Shrinking the CO2 footprint of air travel could depend on quickly scaling up sustainable aviation fuels

As celebrities come under fire for their frivolous, high-emission private-jet habits, a group of companies, researchers, and engineers are dreaming up a world where jet-setting would come at a much lower carbon cost.

The global aviation industry is responsible for ~2% of all human-induced greenhouse-gas emissions annually, according to the IPCC. US airlines aim to reduce their CO2 emissions by 50% in 2050 compared with 2005 levels, but unlike other forms of transportation, planes can’t rely on electrification alone. While there are startups developing batteries for planes, long flights will likely require a different solution.

One answer is sustainable aviation fuel (SAF), a biofuel that’s created from plants or waste materials and performs similarly to today’s petroleum-based jet fuel while producing 50%–80% fewer carbon emissions over its lifecycle. This technology also provides an opportunity to create low-carbon fuels that could even perform better than traditional jet fuel, but at the moment, SAFs are more expensive than the petroleum-based options.

For airlines to meet their climate goals, SAF production and use will need to scale quickly. With rising demand from airlines and federal funding, companies are working to drive costs down and make that rapid growth a reality.

By the numbers

Reaching net-zero emissions in aviation by 2050 would require continued fuel-efficiency improvements in planes as well as a much, much greater supply of SAFs, according to a July report from climate experts and industry leaders on reaching net-zero. It would also require commercialization of some novel aircraft in the mid-2030s.

Scale: Global SAF production capacity would need to grow to at least 5x the size of the current pipeline by 2030.

• The industry would need about 300–400 new SAF plants—which typically take at least five years to build—by 2030 to scale up that quickly. The production capacity would then need to increase even faster, by as much as 9x from 2030 to 2050, according to the report.
• Just to keep aviation emissions at the same level as in 2019 as air-travel demand continues to grow would require ~$40 billion to $50 billion in average investments each year through the end of the decade, the vast majority of which would go toward the expansion of SAF production and upstream infrastructure.
• The US has set a goal of producing 3 billion gallons of SAF annually by 2030, and 35 billion gallons by 2050.

Price: SAFs remain more expensive than petroleum-based jet fuel, which is a significant challenge. Fuel is expected to make up 24% of the airline industry’s operating costs this year, according to estimates from the IATA.

• Jet-fuel prices reached $4.04 per gallon in June—double what they were in 2019, according to the US Bureau of Transportation Statistics. Rising fossil-fuel costs could help boost demand for alternatives, but the average price of SAF in the US is still much higher at $8.14 per gallon, according to GlobalAir.
• The upside is that many SAFs are considered drop-in fuels, which can be refined with existing equipment and infrastructure and used by current aircraft. This means capital costs for airlines to begin swapping in SAFs are negligible compared with the investments needed in fuel production capacity, according to the report.

Public and private progress

Meeting the emissions-reduction goals set by the Biden administration and the aviation industry will require a push by both the public and private sectors.

The federal government is working  to accelerate SAF R&D, demonstration, and deployment. The version of the Inflation Reduction Act passed by the Senate includes $500 million in grant funding aimed at increasing the sale and use of biofuels as well as a tax credit for SAFs.

Companies are also moving forward with bringing SAFs to market:

• In July, Boeing announced a partnership with Alder Fuels to expand global production of SAFs. The company expects to complete its first plant by 2024.
• LanzaJet, which produces an SAF by converting waste carbon-rich gasses from industrial processes to ethanol, has received investments from Microsoft and Shell and is building its first plant in Georgia.

Looking ahead: One of the biggest challenges of relying more on biofuels is ensuring there is enough sustainable biomass to supply the production of SAFs.

Global demand for jet fuel is projected to more than double from 2019 to 2050, so producing enough SAFs could require several hundred million tons of biomass each year. There are about 340 million tons of biomass available in the US, and there’s competition for that total from other sectors. And producing some of the feedstocks for these biofuels could require changes in land use that disrupt other carbon-sequestration cycles, according to researchers.