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Biodiesel is a renewable, biodegradable liquid fuel. It is often referred to as B100, pure, or neat biodiesel in its unblended form. Biodiesel is also approved for blending with petroleum diesel Like petroleum diesel, biodiesel is used to fuel compression-ignition engines such as diesel engines.

Vegetable oils (mainly soybean oil) are the main feedstocks for U.S. biodiesel production. Even Rudolf Diesel, the inventor of the diesel engine in 1897, used diesel as well as vegetable oil to fuel in his engines. Other major U.S. biodiesel feedstocks include animal fats from meat processing plants and used/recycled cooking oil and yellow grease from restaurants. Rapeseed oil, sunflower oil, and palm oil are major feedstocks for biodiesel production in other countries.

The feedstocks used for biodiesel production can affect the physical properties and uses of biodiesel. Biodiesel performance in cold weather depends on the blend of biodiesel, the feedstock, and the petroleum diesel characteristics. In general, blends with smaller percentages of biodiesel perform better in cold temperatures. Typically, No. 2 diesel and B5 (up to 5% biodiesel) perform about the same in cold weather. Both biodiesel and No. 2 diesel have some compounds that crystallize in very cold temperatures. In winter weather, fuel blenders and suppliers combat crystallization by adding a cold flow improver, which is a chemical used in fuel to reduce friction and increase performance. For the best cold weather performance, users should work with their fuel provider to ensure the blend is appropriate.

Biodiesel is the second-most used and produced biofuel in the United States

Only small amounts of biodiesel were consumed and produced in the United States until the early 2000s. Since then, U.S. biodiesel consumption and production increased substantially, largely because of the availability over time of various government incentives and requirements to produce, sell, and use biodiesel. In 2020, biodiesel was second to fuel ethanol as the most produced and consumed biofuel in the United States, and accounted for about 11% and 12% of total U.S. biofuels production and consumption, respectively.

Most U.S. biodiesel is consumed as blends with petroleum diesel in ratios of 2% (referred to as B2), 5% (B5), or 20% (B20). There are some vehicle fleets that use B100 (neat biodiesel). Much of petroleum diesel fuel sold in the United States contains up to 1% biodiesel because of biodiesel's lubrication qualities that potentially prolong the lifetime of certain engine components. Biodiesel is added to petroleum diesel only at blending terminals into tanker trucks for local distribution.

About 62% of the production capacity of biodiesel is located in midwestern states. In 2020, U.S. biodiesel production equaled about 1.8 billion gallons, imports equaled about 197 million gallons, and exports equaled about 145 million gallons. About 1.9 billion gallons of biodiesel were consumed in 2020 nearly all in blends up to B20.

Renewable Diesel

Biodiesel and renewable diesel have similar physical properties and can be used for the same purposes as petroleum distillate fuels.  However, while renewable diesel is a biomass-based diesel fuel similar to biodiesel, it is distinct from biodiesel because of some fundamental differences.

Renewable diesel can be produced from nearly any biomass feedstock, including those used for biodiesel production.  Because renewable diesel is a hydrocarbon that is chemically equivalent to petroleum diesel, it may be used in its pure form—called R100—as a drop-in biofuel.  As a  drop-in fuel, it can be co-processed with petroleum diesel, seamlessly blended with petroleum diesel and/or biodiesel in various amounts, transported in petroleum pipelines, sold at retail stations with or without blending.

Renewable diesel-petroleum diesel blends are labelled with an R followed by the percentage (by volume) of the renewable diesel content. For example, a blend of 20% renewable diesel and 80% petroleum diesel is called R20. A blend of 20% biodiesel and 80% of renewable diesel is called B20R80 to make a 100% biofuel. A blend of 20% biodiesel, 20% renewable diesel, and 60% petroleum diesel is called B20R20.

In 2021, U.S. renewable diesel production equaled about 815 million gallons (0.82 billion gallons) and consumption equaled about 1,163 million gallons (1.16 billion gallons), which included about 392 million gallons of imports. California uses most of U.S. renewable diesel fuel imports.





What Happens if Gasoline is Placed into a Diesel Vehicle?

Fuel pumps are equipped with nozzles for diesel that are different in size from gas and are colored green, so it is highly unlikely gasoline will accidently be placed in a gasoline vehicle. However, if this happens, have the vehicle towed and immediately serviced to drain the fuel and clean out the injection system to avoid severe damage. Gasoline is a lot more volatile than diesel and once it mixes with the fuel, it can cause major damage and can be dangerous.

Can Off-road Diesel Be Used in a Passenger Diesel Vehicle?

Diesel fuel used for off-road going vehicles like construction and farm equipment is similar to the diesel used for on-road applications while being less expensive because it is not subject to road taxes. Nonetheless, it is not recommended for on-road vehicles, and it is dyed red to indicate its intended use in off-road applications. In addition, using off-road diesel for on-road vehicles carries hefty fines - generally $1,000 per incident and $10 per gallon of fuel.