The Solidia Technologies concrete manufacturing plant in Piscataway, New Jersey doesn’t look like it houses the cutting edge of climate change solutions. It’s a drab, low-slung warehouse in a charmless industrial park a few miles from the Rutgers University campus. There are no solar panels or wind turbines in sight. Inside, a series of car-size machines mix cement—the powdery substance that, when blended with water, binds sand and stone into concrete—and press it into bricks. At first glance, it all seems a bit dull.
But then a bit of magic happens.
The bricks are transferred to a chamber that resembles an enormous pizza oven, built into a shipping container. Normally, at this stage of the concrete production process (known as “curing”), the bricks would be soaked in steam, catalyzing the chemical reaction that transforms them from sticky globs into durable building materials. But Solidia’s signature innovation is a cement formula that reacts not to water, but to the world’s most pernicious greenhouse gas.
Over the next 24 hours, the chamber is pumped full of carbon dioxide. The bricks gradually harden and gain weight as the gaseous CO2 soaks in and reacts with calcium in the cement to form solid calcium carbonate. Each ton of cement cured within concrete sequesters about one-quarter of a ton of CO2. One ton of concrete pavers contains about 3.5 percent CO2.
Concrete is so ubiquitous and boring that it’s often overlooked in conversations about climate change. But traditional cement production generates a massive quantity of greenhouse gas emissions, both from the fossil fuels burned to power the superhot kilns that combine limestone, shale, and other raw materials into cement, as well as directly from the heated limestone itself. These emissions account for up to eight percent of the planet’s total carbon footprint. If cement were a country, it would produce a greater share of the world’s carbon dioxide emissions than India.
Solidia’s technology aims to not only slash that footprint, but potentially flip it negative—that is, to sequester more CO2 from the atmosphere inside the bricks than is released in the production process. It’s not quite there yet. The company’s signature cement is greener than your average slab, but not carbon neutral, and for the most part, the CO2 it uses comes from sources like the beverage industry—the same gas that makes your Coke bubbly—rather than captured from a power plant smokestack or pulled directly from the air.
But that scenario is not far off, as a growing number of scientists, entrepreneurs, and cleantech market analysts believe. If it worked—and was deployed on a global scale—every new sidewalk and skyscraper could effectively capture some of the greenhouse gas emissions pumped out by vehicles and power plants. The same CO2 molecules responsible for global warming could be repurposed as the literal building blocks of a more sustainable society.
“The goal is to create a value to carbon dioxide, in an application that uses a lot of volume,” says Solidia CEO Tom Schuler, an energetic concrete evangelist with a self-professed addiction to Bikram Yoga. “Concrete in New Jersey is not sexy, but the impact is dramatic.”
Solidia is among a wave of dozens of startup companies looking for new ways to use carbon dioxide as an industrial raw material, an emerging industry known to insiders as “carbontech.”
This industry includes several companies focused on different approaches to concrete, including companies like CarbonCure, Blue Planet, and Carbicrete. The proliferation of such companies is unsurprising: Each slab of concrete has the potential to consume a lot of CO2 and concrete is used in massive quantities around the world, giving the industry promise as a major carbon sink.
But concrete isn’t the only thing carbontech companies are looking to revolutionize: There’s also liquid fuel, ink, plastics, carpet tile, batteries, and even high-end sneakers. The Global CO2 Initiative, a research lab at the University of Michigan, identified more than 25 commercial materials that could be made from CO2; an ongoing research and development competition for CO2-based technologies called the Carbon X Prize features contestants from labs in the U.S., the U.K., China, India, and Canada.
What all these companies have in common is an interest in tackling an oft-neglected front in the global war on climate change: What do we do about all the carbon dioxide that’s already in the atmosphere?
Even if every car, airplane, power plant, and other man-made source of carbon dioxide around the world were sealed off today, climate change would continue to be a major threat, because CO2 lingers in the atmosphere for hundreds of years. A more likely scenario, according to a June report from Bloomberg New Energy Finance, is that global CO2 emissions will peak in the mid-2020s and then very gradually decline through the end of the century. But in order to limit global warming to no more than two degrees Celsius above pre-industrial temperatures—the threshold prescribed by the 2015 Paris Agreement—emissions need to decline much more quickly.
