August 10 is International Biodiesel Day.  Why does a fuel deserve its own holiday?  Well, biodiesel is no ordinary fuel.  It is comprised of sustainable materials, or even waste materials, and is used either as a fuel itself or is used to make traditional diesel fuel go further, thereby making the country more energy independent.

What is Biodiesel?

Biodiesel is a fuel made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled cooking grease. Biodiesel can be used in diesel engines as an additive to petroleum diesel fuel to reduce vehicle emissions or in its pure form as a renewable alternative fuel. Biodiesel can be blended and used in many different concentrations. The most common are B5 (up to 5% biodiesel) and B20 (6% to 20% biodiesel). B100 (pure biodiesel)

By definition, biodiesel means 100% biodiesel, which is why it is labeled B100. Since it is derived from vegetable oils and other organic oils, and contains no petroleum, only B100 is recognized as an alternative fuel. 


A common misconception is that biodiesel is the same as raw vegetable oil. Although biodiesel can be, and usually is, derived at least partly from vegetable oil, vegetable oil must be chemically processed into biodiesel. Raw vegetable oil cannot and should not ever be used as a fuel. You can learn more about the myths and dangers of using vegetable oil as a the Energy Saver fact sheet on the issue.

B100 is typically used as a something known as a blendstock, which is used to produce lower blends of biodiesel, and less commonly used as a direct transportation fuel for several reasons:

  • B100 can impact engine warranties may require equipment modifications
  • B100 cleans a vehicle's fuel system and releases deposits accumulated from petroleum diesel use, initially clogging filters and requiring frequent filter replacement in the first few tanks
  • B100 contains less energy on a volumetric basis than petroleum diesel, therefore the higher the percentage of biodiesel (above 20%), the lower the energy content per gallon
  • B100 tends to gel in cold temperatures

Mixtures of biodiesel and petroleum diesel are referred to as biodiesel blends and are designated as B2, B10, B20 ,etc., with the number indicating the percentage of biodiesel in the blend. There are about 1,000 filling stations throughout the United States that offer blended biodiesel. Blends of 5 percent (B5) and over are required to be labeled at the pump. Look for the Black and Blue biodiesel sticker when filling up. Biodiesel concentrations below B5 are not technically diesel fuel, therefore no separate labeling is required at the pump.

Biodiesel blends of 20 percent and below can be burned in most compression-ignition (diesel) engines, either undiluted or mixed with petroleum diesel in any ratio, with little or no required engine modifications. These blends will operate in diesel engines just like petroleum diesel. If the blend has been properly treated by the petroleum company, it will work year-round, even in cold climates. B20 also provides similar horsepower, torque, and mileage as diesel.

There are some things to take into account when using B20:

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    Biodiesel can be purchased nationwide so make sure to purchase B20 through reputable distributors or at retail locations you buy from a source. Never buy from someone making fuel in their garage or backyard.
  • Buy fuel that is already blended. This will help ensure that the biodiesel has been properly handled and treated for climatic needs.
  • Because biodiesel is a cleaning agent, stick to your regular maintenance schedule, unless your vehicle feels sluggish when accelerating.  This is a symptom of a plugged filter and should be checked immediately.

Why Biodiesel?

Biodiesel has several environmental benefits when compared to petroleum-based diesel fuel:

  • Uses readily available, diverse resources, so new land is not required for production.
  • Reduces
    • Llifecycle greenhouse gases by 86 percent
    • Hydrocarbon emissions by 67 percent
    • Particulate matter by 47 percent
  • The biodiesel industry supports nearly 60,000 jobs and generates billions of dollars in GDP, household income, and tax revenues.

For more information on biodiesel and its benefits refer to the Energy Saver biodiesel fact sheet.