On the design of environmentally sustainable aircraft for urban air mobility

Urban Air Mobility (UAM), recently envisioned as faster and flexible mean of transportation in large urban centers, faces considerable challenges inherent in its operation in densely populated cities and related environmental issues such as pollutant and noise emissions. To address the environmental challenges, the proposed concepts are either hybrid-electric or all-electric vehicles enabled with propellers that rotate at lower speeds than conventional rotorcraft configurations, such as helicopters. However, the feasibility of UAM in the near future requires significant progress on the all-electric propulsion systems since current battery technology still falls short when compared with fossil fuel in terms of specific energy density. In this work, a methodology is proposed to evaluate the environmental footprint of Vertical Take-Off and Landing (VTOL) aircraft for the UAM market. This methodology is applied to existing concepts for exploratory studies on mission critical performance and environmental parameters. All-electric aircraft were found to be feasible for the UAM segment from the performance perspective. However, further improvements in battery technology and electricity generation from renewable sources are required. Sustainable aviation fuels, such as Alcohol-To-Jet (ATJ) obtained from wheat straw, present a substantially lower environmental impact than conventional fuels while providing the same performance. These biofuels also contribute less to global warming and climate changes than batteries which: (i) are recharged from electric grids still dependable on non-renewable sources; and (ii) have a low number of recharge-discharge cycles.

Automated summary

Urban Air Mobility (UAM) is envisioned as a faster and more flexible means of transportation in large urban centers, but faces challenges in operation in densely populated cities and environmental issues. The feasibility of UAM requires significant progress in all-electric propulsion systems and further improvements in battery technology, as well as utilization of renewable energy sources. Sustainable aviation fuels, such as Alcohol-To-Jet (ATJ), present a lower environmental impact than conventional fuels and batteries, contributing less to global warming and climate change.