Techno-Economic Comparison of Low-Carbon Energy Carriers Based on Electricity for Air Mobility

Abstract

The decarbonization of air mobility requires the decarbonization of its energy. While biofuels will play an important role, other low-carbon energy carriers based on electricity are considered, such as battery electrification and liquid hydrogen (LH2) or eFuel, a hydrogen-based energy carrier. Each energy carrier has its own conversion steps and losses and its own integration effects with aircraft. These combinations lead to different energy requirements and must be understood in order to compare their cost and CO2 emissions. Since they are all electricity-based, this study compares these energy carriers using the well-to-rotor methodology when applied to a standard vertical take-off and landing (VTOL) air mobility mission. This novel approach allows one to understand that the choice of energy carrier dictates the propulsive system architecture, leading to integration effects with aircraft, which can significantly change the energy required for the same mission, increasing it from 400 to 2665 kWh. These deviations led to significant differences in CO2 emissions and costs. Battery electrification is impacted by battery manufacturing but has the lowest electricity consumption. This is an optimum solution, but only until the battery weight can be lifted. In all scenarios, eFuel is more efficient than LH2. We conclude that using the most efficient molecule in an aircraft can compensate for the extra energy cost spent on the ground. Finally, we found that, for each of these energy carriers, it is the electricity carbon intensity and price which will dictate the cost and CO2 emissions of an air mobility mission.