Design Exploration for Sustainable Regional Hybrid-Electric Aircraft: A Study Based on Technology Forecasts

Abstract

The environmental impact of aviation in terms of noise and pollutant emissions has gained public attention in the last few years. In addition, the foreseen financial benefits of an increased energy efficiency have motivated the transport industry to invest in propulsion alternatives. This work is collocated within the Clean Sky 2 project GENESIS, focused on the environmental sustainability of 50-passenger hybrid-electric aircraft from a life-cycle-based perspective to support the development of a technology roadmap for transitioning towards sustainable and competitive electric aircraft systems. While several studies have already focused on the definition of possible aircraft designs combining several propulsion systems, the novelty of the present work is to consider technology forecasts and more comprehensive indicators in the design phase. These include the performance and emissions on a 200 nmi typical mission, which reflects the most economically attractive range for aircraft in the regional class. The work proposes a complete exploration of three major technology streams for energy storage: batteries, fuel cells, and turbine internal combustion engine generators, also including possible combinations of those technologies. The exploration was carried out through the execution of several designs of experiments aiming at the identification of the most promising solutions in terms of aircraft configuration for three different time horizons: short-term, 2025–2035; medium-term, 2035–2045; and long-term, 2045–2050+. As a result, in the short-term scenario, fuel energy consumption is estimated to be reduced by around 24% with respect to conventional aircraft with the same entry-into-service year thanks to the use of hybrid propulsive systems with lithium batteries. Fuel saving increases to 45% in the medium-term horizon due to the improvement in the energy density of storage systems. By the year 2050, when hydrogen fuel cells are estimated to be mature enough to completely replace kerosene-based engines, the forthcoming hybrid-electric aircraft promise no NOx and CO2 direct emissions, while being approximately 50% heavier than conventional ones.

Decarbonised Future Regional Airport Infrastructure

“…New secondary electric machines were designed based on nominal RPMs equal to 8000 since it was found that it is optimal to delegate to gearboxes the task of adapting the number of revolutions to that of the propellers. The specific fuel consumption reflects the usage of pure hydro-processed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK) as fuel [10].…”

“…This paper is framed in the context of GENESIS, which corresponds to the EU theme JTI-CS2-2020-CFP11-THT-13 under the Clean Sky 2 programme for Horizon 2020 and presents a forward-looking view focusing on the assessment of appropriate energy supply technologies for ground energy storage, grid connection and power transmission to aircraft. Based on these technologies, a flight plan and the design of a 50 PAX HEA developed in the project, the energy requirements for operations at a regional airport can be estimated [10]. The fuel types for HEA change depending on the time horizon.…”

Comparative reliability analysis of electric aircraft versions for NASA’s X-57 based on Lz-transform method

“…NASA is developing a battery powered electric airplane X-57 "Maxwell" with an innovative distributed propulsion system, which allows for a reduction in wing area, while providing the same lift with less motor power [40,8]. A similar distributed propulsion system is featured in the "ECO-150-300" [43] and the "DRAGON" [44] electric airplane models, as well as in the hybrid-electric plane design exploration in [36].…”

Study on RP-3 Aviation Fuel Vapor Concentration

“…Aircraft fuel tanks house a substantial volume of aviation fuel, posing a significant threat to flight safety. As per records, 18 incidents of fuel tank explosions have occurred in transport aircraft, resulting in a total of 542 fatalities in the last 50 years [1][2][3]. In July 1996, 12 min after the take-off of Boeing 747 aircraft TWA800, the fuel vapor in the central wing fuel tank combusted and exploded, leading to the deaths of all 230 crew members [4][5][6].…”