Biodiesel production

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Bioenergy > Technologies > Biochemical technologies > Biodiesel production

Biodiesel production is a Biochemical conversion technology used to produce energy from biomass, such as soybeans or palm oil.


Types of Biodiesel Production

The main technology in biodiesel production is transesterification.


  • Transesterification requires heating a mixture of 80–90% oil, 10–20% methanol, and a catalyst.1
  • The catalyst is usually an acid or a base, but bases such as NaOH and KOH are more common, in part because transesterification can happen at a lower temperature.1
  • Methanol is more commonly used in the production of biodiesel than ethanol.1

Safe Chemical Handling in Biodiesel Production

Here is a YouTube video on biodiesel safety for small biodiesel producers.

Safety is extremely important, because while biodiesel itself is non-flammable and biodegradable, the chemicals used to make it can be very dangerous.

Methanol is colorless and tasteless, and can cause blindness or death if it enters the body through the nose, mouth, or skin. It is a cumulative poison: repeated, brief exposures can cause a toxic reaction. Methanol is also very flammable, and burns with an almost invisible flame, making the fire difficult to see. Methanol vapors are heavy, and can travel along the ground to a source of ignition.

Sodium hydroxide and potassium hydroxide are strong bases which can burn unprotected skin and kill nerve cells before pain can be felt. When sodium hydroxide or potassium hydroxide is mixed with alcohol and stirred, a fine mist can be produced which can cause irritation to the respiratory tract.

Feedstocks for biodiesel production

  • Oils, fats, used cooking oils, greases, methanol or ethanol and a catalyst (generally sodium hydroxide or potassium hydroxide- an acid catalyst is used for pretreatment)
    • Pretreatment: Used cooking oils, yellow greases and some tree oils are taken through an esterification process to remove fatty acid, which should, preferably, be reduced to less than 1% (at least below 4%). In the esterification process, the methanol or ethanol/acid catalyst is used to reduce the fatty acids. Dewatering is required as part of this process.
    • Qualifications: Essentially any biomass based oil, animal fat or tallow, used cooking oil, yellow/trap grease, plant or tree oil can be converted into biodiesel if the fatty acid content is low enough. If not, it must be pretreated.


Products of biodiesel production include:

Advantages of biodiesel production

  • Biodiesel has slightly lower energy content than fossil diesel. It has a higher cetane value, is essentially free of contaminates like sulfur and aromatics, and burns cleaner than diesel fuel. It significantly reduces smoke, unburned hydrocarbons and carbon monoxide. It does, however, slightly increase oxides of nitrogen. The level of these reductions is a function of the blend levels. B-5 is acceptable by most engine manufacturers. B-20 by a few, and, in the US, essentially none at B-100. B-2, used to decrease emissions and improve lubricity, is becoming increasingly attractive.
  • The production of biodiesel is relatively easy and there is no need for significant infrastructure changes to gain full access to the market.
  • Its capacity is more limited than ethanol because of feedstock availability and does not have the ability to use most most biomass waste streams and cellulosic and woody biomass. However, thos feedstocks can be converted to a diesel type fuel, like Sun Diesel in Germany. In the US, biodiesel is defined by law as a mono ester of a long chain fatty acid. This requires a transesterification process.

Commercialization status


Sustainability and environmental concerns

These factors are similar to those covered in the ethanol production section. There are fuel versus food and feed factors as well as the potential of environmental degradation. These are all manageable if proper procedures are followed and research, development and deployment are aggressively pursued in advancing technologies that will enhance the environment and provide opportunities for low-income people throughout the world.

According to the EPA's Renewable Fuel Standards Program Regulatory Impact Analysis, released in February 2010, biodiesel from soy oil results, on average, in a 57% reduction in greenhouse gases compared to fossil diesel, and biodiesel produced from waste grease results in an 86% reduction. See chapter 2.6 of the EPA report for more detailed information.

For more information on biodiesel sustainability issues, please see Roundtable on Sustainable Biofuels and Sustainable Biodiesel Alliance.

Societal impacts

There are major opportunities to improve the well being of farmers and ranchers and low-income rural citizens throughout the world. This will occur by having access to locally produced fuels, through job creation, and opportunities for ownership in production facilities. Energy and economic security factors are also improved.


  • The Glycerol Challenge - The Glycerol Challenge is a consortium of industry and Cardiff University funded by the UK Department of Transportation to develop alternative uses for glycerol, a major by-product of biodiesel production.


1Biofuels for Transportation (2006, Worldwatch Institute), p.13-14. Used with permission.


This page has been modified from information that was developed by the United States Environmental Protection Agency, Office of Research and Development, in cooperation with the Biomass Coordinating Council of the American Council on Renewable Energy (ACORE).

Biodiesel edit
Biodiesel production | Biodiesel companies
Biodiesel producers by country | Biodiesel organizations
Biodiesel feedstocks: Currently in use: soybeans | palm oil | coconut oil | rapeseed | sunflower seed | castor beans | jatropha | karanj | jojoba | waste vegetable oil | animal fat
Currently in research and development: algae | halophytes (saltwater plants)
Bioenergy conversion technologies edit
Technologies categorized by bioenergy processes:

Biochemical: Aerobic, Anaerobic, Landfill gas collection (LFG), Biodiesel production, Ethanol production
Thermochemical: Combustion, Gasification, Pyrolysis, Depolymerization

Technologies categorized by feedstock:
Algae | Cellulosic technology

Technologies by commercialization status:

Analysis of technologies: Life-cycle analysis


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