(Bloomberg Businessweek) —
The path to tackling climate change used to be fairly straightforward: Cut greenhouse gas emissions to zero, and global temperatures would start to stabilize. But straightforward doesn’t mean cheap, convenient, or politically expedient, and nations have dragged their feet so much that scientists now say we risk a climate catastrophe even if we reach zero emissions in the next couple of decades. That’s why, after years of discussion and development, the idea of removing carbon dioxide from the air and storing it where it can’t reenter the atmosphere is gaining momentum.
The need for carbon removal—a task that’s far more difficult than trapping gases at the top of smokestacks—is “unavoidable” if the world is to reach global temperature targets, according to an April report by the United Nations’ Intergovernmental Panel on Climate Change. And the European Union has set a goal of increasing use of the technology a thousandfold within a decade. “We need to get to zero emissions globally and then go negative by a significant amount,” says Niall Mac Dowell, an energy systems engineer at Imperial College London. “To fully compensate for the damage to the planet, you need to permanently remove the CO₂ from the atmosphere.”
In the past month, Google’s parent company, Alphabet; Tesla Inc. boss Elon Musk; and several groups of private equity investors have committed a total of more than $2 billion to startups that propose solutions such as vacuuming CO₂ out of the sky, crushing minerals to trap carbon like a magnet attracts iron filings, or planting vast seaweed forests on the ocean floor. That’s on top of $3.5 billion earmarked by the Biden administration to set up four carbon removal hubs where various technologies can be developed and tested.
“This is a watershed moment,” says Erin Burns, executive director at Carbon180, a climate protection group in Oakland, Calif. “We are seeing massive amounts of private-sector and federal investment, with bipartisan support.”
Carbon removal is similar to carbon capture and storage, which involves catching greenhouse gas emissions from smokestacks and pumping them into the Earth. That technology will also be needed to reduce emissions from factories, such as steel mills and cement plants. But so far it has had a limited effect, because most of the captured gas has been simply injected back into oil wells to squeeze the final barrels of crude out of near-depleted reservoirs.
Since CO₂ makes up more than 10% of exhaust gases but just 0.04% of air, carbon removal machines require a lot more energy to gather the same amount of greenhouse gas. So while grabbing carbon from a factory smokestack runs about $60 per ton of CO₂, removing it from ambient air can cost more than 15 times that.
Today’s new crop of entrepreneurs, hailing from businesses ranging from forestry and soil management to software and cryptocurrencies, say they can make the idea work. Swiss startup Climeworks, which in April raised $650 million from the likes of insurer Swiss Re and Baillie Gifford, an early backer of Tesla and Amazon.com Inc., has built a machine in Iceland with giant fans that can suck 4,000 tons of carbon from the atmosphere annually by trapping it in a special filter. The captured CO₂ is then mixed with water and pumped underground, where it reacts with Iceland’s basalt rock and turns into stone within a few years.
U.S. startup Verdox Inc. has developed a plastic that can pull CO₂ out of the air when charged with electricity. The spinoff from Massachusetts Institute of Technology says its methodology is more efficient and cheaper than running huge vacuum-like machines. The company is one of 15 winners of million-dollar grants in a carbon removal competition bankrolled by Musk that will ultimately distribute $100 million to promising technologies. While the method has only been proven in the lab, Verdox says a recent breakthrough with its key material will help it operate at an industrial scale with costs of $50 a ton or less. In February, Verdox raised $80 million from investors including Breakthrough Energy Ventures, a fund led by Microsoft Corp. founder Bill Gates.
Other companies combine technology with the power of nature, using plants to gather the carbon—they consume CO₂ as they grow—and then storing it so the greenery doesn’t re-release the gas as it rots or burns. Australian startup InterEarth harvests trees in a way that allows them to grow back, and buries the wood in soil that’s as much as 10 times saltier than seawater, effectively pickling it. The salt and the absence of oxygen keep microbes from breaking up the wood, so the CO₂ will stay underground. InterEarth, which has raised about $500,000 and aims to get $30 million, says there’s enough salty land around the world to bury up to 1 billion tons of carbon every year.
Charm Industrial in San Francisco gathers green waste from cornfields, breaks it down in chemical reactors to produce a gooey black mixture that looks like crude oil, and injects the carbon-rich gunk into closed oil and gas wells, where it solidifies. The company says it captured more than 5,000 tons of carbon at a cost of around $600 per ton last year, but it expects to bring the price down sharply as the technology develops. Charm, which researcher Pitchbook says has raised roughly $25 million, aims to deploy dozens of mobile units that roam the U.S. turning cheap biomass into ready-to-bury bio-oil.
There’s still the problem of paying for these new technologies. Carbon cap-and-trade schemes have created markets for CO₂ emissions, but prices remain well below the cost of carbon removal today. So Alphabet (Google’s parent), McKinsey & Co., Stripe, Shopify, and Meta Platforms (previously Facebook) have contributed to a $925 million fund that will pay companies for taking carbon out of the atmosphere. The fund, called Frontier, aims to sign up other donors and spread the money among as many startups as possible in hopes of reducing prices by backing a variety of technologies, including Charm’s. “We need to buy down the cost curve just like we’ve done for solar and wind, and Frontier is a huge step,” says Charm Chief Executive Officer Peter Reinhardt, a former software executive who studied aerospace engineering at MIT.
The challenge remains tremendous. Last year, global CO₂ emissions increased to more than 36 billion tons, ending a brief pandemic respite. And that’s after years of pledges by governments and companies to reduce carbon output. Even the most ambitious technologies aim to store perhaps a few million tons of carbon annually, but that’s like trying to empty a lake with a teacup. The industry must remove tens of billions of tons from the atmosphere this century, which will require growth that eclipses even that of the computer and software sectors in recent decades. “We are scaling by tons of steel,” says Climeworks CEO Christoph Gebald. “The trillions required to make this industry really big is still a journey.”
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