Meeting Liquid Biofuel and Bioproduct Goals: Biotechnological Design of the Intermediate Oilseeds Pennycress and Camelina, and Beyond.

The European Union (EU) and United States (U.S.) have set ambitious goals to produce biofuels as part of broader decarbonization and energy security initiatives. One of the more feasible routes to liquid biofuels production is the conversion of seed oils (triacylglycerols; TAG) to renewable diesel, biodiesel, and sustainable aviation fuel (SAF) using the Hydrotreated Ester and Fatty Acids (HEFA) process. Camelina and pennycress are attractive oilseed feedstocks in that they can be grown in the offseason as intermediate crops on tens of millions of hectares of farmland annually, providing ecosystem benefits and not competing with established food crops. Considerably more TAG could be produced by engineering vegetative portions of crops such as sorghum and miscanthus to accumulate economic amounts. This review highlights recent advances in developing pennycress and camelina as intermediate oilseed crops not only for biofuels production but for making higher value oils such as those enriched in astaxanthin, vitamin E, and medium-chain fatty acids. Given the magnitude of renewable liquid fuel demands, we also describe how advances in vegetative oil production in biomass crops can complement intermediate oilseed cropping systems to meet biofuel and bioproduct targets.