Some of the biggest names in tech have inked a deal to turn corn stalks and tree trimmings into a barbecue sauce ingredient and then pump the stuff underground to try to fight climate change.

That sounds wild, so let’s break it down from the start. Alphabet, Meta, Stripe, Shopify, and McKinsey Sustainability launched a new climate initiative called Frontier about a year ago. The goal is to boost new technologies capable of sucking carbon dioxide out of the atmosphere by convincing other companies to buy into them.

Today, a San Francisco-based climate tech startup called Charm Industrial announced that Frontier’s founding members and a smattering of other companies have agreed to pay Charm a total of $53 million to capture and store 112,000 tons of carbon dioxide between 2024 and 2030.

Charm has an unconventional way of getting that done. First, it collects agricultural and forestry waste — i.e., discarded corn stalks or branches leftover from logging. Wherever it finds that stuff, it sends its fleet of flatbed semi trucks hauling reactors that heat up the waste to 500 degrees Celsius without burning it. That turns the waste into bio-oil, a tarry-looking carbon-rich liquid.

The watery part of the bio-oil is essentially the same thing as liquid smoke, an ingredient used to give barbecue sauce and other foods a smokey flavor, according to Charm CEO and co-founder Peter Reinhardt.

Bio-oil also holds the carbon dioxide that the plants or trees its made from absorbed for photosynthesis. Had those corn stalks or tree branches been disposed of by burning or simply left to rot, that CO2 would have escaped again — heating the planet along with all the other emissions that come from burning fossil fuels.

Trapped in the bio-oil, Charm Industrial thinks it can store the CO2 underground for thousands to millions of years to keep it from making climate change worse. That’s how the startup can now sell carbon removal credits, representing tons of captured CO2, to companies that want to use its service to try to cancel out some of its own carbon dioxide pollution.

So far, Charm has successfully stored more than 6,100 metric tons of CO2 in the form of bio-oil. (A previous purchase from Microsoft, at 2,000 metric tons of CO2, is a big chunk of that.) So the deal announced today is a major escalation and a vote of confidence from Big Tech companies that have been early backers of the nascent carbon removal industry.

The advantage Charm says it has is that its plan is decentralized. Other companies are building big plants to suck carbon dioxide out of the air or sea. They need land (or offshore real estate) for their facilities, to start. And then they face lengthy permitting processes for pipelines transporting CO2 to specialized storage wells.

Charm just has its fleet of vehicles hauling equipment and bio-oil. It plans to inject the bio-oil into more common wells used for industrial waste or old salt caverns left behind by oil and gas exploration.

Even so, the startup will face its own challenges to scale up. The reactors it uses to heat up the waste products in the absence of oxygen, called pyrolyzers, are certainly not easy to come by — the company plans to make many of them itself. It also has to ensure that none of its wells leak bio-oil before the substance eventually hardens into rock, although Reinhardt says bio-oil is not as buoyant as oil, gas, or pure CO2 and less likely to make its way back up to the surface.

Crucially, Charm has to check its math to make sure its process is actually leading to negative emissions. That means cutting down its own emissions from firing up reactors and driving trucks. And its process is really only effective as a climate strategy if the wood and plant material the company gathers was just going to burn or rot without Charm stepping in to do something with it. If farmers were going to use the crop waste as extra feed for cattle, for instance, they might now have to buy feed that could wind up being a more carbon-intensive option.

This all has to make business sense, too, of course — and carbon removal is still prohibitively expensive across the industry. The $53 million deal today breaks down to roughly $473 per ton of CO2. That’s already including a bulk discount; prospective customers can find quotes on Charm’s website that are closer to $600 per ton (comparable to what it costs to suck CO2 straight out of the air).

At these prices, companies aren’t likely to make a big dent in their climate pollution. For perspective, one of Charm’s prospective clients might pay $6,000 a month to capture 10 metric tons of CO2 — equivalent to offsetting just three flights from New York to London. And even though Charm is scaling up to capture 112,000 metric tons of CO2 for a group of companies with this deal — it’s still a drop in the bucket compared to the carbon footprint of just one of those new customers, Meta. Meta’s carbon footprint was a whopping 5.7 million metric tons in 2021.

With that kind of carbon accounting, some environmental advocates are wary of companies turning to carbon removal instead of clean energy. Trapping a little bit of CO2 is no replacement for reducing how much pollution they create from burning fossil fuels in the first place. And Reinhardt agrees.

“Well, I think it’s a false choice, but if you’re going to pick which one you’re going to focus on first, you should absolutely focus on reductions,” he says.