When it comes to climate change, there are no “excuses,” but there may be a cheaper alternative: direct air capture.
The technology, more like a community service than a pardon, promises to suck vast amounts of carbon dioxide out of the atmosphere, making up for more than a century of illegal burning of fossil fuels. A scientifically sound idea, but commercially not.
Currently, it costs about $600 to $1,000 to capture a tonne of carbon dioxide, far more than anyone would consider commercially viable, which has led to countless startups racing to reduce costs and capture a tonne of carbon dioxide for under $100.
That price would still largely free burning fossil fuels, so it might be a tough sell, but many investors and even multinationals like Microsoft, Shopify, and Stripe are betting that the world will eventually adopt direct air capture, just like how we treat wastewater today instead of dumping it into rivers.
Large startups like Climeworks and Carbon Engineering are confident that scale will help drive down costs. Both companies extract carbon dioxide using adsorbents, then use heat to release it from the adsorbents so it can be stored elsewhere.
But smaller startups suggest that scale alone isn't enough. “Heat recovery is always an expensive step, energy-wise,” said Malte Feucht, co-founder and CEO of direct air capture startup Phlair. And he might have a point: One study suggests that capturing that much carbon, about 10 gigatons per year, using Carbon Engineering's approach would require nearly three-quarters of all the electricity currently produced in the world.
Feucht's company thinks a different approach, one that doesn't rely on heat, might help reduce costs. Like most direct air capture companies, Phlair uses fans to blow air over an absorbent. But instead of heating the absorbent, it uses acid to release the carbon dioxide. To generate the acids and bases it uses in the process, Phlair, formerly known as Carbon Atlantis, developed a device it calls a hydrolyzer.
Feucht says the hydrolysis device borrows heavily from the hydrogen industry, incorporating elements of both membrane-based electrolyzers and membrane-based fuel cells (electrolyzers use electricity to make hydrogen, while fuel cells consume hydrogen to make it).
“Instead of hydrogen, it only produces acids and bases,” he said.
Phlair's DAC machines use what's called a “pH swing” method to capture carbon dioxide. Inside, a basic (high pH) solvent absorbs carbon dioxide as it passes through an air concentrator. When the saturated solvent leaves the concentrator, it's discharged into a tank where it's doused with acid (low pH). The swing from high pH to low pH drives a chemical reaction that releases carbon dioxide, which can then be piped elsewhere for use or storage. The solvent then flows back into the hydrolysis unit to be regenerated.
Flair plans to begin a trial in the coming weeks that will capture about 10 tonnes of carbon per year, Feucht said, after which the startup is working on a larger, 260-tonne plant that should be operational in the second half of 2025. A plant being built in the Netherlands with Pebble will transport the carbon to help make cement additives, while another in Canada, being built with carbon removal project developer Deep Sky, will store the carbon.
DAC startups have already sold numerous carbon credits to organizations like Frontier, which has worked with Alphabet, Meta, Shopify, Stripe and others to create advanced market commitments for direct air capture.
To complete the larger project, Phlair raised a seed round of €12 million, as well as a €2.5 million grant from the EU’s EIC Accelerator. Exantia Capital led the investment round, with participation from Atlantic Labs, Counteract, Planet A, UnternehmerTUM Funding for Innovators, and Verve Ventures.
“I think this is a unique time in history. Ten years ago, you probably would have had to start an NGO to do what we're doing,” Feucht says. “Now, you can serve clients, build a functioning company, and [carbon] The thing is, for me, that's a huge motivator for me personally.”