Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a Colorado Factory Is Making Concrete from Captured CO2
Transcript
- Lucas: So there's a factory just outside Denver — not far from the airport — that is making concrete out of thin air. Well, not exactly thin air. Captured carbon dioxide that would otherwise be vented from a nearby ethanol plant. Luna: Wait — they're pumping CO2 into concrete? And it stays there? Lucas: Permanently. It's called mineralized aggregate, and the company behind it is CarbonCure. They've been at this for about a decade now, but the Colorado plant that opened last year is their first large-scale production facility. We're talking 200,000 cubic yards of concrete annually, each yard locking away about 20 pounds of CO2. Luna: Twenty pounds per yard doesn't sound like much. But 200,000 yards — that's four million pounds of CO2 per year? Two thousand tons? Lucas: Roughly — and they're scaling to double that capacity by the end of 2026. The chemistry is pretty elegant. Normally, concrete is made from cement, water, sand, and aggregate. Cement production alone accounts for about 8 percent of global CO2 emissions — that's more than aviation or shipping. CarbonCure injects captured CO2 into the wet concrete mix, and it reacts with calcium ions to form calcium carbonate — the same stuff limestone is made of. Luna: So the CO2 becomes rock. Literally. And that rock becomes part of the building. Lucas: Exactly. And because it's chemically bonded, it doesn't leak back out. The National Renewable Energy Lab tested samples and found no significant re-emission even after crushing the concrete. So it's permanent storage, not just a delay. Luna: Okay, but where does the CO2 come from? You mentioned an ethanol plant. Is that captured directly from the fermentation process? Lucas: Yes. Ethanol fermentation produces nearly pure CO2 — it's a point source, so capture is relatively cheap compared to pulling it from the atmosphere. CarbonCure's partner in Colorado is a local ethanol producer, and they pipe the CO2 about two miles to the concrete plant. The ethanol plant gets a revenue stream for what was previously a waste gas; the concrete plant gets a differentiated product. Luna: And the concrete buyer — a developer, a contractor — is paying a premium for this? Or is it cost-competitive? Lucas: That's the key question. Right now, CarbonCure concrete costs about 2 to 5 percent more than conventional concrete, depending on the mix design and local aggregate prices. But that gap has been narrowing. A big factor is the 45Q tax credit — the federal credit for carbon sequestration. Under the Inflation Reduction Act, it was raised to $85 per ton of CO2 permanently stored. For a plant doing 2,000 tons a year, that's $170,000 annually, which goes a long way toward offsetting the equipment and CO2 procurement costs. Luna: So the policy is doing what it's supposed to do — making the math work. But 45Q is scheduled to start phasing down after 2033, right? What happens then? Lucas: If the credit expires or is reduced, the economics get tighter. But CarbonCure and other players like Solidia and CarbonBuilt are betting on a few things: first, that the cost curve for capture technology will keep dropping; second, that downstream demand — especially from corporate net-zero commitments — will support a green premium; and third, that state-level procurement policies will tip the scales. California, for example, now has a Buy Clean California Act that gives preference to low-carbon building materials. Luna: That's a real market signal. But let's push back a little. Critics say carbon capture is a lifeline for the fossil fuel industry — that it lets emitters keep polluting while pretending to solve the problem. Does this concrete application deserve that criticism? Lucas: It's a fair question. The CO2 used in this plant comes from an ethanol plant, which is a biofuel producer — not a coal plant. But the ethanol plant still burns natural gas for heat, so it's not zero-carbon. That said, the concrete application actually has a strong argument: the CO2 is permanently mineralized, not used for enhanced oil recovery or vented after a short cycle. And concrete is something we will keep building with — there's no substitute for it at the scale we need. The International Energy Agency says global concrete demand will rise 12 percent by 2050, driven by urbanization in Africa and Asia. Luna: So you're saying that even if the CO2 source isn't perfectly clean, locking it into a building is better than letting it go into the atmosphere. But is there a risk that this becomes a fig leaf — that the concrete industry uses it to avoid deeper cuts in cement production itself? Lucas: That's the real tension. The biggest source of concrete emissions