Hybrid electric aircraft propulsion systems : economic and environmental prospects

Abstract

Reducing emissions caused by aviation in the light of an expected ongoing rise of the air transport demand is the need of the hour. The drive to achieve net zero requires immediate action including propulsion systems with lower CO2 emissions. Despite the efforts for the hydrogen aircraft, hybrid electric aircraft powered by conventional gas turbines and battery powered electric motors offer a viable and intermediate solution until a fully electric aircraft is feasible. Batteries are expected to play a significant role in reducing future carbon footprint. The main importance should be given on choosing the right energy density and power-to-energy-ratio of a battery according to the future flight missions. In our earlier work, we considered the effect of series and parallel hybrid-electric propulsion systems as a case study of the ATR 42 and ATR 72. We investigated their hybridization potential with increasing passenger capacity and expected improvement in battery energy density over the coming decades. In this paper, we once again use the same aircraft models as a case study and aim to explore this topic further by investigating the environmental aspects in details and giving a preliminary understanding of the airplane ticket economics and the fuel economy. Here, we show that the improvement in degree of hybridization and battery energy density has an impact on the grid emissions and inflight emissions. Additionally, there is a reduction in fuel burn, fuel consumed per seat and cost related to fuel due to change in number of passengers and degree of hybridization.