Sustainable aviation fuel will power more planes

It’s hard to decarbonize a passenger jet.

Planes can make gains through lighter-weight construction materials, better aerodynamics, and improved routes. But at the end of the day, you can’t get around the fuel: global air travel consumes about 400 billion L of jet fuel per year, according to the market research firm S&P Global. In 2022, burning that fuel created 784 million metric tons of carbon dioxide emissions, according to the International Energy Agency. That’s 2–4% of total greenhouse gas emissions.

Most airlines have committed to net-zero greenhouse gas emissions by 2050 and plan to reach that goal by switching to sustainable aviation fuel (SAF). SAF is chemically the same as regular jet fuel, but it’s made from renewable, low-carbon raw materials instead of petroleum. Though hydrocarbon fuels are an imperfect way to fight climate change because they will always release CO₂ when burned, they’re also the most plausible way to defossilize air travel on a large scale.

Airlines and government laboratories estimate that SAF can cut the net CO₂ emissions of a flight by 70 – 84% ; academic research suggests that some SAF processes could yield fuel that carries a net reduction in atmospheric CO₂ even after it’s burned (ACS Sustainable Chem. Eng. 2022, DOI: 10.1021/acssuschemeng.2c00977). Airlines are eager to buy in to that appeal and have signed many advance purchase agreements for future SAF volumes.

But not much is available today. SAF accounted for only 0.15% of global jet fuel volume in 2023, according to the International Air Transport Association (IATA), a trade group for airlines.

Several projects are underway to boost SAF supply. The oil refiner Neste arguably heads the field with a current SAF capacity of 1.3 billion L per year, at plants in Finland and Singapore. Jorrian Dorlandt, who leads communications for Neste’s SAF business, says the firm will boost SAF capacity to more than 1.8 billion L in 2024 by modifying its biofuel refinery in the Netherlands. The firm announced in late December that it plans to exit fossil fuels entirely.

World Energy’s plant in Southern California can make about 270 million L per year of SAF, the firm’s chairman, John Risley, said in a pair of early December interviews with the Canadian Broadcasting Corporation. An expansion that is halfway done, he said, will bring its capacity to more than 950 million L in late 2026. Also serving the West Coast market, Montana Renewables says it expects to reach 227 million L of capacity early in 2024 and complete an expansion to 870 million L later in the year.

IATA tracks volumes delivered, a more conservative estimate than the plant capacity that SAF makers usually cite. The group projects that the amount of SAF produced globally will reach a total of about 1.9 billion L in 2024, triple current volumes. That’s a good growth rate, but not fast enough to put aviation on a path to net-zero greenhouse gas emissions by 2050, IATA says.

The current stock of SAF is almost entirely made by upgrading plant and animal oils. IATA anticipates that additional chemical routes to SAF will help with the supply crunch. Gevo, LanzaJet, and Honeywell UOP are among the firms commercializing jet fuel made from biobased ethanol and methanol. Meanwhile, Air Company, Johnson Matthey, Sasol, and others are working on processes that start with hydrogen and various combinations of CO₂ and carbon monoxide.

“Demand is not the issue: Every drop of SAF produced has been bought and used,” IATA writes in its year-end report on SAF. “Unlocking supply to meet demand is the challenge that needs to be solved.”