Carbon capture is here—it just isn’t evenly distributed

Global emissions have continued to burn through the carbon budget, meaning each year brings us closer to having put enough CO2 in the atmosphere that we'll be committed to over 2°C of warming. That makes developing carbon-capture technology essential, both to bring atmospheric levels down after we overshoot and to offset emissions from any industries we struggle to decarbonize.

But so far, little progress has been made toward carbon capture beyond a limited number of demonstration projects. That situation is beginning to change, though, as some commercial ventures start to either find uses for the carbon dioxide or offer removal as a service for companies with internal emissions goals. And the Biden administration recently announced its intention to fund several large capture facilities.

But I recently visited a very different carbon-capture facility, one that's small enough to occupy the equivalent of a handful of parking spaces in the basement of a New York City apartment tower. Thanks to a local law, it's likely to be the first of many. CarbonQuest, the company that installed it, already has commitments from several more buildings, and New York City's law is structured so that the inducement to install similar systems will grow over time.

Carbon city

Because of its vast number of large buildings, New York City has a dizzying variety of fossil fuel-burning hardware tucked away in basements or hidden behind facades. All of the major buildings need significant hardware to provide heat and hot water, and many use co-gen facilities that generate on-site electricity and use the waste heat for these purposes. These co-gen plants can be quite large if they service one of the city's college campuses or major hospitals. There are also steam systems that boil water at a central facility and distribute it through pipes to many buildings.

So while dense urban housing has lower per-capita emissions, individual sources in New York remain considerable and difficult to decarbonize quickly. While the long-term goal would be to switch everything to electric so emissions will go down with grid improvements, it will take many decades for some of this equipment to reach its end of life. And those are decades that New York City's climate goals will not allow.

As a result, the city passed Local Law 97, which sets emissions-based fines starting next year and ramping up over time. The fines are agnostic about how emissions were reduced, however, allowing for the continued use of recent hardware as long as enough of its carbon is kept from reaching the atmosphere. CarbonQuest's business is based on performing that service.

"While we're waiting on this journey for 100 percent renewables, the conversion of electrification, we can take buildings and make a significant impact in their carbon footprint right away," Shane Johnson, the company's CEO, told Ars.

The CarbonQuest's system is designed to work with any hardware that burns natural gas, which can include boilers and combined heat and power systems. It diverts exhaust gases from these systems to a cooler and dehumidifier that pulls out the water. The remaining gas is then pressurized and exposed to a solid material that selectively retains the CO2. Once the remaining gases (mostly nitrogen and oxygen) are removed, the carbon dioxide comes back out. It's then re-pressurized and stored as a liquid until a truck removes it.

The process is powered by electricity and doesn't require any consumable materials. "These are smaller plants; they need to operate lights out 24/7, low maintenance, can't have toxic chemicals," Johnson said. "You know, they can't have a guy in a white suit."

The system is modular, allowing it to be constructed from a series of pallets that can fit in a typical freight elevator. This also allows the system to be scaled up to handle higher-volume facilities.

Putting it to use

Brian Asparro, the company's chief operating officer who gave Ars a tour of a company installation at 1930 Broadway, said that the output pumped into the truck is "beverage grade," meaning it's pure enough to be used for human consumption. CarbonQuest wants to avoid the carbon being used in beverages, though, where it would end up in the atmosphere after a short delay. Instead, it's looking to have the carbon dioxide taken out of circulation for the long term.

And right now, that means use in concrete. CarbonQuest has been partnering with a company that uses carbon dioxide as part of its concrete-making process, with the gas being chemically incorporated into the final product. "Want to avoid re-emissions," Asparro said. Capturing carbon from most of New York City's buildings would ultimately outstrip the demand for its use in concrete, but he said that's unlikely to happen for a while, and there's an opportunity to develop new uses in the meantime.

Paying customers, however, are just part of what makes the economics work. The system monitors how much carbon is removed, allowing owners to participate in fledgling carbon markets. Large enough systems would benefit from federal tax credits—and potentially state or local ones. Finally, many organizations are placing a price on carbon emissions internally, which could contribute to the bottom line. Fines like the ones New York City will be imposing on emissions can also play a role.

"New York City is a thought leader and leading the process in how they've implemented their goals and then implemented policy, but there's a whole suite of cities that are following suit," Johnson said. "And not just cities. In some cases, entire countries."

Scaling up the small scale

For this system to be a net positive for the climate in the longer term, however, we'll need to find permanent uses beyond concrete. "I think the total capacity for concrete is meaningful compared to the current scale of this kind of CCS or direct air capture but relatively small in the sort of global climate scheme of things," said Anu Khan, the deputy director of science and innovation at Carbon180, a nonprofit that promotes government policies to pull carbon out of the atmosphere.

Implicit in Carbon180's advocacy is the idea that we're unlikely to develop uses for all the carbon we've put in the atmosphere quickly enough to reach our climate goals. As such, we'll need to find ways of storing it in geological repositories to keep it out of the atmosphere. And that will have to include paying for operating those repositories. "We're looking at opportunities for geologic storage of CO2, where really, the removal is the benefit—that's what you're paying for," Khan said.

While the general assumption has been that large-scale carbon capture facilities would supply the CO2 used in these repositories, Khan said we don't know enough about how to do this efficiently to say. "We don't necessarily know what the answer is," Khan said. "It might be that technologically, you need the big facilities for this to scale. But it might be that there are ways to do this that are more distributed and that can generate different benefits for communities that are very much worth exploring in these early days."

Khan was excited by a comparison of the CarbonQuest system, where a truck simply picks up the carbon dioxide for disposal, to how we handle municipal waste using garbage trucks. Whether residential fossil fuel use remains a problem long enough to compel the development of such a system, however, is also a big unknown.

But overall, Khan was hopeful about two aspects of CarbonQuest's installation. The first is that small installations and a large potential market for individual installations should give the company a chance to make improvements to its system—the company has already updated the design of its first system and has plans for outdoor installations as well. "Rapid iteration is very much the name of the game right now," Khan said. "The big question that everybody's talking about in this space is 'how quickly can we move down the learning curve?' And rapid iteration—learning by doing—is one of the primary mechanisms for this."

Finally, Khan argued that the company deserves credit simply for doing something concrete. "Just making these technologies real to people, like having a physical example that you can go see—it's hard to imagine a gigaton-scale carbon-removal industry where nobody has ever seen it or interacted with it or doesn't know what it looks like," she told Ars. "So that alone, I think, is huge."