by Before the jet fuel that powers an aircraft’s engines is burned, it begins its life on the ground as a fossil fuel. But the US military is exploring new ways to produce this fuel, synthetically and on-site, where it needs to be used. They just announced a $65 million contract to Air Company, a Brooklyn-based company that has developed a synthetic fuel that doesn’t take raw materials from the ground.
In announcing the contract, the Department of Defense notes that it is monitoring both safety and environmental concerns. Getting jet fuel to where it’s needed, the Defense Department notes, “often involves a combination of ships, tanker planes and convoys.” And those same transport mechanisms, the military adds, can “become extremely vulnerable.”
Here’s how the fuel works, why the military is interested, and what the pros and cons of this type of approach are.
The chemistry of synthetic jet fuel
This DOD initiative is called Project SynCE, which is pronounced “sense” and stands for Synthetic Fuels for the Challenged Environment. By contested environment, the military refers to a space, such as a battlefield, where a conflict may occur.
The building blocks of fuel from the Air Company include hydrogen and carbon, and the process requires energy. “We’re starting with renewable electricity,” says Stafford Sheehan, Air Company CTO and co-founder. That electricity, he adds, is used “to split water into hydrogen gas and oxygen gas, so we get green hydrogen.”
But fuel also requires carbon, so the company needs carbon dioxide to get that element. “Specifically for Project SynCE, we’re looking at in situ direct air capture or direct ocean capture technologies,” he says. But more generally, he adds, “We capture carbon dioxide from a variety of sources.” Currently, he notes, their source is CO2 “that was a byproduct of biofuel production.”
So the ingredients in the recipe require carbon dioxide, plus the hydrogen that comes from water. These elements are combined in a fixed-bed flow reactor, which is “a fancy way of saying a bunch of tubes with catalysts,” or, even more simply, “tubes with rocks in them,” Sheehan says.
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Jet fuel itself is mostly made up of molecules – known as paraffins – made of carbon and hydrogen. For example, some of these paraffins are called regular paraffins, which are a straight line of carbons with hydrogens attached to them. There are also hydrocarbons called aromatic compounds.
“You have to have these aromatic compounds to make a jet fuel that’s identical to what you get from fossil fuels,” he says, “and it’s very important to be identical to what you get from fossil fuels because everybody engines are designed to run on what you get from fossil fuels.”
Okay, enough chemistry. The thing is, this fuel is synthetically made, it didn’t come out of the ground, and it can be a direct substitute for the refined dinosaur juice commonly used in aircraft. “You can actually make jet fuel with our process that also burns cleaner, so it has less trace,” he says. However, it will still emit carbon when burned.
Why does the Ministry of Defense care?
This project involves a few government entities, including the Air Force and the Defense Innovation Unit, which acts as a kind of bridge between the military and commercial sectors. So where will they start cooking this new fuel? “We plan to combine this technology with other renewable energy projects on several common bases, which include solar, geothermal and nuclear,” says Jack Ryan, project manager for DIU, via email. “While we can’t share exact locations yet, this project will initially be based in the Continental US and then over time, we expect that the shrinking size of the machine will allow the system to be configured and used in operational settings.”
Having a way to produce fuel in an operational environment, as Ryan describes it, could be useful in a future conflict because ground vehicles like tanker trucks can be targets. For example, on April 9, 2004, in Iraq, an attack known as the Good Friday Ambush resulted in many deaths. a large American motorcade was making an “emergency jet fuel delivery to the airport” in Baghdad, Iraq, as the Los Angeles Times noted in an extensive article about the incident in 2007.
“With the development and deployment of on-site fuel generation technology, our Joint Force will be more resilient and sustainable,” says Ryan.
(Related: All your burning questions about sustainable aviation fuel, answered)
Nikita Pavlenko, program manager at the International Clean Transportation Council, a nonprofit organization, says he’s excited about the news. “It’s also likely something that’s still a long way off,” he adds. “Air Company is still in the very, very early stages of commercialization.”
These types of fuels, called e-fuels, are not available in large quantities, nor are they cheap. “I expect that finances and availability will be big constraints,” he says. “Just based on the underlying costs of green hydrogen (and) CO2, you’re probably going to end up with something much more expensive than conventional fuel.” As for how much fuel they will be able to produce synthetically, DIU’s Ryan says, “It will be smaller amounts at first, providing resilience to existing fueling and base microgrids,” and then it will grow from there. .
(Related: Airbus just flew its largest plane using sustainable aviation fuel)
Still, these types of fuels have environmental benefits, Pavlenko says, although it’s important that the hydrogen they use is created through green means—from renewable energy sources, for example. The fuel still emits carbon when burned, but the benefits come because the fuel was created by removing carbon dioxide from the atmosphere in the first place, or preventing it from leaving a chimney. Even this chimney scenario is environmentally attractive to Pavlenko, because “you’re just borrowing that CO2 from the atmosphere—you’re just delaying it before it disappears into the atmosphere, rather than taking something that’s been underground for millions of years and releasing it. ” (A caveat is below the line, ideally there are no carbon dioxide belching fumes that could be captured in the first place.)
For its part, the Defense Innovation Unit says it’s interested in many different ways of getting the carbon dioxide, but is most excited about getting it from the air or the ocean. That’s because these two methods “serve the dual purpose of extracting CO2 from air/water while also providing a feedstock for the synthetic fuel process,” says Matt Palumbo, project manager with DIU, via email. Palumbo also notes that he expects this contract period to last about two to five years and believes the effort will continue from there.
