On Thursday, JetBlue, Virgin Atlantic, the US Air Force and others announced their commitment to purchase sustainable jet fuel from a New York-based startup called Air Company.
JetBlue has agreed to purchase 25 million gallons of the Air Company’s sustainable jet fuel over a five-year period, and Virgin Atlantic has agreed to purchase up to 100 million gallons over a 10-year period. Boom Supersonic, a company trying to bring back supersonic passenger flight, plans to purchase up to 5 million gallons of this fuel annually as part of its Overture flight test program.
According to a press release, the US Air Force, which placed the order with the company, has already conducted a “first-of-its-kind unmanned flight using the Air Company’s 100% pure CO2-derived jet fuel.”
“Aviation as a whole accounts for 2-3% of global CO2 emissions and is widely recognized as one of the most difficult industries to decarbonize,” Air Company noted in a statement. “Using the same proprietary technology that mimics photosynthesis to produce its consumer ethanol, Air Company developed and deployed its one-step process for CO2-based fuel production using renewable electricity.”
There has been much research and investment into the development of sustainable aviation fuels as more attention is focused on technologies that can help companies reduce their dependency on fossil fuels. While electric and battery-powered vehicles are also being considered as alternatives to air transport, they can present their own challenges. Electric planes might work for short jumps, but they’re not feasible for long journeys. Therefore, there is a need for more environmentally friendly ways to power the internal combustion engines in aircraft.
So what is sustainable aviation fuel?
Conventional jet fuel, or kerosene, is a mixture of hydrocarbons produced through a series of chemical reactions. But to make it sustainable instead of using fossil fuels, engineers would instead use more renewable feedstocks like raw materials or waste products like used cooking oils (read PopSci’s explanation on sustainable aviation fuel here). In general, the idea is that even if they still emit carbon emissions when burned because they took carbon out of the air in the production process, they end up being “carbon neutral”.
Sustainable aviation fuels (SAF) can be made from carbon dioxide and hydrogen. This subset of products is referred to as synthetic SAFs.
[Related: The truth about carbon capture technology]
“The application of our new carbon conversion process has the potential to replace old Fischer-Tropsch systems by simplifying a multi-stage conversion to a single-stage CO2 hydrogenation to fuel-grade paraffin,” said Air Company co-founder Stafford Sheehan in a press release. (Fischer-Tropsch systems convert hydrogen gas and carbon monoxide to water vapor and hydrocarbons through reactions that rearrange the bonds between the compounds. The source of the carbon monoxide is usually coal or natural gas.) “Additionally, with additional reactor modifications, we can produce a fuel composition , which can be used in a jet engine without the need for fossil fuel blending, as demonstrated in our test flight with the US Air Force. Our one-step process will make SAF more cost-effective towards widespread adoption.”
The company laid out its complete fuel production process in a white paper published in the magazine ACS energy letters. Earlier this year, the company experimented on a smaller scale with making ethanol from scratch through products like vodka, hand sanitizer and perfume.
The US has already approved the use of SAFs in a blend with conventional kerosene. Researchers in Europe have been looking for ways to reconfigure the original jet fuel manufacturing process using renewable energy and non-fossil fuel feedstocks. However, efficiency is an obstacle, as is cost. Reportedly, SAFs cost two to four times more than conventional jet fuel, and Air Company is no exception to this problem. This was announced by the company’s CEO axios that their SAF “is nowhere near the cost of traditional jet fuel,” but SAF-specific incentives included in the Inflation Reduction Act should be able to reduce some of the cost. Another obstacle is the availability of SAFs compared to traditional kerosene.
Although some companies have tested small flights using this greener kerosene alternative, questions remain about how compatible SAFs are with the materials that make up long-haul aircraft.
But despite skepticism and hurdles, many companies are still investing in this vision. In July, Alaska Airlines, Microsoft and Twelve announced they were working towards a demonstration flight that would use fuel made from reclaimed CO2 and renewable energy. And last year, Lufthansa announced a similar agreement to produce and use synthetic kerosene.