California | A factory to extract carbon from the air

(Tracy, California) In an open-air warehouse in California’s Central Valley, four-meter-high racks hold hundreds of trays filled with a white powder that turns crusty as it absorbs carbon dioxide present in the sky.

The startup that built the facility, Heirloom Carbon Technologies, calls it the first commercial plant in the United States to use direct air capture, which involves sucking greenhouse gases from the atmosphere. Another plant is operating in Iceland, and some scientists believe the technique could be crucial in the fight against climate change.

Heirloom will take the carbon dioxide it extracts from the air and seal it permanently in concrete, where it cannot warm the planet. To make money, the company sells carbon removal credits to companies that pay a premium to offset their own emissions. Microsoft has already signed a deal with Heirloom to remove 315,000 tons of carbon dioxide from the atmosphere.

The company’s first facility in Tracy, Calif., which opened in early November, is relatively small. It can absorb a maximum of 1,000 tonnes of carbon dioxide per year, the equivalent of the exhaust fumes of around 200 cars. But Heirloom hopes to expand quickly.

“We want to reach millions of tonnes per year,” said CEO Shashank Samala. This means copying and pasting this basic design endlessly. »

The idea of ​​using technology to suck carbon dioxide out of the sky has gone from science fiction to big business. Hundreds of young plants have emerged. In August, the Biden administration awarded US$1.2 billion to help several companies, including Heirloom, build larger direct air capture plants in Texas and Louisiana. Companies such as Airbus and JPMorgan Chase are spending millions to buy carbon credits to meet their climate commitments.

Critics point out that many artificial methods of removing carbon dioxide from the air are extremely expensive, on the order of US$600 per ton or more, and some worry that they will distract from efforts to reduction of emissions.

Environmentalists are wary of oil companies investing in the technology, fearing it will prolong the use of fossil fuels.

Others believe it is essential to try. Countries have been so slow to reduce their greenhouse gas emissions that it is virtually impossible to keep global warming at tolerable levels, scientists say, unless countries sharply reduce their emissions and remove billions of tons of carbon dioxide from the atmosphere by mid-century, which is far more than can be achieved by simply planting trees.

“The science is clear: reducing carbon emissions using renewable energy will not be enough to stop the damage caused by climate change,” said US Energy Secretary Jennifer Granholm, who plans to Attend the grand opening of the Heirloom facility.

Carbon absorbing rocks

Heirloom’s technology relies on a simple element of chemistry: limestone, one of the most abundant rocks on the planet, forms when calcium oxide bonds with carbon dioxide. In nature, this process takes years. Heirloom speeds it up.

At the California factory, workers heat the limestone to 900°C in a furnace powered by renewable electricity. Carbon dioxide is released from the limestone and pumped into a storage tank.

The remaining calcium oxide, which looks like flour, is then sprinkled with water and spread onto large trays, which are transported by robots to tower-high racks and exposed to the open air. Over three days, the white powder absorbs carbon dioxide and turns back into limescale. The cycle then repeats in the oven.

“That’s the beauty of it, it’s just stones on platters,” observed Mr. Samala, who co-founded Heirloom in 2020. The hardest part, he adds, was years of adjusting variables such as particle size, tray spacing and humidity to speed up absorption.

The carbon dioxide still needs to be processed. In California, Heirloom works with CarbonCure, a company that mixes the gas with concrete, where it mineralizes and can no longer escape into the air. In future plans, Heirloom also plans to pump carbon dioxide into underground storage wells and bury it.

Heirloom won’t disclose its exact costs, but experts estimate that direct air capture currently costs between US$600 and US$1,000 per tonne of carbon dioxide, making it by far the most expensive way to reduce emissions. , even after the allocation of new federal tax credits of up to US$180 per tonne.

Heirloom has set a long-term goal of US$100 per tonne and plans to achieve this, in part, through economies of scale and mass-produced components. For its next plant, planned in Louisiana, Heirloom will use a more efficient furnace and a denser layout to reduce land costs.

Paying for carbon removal

Although direct air capture remains expensive, some customers are willing to pay.

Microsoft, which is Heirloom’s largest customer, has set a goal of becoming carbon neutral by 2030. This means first doing everything possible to reduce emissions, for example by powering data centers with renewable electricity. But the company also wants to offset emissions from activities that are not easy to clean up, such as the production of the cement it uses, and plans to offset its historical emissions.

Microsoft won’t purchase traditional offsets, such as paying for forest protection, because they are difficult to verify and may not be permanent. Extracting carbon dioxide from the air and burying it seems more sustainable and easier to measure.

“Carbon removal can be much more expensive than offsets, but what you pay for in climate impact is dramatically different,” said Brian Marrs, senior director of energy and carbon at Microsoft.

It’s too early to predict which carbon removal technologies will be most effective, Marrs said, which is why the company is investing in various approaches besides Heirloom’s. These include a direct air capture project in Wyoming and a new company that claims to remove atmospheric carbon by burying algae in the depths of the ocean.

However, to date only a small number of wealthy companies have been willing to pay for engineered carbon removal.

To build confidence in the market, the Department of Energy announced in September that it would purchase US$35 million worth of carbon credits from up to ten suppliers to establish new lines. guidelines on what constitutes a “high quality” project.

“Carbon removal is getting a lot of attention, but there aren’t yet enough buyers to reach the scale we need,” said Noah Deich, assistant secretary at the Bureau of Management. of the Department of Energy. “We are trying to change that. »

This article was originally published in the New York Times.