Aviation's best bet for cutting emissions is a new kind of fuel — but there's nowhere near enough of it

• The US accounts for 25% of global aircraft emissions.
• Sustainable aviation fuel can be up to 80% less carbon intensive than conventional jet fuel.
• The US wants 3 billion gallons of sustainable aviation fuel by 2030. Today, it produces a fraction.

Of all global aircraft emissions, the US accounts for 25%. There's a goal to reduce that to zero by 2050, but it won't be easy. 

Aviation is one of the most challenging industries to decarbonize. The batteries we're using to electrify cars are generally too heavy for planes, and hydrogen-powered aircraft are many years off, at least from a commercial point of view. 

"The aviation sector does not have many options in terms of what it can do," Puneet Diwedi, a professor at the University of Georgia who has been studying sustainable aviation fuel production, told Insider. "There's a 2,000-pound — 20,000 pounds! — gorilla in the room, and it's fuel. You have to sort out fuel." 

Sustainable aviation fuel, or SAF, is similar to conventional jet fuel, but it's much less carbon-intensive during its full lifecycle. From production to combustion, it releases up to 80% less carbon dioxide than conventional jet fuel, according to data from the International Air Transport Association. 

Thanks to its similar physics and chemistry to conventional jet fuel, SAF is a "drop-in" fuel that can be mixed with other fuel and, for the most part, be stored in the same tanks and run in the same engines. It's so easy to swap in, that some industry experts have called it a "miracle drug." 

Problem is, there's not enough. 

Current US production of sustainable aviation fuel is around 4.5 million gallons per year, according to recent research by the Rhodium Group. The White House wants to up production to 3 billion gallons by 2030, in order to fully decarbonize aviation by 2050, but that's still not enough to replace the 4 billion gallons of fuel that were consumed in the US in 2022. 

"There are many refineries that can produce jet fuel from fossil fuel," Chris Cooper, US president of Neste, one of the main producers of SAF globally, told Insider. "There are very few that have seen the vision" of converting to SAF production. 

SAF is mostly made from chemicals called hydroprocessed esters and fatty acids, usually in the form of vegetable oils and used cooking oil. But, as much as Americans like their french fries and donuts, there's still not enough used oil. 

Luckily, SAF can be made from a lot of other things: trash, wood, carbon dioxide, to name a few. Diwedi, at the University of Georgia, for example, is working with a process that would turn a mildly poisonous grass called carinata that can be grown in the US into SAF. 

As more refineries get equipped to produce SAF, and more methods of production get approved, the goal of 3 billion gallons by 2030 is, according to experts, doable. 

Despite being potentially "miraculous," SAF won't be an overnight switch. It needs to be phased in incrementally. 

"There's a certain portion of the population that just wants to wait until they have a zero emissions aircraft," Carol Sim, assistant director for the Aviation Sustainability Center, told Insider. "That's not gonna be flying for many, many years to come. But we have this opportunity to have emission reductions before those vehicles are introduced. Because SAF is approved now, it's been used, it's accepted by airlines, it's accepted by the aircraft manufacturers, airports, the governments, globally, it is the immediate thing that we can do to reduce emissions."