Comparative Assessment of the Societal Cost of PtL and LH₂ as Aviation Fuels

Abstract

Alternative fuels produced from green hydrogen will play a critical role in decarbonization of aviation, owing to their globally scalable production and mission flexibility. However, there is no consensus whether it is preferable to liquefy hydrogen and use it directly as a fuel (LH₂) or to combine it with CO₂ captured from point sources or the atmosphere to create a synthetic hydrocarbon fuel (PtL). Much of this disagreement is a result of the wide range of uncertainty that exists in the variables affecting the cost and environmental impact of each fuel. To determine which of these uncertainties are the most critical to driving this decision, a parametric system-level model of the well-to-wake life-cycle of each fuel was constructed. which combines the economic and environmental cost of flight with each fuel into a single societal cost metric. A series of sensitivity analyses were conducted to quantify the impact of each input assumption on the total societal cost of flight with each fuel. The results showed that the relative favorability of future hydrogen aviation fueling strategies will depend on how technological developments and scientific knowledge evolve, specifically in the fields of direct air capture (DAC), LH₂ aircraft design, and warming from persistent contrail formation.