The REEACH program objective is to develop a disruptive system to convert the chemical energy contained in energy-dense carbon neutral liquid fuels (CNLFs) into electric power for aircraft propulsion via electric powertrains and other key systems. With a developmental prototype as the ultimate goal, REEACH performers will work to create innovative, cost-effective and high-performance energy storage and power generation (ESPG) sub-systems. The developed ESPG system must deliver adequate electric power to propel a fully electric, narrow-body aircraft through all the various flight phases (i.e., taxi, take-off, climb, cruise, and descent) and store sufficient energy to power the entire aircraft during a long-range mission with adequate safety reserves. The developed ESPG should be efficient and light enough to enable operations commensurate with existing commercial single-aisle aircraft missions. In the design of their ESPG systems, applicants are given latitude to select the CNLF, system architecture, and individual component technologies. REEACH will develop the critical enabling components and sub-system architectures for high-efficiency conversion of CNLF energy into electricity with sufficient power density for aircraft propulsion.

Air travel is responsible for a growing portion of U.S. energy usage and associated greenhouse gas (GHG) emissions. In 2017, air travel in the U.S. consumed nearly 3.5 quadrillion BTUs of jet fuel and accounted for about 175 million metric tons of CO2 or about 2.6% of domestic GHG emissions. It is estimated that narrow-body aircraft, such as the Boeing 737, are responsible for nearly half of aviation-related GHG emissions. Consequently, a decarbonized, B737-like aircraft with electrified propulsion would provide the greatest impact on GHG emissions from a single aircraft type. ARPA-E seeks to mitigate the growing environmental burden associated with commercial air travel at minimum economic cost by developing elements of an ultra-high efficient, electrified aircraft propulsion system that uses CNLFs. Ultra-high conversion efficiency and high specific power and energy are critical for its commercial success due to CNLFs’ generally either lower specific energies or higher projected cost compared to incumbent fossil-based jet fuels. It is anticipated that the developed energy conversion devices will find direct application as both power sources and range extenders in the emerging urban air mobility, unmanned aircraft aerial vehicle, and select regional aircraft markets. These markets are likely to be the first adopters before the technology scales to a single-aisle commercial aircraft.

Electrified aviation propulsion systems have the potential to achieve ultra-high fuel-to-propulsive power conversion efficiencies compared with existing turbofan and turboprop systems.