Mitigating international aviation emissions: Risks and opportunities for alternative jet fuels
Policy and Environmental Implications of Using HEFA+ for Aviation
The aviation sector must confront rapidly increasing greenhouse gas (GHG) emissions and ambitious decarbonization targets. Alternative jet fuels (AJFs) could be route to decarbonizing this sector, though these fuels can vary widely in feedstocks used, cost, and environmental performance. To facilitate the transition to AJF, Boeing has begun testing the technical suitability of HEFA+ (Hydroprocessed Esters and Fatty Acids+) on flights as a petroleum jet fuel substitute. HEFA+ proponents have touted this fuel as a promising AJF due to its low cost—producing HEFA+ is similar to manufacturing renewable diesel in the road sector, a technology that has already reached a commercial scale and is cheaper than some other AJF pathways.
This working paper evaluates the state of HEFA+ deployment and its potential to reduce the climate impacts of aviation. This study assesses the production of HEFA+ and how it differs from other AJFs, as well as the impact of feedstock choice on the sustainability and GHG performance of the finished fuel. We also assess the state of deployment, near-term availability and policy implications of expanding HEFA+ deployment within the aviation sector and the risks of competition for feedstocks with the road sector.
This study finds that the existing deployment and supply of renewable diesel production for the road sector suggests that HEFA+ deployment could occur earlier and at a larger scale than other AJFs in the earlier stages of development. However, mobilizing significant volumes of fuel is not a meaningful policy impact on its own. Instead, ramping up HEFA+ deployment in the aviation sector would likely create competition for a limited supply feedstocks between aviation and renewable diesel in the road sector. This outcome could lead to market-mediated effects such as diversion from existing uses for waste feedstocks, or alternately, indirect land-use change (ILUC) from increased use of food crops to create renewable diesel and HEFA+, thereby undermining the climate benefits of AJF deployment.