Environmental and Economic Impact of Transport Aircraft Using Sustainable Aviation Fuel or Liquid-Hydrogen as Alternative Fuels
Open Access
- Author:
- Vanlandingham, Aaron
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 18, 2024
- Committee Members:
- David K Hall, Thesis Advisor/Co-Advisor
Mark David Maughmer, Committee Member
Amy Pritchett, Program Head/Chair
Ashwin Renganathan, Committee Member - Keywords:
- aircraft design
alternative fuels
sustainability
hydrogen
sustainable aviation fuel
optimization
geometric programming
design for sustainabilitiy
transport aircraft
environmental impact of aviation - Abstract:
- Sustainable Aviation Fuel (SAF) and liquid-hydrogen (LH2) have been proposed as alternative fuels to reduce the environmental impact of aviation. LH2 requires cryogenic tanks that present a complex integration challenge and impact aircraft sizing and performance. A conceptual design optimization framework for analyzing aircraft fueled by SAF or LH2 is developed to explore the tradeoffs in environmental and economic performance of alternative fuels. Models of well-to-wake environmental impact and operating cost are implemented to quantify the impact of conventional jet fuel (Jet-A), SAF, and LH2. Two sets of aircraft designs are presented, based on a regional turboprop similar in performance to a DHC-8-200 and a single-aisle transport similar to a 737-8. Integrating LH2 tanks into the fuselage results in increased fuselage length and landing gear mass. Energy consumption increases 3% for regional turboprop and 11% for single-aisle aisle with LH2 compared to with Jet-A or SAF. For the size classes studied and assuming a fixed fuselage cross-section, the penalty of integrating hydrogen tanks increases as the design range increases. The results show that both SAF and LH2-powered aircraft can have reduced CO2-equivalent emissions relative to today’s Jet-A aircraft, 43% for SAF and 57–60% for LH2, but at increased operating costs, 42–73% for SAF and 30–61% for LH2. Assumed fuel characteristics drive differences between SAF and LH2 aircraft. LH2 is assumed to produce 32% less CO2-equivalent emissions and cost 21% less than an energy-equivalent mass of SAF. Relative to the SAF configuration, the LH2-powered aircraft has reduced CO2-equivalent emissions, 30% for regional turboprop and 25% for single-aisle, and reduced operating costs, 9% for regional turboprop and 7% for single-aisle. When considering uncertainties in emissions from fuel production and the warming impact of contrails, LH2 and SAF aircraft have similar emissions and cost impacts relative to Jet-A aircraft. The optimization framework developed in this research is well-suited for further exploration of the LH2 aircraft design space. An integrated atmosphere model could identify optimal mission ranges and explore variations in CO2-equivalent emissions with altitude and Mach number. Development of scaling relationships for propulsor geometry and wing and fuselage structural sizing, enabling further exploration of alternative tank configurations and optimal fuselage cross-sections, are recommended as areas for future work.