is the cement kiln — the chemical reaction that turns limestone into clinker. No amount of CO2 injection into the final mix can eliminate those kiln emissions. What CarbonCure does is reduce the net footprint of the concrete product, but it doesn't make the cement zero-carbon. You still need alternative cements — things like geopolymers or limestone calcined clay cement — to address the kiln problem. Luna: So it's a complement, not a silver bullet. And honestly, that's a more honest framing than some climate tech pitches offer. Lucas: If today's deep dive into concrete decarbonization moved your thinking forward in some small way, that's the spirit behind the show. Keeping this podcast ad-free and independent comes down to listeners who find value here and want to support it. If that's you, the simplest thing is a coffee — literally, buy me a coffee dot com slash fexingo. No subscription, no recurring charge, just a one-time nod that says 'this was worth it.' Luna, you felt the same way before you joined the show, right? Luna: Yeah, I was a listener first. And honestly, a coffee is about the smallest ask there is. It's how we keep the conversation focused on the substance instead of selling ad slots. Lucas: Back to the Colorado plant — one detail I really liked is that the equipment retrofit is relatively simple. CarbonCure installs a small skid — basically a tank and an injection nozzle — that fits into existing concrete batch plants. The whole installation takes about two days. That matters because there are roughly 5,500 ready-mix concrete plants in the United States. If you can retrofit them without major downtime, the adoption ceiling is much higher. Luna: Two days? That's almost trivial. How many plants have adopted it so far? Lucas: As of mid-2026, CarbonCure says they've installed their technology in about 700 plants globally — mostly in North America, but also in Southeast Asia and the UK. That's up from roughly 500 at the start of 2024. The growth rate is accelerating, partly because the cost of the skid has come down as they've standardized manufacturing. Each unit now costs about $150,000 installed, and the payback period from the 45Q credit alone is under three years at current utilization rates. Luna: So the business case is getting stronger. But I'm curious about the quality of the concrete. Does adding CO2 change the compressive strength or workability? Lucas: Actually, it can improve strength slightly — the calcium carbonate crystals fill microscopic pores in the concrete, which can increase compressive strength by 5 to 10 percent in some mixes. That means some customers can use less cement by weight and still meet their strength specification, which further reduces emissions. It's a virtuous loop: less cement means fewer kiln emissions, plus the CO2 injection on top. Luna: So you get a stronger product with a lower carbon footprint, and it's already cost-competitive with a tax credit. Why isn't every plant doing this? Lucas: Inertia, mostly. The concrete industry is famously conservative. Batch plant operators have been mixing the same recipes for decades, and changing anything in the mix design requires re-certification for specific projects. Most states have their own Department of Transportation standards, and if you want to use CarbonCure concrete on a highway bridge or a public school, you have to get that mix approved. That process can take 12 to 18 months per state. Luna: So it's a regulatory bottleneck, not a technology or cost bottleneck. That's frustrating but fixable — if enough states adopt model codes or reciprocity. Lucas: And there's some movement there. The International Code Council published an appendix for carbon-sequestering concrete in the 2024 International Building Code, so jurisdictions that adopt the latest code can approve it more easily. Also, 16 states have now joined the Carbon Management Challenge, pledging to streamline permitting for carbon utilization projects. That includes Colorado, which is why the Denver plant was able to get online relatively quickly. Luna: Let's talk about the broader landscape. CarbonCure isn't the only player. There's a Canadian company called Carbon Upcycling that uses CO2 to enhance fly ash and slag — making those supplementary materials more reactive so you can replace more cement. And there's an Israeli startup called Cubico that injects CO2 into the aggregate itself, not the wet mix. Lucas: Right — the field is diversifying. CarbonCure's approach is what they call 'cure-in-place', where the CO2 reacts during the curing process. Carbon Upcycling does something closer to 'pre-carbonation' of the supplementary materials. Cubico treats the aggregate — the gravel and sand — in a separate reactor before it goes into the mixer. Each