment and personal property. Buying from a reputable dealer may be less expensive, especially when you figure your time. In either event, as is true with everything we do, responsible action requires careful consideration and thorough understanding.


1) Biodiesel Fuel (B100) Blend Stock for Distillate Fuels, 2002, ASTM D6751-02a.

2) Tyson, Biodiesel Research Progress 1992-1997, 1998, NREL/TP-580-24433.

3) Tyson, Biodiesel Handling and Use Guidelines, 2001, NREL/TP-580-30004.


4) National Biodiesel Board, NBB,

5) American Society for Testing Materials, ASTM,

6) National Renewable Energy Lab, NREL,

About the author: Ralph Turner is a professional engineer and co-owner of Laughing Stock Farm in Freeport with Lisa Turner, MOFGA’s board president. He can be reached at [email protected].

Scroll to Top
Sign up to receive our weekly newsletter of happenings at MOFGA.