When SpaceX launches its Starship rocket, designed to send crew members to the International Space Station, deliver satellites to space, and travel to Mars as early as 2024, each launch will emit an estimated 715 tons of CO2, roughly as much as 10 cross-country flights on a 747. If spaceflight becomes common—and if the rocket is also used for quick trips in place of jets on Earth—it could become a meaningful source of emissions. But rockets can also use zero net carbon fuel.
Air Company, a New York City-based startup that turns captured CO2 into products, launched in late 2019 with an entirely different offering—carbon-negative vodka. But it saw an opportunity to begin making rocket fuel from captured CO2 as its researchers were experimenting in the lab. “We discovered that we can make fuel very efficiently as somewhat of an accident,” says Stafford Sheehan, an electrochemist and cofounder of the startup. “We were running our systems at higher temperatures than normal, under some conditions that we don’t typically do, and found out that we could very efficiently make these fuel molecules.” The technology could also be used to make carbon-neutral fuel for some other applications, such as ships, though the company is focused on rocket fuel.
By making liquid methane—the fuel used by new rockets such as the Starship—from captured CO2 instead of natural gas, the net carbon footprint of each flight will be eliminated. The fuel also solves a second challenge: Assuming reusable rockets make it to Mars, they’ll need to refuel for the flight home, and the fuel could be made using materials found on the planet. “[On] Mars, you have water,” Sheehan says. “It’s frozen, but you can unfreeze it, if you have enough energy to do that, and you do have energy in the form of solar energy. And you have an abundance of carbon dioxide, because the atmosphere is 95% CO2.”
The company built a prototype that successfully created liquid methane and liquid oxygen. “We’ve made it and we’ve really studied in-depth how it works,” he says. “We’re taking that knowledge that we gather from our first facility, and then designing a strong pathway forward in how it scales up for use on Mars as well.”
The next steps will be designing and building a refueling station, and beginning to work closely with the space industry. “We need the industry to come along with us,” he says. “While we’ve won some funding from NASA in the past, and we’re hoping to do some more, we really want to have those key industry players and partners, like the SpaceX and Blue Origin of the world, to really help push these technologies forward as well.”