Conceptual Design Optimization of Liquid-Hydrogen-Fueled Transport Aircraft for Environmental and Economic Performance

Sustainable Aviation Fuels (SAFs) and liquid hydrogen (LH2) have both been been proposed as alternative fuels to Jet-A that could reduce the environmental impact of aviation. LH2 tanks present a complex integration challenge that impacts aircraft sizing and performance. Significant investments in infrastructure are required to make both SAFs and LH2 a commercially viable aviation fuel. To explore the tradeoffs in environmental and economic performance of alternative fuels, a conceptual design model for analyzing liquid-hydrogen aircraft has been developed. Models of well-to-wake environmental impact and operating cost are implemented to quantify the impact of Jet-A, SAFs, and LH2. Two LH2-powered aircraft are presented; a regional turboprop similar in performance to a DHC-8-200, and a single-aisle turbofan similar to a 737-8. The analysis shows that LH2-powered aircraft can reduce the environmental impact of Jet-A aircraft by 88%. As a result of higher assumed fuel costs, the operating costs are higher (+28% for the regional and +53% for single-aisle) for the LH2-powered aircraft. SAFs are also shown to significantly reduce the environmental impact relative to Jet-A. Operating costs are comparable for both LH2 and SAF aircraft. Sensitivities to uncertainties in the environmental and economic models are shown and areas for relevant future work are identified.