Glossary of Biodiesel-Related Terms

Acid-catalyzed esterification

Adding acid to reduce acidity in feedstock oils. [Springboard Biodiesel website] [Chemistry LibreTexts]


The grade of fuel approved for sale by the US federal government. []


A blend of biodiesel and diesel containing 20% biodiesel and 80% diesel (the B stands for biodiesel and the number stands for the percentage in the blend.


99% biodiesel


Pure biodiesel – what the BioPro equipment makes.


A clean burning fuel that can be made from a long list of vegetable and animal oils and which will run in any diesel engine. Biodiesel is diesel fuel made from vegetable oils, animal fats, or recycled restaurant greases. It's safe, biodegradable, and produces less air pollutants than petroleum-based diesel. Biodiesel can be used in its pure form (B100) or blended with petroleum diesel. Common blends include B2 (2% biodiesel), B5, and B20. [, U.S. Department of Energy]

Diesel Fuel

Petroleum based fuel.

Drywash Systems

Any system, like the SpringPro™ T76, that uses solid media to filter and clean biodiesel after the reactions, obviating the need to wash the fuel using water. [Springboard Biodiesel website]

Dual Reaction

An acid reaction (esterification) followed by a base reaction (transesterification), allowing dirtier oils to be converted into ASTM grade biodiesel. Also sometimes referred to as the acid/base reaction.


A mixture of biodiesel, water, and soap. [Wikipedia]


An acid reaction usually performed by adding an alcohol and an acid to a feedstock oil.

Feedstock Oil

Any oil that can be converted into biodiesel fuel including but not limited to used cooking oil (UCO), animal fats, canola oil, sunflower oil, coconut oil, etc. [Science Direct]


The temperature at which a liquid is ignitable when sparked.


Free fatty acid. [See Free Fatty Acids, Science Direct]

Greenhouse Gas Emissions

Carbon dioxide (CO2) makes up the vast majority of greenhouse gas emissions from the sector, but smaller amounts of methane (CH4) and nitrous oxide (N2O) are also emitted. These gases are released during the combustion of fossil fuels, such as coal, oil, and natural gas, to produce electricity.

Greenhouse gases trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years.1 The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation.EPA tracks total U.S. emissions by publishing the Inventory of U.S. Greenhouse Gas Emissions and Sinks. This annual report estimates the total national greenhouse gas emissions and removals associated with human activities across the United States. [From Sources of Greenhouse Gas Emissions, U.S. EPA]


The quality of lubrication in a fuel. Lubricity is the measure of the reduction in friction and or wear by a lubricant. [Wikipedia]


A measurement of the volume of contaminants found in a feedstock oil, specifically, Moisture and volatiles, Insoluble Impurities and Unsaponifiables.

Particulate Matter

PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.
Particle pollution includes:

  • PM10 : inhalable particles, with diameters that are generally 10 micrometers and smaller; and
  • PM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.
  • How small is 2.5 micrometers? Think about a single hair from your head. The average human hair is about 70 micrometers in diameter – making it 30 times larger than the largest fine particle.

[Particulate Matter, U.S. Environmental Protection Agency]


Renewable Identification Numbers. RINs are the credits that the US EPA uses to track and enforce compliance with the renewable fuels mandates set by the RFS in the US. RINs are records of individual batches of renewable fuel being blended into the gasoline and diesel pools. RINs are created when a batch of renewable fuel is made.


Straight vegetable oil. [U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy]


A method for determining the free fatty acid content of a feedstock oil.


A base reaction usually performed by adding a mixture of alcohol and sodium or potassium hydroxide.


Ultra-low-sulfur diesel (ULSD) is diesel fuel with substantially lowered sulfur content. Since 2006, almost all of the petroleum-based diesel fuel available in Europe and North America has been of a ULSD type. [Ultra-low sulfur diesel, Wikipedia]


A measurement of the resistance of a fluid to flow.


Waste vegetable oil that has been filtered.
Vegetable oil can be used as an alternative fuel in diesel engines and in heating oil burners. When vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO) or pure plant oil (PPO). Conventional diesel engines can be modified to help ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel. This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Straight vegetable oil can also be blended with conventional diesel or processed into biodiesel, HVO or bioliquids for use under a wider range of conditions. [Vegetable fuel oil, Wikipedia]