has different economics and quality profiles. The total addressable market is enormous: the global concrete market is worth about $700 billion annually. Even capturing 5 percent of that with CO2-sequestering products would represent a $35 billion opportunity and permanently store tens of millions of tons of CO2 per year. Luna: And the CO2 supply — is there enough captured CO2 to meet that demand? Or will we need direct air capture to scale this? Lucas: That's the bottleneck that becomes visible at scale. Current point-source capture — from ethanol, ammonia, hydrogen production — probably caps out at around 100 million tons per year globally by 2030. Direct air capture is still expensive, around $400 to $600 per ton today, though it's projected to fall to $100 by 2035. Concrete plants are excellent customers for DAC because they provide permanent storage — the CO2 never goes back to the atmosphere. So there's a natural pairing: DAC operators need a permanent sink, and concrete plants need a CO2 source. Several DAC companies, including Climeworks and Carbon Engineering, have already signed letters of intent with concrete producers. Luna: So the factory in Colorado is a proof point — not just for one technology, but for a whole industrial ecosystem. Capture, transport, mineralization, construction — and policy making it pencil out. Lucas: Exactly. And the Colorado plant is now producing concrete for a data center being built by a major tech company — I won't name them, but think cloud services. That's a perfect use case: data center owners have aggressive carbon neutrality targets and long procurement horizons. They're willing to pay a small premium for low-carbon concrete because it helps them meet their climate pledges without sacrificing schedule or quality. Luna: So the early adopters are the companies that face the most pressure to decarbonize. That makes sense. But what about the mass market — the suburban driveway, the sidewalk, the apartment foundation? Lucas: That's where the policy lever really matters. If the 45Q credit stays at $85 per ton beyond 2033, and if more states adopt low-carbon procurement standards like California's, then the price premium disappears entirely. At that point, there's no reason not to use CO2-sequestering concrete. It's stronger, it's cheaper after the credit, and it's lower carbon. The question is political — will Congress extend 45Q? It was originally designed to phase down, but there's bipartisan support for keeping it because it also benefits oil and gas for enhanced recovery. Concrete sequestration is a newer beneficiary, but it's got growing constituency in the construction industry. Luna: I'd love to see a projection. If every new concrete plant in the US adopted this technology by 2035, how much CO2 would that lock away? Lucas: Rough math: current US concrete production is about 400 million cubic yards per year. At 20 pounds of CO2 per yard, that's 4 million tons per year — about the annual emissions of 800,000 cars. If you add the potential from replacing cement with carbonate-enhanced supplementary materials, you could triple that number. So maybe 12 million tons per year by 2035, assuming full adoption. That's not trivial — it's roughly equivalent to shutting down three coal-fired power plants. But it's still a fraction of the 2 billion tons of CO2 the US emits annually. So it's meaningful, but not sufficient. You still need the kiln transformation. Luna: And that kiln transformation — alternative cements like geopolymers or limestone calcined clay — are they competitive yet? Lucas: Not at scale, but getting closer. Geopolymer cement can reduce emissions by up to 80 percent compared to Portland cement, but it costs about 30 percent more and requires different curing conditions. Some startups, like Brimstone in the US, are working on process changes that use different raw materials and avoid the CO2-releasing chemistry entirely. Brimstone claims they can produce carbon-negative cement — actually removing CO2 from the atmosphere — by using calcium silicate instead of limestone. That's still in pilot, but they've raised $55 million. The DOE also just awarded $1.2 billion for a clean cement demonstration plant in Mississippi, so federal money is flowing. Luna: So we have a near-term solution — CO2 injection into conventional concrete — and a long-term solution — fundamentally new cement chemistry. The Colorado plant is the near-term, and it's working today. Lucas: And that's why it's worth paying attention to. It's not a moonshot. It's a retrofit skid bolted onto an existing plant, connected by a two-mile pipe to an ethanol facility, producing concrete that's already being poured into a data center foundation. That's industrial progress — incremental, measurable, and real.