A couple of climate tech startups plan to suck a hell of a lot of carbon dioxide out of the air and trap it underground in Wyoming. The goal of the new endeavor, called Project Bison, is to build a new facility capable of drawing down 5 million metric tons of carbon dioxide annually by 2030. The CO2 can then be stored deep within the Earth, keeping it out of the atmosphere, where it would have continued to heat up the planet.

A Los Angeles-based company called CarbonCapture is building the facility, called a direct air capture (DAC) plant, that is expected to start operations as early as next year. It’ll start small and work up to 5 million metric tons a year. If all goes smoothly by 2030, the operation will be orders of magnitude larger than existing direct air capture projects.

“Project Bison would be the single largest project that has been announced to date, both domestically and internationally,” Peter Minor, director of science and innovation at the nonprofit Carbon180 that advocates for carbon removal, said in an email.

Right now, there are just 18 DAC plants across the world. Combined, they can only capture around 0.01 million metric tons of CO2 annually. The biggest DAC and carbon storage facility yet, called Orca, just came online in Iceland in September 2021. And even that facility is relatively small. It can draw down around 4,000 tons of carbon dioxide per year, about as much climate pollution as 790 gas-guzzling passenger vehicles create annually.

CarbonCapture’s equipment is modular, which is what the company says makes the technology easy to scale up. The plant itself will be made of modules that look like stacks of shipping containers with vents that air passes through. At first, the modules used for Project Bison will be made at CarbonCapture’s headquarters in Los Angeles. In the first phase of the project, expected to be completed next year, around 25 modules will be deployed in Wyoming. Those modules will collectively have the capacity to remove about 12,000 tons of CO2 a year from the air. The plan is to deploy more modules in Wyoming over time and potentially manufacture the modules there one day, too.

“It’s just this idea of being able to build something off-site, ship it easily on-site, and then assemble them kind of like a Lego system on the site itself,” says Adrian Corless, CEO and CTO of CarbonCapture.

Inside each of the 40-foot modules are about 16 “reactors” with “sorbent cartridges” that essentially act as filters that attract CO2. The filters capture about 75 percent of the CO2 from the air that passes over them. Within about 30 to 40 minutes, the filters have absorbed all the CO2 they can. Once the filters are fully saturated, the reactor goes offline so that the filters can be heated up to separate out the CO2. There are many reactors within one module, each running at its own pace so that they’re constantly collecting CO2. Together, they generate concentrated streams of CO2 that can then be compressed and sent straight to underground wells for storage.

The process comes with costs. DAC is still very expensive — it can cost upwards of $600 to capture a ton of carbon dioxide. That figure is expected to come down with time as the technology advances. But for now, it takes a lot of energy to run DAC plants, which contributes to the big price tag. The filters need to reach around 85 degrees Celsius (185 degrees Fahrenheit) for a few minutes, and getting to those kinds of high temperature for DAC plants can get pretty energy-intensive. Eventually, Corless says, Bison plans to get enough power from new wind and solar installations. When the project is running at its full capacity in 2030, it’s expected to use the equivalent of about 2GW of solar energy per year. For comparison, about 3 million photovoltaic panels together generate a gigawatt of solar energy, according to the Department of Energy.

But initially, the energy used by Project Bison might have to come from natural gas, according to Corless. So Bison would first need to capture enough CO2 to cancel out the amount of emissions it generates by burning through that gas before it can go on to reduce the amount of CO2 in the atmosphere.

CarbonCapture is partnering with Dallas-based company Frontier Carbon Solutions to take care of the carbon storage side of things. If Project Bison comes to fruition, it would be the first direct air capture project in the US to use “Class VI wells” designed specifically for permanent CO2 storage.

The geology in Wyoming allows Project Bison to store the captured CO2 on-site near the modules. Project Bison plans to permanently store the CO2 it captures underground. Specifically, project leaders are looking at stowing it 12,000 feet underground in “saline aquifers” — areas of rock that are saturated with salt water. “It’s protected from ever coming back up through the cap rock and the geology that sits above this,” Corless says.

For now, Project Bison developers are keeping mum on where in Wyoming the project will be located. “There’s a danger that publicly talking about that could impact the actual certification process,” Corless says, referring to certifications the project would need to inject the CO2 into Class VI wells.

Both the Biden administration and Wyoming lawmakers are encouraging the carbon removal industry to grow. The Bipartisan Infrastructure Law that passed last year includes $3.5 billion to build up four “regional hubs” for direct air capture. And the Inflation Reduction Act, which passed this year, greatly expands tax credits for carbon removal projects.

“It was hugely impactful,” Corless says of the Inflation Reduction Act. “It was an acceleration. It certainly had us really rethink the scale of the project, and how quickly we would scale this project.”

In 2021, Wyoming Governor Mark Gordon set a goal of making the state “carbon negative.” That means it would capture more CO2 emissions than it releases, a heavy lift since Wyoming is the biggest coal-producing state in the nation. Gordon argues that the state can continue to be a fossil fuel powerhouse while meeting its climate goal, which would make carbon capture and removal essential. Unsurprisingly, the potential for carbon removal technologies to extend the reign of fossil fuels has garnered criticism from grassroots environmental groups.

To prevent catastrophic effects from climate change, the world’s leading climate scientists have found we need to prevent global warming from rising above 1.5 degrees Celsius higher than preindustrial levels. We’ve already reached 1.2 degrees of warming, and that’s driving more massive storms, devastating wildfires, and deadly heatwaves.

Because human activity has already polluted the atmosphere with so much CO2, removing some of that carbon has become “unavoidable” if the world is to avoid breaching that 1.5 degree threshold, a landmark United Nations climate report says. But it also cautions that technologies like direct air capture will have a limited role to play. It can help to remove some carbon dioxide emissions or perhaps industrial pollution that’s really hard to curb; cement manufacturing, for example, also produces CO2. DAC, however, is no replacement for preventing greenhouse gas emissions in the first place. We’ll still need to switch from fossil fuels to cleaner energy sources.

Nevertheless, the fossil fuel industry is a major player in the carbon removal arena in the US. Texas is home to another project that’s been billed as the world’s first large-scale DAC plant, and petroleum company Occidental is one of the developers. The Texas plant is supposed to eventually have the capacity to remove 1 million tons of CO2 from the atmosphere a year. It could come online as early as 2024. Like Bison, it’ll start with a lower capacity for capturing CO2 and then scale up from there.

One big difference is that Occidental plans to pair the carbon removal project with its oil business in an audacious attempt to somehow sell oil as a sustainable product. For years, oil companies have used captured carbon in a process called “enhanced oil recovery” — shooting the CO2 into the ground to extract hard-to-reach reserves. Now, Occidental is attempting to brand oil produced in that process as more environmentally friendly “net-zero oil.”

When it comes to using captured CO2 to produce more oil, “That’s something that as a company we have no interest in aligning ourselves with. Our company is just about carbon removal,” says Corless, who was previously the CEO of the rival DAC tech company Carbon Engineering that’s partnering with Occidental on the Texas project.

Project Bison’s completion would ultimately be a major milestone for the carbon removal industry, and it has a chance to escape some of the ties to fossil fuels that its competitors hold. Even if all goes well, Bison isn’t expected to reach its full capacity until the end of the decade — when the US is supposed to have slashed its carbon dioxide emissions in half from peak levels under commitments it’s made as part of the Paris climate agreement. That target can only be reached if direct air capture projects like Bison complement, rather than derail, a transition to cleaner sources of energy.