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Ten miles above the Earth, these machines can capture CO2 from the air

The temperatures high in the atmosphere change the physics of carbon removal. Can these balloons make it cost-effective?

Ten miles above the Earth, these machines can capture CO2 from the air
[Photos: umesh chandra/iStock, Chris Nguyen/Unsplash]
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On April 16, a team of engineers in Germany launched a balloon in the air and watched as it ascended. It was carrying new technology designed to capture CO2 from the atmosphere at a height of 52,800 feet.

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The startup, an Israel-based company called High Hopes with a German subsidiary, isn’t the first to develop so-called “direct air capture” technology to fight climate change. In 2017, the Swiss startup Climeworks launched the first commercial plant of its kind, using fans on a rooftop to pull air into a machine where spongelike filters capture carbon dioxide. Others followed, including Global Thermostat, a startup that built a giant carbon capture plant in Alabama. Major companies, from United Airlines to oil giants, are investing in the technology in attempts to address their own carbon footprints. But High Hopes is taking a new approach to the problem.

Existing direct-air-capture tech is expensive to run because of the energy it takes; one type of the technology requires heating up the system to more than 1,600 degrees Fahrenheit to release the captured CO2 so it can be stored or used in products. “If you look at the numbers, a huge part of it is energy,” says Eran Oren, cofounder and chief scientist at High Hopes. “So it makes sense to think of this problem as, how can I constrain the amount of energy needed per metric ton of carbon dioxide that I capture?”

A year and a half ago, Oren suddenly realized that another method might work and called a collaborator in the middle of the night. “I got a call at 4 a.m.,” says Nadav Mansdorf, now a cofounder of the startup. “My wife was panicked. Eran was on the line, saying, ‘Oh my God, I have the solution for the biggest problem in the world.'”

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The key was working in a different location—instead of pulling in the air near the ground, they could use machines at high altitudes, where temperatures can dip to minus 70 degrees Celsius (minus 94 Fahrenheit). At minus 80 degrees Celsius, carbon dioxide freezes into what are essentially snowflakes. With relatively little energy, the air can be cooled enough to freeze the carbon out of the air and capture it in an adsorbent material. Then it’s brought back to earth, to be buried underground or used in manufacturing products (say, vodka made from captured CO2, or carbon-neutral jet fuel). Because the equipment will work at an altitude where the wind constantly is pushing more CO2 into the balloons, it also won’t require the large fans that are used by companies working on the ground.

In early tests with small balloons, the startup is proving that the process works. The basic machine is fairly simple. “If you just cut it open, what you see is something relatively similar to a fridge, meaning a compressor and cooling fluid,” Oren says. At full scale, the box holding the equipment will be roughly the size of two regular refrigerators, carried by a balloon around the size of the balloons tested by Google’s satellite internet tech, Project Loon. Each will float upwards for 8 to 10 hours, capture the cold CO2, bring it back down to a ground station to unload, and then immediately return to capture more. The company hopes to begin operating a site with several devices within the next year, and to continue tweaking the technology so that a single balloon can capture a metric ton of CO2 each day. It’s expected to cost around $100 to capture a ton, and could drop further to $50 a ton; that’s far less than other direct-air-capture technology, at least right now, with costs ranging from $250 to $600 per ton of CO2 at the moment.

To tackle climate change, a network of the balloons would have to be deployed on a massive scale. While major, policy-driven changes to how we produce and consume energy are the key to stopping climate change, some type of direct-air-capture tech will almost certainly be necessary as part of the process; one study calculated that direct-air-capture technology will have to suck as much as 1,850 million metric tons of CO2 out of the air by 2045, even as the world simultaneously moves as quickly as possible to scale up solutions such as renewable energy and reforestation. CO2 levels in the atmosphere are at a record high—417.14 parts per million in March, versus around 278 parts per million before the Industrial Revolution.

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The first facility, they say, will start with 100 balloons, capturing around 30,000 metric tons of CO2 each year. This year, humans will likely pump another 33 billion tons of greenhouse gases into the atmosphere. If each balloon can capture 1 metric ton a day, the company would need to operate around 50 million balloons.

About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."

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