July 15, 2024     


NREL scientists Eric Karp (left), Davinia Salvachua, Jeffery Linger, and Patrick Saboe have developed an energy-efficient and cost-effective process to produce butyric acid from biomass, which can be used as a precursor for renewable diesel and jet fuel. Photo by Dennis Schroeder, NREL

Biointermediates (a.k.a. biointermediate feedstocks, or biointermediaries) are a complicated yet increasingly critical part of the discussion around the future of the Renewable Fuel Standard (RFS) and liquid biofuels in general. To provide energy market participants with a better understanding of this issue, here is a quick primer on biointermediates.

What is a biointermediate?

Any biofuel feedstock that is treated, refined or otherwise “substantially altered” somewhere other than at the plant where it is finally processed to become biofuel can be considered a biointermediate. Pyrolysis oil is an oft-cited example, as it can be made using everything from soybean oil to cellulosic biomass.

But this is just one of many intermediates. Scientists at the National Renewable Energy Laboratory recently developed a process to produce another viable intermediate, butrylic acid, from ceulllosic biomass.

How does this apply to the RFS?

Current regulations place strict limitations on which biointermediate processes do and do not generate RIN credits under the RFS. Thus, while there are numerous methods to get to biofuel from feedstock, only some of these methods are widely utilized by market participants today.

Much more biofuel could be produced if restrictions on biointermediates were removed. In a recent interview, Advanced Biofuels Association President Michael McAdams cited a Department of Energy finding that up to 740 million tons of feedstock could become available, allowing for the replacement of approximately 30% of all fossil-based transportation fuels used in 2005.

What’s being done to address this?

The “Renewables Enhancement and Growth Support Rule,” proposed by EPA in 2016 and re-proposed this week, would lift the aforementioned restrictions on certain biointermediates, allowing them to produce RIN-eligible biofuels under the RFS. Last issue, reported that this proposal was back on the docket at the White House Office of Management and Budget (see “‘Back on Track or Out of Whack’: What’s Happening with the RFS?”). This week, the EPA laid out its "proposed regulatory framework to allow biointermediates to be included in the RFS program." The final rule could be published in the near future, following a public comment session in early January.

At least, that’s the hope among several parties that see liquid biofuels as a growing part of the clean-energy future. It’s worth noting that backers of the “Renewables Enhancement and Growth Support Rule” include not only feedstock growers, but also major oil refiners. And it’s no wonder why. These very same companies have invested millions in using biointermediate feedstocks to produce biodiesel, renewable diesel, marine biofuel, sustainable aviation fuel, and other advanced or cellulosic biofuels.

Look for updates on this topic, along with the latest news on the RFS, in our next issue.