Rethinking Sustainable Aviation Fuel

One prevailing assumption is that SAF will be the primary driver for decarbonisation. However, airline leaders are voicing concerns over the availability of SAF in the necessary volumes by 2050. This has led to increased calls for the industry to embrace new aircraft technologies more aggressively.

John Langford, founder and CEO of hybrid-electric start-up Electra.aero, highlighted the limitations of relying predominantly on SAF. Referring to a chart from the 2021 US Aviation Climate Action Plan, Langford pointed out that the plan heavily emphasizes SAF while offering minimal contribution from new aircraft technologies. “There is a lot more that needs to be done there, as SAF does not change the carbon coming out of the tailpipe,” he said.

Exploring New Pathways

In a recent report, German aviation think tank Bauhaus Luftfahrt outlined three scenarios for achieving decarbonisation. The first scenario involves an aggressive increase in SAF production combined with more efficient conventional aircraft, potentially bringing aviation closer to net-zero by mid-century.

The second scenario, termed “radically efficient aircraft,” combines a vigorous ramp-up in SAF production with the introduction of revolutionary kerosene-fueled aircraft that consume 50% less fuel. This approach could enable quicker decarbonisation with lower cumulative emissions and fuel costs.

The third scenario considers the introduction of hydrogen-powered aircraft alongside a slower increase in SAF production. However, Bauhaus Luftfahrt notes that aviation may not achieve decarbonisation by 2070 under this model.

The Role of Electric and Hydrogen Propulsion

Europe’s Alliance for Zero-Emission Aviation (AZEA) envisions a more significant role for electric and hydrogen propulsion. In its ambitious scenario, AZEA forecasts that nearly 40,000 aircraft could be delivered by 2050, with a potential reduction in short- and medium-haul emissions by up to 31%.

The alliance emphasizes the potential for further CO2 savings beyond 2050, given the lengthy aircraft development and fleet renewal cycles. “The transition to electric and hydrogen aviation represents a considerable challenge … [but] beyond those hurdles is an opportunity that is even greater—to reshape the way we travel,” AZEA noted in its vision document.

Emboldened Start-ups

The call for a more radical approach has emboldened start-ups like Dutch newcomer Elysian and Whisper Aero. Elysian aims to develop a 90-seat, 500-mile-range all-electric airliner by 2035, challenging the notion that battery-powered aircraft must be small and short-range.

Whisper Aero, meanwhile, has unveiled a concept for a 100-seat, 770-mile-range all-electric airliner. “Smaller aircraft are not more feasible for battery electric,” said Whisper cofounder and CEO Mark Moore. Whisper has submitted its concept for a NASA program aimed at designing airliners to help meet net-zero goals by the 2040s.

Electra.aero is also targeting the same NASA program with a 200-seat airliner concept using distributed hybrid-electric propulsion to cut fuel consumption by 50% over 1,000-mile stage lengths. “First-generation hybrid-electric with an existing turbine works, but it’s only scratching the surface,” Langford said.

The Road Ahead

As the aviation industry grapples with its decarbonisation goals, it is clear that incremental improvements alone will not suffice. Embracing radical new technologies and significantly ramping up SAF production are crucial steps. The industry’s future hinges on its willingness to adopt a bold and comprehensive approach to sustainable aviation.