This paper examines past and future trends for non-conventional biofuels in transportation in the next decade and beyond in California and the U.S., drawing on existing literature. It finds policy was geared toward expanding use of technology-ready biofuels in the 2010s; hydroprocessed renewable diesel from lipid feedstocks and biogas were beneficiaries alongside conventional ethanol and biodiesel. Cellulosic ventures largely failed due to lack of technological readiness, high cost, and an uncertain and insufficient policy environment. Policy goals for competitive cellulosic fuels remain, yet fuels from technologies already in the market may suffice to meet low carbon fuel policy targets, at least in California until 2030, considerably more oilcrop-based biofuels. How much biofuel will be needed there and elsewhere to meet climate targets hinges critically on the pace and scope of zero emission vehicle, and particularly electric vehicle, rollout. Analysis of unintended market consequences like indirect land use change has evolved over the decade but remains uncertain; current policy structures do not comprehensively safeguard against increased emissions. Market activity for non-conventional fuels has targeted biojet. Pioneer plants using new conversion technologies, if successful, will take some time to scale. Technoeconomic analyses (TEAs) for such non-conventional fuels point to no clear biofuel conversion technology winner as yet, given uncertainties. TEAs are evolving to reduce uncertainty by concentrating more on robust returns in the face of uncertain policies, potential additional cost-cutting for new technologies given what is known about processes involved, and potential revenue-raising through new coproducts or shifting product slates. Policies are needed to make initial financing more secure. Additional policy and societal attention to appropriate use of biomass, and land more generally, in a low carbon future is needed to clarify likely feedstock supply for biofuels that will enhance climate goals with low risk of unintended consequences.
