Understanding the similarities, differences between renewable diesel, biodiesel

Written by: Jane Marsh Edited by: Bailey Arnold, Ainsley Kelso

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FuelsFix would like to apologize for any incorrect information included in the original publication of this article. The article has been reviewed and edited accordingly to provide the best information possible at this time.

Alternative fuels can include fuels such as natural gas, propane autogas, biodiesel, ethanol, electric vehicle, renewable fuel options and more.

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There are two main kinds of sustainable fuel meant specifically to replace traditional diesel engine technology – renewable diesel and biodiesel. While they sound similar, these are distinct categories with some important differences between them. Understanding these differences is the first step to making the most informed decision for gasoline and diesel alternatives.

What is Renewable Diesel?

Renewable diesel is identical to petroleum-derived diesel on a chemical level, but it comes from feedstocks like soybean oil, distillers’ corn oil or recycled animal fats and waste greases. Because it’s so similar, it can generally run in any diesel engine without any blending or modification, and it produces few emissions. Currently, there are eleven refineries producing renewable diesel in the U.S., with 1.75 billion gallons of production capacity.

Most renewable diesel comes from a process called hydrotreating, which uses hydrogen to remove water and oxygen particles from oil. Petroleum-based diesel uses a similar approach, but renewable diesel uses recycled or plant-derived oils instead of crude oil. However, this is not always the case even for renewable diesel. Some companies are co-processing crude petroleum with renewable oils and fats and call it renewable diesel even though the resulting fuel does not qualify as an advanced biofuel.

What is Biodiesel?

Biodiesel is similar in that it also comes from non-fossil-fuel feedstocks, mostly the same feedstocks as renewable diesel. However, renewable diesel can be made from feedstocks such as municipal solid waste, while biodiesel cannot.

Biodiesel can run in a traditional diesel engine without modification like renewable diesel, too. However, biodiesel is commonly mixed with petroleum diesel to create blends such as B20 (Biodiesel 20%, Petroleum Diesel 80%). Some fleets can utilize B100 (Biodiesel 100%) without any modifications to the vehicles.

There are two main concerns when it comes to utilizing B100 in fleets. Higher biodiesel blends and B100 can experience gelling in the system when used in colder climates as well as they have a higher flash point and can take a higher temperature to ignite and burn in a diesel particulate filter (DPF). The good news – both of these issues are addressed by a technology called the Vector System developed by Optimus Technologies.

Similarities and Differences

Both biodiesel and renewable diesel offer a much more sustainable alternative to fossil fuels. Utilizing either fuel can bring significant economic and environmental benefits to a fleet.

One of the biggest differences between biodiesel and renewable diesel is that biodiesel comes from a different process: transesterification. Unlike hydrotreating, transesterification doesn’t remove oxygen. The result still produces fewer greenhouse gases than conventional diesel, but it does not perform as well in colder climates. However, lower blends such as B5 are considered standard diesel fuel and blends all the way up to B20 can be used relatively easily with proper additives. Much of biodiesel use depends on the climate it is being used in.

However, it is important to note that renewable diesel is largely unavailable to most of the U.S. outside of the West Coast. There is a significant cost differential as renewable diesel benefits from state LCFS programs in California, Oregon and Washington. Biodiesel is nationally available at a more affordable price right away for most fleets in the U.S. looking to switch immediately.

Renewable diesel also creates slightly more greenhouse gas emissions than biodiesel to produce, mostly because it takes 8.5 pounds of feedstock per gallon to produce while biodiesel takes 7.5 pounds of feedstock.

Biodiesel is also nontoxic and biodegradable. Renewable diesel is still considered as toxic as petroleum diesel fuel.

Blending biodiesel and renewable diesel together to produce an alternative fuel source can have many benefits itself. Biodiesel is a lower-cost fuel when compared to renewable diesel. Renewable diesel can cost as much as 2x that of diesel fuel. Biodiesel also has superior lubricity which reduces wear on the engine over time. Finally, blending biodiesel and renewable diesel can improve emission reductions over pure renewable diesel or pure biodiesel.

Sustainable Fuels Come in Many Forms

Businesses and consumers today have more options than they may realize when it comes to sustainable fuels. Learning more about these power sources and their unique advantages will help make the best, most environmentally friendly choices.

Biodiesel and renewable diesel are similar but different fuels. As the alternative fuel industry grows in the U.S., more fleets will have the opportunity to consider which of these fuels could be the right fit for them.


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