Most of the economic models used by the Intergovernmental Panel on Climate Change and other top-tier research outfits agree that avoiding that threshold isn’t possible only through the use of solar power, electric vehicles, energy efficiency, and other measures and technologies aimed at reducing emissions. In other words, we need to go negative. By 2050, the world needs to be actively removing eight gigatons of CO2 from the atmosphere every year, according to the UNEP Emissions Gap Report—more than the U.S. currently emits
Some approaches to negative emissions rely on natural resource management, such as planting carbon-hungry trees and using farming techniques that absorb CO2 into the soil. A few companies are building machines that suck CO2 directly from the air, but these are expensive to operate—between $100 and $600 per ton of CO2, depending on the technology, according to a June report in the journal Nature. Systems that capture CO2 on its way out of power plant smokestacks have faced similar financial hurdles: A project to equip a large coal plant in Mississippi with this technology—America’s biggest-ever foray into so-called “clean coal”—was scrapped in 2017, years behind schedule and billions of dollars over budget.
Part of the problem is that after you capture CO2, there’s not much you can do with it. Today, CO2 captured from the ambient air or on its way out of smokestacks is mostly buried underground or, ironically, used in a process called enhanced oil recovery that helps coax oil out of wells—not a particularly sustainable means of disposal. Additionally, the gas is cumbersome and expensive to transport in large volumes, so any potential use of it needs to remain close to its source.
That’s where these companies are looking for business opportunities: If there were a bigger market for products made from recycled CO2, it would make both smokestack and direct air capture technologies more economically viable, paving the way for significant negative emissions.
“If you’re going to pay to capture and transport carbon, it would be wonderful to convert it into something you can sell at the end of the day,” says Kimberly Henderson, a cleantech analyst with the market research giant McKinsey. “‘Carbon capture and utilization’ is the new kid on the block. Clearly you need this if you’re ever going to get to negative emissions.”
In January, Henderson co-authored a report in which she found that the market for “CCU”—aka carbontech—businesses could offset up to one billion metric tons of CO2 per year by 2030. That’s just a small bite of the nearly 40 billion metric tons analysts expect the world to produce annually by that time, but it’s a potentially lucrative one: A separate analysis by Carbon180, an Oakland, CA-based research and advocacy nonprofit, found that the combined market value for all the possible industrial uses of CO2 is up to $1 trillion per year.
For Vahit Atakan, that was a bite worth taking.
Atakan is Solidia’s chief scientist, the brains behind the cement. He came to New Jersey from his native Turkey in the early 2000s to pursue doctoral research in Materials Science and Engineering at Rutgers, having earned degrees from Middle East Technical University in Ankara, Turkey’s version of MIT. Atakan is as reserved and pensive as his business partner Schuler is ebullient, but he’s equally motivated by the allure of carbontech as not just an intellectual exercise, but a promising business model.
“I was never that interested in academia,” he shouts over the din of Solidia’s production floor, from behind plastic goggles and a green hard hat. “From a young age, I always wanted to work in industry.”
Atakan started thinking about CO2 after hearing that fossil fuel companies were interested in finding ways it could be put to use after being captured. Having worked with cement before, he thought it seemed like a promising avenue. So he started to experiment with different chemical combinations to upgrade the traditional Portland cement used almost exclusively by concrete producers around the world and whose formula has remained largely unchanged from the one first patented in Leeds in 1824.
Over the next few years, Atakan, his colleague Rik Riman, and others at Rutgers tried more than 100 compounds that could cure using CO2 instead of steam. They finally settled on one that seemed the most promising for the production of a concrete that would cure quickly and be strong enough to market as an alternative to the change-averse concrete industry. It was CaSiO3, also known as wollastonite: a naturally occurring mineral sometimes used in fire retardants, electrical insulation, ceramic glaze, and a few other niche industries. After a successful trial run in the lab, Atakan began carrying a quarter-size piece of wollastonite-based concrete in his pocket to show off at parties.
“No one could break it,” he says.
But there was a problem: Global wollastonite production from mines in New York, Mexico, China, and elsewhere is only 700,000 tons per year. Global cement production is around 4.2 billion tons—and growing rapidly to feed demand in China, sub-Saharan Africa, and elsewhere. Even if every ounce of wollastonite was channeled into cement production, it could only offset around one-fifth of one percent of the market, which would not be enough to make a difference on climate change.
So—as has often been the case at key turning points in the history of science—Atakan and his friends repaired to a colleague’s apartment for a beer. There, on paper napkins, they hashed out the steps needed to produce synthetic wollastonite in their lab. When they figured it out, Atakan says, “I knew it was a game-changer.”
