It’s not enough to slash greenhouse gas emissions. Experts say we need direct-air capture of atmospheric carbon
West Texas is a hydrocarbon hot spot, with thousands of wells pumping millions of barrels of oil and billions of cubic feet of natural gas from the Permian Basin. When burned, all that oil and gas will release vast amounts of greenhouse gases into the atmosphere.
A new facility there aims to do the opposite. Rows of giant fans spread across a flat, arid field will pull carbon dioxide from the air and then pump it deep underground. When completed, the project could capture 1 million metric tons of carbon dioxide per year, doing the air-scrubbing work of some 40 million trees.
Canadian firm Carbon Engineering is designing and building this “direct-air capture" facility with 1PointFive, a joint venture between a subsidiary of Occidental Petroleum Corp. and the private equity firm Rusheen Capital Management. Carbon Engineering will devote much of 2021 to front-end engineering and design work in Texas, with construction slated to start the following year and operations by 2024, the partners say. The project is the biggest of its kind in the world and will likely cost hundreds of millions of dollars to develop.
Carbon Engineering is among a handful of companies with major direct-air capture developments underway this year. Zurich-based Climeworks is expanding across Europe, while Dublin's Silicon Kingdom Holdings plans to install its first CO2-breathing “mechanical tree" in Arizona. Global Thermostat, headquartered in New York City, has three new projects in the works. All the companies say they intend to curb the high cost of capturing carbon by optimizing technology, reducing energy use, and scaling up operations.
The projects arrive as many climate experts warn that current measures to reduce emissions—such as adopting renewable energy and electrifying transportation—are no longer sufficient to avert catastrophe. To limit global warming to 1.5 °C, the world must also use “negative-emission technologies," according to the United Nations Intergovernmental Panel on Climate Change's 2018 report.
Global CO2 emissions from fossil fuels reached 33 billion metric tons in 2019. Existing direct-air capture projects would eliminate a tiny fraction of that total, and not all of the captured CO2 is expected to be permanently sequestered. Some of it will likely return to the atmosphere when used in synthetic fuels or other products. Companies say the goal is to continuously capture and “recycle" the greenhouse gas to avoid creating new emissions, while also generating revenue that can fund the technology.
Carbon removal can help compensate for sectors that are difficult to decarbonize, such as agriculture, cement making, and aviation, says Jennifer Wilcox, a chemical engineer and senior fellow at the World Resources Institute. “The climate models are saying clearly that if we don't do carbon removal in addition to avoiding emissions, we will not reach our climate goals."
Carbon Engineering's plant in Texas will use banks of fans, each about 8.5 meters in diameter, to draw air into a large structure called a contactor. The air is pushed through a plastic mesh coated with a potassium hydroxide solution, which binds with the carbon dioxide. A series of chemical processes concentrate and compress the CO2 into tiny white pellets, which are then heated to 900 °C to release the carbon dioxide as a gas. Steve Oldham, CEO of Carbon Engineering, likens the plant to a refinery that produces chemicals at an industrial scale. “That's the type of capability we're going to need, to make a material impact on climate change," he says.
Carbon Engineering is expanding its British Columbia pilot plant to capture 4 metric tons of carbon dioxide per day. Photo: Carbon Engineering
At its pilot plant in British Columbia, Carbon Engineering combines the pure CO2 with hydrogen to produce synthetic crude oil. The facility can capture 1 metric ton of carbon dioxide per day; by comparison, the Texas operation is expected to capture over 2,700 metric tons daily. At the larger site, the captured gas will be injected into older oil wells, both sequestering the CO2 underground and forcing up any remaining oil. In addition to the work in Texas, the company is scaling up its Canadian operations, Oldham says. In 2021, it will open a new business and advanced-development center and expand research operations; the new facility will capture up to 4 metric tons of CO2 per day from the air.
Other direct-air capture firms are opting for a modular approach. Climeworks' carbon collectors can be stacked to build facilities of any size. The system also uses fans, but the air runs over a solid filter material. Once saturated with CO2, the filter is heated to between 80 and 100 °C, releasing highly concentrated CO2 gas, which can be used in various ways.
For example, at Climeworks' pilot site in Iceland—which is powered by geothermal energy—the company's partner Carbfix reacts the concentrated CO2 with basaltic rock to lock it below ground. The site is now being expanded to capture 4,000 metric tons of carbon dioxide a year; it should be operational in the first half of 2021, says Daniel Egger, head of marketing and sales for Climeworks. The CO2 could also be used to make a more sustainable form of jet fuel; Climeworks is seeking financing for two CO2-to-fuel projects in Norway and the Netherlands.
Swiss firm Climeworks' cofounders and co-CEOs Christoph Gebald (left) and Jan Wurzbacher (right) plan to use captured CO 2 from the company's stackable collectors to make sustainable jet fuel. Photo: Julia Dunlop/Climeworks
Meanwhile, the company will continue working with the e-commerce platforms Stripe and Shopify. To cancel their carbon footprints, the two companies have committed to purchasing carbon credits from Climeworks, reflecting the amount of CO2 that Climeworks has removed from the air. Major tech firms in general are investing in carbon-reducing schemes to help meet their corporate environmental goals. Microsoft has pledged to be carbon negative by 2030 and to spend $1 billion to accelerate the development of technology for carbon reduction and removal.
“For all these companies that have targets to bring their emissions to 'net zero,' technologies like ours are absolutely needed," Egger says.
Global energy giants are also backing direct-air capture to undo some of the damage caused by their products and operations. In September, for instance, ExxonMobil expanded an agreement with Global Thermostat to help scale the startup's technology. Global Thermostat's machines are the size of a shipping container and capture CO2 using amine-based adsorbents on honeycombed ceramic cubes, akin to a car's catalytic converter.
Cofounder Peter Eisenberger, a professor of Earth and environmental science at Columbia University, says Global Thermostat's goal is to remove billions of tons of carbon dioxide every year by licensing its technology to other firms. He believes the world will have to remove 50 billion metric tons of carbon dioxide over the next two decades to avoid catastrophic climate shifts. In 2021, the company will add three pilot projects, including a 2,000-metric-ton plant in Chile to produce synthetic fuels, as well as facilities in Latin America and the Middle East that will provide CO2 for bubbly beverages and water desalination, respectively.
This artist's rendering shows Silicon Kingdom Holdings' CO 2 -absorbing “mechanical trees." A dozen trees can capture 1 metric ton of carbon dioxide a day. Photo-illustration: Silicon Kingdom Holdings
Unlike its peers, Silicon Kingdom Holdings uses a passive system to draw in air. Klaus Lackner, a professor at Arizona State University, developed the company's mechanical-tree technology. Each tree will have stacks of 150 disks coated in a carbon-adsorbing material; as wind blows over the disks, they trap carbon on their surfaces. The disks are then lowered into a bottom chamber, where an “energy-efficient process" releases the CO2 from the sorbent, says Pól Ó Móráin, CEO of Silicon Kingdom Holdings. The high-purity gas could be sequestered or reused in beverages, cement, fertilizer, or other industrial products. The startup plans to build and operate the first commercial-scale 2.5-meter-tall tree near the ASU campus in Tempe in 2021.
Ó Móráin says a dozen trees can capture 1 metric ton of carbon dioxide daily. The goal is to install carbon farms worldwide, each with up to 120,000 mechanical trees.
Wilcox of the World Resources Institute says there's “no clear winner" among these emerging technologies for capturing carbon. They're distinct from one another, she notes. “I think we need them all."
An abridged version of this article appears in the January 2021 print issue as “The Carbon-Sucking Fans of West Texas."