Bushwick is probably not the first place that comes to mind when you think of jet fuel production, but tucked away in an industrial corner of the hipster haven of Brooklyn is an unassuming, windowless warehouse that could hold the key to a future of more environmentally friendly flying.
Air Company, which was founded in 2017, is using this Brooklyn location to experiment with making sustainable aviation fuel (SAF) out of water and carbon dioxide. The method they’re using is known as power to liquid. I’ve heard of and written about this process before, and honestly, I don’t understand why it’s not getting more attention.
Air Company’s Brooklyn production facility.
I had a chance to visit Air Company’s SAF production facility in March, and although the quantities it’s producing now are small, in the coming years they plan to open a new plant that could produce thousands of gallons a day. However, that’s still a piddling amount compared to the aviation sector’s overall thirst for fuel. (For reference, U.S. airlines used 1.41 billion gallons of fuel in January 2023 alone, according to the Bureau of Transportation Statistics.)
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Still, Stafford Sheehan, one of Air Company’s co-founders and its chief technology officer, told me that by the end of this decade, they hope to have a larger number of industrial-scale production facilities in operation across the country.
How does power to liquid work?
Here’s how Sheehan and his colleagues explained the process.
First, Air Company draws a relatively small amount of water – “a couple gallons an hour” – from the municipal water supply. That water (which you may remember is H2O from your high school chemistry class) is broken down via electrolysis into hydrogen and oxygen. The oxygen is vented back out into the atmosphere and the hydrogen is stored at high pressure awaiting the next step.
The machine used to separate hydrogen and oxygen from water molecules.
Near the hydrogen storage tank is a much larger carbon dioxide storage tank, which is used for the crucial next phase.
Sheehan said that, for now, Air Company uses biogenic CO2 sourced from traditional ethanol fermentation, captured from another facility in upstate New York before it is released into the atmosphere, which allows the company to mitigate those emissions altogether.
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“Literally, all we did was put a compressor at the end of the smokestack,” he said. The captured, compressed carbon gets trucked down to Brooklyn and ultimately turned into fuel when mixed with the compressed hydrogen.
“We don’t need deliveries (of captured carbon) very frequently, like less than once a month,” Sheehan said.
For larger-scale production, he added, Air Company is considering locating its facilities closer to the source of the captured carbon.
Although the technology it uses can be placed anywhere, the overall lifecycle emissions of Air Company’s SAF are lower when the carbon source is closer to the fuel production facility, because it eliminates the need to transport the captured carbon from the source to where the fuel is ultimately produced, which is currently one of the more emissions-intensive parts of the process.
Air Company’s carbon storage tank.
Other companies are developing technology that will capture carbon dioxide directly from the atmosphere to feed the power to liquid process, but Sheehan said that work is still in its infancy.
Sheehan also said that the machinery required for capturing carbon emissions is prohibitively heavy to install on airplanes, so it’s not likely that your flight’s exhaust will ever be directly captured and turned into fuel for the return trip.
How is sustainable aviation fuel created?
The next step is bringing the ingredients together.
Compressed hydrogen and carbon are introduced to a catalyst in a carbon conversion reactor, producing flammable paraffins, methanol, ethanol, and wastewater. Those products are then distilled and turned into fuel, among other things.
Sheehan said the exact catalyst for that reaction is proprietary, but Air Company uses a standard reaction chamber to make it happen.
The chamber where hydrogen and carbon are combined to make paraffins and other byproducts.
“Every single reactor in the chemical and the petrochemical industry is essentially the same as that: they’re tubes with rocks,” he said. “Because this is the most standard reactor type in the entire chemical industry, the scale-up of it is well known. Our approach is to have as many things as possible that are similar to oil and gas or drop-in replacement because all the infrastructure in the world is made for oil and gas.”
Even at this small scale, the efficiency of power to liquid shows promise. Lauren Riley, United Airlines’ chief sustainability officer, recently told USA TODAY that she views this method as the future of aviation fuel production.
The reaction produces paraffins and wastewater, with some other byproducts that are also extracted.
Paraffins and water are the two major products of Air Company’s process.
Sheehan emphasized that power to liquid’s process efficiency is a major advantage over other kinds of sustainable aviation fuels, which require more refining to deploy.
“We can go from literally CO2 and water to SAF in one step,” he said.
The paraffins produced by the reaction are converted into aviation fuel. Through Air Company’s partnerships with the Department of Defense, its product has already powered experimental jet flights and does not have to be mixed with traditional aviation fuel to be used, as other forms of SAF sometimes do.
“With the military, we fly only 100%, we don’t do any blending,” Sheehan said. “This can be drop-in” as a replacement for petroleum-based jet fuel.
The production process also creates wastewater, which can be recycled to make more fuel, along with methanol and ethanol, which Air Company puts into consumer products including perfume and vodka.
These tanks hold wastewater, which is recycled to make more fuel, as well as ethanol and methanol, which are used in consumer products like vodka and perfume.
How quickly can power to liquid be deployed for commercial flights?
Sheehan acknowledged that Air Company’s fuel isn’t going to be on your own flights any time soon, even if their current production facility is just a few miles from New York’s major airports.
“The scale that we’re producing here is small compared to commercial jets,” Sheehan said. “But out of our next facility, that’s going to be flying commercial jets,” and is set to come online in the next few years.
Economic and other roadblocks are a drag on scaling up, too.
The process Air Company uses is energy intensive. At the scale they are producing fuel in Brooklyn, they can purchase renewable energy certificates to account for the power they’re using from the ConEd grid, but at larger facilities, they plan to co-locate with sustainable energy producers.
“You have to buy a lot of renewable electricity and deploy a lot of costly renewable electricity,” Sheehan said.
The core section of Air Company’s fuel production process.
Finding enough renewable energy to make more fuel through this method is one of the major obstacles to growing Air Company’s overall eco-friendly production.
The economics of the industry also complicate its growth, because SAF production by any method remains more expensive than drilling for fossil fuels, but tax credits passed by the Biden administration under the Inflation Reduction Act allow the end cost of SAF to be similar to that of traditional petroleum aviation fuel.
And as exciting as power to liquid sounds, it’s just one part of the solution to climate change.
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“What’s evident is it’s going to take a portfolio of solutions to solve climate change,” Sheehan said. “We don’t need to be reliant on fossil fuels. That’s good for the climate and it’s good for people in general because then you don’t have a concentration of wealth and power in the few people and the few countries and the few groups that run oil wells.”
https://www.usatoday.com/story/travel/airline-news/2023/04/23/how-is-sustainable-aviation-fuel-made/11557727002/