Aircraft electric propulsion technology review – A shift from turbofan to the ethrust era 2018-36-0096

Following the electrification trend observed in the automotive industry, the idea of an electric propulsion aircraft has also drawn attention and investments from a range of aviation industry stakeholders (including the world's largest aerospace companies) focused on both fuel burning reduction and environmental performance improvement (greenhouse gases (GHG), pollutants and noise emissions) potential of electric propulsion technology. Electric propulsion has the potential to provide more efficient, cleaner, quieter and more profitable aviation services, with potential benefits to both airlines and passengers. Furthermore, with its inherent quiet feature, it has also the potential to lead to a reassessment of the role of airports along the world cities, as well as revitalize regional short-haul flights and helps the launch of air service into underserved regions around the world. From a technical perspective , the aviation propulsion electrification strategy might involves the integration of electric powetrains into aircrafts into the i) all electric; ii) hybrid and iii) turboelectric approach. The former might rely solely on batteries as energy sources and requires engines up to 300 times more powerful than current available electric aviation motors (currently used for two-seater prototypes). The hybrid configuration uses gas turbines, for turbofan propulsion, and to charge batteries (with turbogenerators), which also provides energy for electric propulsion for one or more phases of flight. Finally, turboelectric configurations do not rely on batteries to supply propulsion energy. Rather, they use gas turbines to drive electric generators to feed distributed electric driven fans, with their inherent aerodynamic benefits associated with distributed propulsion. Hybrid architectures might provide a more realistic near-term pathway, while key enabling technologies - batteries, high power electric motors and superconducting electric power - reach the required improvement, into an expected 10 to 20 year timeframe.

The most likely niche of the industry to first commercially launch this groundbreaking technology is the commuter and regional jet category, with a 50 to 70 passenger capacity and a short to mid range. This work is supposed to present an overview of aircraft electric propulsion technology, followed by an assessment of its potential operational, environmental and economic benefits, as well as the required technological breakthrough to reach the electric thrust era.