From there, it took several more years of experimentation, research and development, and fundraising to move the special cement out of a Rutgers lab and into a fully functioning factory. Today—just a few miles from where Atakan made his first quarter-size cement chunk—the Solidia factory is equipped to produce a 100-foot, 15-ton reinforced concrete slab. Their business model is to sell both the cement and the curing equipment to large-scale concrete producers around the country and the world. Schuler convinces these producers to send him a few bags of their “aggregates” (each company’s special cocktail of sand, gravel, and other minerals), which his staff mix with Solidia cement, shape into bricks, cure in a Solidia chamber, then send back to the producers as proof that the stuff really works. Hopefully, it works even better than the cement they had been using.
“We’re focused on making a better product,” Schuler says. “Sustainability is the icing on the cake.
Carbontech is not without controversy. Sustainability may also be a secondary concern for the major fossil fuel companies most eager to see the industry take off. Solidia received seed funding from the Oil and Gas Climate Initiative, a group that includes Shell, BP, Total, and other multinational oil majors. The Carbon X Prize is sponsored primarily by NRG, a Texas-based, natural gas- and coal-reliant electric utility, and COSIA, a research collaboration of the major players in Canada’s heavily polluting tar sands industry. In other words, these are the companies with the greatest need to offload a lot of carbon dioxide as pressure from governments and investors mounts to cut emissions.
“It’s political protection for the oil industry,” says David Keith, a Harvard professor and founder of Carbon Engineering, one of only a few companies in the world focused on the commercialization of Direct Air Capture of CO2 from the atmosphere. In June, Keith published a paper in the peer-reviewed journal Joule that proves CO2 can now be captured from the atmosphere using the company’s Direct Air Capture (DAC) technology for less than $100 per ton.
Keith says companies like Solidia have a long way to go before they become carbon-negative, since it still requires a lot of (usually fossil fuel-powered) energy to convert CO2 into concrete, plastic, or other materials. At the same time, a robust carbontech industry may simply prolong the global transition away from fossil fuels, which, even in the most optimistic outlook for negative emissions technologies, is still the top priority to stay below two degrees Celsius of warming.
“Some people perceive these technologies to be an excuse for the [fossil fuel] industry to not act as quickly as they need to,” McKinsey’s Henderson explains.
The nascent carbontech industry recently got a boost from another surprising source: Donald Trump. In February of last year, after last-minute bickering in Congress forced a five-hour government shutdown, President Trump signed a budget bill that included a substantial new tax credit, known as 45Q, for the carbon-capture industry. 45Q had been inching through Congress since 2014, when it was introduced by Sen. Heidi Heitkamp, a Democrat from North Dakota, the nation’s second-most oil producing state. It allows companies that utilize captured CO2 to reduce their tax bill by $35 per ton. A large coal-fired power plant that was able to capture and use 90 percent of its emissions could generate nearly $3 billion in savings over its lifetime, according to Carbon180, which has lobbied in favor of the credit.
The credit has limitations on size: Small companies like Solidia may not be able to qualify (the company is viable without a tax credit anyway, Schuler says). But it should make future carbon capture projects like the failed one in Mississippi more feasible. That will create a new source of CO2 emissions for the carbontech industry to piggyback on, which could drive demand for negative-emissions technologies and kick off a self-perpetuating cycle that will allow the industry to grow to where it could have a real impact on climate change, says Matt Lucas, Carbon180’s associate director for carbontech.
“If there’s a lesson from cleantech 1.0, it’s that going really big before you’re ready is really bad for your finances,” Lucas says, referring to the rocky early days of solar and wind power. “The more supply we have online, the more projects, the more the costs come down. That makes it cheaper for the next guy.”
In the meantime, expect to see more CO2 popping up in your life—maybe even on your feet. Marcel Botha is the CEO of 10XBeta, the Brooklyn-based design firm behind Footprintless, a slick, white sneaker made from recycled CO2-based custom polymers produced to promote the Carbon X Prize. The company chose to develop a shoe, he says, because shoes are trendy and an accessible entry point for the general public to ponder fashion’s carbon footprint, carbontech, and how recycled materials can play a more central role in our daily lives.
But for now, you can forget about owning a pair: Only six were made, each at a cost of more than $36,000. Botha keeps one pair in his office—size 11—but he says that “they’re too expensive to wear.”
Overall, the shoe industry’s ability to take up consumer recycled CO2 is much more limited than concrete or other industrial products, Botha admits. But the fight against climate change needs every resource it can get.
“I think that science and engineering need to respond on all channels, in all industries, in all ways that we can potentially capture and reverse greenhouse gases,” he says. “I don’t think there’s a silver bullet, given the scale of the problem. But in a sophisticated future world, it’s going to become commonplace.”