When it comes to climate change, there’s no such thing as a “get out of jail free” card. But there might be an inexpensive alternative: direct air capture.

The technology isn’t exactly an exoneration, but more like community service; it promises to suck massive amounts of carbon dioxide out of the atmosphere, atoning for our century-plus of transgressive burning of fossil fuels. Scientifically, it’s a sound idea. Commercially, it has been less so.

Currently, it costs about $600 to $1,000 to capture a metric ton of carbon, which is far more than anyone thinks is commercially viable. So myriad startups are racing to cut costs, aiming to capture one metric ton of carbon dioxide for $100 or less. 

Even at that price, it could be a difficult sell since burning fossil fuels remains, for the most part, free. But many investors and even a few multinational corporations like Microsoft, Shopify, and Stripe are betting that eventually, the world will embrace direct air capture, much like how we treat wastewater today instead of dumping it into a river.

Larger startups like Climeworks and Carbon Engineering are betting that scale will help rein costs in. Both companies use sorbents to draw out the carbon dioxide and use heat to release it from the sorbents so it can be stored elsewhere.

Smaller startups suggest that scale alone won’t be enough, though. “Thermal regeneration is always the expensive step, energy wise,” said Malte Feucht, co-founder and CEO of Phlair, a young direct air capture startup. He may have a point. One study says that capturing a meaningful amount of carbon, around 10 gigatons per year, using Carbon Engineering’s approach would require nearly three-quarters of all the electricity generated in the world today.

Feucht’s company thinks that a different approach that doesn’t rely on heat might help bring costs down. Like most direct air capture companies, Phlair uses fans to blow air over an absorber. But instead of heating the sorbent, it uses an acid to liberate the carbon dioxide. To produce the acid and base used in the process, Phlair, formerly known as Carbon Atlantis, developed a device it calls a hydrolyzer.

The hydrolyzer borrows heavily from the hydrogen industry, taking elements from both membrane-based electrolyzers and membrane-based fuel cells, Feucht said. (An electrolyzer makes hydrogen using electricity, whereas a fuel cell consumes hydrogen to produce it.) 

“Instead of hydrogen, we only produce acids and bases,” he said.

Phlair’s DAC machine employs what’s known as the “pH swing” method to capture carbon dioxide. Inside, the basic (high pH) solvent absorbs carbon dioxide as it flows through the air contractor. After the saturated solvent exits the contractor, it is dumped into a tank where it’s doused with acid (low pH). That swing in pH from high to low spurs a chemical reaction that releases the carbon dioxide so it can be piped elsewhere to be used or stored. The solvent then flows back into the hydrolyzer where it’s regenerated.

Phlair is deploying a pilot in the next few weeks, Feucht said, that can capture around 10 metric tons of carbon per year. After that, the startup is working on larger, 260-metric-ton plants that are scheduled to come online in late 2025. One being built with Paebble in the Netherlands will deliver carbon to help make a cement additive, while the other in Canada will be built with Deep Sky, a carbon removal project developer, which will store the carbon. 

The DAC startup has already sold a number of carbon credits to organizations like Frontier, which works with Alphabet, Meta, Shopify, Stripe, and others to create an advanced market commitment for direct air capture.

To help complete the larger projects, Phlair has raised a €12 million seed round along with a €2.5 million grant from the EU’s EIC Accelerator. Exantia Capital led the investment round with Atlantic Labs, Counteract, Planet A, UnternehmerTUM Funding for Innovators, and Verve Ventures participating.

“I think this is a sort of a unique time in history. Ten years ago, you would have probably needed to found an NGO to do what we’re doing,” Feucht said. “Now, there’s a real opportunity to serve customers, to build a functioning company, but then also to address that [carbon] problem. For me, that’s my personal, super big motivation.”