Renewable diesel demand is booming. Last year, U.S. refiners expanded capacity to be able to supply 2.6 billion gallons of the lower-carbon fuel. And that production capacity could double in the next two years.
At the same time, EIA estimates the U.S. had about 2.3 billion gallons of annual biodiesel capacity at the end of 2022. In late 2022, renewable diesel production capacity exceeded biodiesel production capacity for the first time.
Both renewable diesel and biodiesel play important roles in a more sustainable transportation sector. But do you know what the differences between these two fuels are?
Renewable Diesel |
Biodiesel |
Feedstock |
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Can be made from a variety of feedstocks, including vegetable oils (like soy or canola), animal fats, used cooking oil, and even municipal waste. The feedstock must be pre-treated to remove impurities. |
Made from feedstocks similar to renewable diesel, like vegetable oils and animal fats. Biodiesel feedstock must also be pretreated, but the process is typically less rigorous than for renewable diesel. |
Processing |
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Renewable diesel can be produced with a variety of technologies. Most commercial production starts with a process called hydrotreating, where the feedstock is reacted with hydrogen at high temperatures to remove oxygen to produce a hydrocarbon. That product is ultimately fractionated where the renewable diesel is separated out. |
Biodiesel production utilizes a process called transesterification, where the feedstock is put through a chemical reaction with an alcohol (typically methanol). The output is an ester and glycerin. The glycerin is removed, and the ester is fractionated to produce biodiesel. |
Transportation |
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Renewable diesel is a hydrocarbon, like petroleum-based diesel, so it can use any of the same midstream infrastructure. Notably, this means that renewable diesel can use existing pipelines. |
Biodiesel is chemically different from petroleum diesel. Because of its differences, it can’t usually be transported via fuel pipelines. |
Engine compatibility |
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Renewable diesel is a 'drop-in' fuel, which can currently be used in existing diesel engines at high blend levels without modification. |
Biodiesel is usually blended with petroleum diesel and can be blended with renewable diesel. High blend levels are limited by some engine warrantees. |
Emissions reductions |
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Renewable diesel and biodiesel can provide comparable lifecycle greenhouse gas reductions, on the order of 80%. These reductions are dependent on the feedstock, processing technology, and energy inputs. Reduction of vehicle tailpipe criteria pollutants depends on vehicle configuration and the percentages of renewable diesel or biodiesel in the fuel blend. |
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