Despite accounting for fewer than 10% of all vehicles, freight trucks are responsible for around 40% of road transport greenhouse gas (GHG) emissions and roughly 5% of global CO2 energy-related emissions, according to a research report from Nature. Some solutions, including electrification and hydrogen are maturing and they hold the potential to help the transportation sector reach net-zero. However, more scalable and cost-effective strategies are needed to meaningfully reduce emissions over the next decade.
With a significantly lower lifecycle GHG emissions footprint than fossil diesel, as well as the compatibility with all diesel engines and fueling infrastructure, renewable diesel (RD) represents a practical, today solution to decarbonize road freight, particularly medium- and heavy-duty trucks. In this article, we discuss the unique advantages RD provides over biofuels and highlight concrete examples where it is helping freight providers meet sustainability goals.
Understanding Differences Between RD and Biodiesel
RD, or HVO (hydrotreating vegetable oil) as it is sometimes called, is often confused with biodiesel or FAME (fatty acid methyl ester). While both are derived from renewable raw materials (e.g., used cooking oil, animal fat waste, etc.), they are produced through very different processes.
RD is produced via hydrotreating, which involves treating triglycerides with hydrogen. The primary objective of hydrotreating is to remove oxygen molecules from the feedstock raw material, producing hydrocarbons that are chemically similar to those in fossil diesel. Biodiesel, on the other hand, is produced via transesterification, where triglycerides are reacted with an alcohol in the presence of a catalyst.
The different production pathways result in RD and biodiesel having different chemical compositions which impact their performance.
Biodiesel has a higher viscosity and a lower cetane number. This can affect fuel injection systems and lead to undesirable consequences, such as deposit formation, filter plugging, oil dilution, and other operational issues. As a result, blends of biodiesel greater than 20% (i.e., B20) are typically not approved by engine OEMs. Biodiesel can greatly be affected by cooler temperatures, while renewable diesel performs well in cold conditions.
RD delivers the same high performance and range as fossil diesel, but with cleaner combustion and without impurities like sulfur, oxygen, or aromatic compounds. Unlike biodiesel, it can be used as a drop-in replacement (neat or blended) in any engine without modifications and meets ASTM D975 and EN 15940 standards. It can also be distributed through existing fueling infrastructure, making it versatile in terms of logistics and application.
As previously mentioned, lifecycle (i.e., cradle-to-grave) GHG emissions associated with RD are significantly lower, up to 75% less GHG emissions over the fuel’s life cycle compared to fossil diesel*. This is because of the renewable raw materials used, the refining process, and all transportation steps along the value chain, as well as end-of-life emissions. As RD is produced by utilizing the already existing carbon stored in the renewable raw materials, when the fuel is combusted, it does not add any new CO2 to the atmosphere. Depending on truck make and year, NOx, SOx, and particulate matter (PM) emissions can also be significantly lower than fossil diesel.
Looking Ahead
RD continues to play a key role in accelerating the road freight industry’s path to net-zero by reducing its reliance on fossil fuels. Today, opportunities to transition truck fleets are most pronounced on the U.S. West Coast, where producers can offer RD at a lower price by taking advantage of RIN credits from the Renewable Fuel Standard (RFS) program, along with state-level credits in California, Oregon and Washington.
In the coming years, as more domestic RD production facilities come online and policy frameworks that incentivize production and adoption mature, the economics of phasing out diesel fleets in other regions of the country are expected to improve. In the meantime, companies across the freight industry can do their part to foster renewable fuel procurement by establishing supply chains and promoting the environmental benefits of RD to customers and partners.