Impact of Well-to-Tank Efficiency and Emissions on Hybrid Aircraft Design Optimization

We present a general framework for the design of sustainable hybrid aircraft which pursues minimal renew- able energy consumption and climate effect. Thus, the approach takes into account the complete well-to-wake energy route, from the primary energy source to the aircraft end use, including the simultaneous usage of mul- tiple energy carriers, such as electricity and sustainable aviation fuels (SAFs) obtained via different pathways. The framework builds on well-established hybrid aircraft design models, and accounts for unknown battery performances considering ebat as a parameter. Nowadays and future leading-edge technologies such as Di- rect Air Capture (DAC) are investigated within a Life-Cycle Assessment (LCA) framework to estimate the SAF production efficiency and the emissions for the on-ground processes. We test the approach on the design of a hybrid SAF/electric regional aircraft that minimizes the total Well-to-Wake (WTW) energy and the average tem- perature response (ATR), in addition to the maximum take-off weight and fuel consumption, searching for the optimal power ratio in five different scenarios of European electric grid mix and Fischer-Tropsch SAF process- ing pathway. Results show that the impact of different Well-to-Tank (WTT) scenarios is more significant than adopting the optimal power management strategy. Nevertheless, by coupling these two aspects, an aircraft design with minimal climate impact and comparable to the baseline regional configuration can be achieved.