Energy demand comparison for carbon-neutral flight

Abstract

Aviation’s emissions are among the hardest to eliminate. There are a handful of solutions: battery-electric propulsion, hydrogen fuel cells, hydrogen combustion, and synthetic hydrocarbon fuel produced with carbon from the air. All of these solutions rely on renewable electricity, a resource that will be in short supply as other industries use it to decarbonize. Depending on the flight distance and speed, some carbon-neutral aircraft types demand less renewable electricity, while others are infeasible. Previous work focuses on the cost and climate impact of these alternative fuels and their effects on individual aircraft designs, but not when each solution is viable. We determine the cruise speed and flight range limitations of each. We find that battery-electric aircraft are the most efficient option for short flights, and a combination of hydrogen combustion and fuel cell aircraft are most efficient when batteries are too heavy. We also show that battery and fuel cell technology improvements could enable them to serve all missions. Determining the potential and limitations of different sustainable aircraft enables future efforts to focus on the most impactful technologies.