Considerations for Reducing Aviation’s CO2 with Aircraft Electric Propulsion

The reduction of aviation’s CO2 emissions is a major objective of the aviation industry. About 98% of the world’s aviation CO2 is produced by aircraft with gross takeoff mass above 25 metric tonnes, referred to herein as airliners. Propulsion of such aircraft can require power and energy levels of tens of megawatts and hundreds of thousands of kilowatt hours per flight. The challenges to electrically powering these airliners are examined in the context of CO2 reduction. Additional possible benefits such as noise and cost reduction are explored. All electric (battery), hybrid, and turboelectric approaches are considered. Technical issues including weight, efficiency, and heat rejection are examined. In addition, economic and policy implications of an industry conversion to electric propulsion are discussed. The conclusion of this study is that electric propulsion is not a promising path to significant reduction of aviation’s CO2 in the first half of the 21st century.