Decarbonization challenges

By 2050, commercial aviation can expect 10 billion passengers to fly 10.8 trillion nautical miles, generating 2.35 billion tons of CO₂ emissions – 2.6x the emissions generated in 2019. That’s the conclusion of John Coykendall, leader of Deloitte’s U.S. Aerospace & Defense practice, and his colleagues Steve Shepley and Aijaz Hussein in their report, “Decarbonizing aerospace: A road map for the industry’s lower-emissions future.”

Commercial aviation accounts for about 2% to 3% of global CO₂ emissions, and from 2013 to 2018, CO2 emissions from commercial flights increased 32%. These figures aren’t encouraging. The International Air Transport Association (IATA) in 2009 initiated strategic targets for aviation, including carbon-neutral growth from 2020 and net aviation CO₂ emissions reduced 50% by 2050 compared to 2005 – a target of 325 million tons (see Gaining Altitude, p.12).

Without decarbonization, aviation emissions could grow 3.6x the emissions generated in 2005 and be responsible for 22% of the planet’s total emissions by 2050. However, the aerospace industry has embraced the call to action, with the major commercial airplane and turbine engine manufacturers supporting a goal to decarbonize aviation by 2050.

Aerospace is a challenge to decarbonize. Emissions linked directly or indirectly to manufacturing or supplier operations can be managed by corporate policy. Emissions that are indirectly the manufacturers’ responsibility are emissions aircraft generate in use, about 70% of industry total.

Several solutions have potential to reduce aircraft emissions meaningfully. While electric or hydrogen propulsion and innovative aircraft design represent nearly a third of possible emission reductions for smaller aircraft and short-haul flights, sustainable aviation fuels (SAFs) are likely the best solution – counting for 45% of emission reductions – and applicable to medium-to-long-haul flights.

Produced from sustainable feedstocks, SAFs have chemistry similar to traditional fossil jet fuel. They don’t require significant changes to aircraft, engines, or fueling infrastructure. However, bio-SAFs cost 2x to 4x the cost of traditional jet fuel, and synthetic SAFs made from hydrogen and CO₂ are 6x to 10x more expensive. Economies of scale are needed to increase SAFs availability, lower costs, and create more demand.

In the largest SAF procurement by an airframer, Boeing officials announced in February they would purchase 2 million gallons (7.5 million liters) of blended SAF to power the company’s commercial airplanes operations in Washington and South Carolina through 2022. SAF is currently approved for a 50/50 blend with conventional jet fuel for commercial flights.

Sustainably produced jet fuel, which reduces CO₂ emissions by as much as 80% throughout the fuel’s life cycle with the potential to reach 100% in the future, offers the most immediate and greatest potential to decarbonize aviation during the next 20 to 30 years.

The full emissions-reducing potential of cleaner fuels will only be realized, however, when SAFs become available in much greater quantities than today, and at a more competitive price. – Eric