Biodiesel Profile

By Connie Hardy, content specialist, AgMRC, Iowa State University,

Revised January 2017


Biodiesel is a clean burning alternative fuel made from renewable resources. The most common process uses transesterification whereby methyl esters are produced from fats and oils, yielding biodiesel, a non-toxic, biodegradable fuel that can be burned in diesel engines, and glycerin, which can be used in industrial and pharmaceutical applications. Biodiesel contains no petroleum, but it is usually mixed with petroleum diesel fuel and sold as, for example, 'B2', 'B5' and 'B10' to reflect the percentage of biodiesel (2%, 5%, 10%) included in the mix. It is also used alone as a diesel fuel, called ‘B100’.

In the United States, biodiesel is produced from plant oils, animal fats, recycled restaurant grease and waste grease.  Soybean oil has been, by far, the most commonly used feedstock for US biodiesel production, accounting for more than half of the nation’s biodiesel feedstock. Research continues to develop other plant-based feedstock sources for biodiesel, including algae, to make biodiesel production affordable in many different locations. Oils from non-food plants, such as camelina, jatropha and pennycress, are potential feedstocks for biodiesel. Biodiesel producers estimate that feedstock costs represent more than 80 percent of production expenses.

 Recently, corn oil from ethanol production (distillers corn oil or “DCO”) has entered the US feedstock market and is being rapidly adopted by biodiesel manufacturers who have processing capability for multiple feedstocks.  The availability of DCO at a competitive price has not only affected prices of other feedstocks, including soybean oil, but it has led to opportunities to co-locate ethanol and biodiesel production. New technological developments help existing biodiesel plants to become more efficient in the use of multiple feedstocks and in their ability to convert free fatty acids to usable biodiesel. Manufacturing flexibility and increased efficiency have spurred rejuvenation in the biodiesel industry and, in some cases, a closer tie between ethanol and biodiesel production in the Corn Belt region of the US.

The Renewable Fuels Standard (RFS), proposed by the US Environmental Protection Agency, defines the mandated production of biofuels by category. The quantities mandated in the RFS have historically served as market goals for domestic consumption, thus influencing total production.   Under the RFS, biodiesel is categorized as Advanced Biofuel quantity was 3.61 billion gallons in 2016 and is 4.28 billion gallons in 2017. The new RFS volume requirements grew by nearly 700 million gallons between 2016 and 2017, contributing to an overall 6 percent increase (to 10.28 billion gallons) in volume requirements for all renewable fuels. 


Biodiesel Magazine's US processing plant map shows that the 160 existing biodiesel plants have a total production capacity of 2.7 billion gallons per year (bgy), and 15 more plants are under construction, which would add 610 million gallons per year (mgy) of production capacity.

The production of biodiesel is a proven science. Simplified to its core steps, the process is accomplished by combining refined soy oil with an alcohol and a catalyst. When the catalyst is removed, the resulting components are methyl esters (biodiesel) and glycerin. The biodiesel product can be burned as 100 percent pure biodiesel (B100), but it is generally marketed as either a B2 blend or a B20 blend, meaning 2 percent or 20 percent biodiesel in a petroleum fuel.  Besides the benefits of producing lower emissions when burned and coming from a renewable source, biodiesel adds lubricity to petroleum diesel. Lubricity benefits and emission reduction are significant at levels as low as 2 percent (B2).

Soybean oil has been the feedstock of choice by most biodiesel processors because of its abundant supply and its favorable fatty acid profile. In 2015-2016, an estimated 5.5 billion pounds of soybean oil (methyl esters) was used for biodiesel, compared with the total U.S. soybean oil usage (21.7 billion pounds) for food and industrial. 


BQ-9000 is a voluntary fuel quality assurance program, overseen by the National Biodiesel Accreditation Commission (NBAC) and adopted by the National Biodiesel Board and the Canadian Renewable Fuels Association. It couples the foundations of universally accepted quality management systems with the product specification ASTM D 6751 and has become the premier quality designation in the industry. The program covers storage, sampling, testing, blending, shipping, distribution, and fuel management practices. Both producers and marketers are eligible to become either a BQ-9000 producer or BQ-9000 marketer.


Environmental Protection Agency,

Biodiesel Magazine,

Renewable Energy Newsletter,

Energy Information Administration,

National Biodiesel Board,