The concrete industry has a fly ash problem. Terra CO2 is trying to fill the gap.
Ready mixed concrete (RMC) suppliers often use supplementary cementitious materials (SCM) like fly ash to increase concrete performance and lower its carbon footprint. Coal-fired power plants produce fly ash as a byproduct, but climate concerns are both forcing coal plants to close and demanding even lower-carbon concrete. The result is a severely reduced regional supply of fly ash and, consequently, increased transportation distances and climbing market prices for the material.
Terra CO2, founded in 2016 and based in Golden, Colorado, is approaching the problem from a different direction—perhaps even upside down. According to CEO Pete Lyons, the Terra team started with abundant materials and then engineered a solution. A paradox can be considered a truth standing on its head, and this is just what spurred the materials manufacturer onward.
Fly ash is largely glassy material left over after most of the carbon is burned out of coal. Terra identified abundant materials like shale, clay, slate and other silicate-bearing rocks, then engineered a process to vitrify them into a reactive glass suitable for concrete. The result is intended to be a consistent SCM with a substantially smaller carbon footprint, competitive economics, and the potential to be manufactured wherever suitable raw materials and market demands exist.
Whoa, Nellie! Fly ash sans coal, potentially available anywhere, anytime and priced competitively? Let’s dig into the details.
The chemistry
The manufacture of clinker for ordinary portland cement (OPC) is a major carbon emitter, with 60 percent of its emissions resulting from calcining limestone and the rest coming from the fuel from the kiln. Given that concrete is essential to modern civilization, one of the best ways to reduce its carbon footprint while maintaining performance is to use SCMs that replace clinker. Fly ash has been a go-to solution because it comes with a sunk-cost carbon footprint.
Traditional fly ash also carries two complications. First, its availability depends upon coal combustion, which is an industry that is shrinking in the United States. Second, residual carbon, measured by “loss on ignition,” can interfere with air-entraining admixtures. Anyone producing concrete in a freezing climate understands the operational problem: inconsistent air can quickly become rejected concrete.
Our industry has one of the highest potential liability-to-profit ratios out there. Batching consistent concrete helps mitigate that liability. Terra’s commercial product, OPUS SCM, is an engineered material designed for consistency. When compared against ordinary portland cement, ton for ton, it is claimed to deliver around a 70-percent reduction in CO2 emissions and a 90-percent reduction in nitrogen oxide (NOx).
The race to be … second
Our industry carries huge liability, and as a result, we are understandably a bit gun-shy about new technology. We want someone else to take the initial risks, and only after it’s proven do we migrate. Lyons offers a clear-headed response to this impediment: “We are just making fly ash without the coal.”
The product pitch is straightforward: a one-for-one replacement for traditional fly ash, only better. Same concrete mix design, same equipment, same infrastructure. Same water demand and admixture interactions. There is no real change for the RMC producer.
According to Lyons, Terra operated a bench-scale production system for six years. It now has a 24/7 pilot production in Golden that has been running for more than four years, producing roughly 1 ton of product per day for emissions monitoring, testing and performance. The manufacturer is now building a scaled-up production plant capable of producing 240,000 tons per year, which will serve as a model for the future.
Think of Taco Bell. Anywhere there are kids who love tacos, a new “plant” goes up. Lyons’ vision is to site plants wherever there is demand, because the input materials are plentiful almost everywhere.
Follow the money
Type F fly ash pricing is variable, and supply is very limited in some regions, including South Florida, Colorado and the Northeast. Back-of-the-envelope math suggests it costs about $70-$80 per ton when delivered where it is highly available. If it must be shipped long distance, the price can climb to $130 per ton or more. On the other side of the envelope, OPC or portland limestone cement is around $150-$170 per ton.
Lyons says their SCM’s economics will be directly competitive with current Type F fly ash, but for a much more consistent and always available product. Investors have responded. Terra closed on $147.6 million total Series B financing in 2025. More revealing than the dollar amount is who participated. Eagle Materials, a major portland cement and gypsum producer, is a strategic investor, while Cemex has invested through Cemex Ventures. The U.S. Department of Energy has supported deployment of the technology.
The identity of those investors may matter more than the dollars. Cement companies investing in a technology designed to replace part of cement tells us something. Smart companies would rather participate in disruption than have disruption happen to them.
Binding it all together
If we dare to believe, Terra’s SCM is a one-for-one direct replacement for F-type fly ash, but with more consistency and availability. Combining the product with slag appears to put it in reach of the Holy Grail of 60-percent OPC replacement. And further, the company’s new product in early development, OPUS Zero, is intended as a 100-percent direct replacement for OPC.
This all sounds so good that it borders on too good to be true. Except that I know Pete Lyons, and he is not one prone to exaggerate.
