At a startup in San Francisco, a team of engineers is building a system for capturing CO2 from the air using rocks—a solution that could eventually be cheap enough to operate on a large scale and begin to chip away at the 2.4 trillion tons of carbon dioxide (and counting) that humans have dumped into the atmosphere since the Industrial Revolution.
The company, called Heirloom Carbon, starts with limestone, which it heats in a renewably powered kiln so it breaks down into calcium oxide and CO2. Then it spreads out the calcium oxide on stacked trays—a little like a baking rack—and lets the mineral suck up carbon dioxide. (As it works, the mineral grows in size, a little like rising cookies.) “The oxide is effectively your sponge for CO2,” says founder and CEO Shashank Samala. Back in the kiln, the CO2 is separated out so it can later be stored underground. By next year, the startup plans to begin capturing and selling its first tons of CO2.
Heirloom Carbon is one of a small but growing number of companies focused on carbon removal through various new approaches, from robotic seaweed farms to plant-based “bio oil” that can be injected underground to direct air capture machines that are now sucking carbon dioxide from the air in Iceland. While some are further along than others, all are at an early stage; almost all carbon removal now is happening in trees and other parts of nature. But this type of technology will have to radically grow to deal with the scale of the problem.
The latest report from the UN’s Intergovernmental Panel on Climate Change (IPCC) explains that large-scale carbon removal must now be an essential tool to limiting global warming to 1.5 degrees Celsius and avoid some of the worst impacts of climate change. By some estimates, the world will need to remove 10 billion tons of CO2 from the atmosphere each year until 2050 to stave off those effects.
The world also needs to decarbonize, moving rapidly away from fossil fuels. But to deal with some emissions that are harder to quickly eliminate, as well as the legacy emissions that are already in the atmosphere, we’ll also need carbon removal. From now until the end of the century, the IPCC report says, direct air capture technology alone may have to collect as much as 310 billion metric tons of CO2 from the air. The carbon removal industry barely exists now, but by the middle of the century, it may need to be the size of the current oil and gas industry. How can it grow quickly enough?
Investment is critical, and growing now. Frontier, a new “advanced market commitment” from Stripe, Alphabet, Shopify, Meta, and McKinsey Sustainability, has committed to buy at least $925 million in carbon removal services from startups over the next nine years. It’s a signal to companies that it’s worthwhile to invest in creating new technology. “That can catalyze a lot of scale and innovation that maybe wouldn’t have existed otherwise because people didn’t know if there would be buyers or if the numbers would pencil out,” says Peter Minor, the director of science and innovation at Carbon180, a nonprofit focused on carbon removal. The new commitment builds on Stripe’s pioneering work to pay startups for carbon removal at any cost.
“You create an environment for the right talent to be motivated to develop these technologies,” says Mark Patel, a senior partner at McKinsey. “That can be entrepreneurs who are looking to take a risk and build companies, but it can also be scientists who are looking for the environment in which to be able to pursue their ideas and have them commercialized.” It also can help turn a small field into an industry. “We need thousands of people who engage in this and understand it,” he says. Some may come from the fossil fuel industry, helping ideas that are still at the pilot stage go through the development and engineering necessary to work at a large scale.
More projects like Frontier are needed, says Heirloom’s Samala. “We want long-term purchasing agreements, whether that’s from a corporate or from the government, that gives you a predictable revenue source, which you can use to go and finance these deployments,” he says. Similar long-term purchase agreements are commonly used in the wind and solar industry, and helped those industries grow and the cost of the technology drop. One recent report says that investment in all kinds of carbon removal, including nature-based solutions, needs to grow twentyfold by the end of the decade, and that governments should play a major role in that funding.
The U.S. Department of Energy is planning to roll out four direct air capture “hubs” that will help companies solve challenges with deployment; the details of how the hubs will work will be released later, but the basic concept is to build large plants that companies can use to test their tech at scale—and solve problems like how to source renewable energy 24 hours a day, 7 days a week. The government is also working to help companies figure out the logistics of storing the captured CO2 underground, whether that’s in old oil wells or elsewhere; for example, it can help speed up the permitting process. (There are some risks in injecting CO2, including the potential for earthquakes or leaks, but experts say that they are well understood and accounted for in regulations.)
The technology itself still needs to evolve—most direct air capture tech, for example, uses so much energy that it’s inherently expensive. But startups like Heirloom are experimenting with approaches that could help make it financially viable. (The company says it sees a path to a cost below $100 per ton of CO2; other direct air capture companies today have costs ranging between $250 to $600 per ton, though they are also working to make it more affordable.) Startups in the space are getting bigger investments; Heirloom recently raised $53 million, and Climeworks, the direct air capture company with the commercial plant in Iceland, recently raised $650 million. Investors are now also actively looking for startups with new solutions. Lowercarbon Capital, Chris Sacca’s investment company, just launched a $350 million fund focused on carbon removal. “When it comes to demand for carbon removal, consider that two years ago, the amount of money trying to buy it rounded down to $0,” Sacca wrote in an announcement. “The few companies attempting removal were basically small demonstrations with no clear path to scaled commercialization. Fast forward to today, and we see major buyers across the spectrum who just plain get it. This isn’t merely lip service.”
Heirloom, which sees itself as one part of the carbon removal ecosystem, aims to be removing a billion tons of CO2 a year by 2035, through a network of “carbon farms” strategically located near renewable energy and geological storage for the carbon dioxide. “This is one of the most ambitious things humanity has ever done, I think—I don’t know if people realize how much a billion tons is,” Samala says. Starting from the scale of capturing single-digit tons of carbon per day next year, it’s a huge leap to make.
The oil industry, he says, extracts around 4 billion tons of oil a year. The carbon removal industry will likely have to more than double that, to 10 billion tons a year, and has little time to prepare to do it. “Technically, it’s a much harder problem because there’s only one CO2 molecule for every 2,500 air molecules; finding those molecules is kind of hard, especially at that scale,” he says. “And then we have only a fraction of the time to do it that the oil industry has had. It’s one of the largest technological, infrastructural, scale-up challenges we will ever face.”