How to accelerate the decarbonization of aviation

In a significant development, the International Civil Aviation Organization’s (ICAO) assembly embraced an ambitious objective last year by establishing an aspirational target for international aviation to achieve net-zero emissions by 2050.

This commitment reinforces existing goals and commitments undertaken by the aviation industry and individual states. However, adopting a net-zero emissions target also acknowledges the formidable challenge faced by aviation, recognizing it as one of the most challenging sectors to decarbonize, requiring all available options, including battery-electric and hydrogen-powered aircraft.

However, anticipated advancements and scalability of technologies, such as Sustainable Aviation Fuels (SAFs), projected to help reduce greenhouse gas (GHG) emissions by 46%-65%, offer the sector a clear trajectory. Although, realizing their potential will require active promotion and appropriate incentives and regulation.

By examining the emissions distribution outlined in the Air Transport Action Group’s Waypoint 2050 report, we find that 96% of aviation emissions originate from aircraft with more than 100 seats. Remarkably, 66% of these emissions are attributed to highly successful single-aisle aircraft dominating the market. The remaining 4% is associated with aircraft with up to 100 seats, commonly deployed for regional routes. Therefore, to decarbonize the bulk of those emissions, in the short term, the focus lies on SAFs, which offer a technically feasible solution utilizing the current infrastructure of aircraft and airports.

However, the key challenge lies in scaling up the production and supply of SAFs. According to the Making Net-Zero Aviation Possible report, meeting the demand will necessitate 300 SAF production plants by 2030, with a projected requirement of up to 3,400 plants by 2050. This need presents a significant challenge regarding feedstock availability, particularly as biomass resources are limited.

To scale SAF in line with the 2050 targets, rapid deployment of power-to-liquid plants will likely be required after 2030 to overcome the feedstock constraint of bio-based routes. Industry will play a key role in meeting this challenge but it is clear government targets, frameworks and policies will be needed to support the widespread adoption of SAF fuels within the aviation industry.

When considering the broader context of decarbonization, the significance of electrification may surpass initial estimations. While projections indicate its importance in the emissions reductions at around 2%, this technology is crucial in supporting the decarbonization roadmap. Notably, battery-electric aircraft offers the advantage of eliminating in-flight emissions.

In recent years, numerous concepts for electrical vertical take-off and landing vehicles have emerged. However, they are not intended to entirely replace existing commercial, regional routes, which typically operate on less than 800-kilometre distances. According to the Forum report, Target True Zero: Unlocking Sustainable Battery and Hydrogen-Powered Flight, by 2035, lithium-ion battery-electric aircraft are expected to have a maximum operating range of approximately 400 kilometres, increasing to 600 kilometres by 2050.

If battery-electric aircraft continue to evolve, electrification could be significant within a global decarbonization framework. Electric motors combined with other technologies, such as electric propulsion with SAFs or hydrogen, as in a hybrid aircraft, can significantly extend the aircraft’s range.

This broader range enhances the regional market’s potential, positioning hybrid aircraft as a viable alternative to new turboprop designs that can substantially reduce emissions compared to smaller jets. Additionally, hybrid aircraft can help to facilitate safety and security certification processes for electric motors and hydrogen concepts. Moreover, in the short term, hybrid aircraft can contribute to decarbonizing on-ground operations during taxiing, take-off and landing stages, offering immediate environmental benefits.

Several technical efforts must be combined to successfully implement battery-electric: ensuring renewable charging sources, optimizing battery life cycles and enhancing energy density. Maximizing energy density can significantly improve the range and efficiency of battery-electric aircraft, further supporting their viability as a sustainable aviation solution.

Overall, a big portion (around 26%) of emissions reduction still depends on another important technology: hydrogen. That means accelerating the production capacity of green hydrogen by 2035.

A sufficient supply of green hydrogen is essential, as blue hydrogen may not yield significant climate improvements compared to conventional jet fuel. Additionally, advancements in fuel cell technology and lighter storage tanks are vital for optimizing the efficiency and range of a hydrogen-powered aircraft. Designing aircraft with hydrogen performance in mind, including strategic placement of hydrogen tanks, is thus crucial for maximizing their capabilities and reducing environmental impact.

Efforts should also focus on researching and mitigating the potential impact of contrails formed by hydrogen-fuelled aircraft containing increased water vapour. By prioritizing these considerations, the aviation industry can unlock the full potential of hydrogen technology and drive the transition towards a sustainable and decarbonized future.

All these technical questions and roadmaps must be supported by regulation. Governments and regulatory bodies may feel overwhelmed about the steps to be followed. In response, the World Econ­omic Forum and the Aviation Environment Feder­ation have published a new report, Target True Zero: Government Policy Toolkit to Accelerate Uptake of Electric and Hydrogen Aircraft.

The aim of this toolkit is to provide governments with both the opportunity and the options to help develop approaches towards accelerating the development of zero-emissions aircraft technologies as part of an overall decarbonization plan for the sector.

As regulators, framing a net-zero aviation strategy will require a comprehensive understanding of market segments, aircraft sizes, airport infrastructure and the potential for renewable electricity or hydrogen supply. This understanding may differ across countries but governments must define clear goals and milestones for battery-electric and hydrogen propulsion based on these insights to attract investors and drive industry action. Building stakeholder partnerships will help to assist this objective by identifying priority actions, while alignment on aviation strategies with economy-wide plans for hydrogen and renewable energy development is also essential for progress.

On the other hand, governments must better understand how to create an enabling environment, supporting International Civil Aviation Organization initiatives while facilitating the development and deployment of alternative propulsion aircraft through research, infrastructure support and regulatory updates. As the aviation industry’s security and safety certifications are crucial to public acceptance, harmonizing certification approaches is potentially the most important step for accelerating progress.

The global aviation industry is responsible for just under 3% of global carbon emissions and is projected to emit more as travel demand rises in emerging economies. There is no single measure to decarbonize the sector and realizing net zero will require a broad focus that maximizes the potential of technological advancements, financial incentives and partnerships, but doing so will put the sector on track with its decarbonization roadmap.