Opportunities and challenges for electric propulsion of airliners

Abstract

The growth of air traffic implies an increase of emissions (greenhouse and ozone depleting gases) from the global air fleet. Innovative solutions are therefore urgently required. Among them, electric aviation is the object of much current interest. The present paper discusses the accompanying opportunities as well as challenges, with a focus on costs and operability. In order to take full advantage of electric propulsion, dedicated airframes are indicated, featuring boundary layer ingestion, distributed propulsion and other elements. Different options for electric propulsion are reviewed, and their pros and cons highlighted. In particular, all electric aircrafts suffer from severe range limitations, turbo electric aircrafts become appealing only if fed with liquid hydrogen (with the accompanying problems), while hybrid-electric aircrafts can lead to a somewhat reduced wing area (then weight). Other economical and operational issues are also considered, including cost per kWh (however shown to be a misleading indicator) and that per unit payload mass, maintenance, sources of electric energy for recharge.