A recent report from the International Air Transport Association (IATA) suggests that the growth in sustainable aviation fuel (SAF) production did not meet previous estimates in 2024.

While worldwide SAF production last year reached 1 million tonnes—0.3% of global jet fuel produced, and double the amount manufactured in 2023—that total was significantly below estimates that pegged 2024 volumes at 1.5 million metric tons.

IATA noted that key SAF plants in the U.S. have pushed back their production ramp-ups to the first half of this year, with total global output expected to exceed 2 million tonnes or 0.7% of total jet fuel production.

That stands in contrast to an assessment made last year by Alejandro Moreno, an official with the DOE’s Office of Energy Efficiency. Speaking at the North American SAF Conference and Expo in Saint Paul, Minnesota, in September, he noted that three years after the Biden Administration issued its SAF Grand Challenge to the U.S. fuel industry to reach a goal of three billion gallons of neat SAF production a year by 2030, the industry is stepping up.

“When we initially set it, there was a lot of discussions about whether that was too ambitious,” Moreno said. “We are now on track at the low end to meet it and even exceed it.”

There are now 11 certified pathways to manufacture SAF, but HEFA—derived from used cooking oils and fats—will account for 80% of the SAF volume over the next half-decade. IATA believes production could be enhanced by investment in the other pathways.

“SAF volumes are increasing, but disappointingly slowly,” said IATA director general Willie Walsh. “Governments are sending mixed signals to oil companies, which continue to receive subsidies for their exploration and production of fossil oil and gas.” He added that investors in new-generation fuel producers seem to be waiting for “guarantees of easy money before going full throttle.”

By its calculations, to reach its goal of net-zero emissions by 2050, IATA sees a need for between 3,000 and 6,500 new renewable fuel plants globally, with an annual average capital expenditure of $128 billion.

“Governments must quickly deliver concrete policy incentives to rapidly accelerate renewable energy production,” stated Walsh. “The good news is that the energy transition, which includes SAF, will need less than half the annual investments that realizing wind and solar production at scale required.”