Is Renewable Diesel the Real Deal?

by Sherry Listgarten (Palo Alto Online) Have you noticed the flags advertising “Renewable Diesel” at local 76 stations? I did and wondered if it was the real deal or a form of “greenwashing,” where eco-claims are not backed up by actual emissions reductions.

If you are driving a diesel car or truck, I would absolutely recommend using renewable diesel. You can find it at several stations in our area (2). But there are a few caveats to keep in mind:

Renewable diesel is sometimes confused with biodiesel, which is not a hydrocarbon and can only be mixed to a level of about 20% for a standard diesel engine.

There is considerable variation in carbon intensity even for a given type of fuel, depending on how it is produced or transported. For example, a fuel made with waste oil will typically have lower carbon intensity than one made with a virgin product. I think this graph is helpful in showing the variation, despite the demented balloon aesthetic.

Carbon intensity of different types of liquid fuels in 2020. The position on the x-axis shows the carbon intensity, and the size of the balloon shows the volume sold. The black circle at 92 marks the 2020 LCFS target. The neon green circles mark the average for the fuel type. Source: LCFS dashboard, 2021

The pathway analysis to determine the carbon intensity can be complex. The sample ethanol pathway shown below reflects the fact that not only does growing the corn produce emissions, for example from the use of fertilizer, but so does the fact that land is being converted for agriculture. Credit is given for useful byproducts that result from ethanol production, typically livestock feed.

Source: LCFS overview, 2020

In comparison, the life cycle analysis for biodiesel made from used cooking oil might look like this, with emissions stemming largely from refinement and transportation.

The analysis for the electricity that powers EVs is somewhat different. The fuel itself, assuming the grid mix, is fairly carbon intensive (83 gCO2e/MJ in 2020). But because the engines are so efficient, using less than one-third the energy of a traditional engine, the analysis is very favorable. And EVs will only get better as the grid gets cleaner.

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It is even possible to have negative carbon intensities when the process for producing the fuel inhibits emissions that would otherwise have occurred. This happens when methane is captured from manure lagoons or from landfills and then used to generate electricity or compressed natural gas.

We see the results every day in our own neighborhoods, even if we are not aware of it. Indeed, Phillips 66 and Marathon Oil both have proposals to convert their crude oil refineries in Contra Costa County to produce renewable fuels. The market is booming, and it’s because innovative policies like LCFS make California a leader in clean energy.

Notes and References
1. Biodiesel and renewable diesel are not the same thing. Biodiesel is made using a process that results in a fatty acid methyl ester rather than one that results in a hydrocarbon. The chemically inclined can find more information here. The non-chemically-inclined can find more information here.

2. You can find renewable diesel at 76 stations on San Antonio Road in Palo Alto, on El Camino in Menlo Park, and on Broadway in Redwood City. The Valero on Whipple in Redwood City also offers it. There may be others as well.

3. The Low Carbon Fuel Standard also offers credits for programs that reduce the emissions of petroleum-based fuel. That might include installing solar panels to power your oil wells or improving the efficiency of your refinery. LCFS also offers credits for installing fast chargers and hydrogen fuel stations. That is somewhat unintuitive, but they understand that the clean fueling supply needs to exceed demand for a while, in order for demand to ramp up, so the state reimburses the stations for unused capacity.

4. The California Air Resources Board, which administers the LCFS program, provides a good overview of the program here. The program also has a great dashboard here.