A $100 million carbon-removal competition enters its final stage

The Elon Musk–backed Xprize competition announced 20 finalists to advance breakthrough solutions for CO2 removal using air, rocks, land, and oceans.
By Maria Gallucci

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Heirloom, an Xprize finalist, uses limestone to absorb CO2 from the air in Tracy, California. (Heirloom)

Over 1,000 companies and research teams are now working to remove carbon dioxide from the sky or ocean and permanently lock it away — up from just a handful of ventures a decade ago. As the planet gets warmer and CO2 levels keep rising, more scientists and entrepreneurs are searching for novel ways to keep Earth’s carbon cycle in check.

Many of these teams were vying for top spots in a $100 million global competition. Now, the 20 most promising projects are advancing to the final round of the four-year-long contest.

On Wednesday, the nonprofit foundation Xprize announced the short list of finalists, including teams in China, Denmark, Kenya, India, and the United States. The grand prize winner, to be announced in April 2025, will take home $50 million, while the runners-up will split a $30 million pot. (The foundation already doled out $20 million in earlier stages to student teams and 15 milestone” winners.)

The competition, which is backed by Elon Musk’s charitable foundation, aims to advance breakthrough solutions for carbon dioxide removal, not only by awarding prize money but also by analyzing and publishing data on each team’s performance throughout the process.

We’re trying to use the platform to advance the industry and to increase the trust and integrity of carbon removal,” Nikki Batchelor, the executive director for Xprize Carbon Removal, told Canary Media.

Climate scientists agree that even with deep cuts to greenhouse gas emissions and widespread adoption of clean energy, at least some carbon removal is likely needed to limit global temperature rise in the coming decades. In the United States, at least 1 billion metric tons (1 gigaton) of CO2-removal capacity may be necessary to achieve net-zero emissions by 2050, experts say.

Today, however, only a smattering of pilot-scale plants and first-of-a-kind facilities are actively removing CO2 worldwide, often using energy-intensive and expensive methods. Companies are still figuring out how to build profitable businesses, while third-party entities are just beginning to develop the scientific protocols and industry standards needed for reporting, monitoring, and verifying their approaches.

Carbon removal is a complicated space,” Batchelor said. Not only do you have to be able to do the carbon removal; you also have to be able to prove that it’s been done and to create trustworthy data along the way in order to gain credibility.”

She said the Xprize finalists are the tip of the spear on innovation” and are leading efforts around standard-setting in the emerging sector. We’re really going to be looking at this cohort to pave the way for a lot of future work in this space,” she added.

Projects use minerals, wastewater, and soil to suck up CO2

The 20 finalists fall into one of four emerging pathways for carbon removal: air, rocks, land, and ocean. Of those teams, six are deploying projects within the United States.

The U.S. firms include Heirloom, a startup that uses limestone to absorb CO2 from the atmosphere. Last November, Heirloom unveiled its first direct air capture” facility in Tracy, California. An industrial kiln heats up limestone, which breaks the mineral down into its constituent parts of calcium oxide and CO2. The kiln pumps the CO2 into a storage tank. When the remaining calcium oxide is exposed to the air, it soaks up atmospheric carbon like a sponge.

Lithos Carbon is a San Francisco–based company that crushes basalt rock into dust and sprinkles it over croplands, including more than 80 farms across nine states. The startup is among a growing number of companies to pursue enhanced rock weathering,” which involves supercharging the natural processes by which minerals absorb CO2 from the atmosphere; ideally, it also boosts crop growth.

Houston-based Vaulted Deep — which works with the biomass waste found in landfills, wastewater treatment facilities, and paper mills — also made the cut. The company turns the carbon-rich residues into a slurry” and then injects it into impermeable salt caverns in Hutchinson, Kansas. Another land-focused startup, Climate Robotics is developing a mobile technology to convert crop residues into biochar, helping to remove excess carbon from the atmosphere.

Seawater flows into Ebb Carbon's experimental facility in Sequim Bay, Washington. (Ebb Carbon)

Ebb Carbon operates a novel marine carbon dioxide removal” system at Pacific Northwest National Laboratory’s facility in Sequim Bay, Washington. Ebb’s technology uses electrochemistry to split seawater into its acidic and alkaline parts. The process returns alkalinity to the ocean, creating chemical reactions that pull CO2 from the air and store it safely in the sea. California-based Captura also uses electrochemical techniques to extract CO2 directly from seawater.

As number of CO2-removal startups grows, so do challenges

To advance in the Xprize competition, finalists will each need to pull 1,000 metric tons of carbon dioxide from the air or seawater over a 12-month period. Companies will also have to demonstrate that their technologies can scale up in ways that are technically, environmentally, and socially sustainable,” said Michael Leitch, the technical lead for Xprize Carbon Removal.

We’re moving into a place where it’s less about testing the scientific viability of the solutions and more about deploying it in the real world,” he added.

Xprize launched its first carbon-focused program in 2015. The $20 million NRG COSIA Carbon Xprize focused on companies working to convert carbon into useful products, including concrete, batteries, and vodka. In 2021, the foundation kicked off the $100 million Carbon Removal competition, which drew interest from over 1,300 teams from 88 countries.

Last month, after three years of judging entries, Xprize published a list of 100 leading innovators” in carbon removal. From there, it whittled the group down to the nearly two dozen finalists.

There’s been a really significant shift in the carbon removal industry over the last 10 years — we see that both in the sheer number of companies that exist, but also the diversity of technologies that they’re working on,” said Giana Amador, executive director of Carbon Removal Alliance, an advocacy group.

Mash Makes, a Danish venture and Xprize finalist, is building a demonstration facility in India that converts agricultural waste into carbon-negative energy and biochar. (Mash Makes)

The nascent industry will need a wide variety of solutions to achieve gigaton-scale” carbon removal by 2050, she said. Still, it will be difficult to hit that benchmark without a more robust market for carbon-removal credits.

The business models of today’s startups largely rest on a combination of government support and, to a larger extent, voluntary commitments from private companies. Startups that have secured significant funding typically sign advance purchase agreements with tech giants like Microsoft and members of the Frontier coalition, which buy CO2-removal credits to support their own corporate sustainability goals. Heirloom, Lithos Carbon, Vaulted Deep, and Captura have all landed such deals.

However, without a strong regulatory framework, no heavily polluting companies or industries will need to buy what CO2-removal startups are selling, meaning the industry could struggle to sustain itself and build large-scale facilities and projects.

The biggest challenge right now is really around market development,” Amador said.

While the Xprize awards alone can’t solve that particular problem, the organizers say they hope the competition can boost public support for and improve the credibility of emerging carbon-removal solutions — particularly as the finalists begin removing their first 1,000 metric tons or more of CO2 this year.

That’s the first milestone that has to happen, before any of these companies can convince people to finance a megaton-scale plant around 2030,” Batchelor of Xprize said. And both of those things have to go well before we get to gigaton-scale carbon removal.”

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