THE CHEETA (Center for High-Efficiency Electrical Technologies for Aircraft) is studying how to incorporate newly-designed hydrogen fuel cells into new designs. A collaboration between NASA's University Leadership Initiative, nine universities, GE and Boeing, the project is researching concepts for fully electric aircraft that generate electricity onboard by combining oxygen with liquid hydrogen carried aboard in fuel cells.
Phillip Ansell, CHEETA's director and an assistant professor at the University of Illinois Urbana-Champaign, said: "Hydrogen is a great energy carrier because there isn't any carbon involved. These fuel cells can be configured to produce zero emissions.
" Water is the only emission from a hydrogen fuel cell, but using it presents various technical challenges. Hydrogen must be cooled to -423°F (-253°C) to work effectively, so fresh thinking is required about how to store such super-cold (cryogenic) liquid aboard an aircraft while generating sufficient energy to power engines and systems. A Boeing 737-sized aircraft would require as much as 20MW in electrical power, NASA noted.
Ansell said: "Since fuel cells are inherently different as a power source, the standard rules of aircraft design change drastically. We are looking to write the book on how you make this system work for an airplane." The partners have worked with GE Research to design a new type of lightweight, long-life hydrogen tank and systems for handling electrical loads, heat and thermal management. Ansell commented: "In collaboration with Boeing, we did some tests to see how fuel cells adjust when changing the power demand on them. We also did tests to see how changes in the way incoming air to the fuel cell is pressurised to improve net power production at high altitudes." CHEETA partners are working with i'llASA aeronautics research centres. Aircraft configurations/propulsion integration is being studied at the Langley Research Center and cryogenics at the Glenn Research Center. The CHEETA project has recently been extended for two more years of study. Researchers plan to eventually produce a scaled aircraft concept.
CHEETA's aircraft design prototype is built around fuel cells. Hydrogen fuel is stored above the aircraft's cabin in lightweight, thermally efficient cryogenic tanks.