Clean energy journalism for a cooler tomorrow

America’s first commercial direct air capture plant just got going

The startup Heirloom says it’s capturing CO2 from the sky and locking away the planet-warming gas, making it the first and only commercial U.S. plant to do so.
By Maria Gallucci

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Two workers in safety gear stand next to very large stacks of metal trays in an industrial facility
Heirloom's direct air capture facility in Tracy, California uses limestone to absorb CO2 from the atmosphere. (Heirloom)

For the first time in the United States, a commercial plant is capturing carbon dioxide directly from the sky and locking away the planet-warming gas.

On Thursday, the startup Heirloom unveiled its direct air capture” facility in Tracy, California, which the company says has so far clocked nearly 1,000 hours of operations. Heirloom’s technology uses limestone to absorb CO2 from the atmosphere. Through a novel process, the captured carbon is then injected into concrete, where it ostensibly stays trapped forever.

The DAC facility is the closest thing on Earth that we have to a time machine, because it can turn back the clock on climate change,” Shashank Samala, Heirloom’s CEO and co-founder, said in a statement ahead of Thursday’s launch event. A slew of federal and state officials, including U.S. Energy Secretary Jennifer Granholm and California Lieutenant Governor Eleni Kounalakis (D), attended the ceremony.

To be sure, Heirloom’s plant is hardly capable of reversing the damage caused by decades of rampant fossil fuel consumption. The open-air warehouse, located some 70 miles east of San Francisco, can absorb a maximum of 1,000 metric tons of CO2 per year — less than 0.1 percent of the annual emissions from a single gas-fired power plant.

Still, flipping the switch on the Central Valley facility is nonetheless a key milestone for a burgeoning field that, until very recently, mainly existed in the realm of research labs and people’s imaginations.

Heirloom’s project will mark the first operational deployment of DAC with storage in the U.S., which is representative of the field today: moving from research to demonstration and deployment across pathways,” said Giana Amador, executive director of the Carbon Removal Alliance, an advocacy group.

We expect to see this trend continue across [carbon dioxide removal] technologies as the industry works to scale at the rate necessary to meet global climate goals,” she said by email.

Three-year-old Heirloom, which raised $53 million in Series A funding last year, joins only a handful of other outfits that are actively capturing and sequestering CO2 worldwide.

In 2017, the Swiss company Climeworks opened the world’s first DAC facility near Zurich, which used large fans to suck air into containers and filter out CO2 molecules. Although that facility stopped operating last year, Climeworks now runs a 4,000-metric-ton plant in Iceland. And while U.S. company Global Thermostat unveiled its own fan-based technology in Colorado earlier this year, the demonstration unit isn’t storing the CO2 it captures.

Heirloom’s own process begins with an industrial kiln, which the company says is powered by renewable electricity from a local provider. Inside the kiln, limestone is heated to 1,650 degrees Fahrenheit, which breaks down the mineral into its constituent parts of calcium oxide and CO2. The same reaction occurs in cement-making, which is why cement is one of the world’s top-emitting industries.

An employee in high-visibility safety gear and a hardhat stands in a production facility
A worker handles trays covered with calcium oxide, which resembles flour. (Heirloom)

But instead of releasing CO2 like cement kilns do, Heirloom’s kiln pumps the gas into a storage tank. The remaining calcium oxide is then spread onto hundreds of flat silver trays that are stacked vertically on 40-foot-tall racks, resembling a bakery of comically large proportions. The racks are exposed to open air for several days, during which time the white powder soaks up CO2 from the air like a sponge. Once saturated, the material heads back into the kiln, and the process starts again.

According to Heirloom, the captured CO2 gas could eventually be permanently stored safely underground.” For now, however, the company is working with the startup CarbonCure to turn the CO2 into a dry-ice-like material and mix it with concrete, where the CO2 mineralizes and gets trapped. (For more on how the process works, read or watch Canary Media’s reporting from inside a New York City concrete factory.)

The promise and perils of carbon dioxide removal 

The launch of America’s first commercial DAC plant arrives at a momentous yet complicated time for the fast-growing field of carbon removal — a broad set of technologies that climate scientists say will be unavoidable” if the world is to avert the worst effects of climate change.

Federal and private funding is flowing into the space like never before. The Biden administration has committed to spending at least $3.7 billion to kick-start DAC and other carbon-removal projects across the United States. Large private companies are pledging to buy credits” from carbon-removal projects to both support technology development and boost their own corporate sustainability goals. Most recently, Microsoft said it would buy up to 315,000 metric tons’ worth of CO2-removal credits from Heirloom, worth an estimated $200 million, over a 10-year period.

Proponents say such investments are necessary to further develop fledgling technologies, many of which still face significant scientific and technical barriers to scaling up — not least of which is their outsize energy consumption. Ideally, the funding can also help drive down the sky-high costs of removing and storing carbon dioxide. By some estimates, DAC currently costs around $600 to $1,000 per metric ton of CO2.

Three very tall stacks of large silver metal trays
Robots place large trays onto 40-foot-tall racks exposed to open air. (Heirloom)

Yet the firehose of funding is also sparking opposition from environmental groups and climate advocates, who argue that the money would be much better spent on building renewable energy projects, which avoid generating planet-warming emissions in the first place. Adding to the backlash is the fact that major oil and gas companies are increasingly embracing carbon removal technologies as a way to justify their continued production of fossil fuels.

Direct air capture allows polluting industries to live on, when we should be focusing on a just transition to renewables,” Marion Gee, co-executive director of the grassroots Climate Justice Alliance, said in an August 11 statement, on the heels of a major federal DAC announcement.

Last summer, the Department of Energy announced over $1 billion for two projects that aim to accelerate DAC development across the United States.

One of the winners is 1PointFive, a subsidiary of Occidental Petroleum. The company is developing what it says could be up to 30 DAC plants on private land just south of Corpus Christi, Texas. Days later, Occidental said it would pay $1.1 billion to acquire its technology provider Carbon Engineering to develop dozens more carbon-capture plants. Separate from the DOE-backed hub, Occidental is also working to use captured CO2 to boost oil production from older wells in the Texas Permian Basin.

The second winner, known as Project Cypress, includes both Heirloom and Climeworks, as well as the applied-sciences organization Battelle. The companies are partnering to design and operate a CO2-sucking machine in southwest Louisiana, which is also intended to capture over 1 million metric tons of CO2 per year. The company Gulf Coast Sequestration will then take the captured CO2 and permanently store it in a deep saline aquifer.

Both projects will seek to secure a number of offtakers for the captured carbon, including voluntary carbon markets and the U.S. government. Microsoft, as part of its purchase agreement with Heirloom, has already committed to buying credits from the facility in Louisiana. Beyond the DAC hubs, the Department of Energy has said it would buy $35 million worth of credits from up to 10 teams, while also creating guidelines for what it considers to be a high-quality” carbon removal project.

Amador of the Carbon Removal Alliance said she believes the U.S. government is the very best customer” for the country’s emerging and early-stage carbon removal projects.

Carbon removal is a public good,” she said. Their involvement will help ensure the industry is scaled both rapidly and with high standards.”

Maria Gallucci is a senior reporter at Canary Media. She covers emerging clean energy technologies and efforts to electrify transportation and decarbonize heavy industry.