“To take a supplemental cement up to 40 percent — and in time, potentially up to 50 percent — on a steady, reliable basis, nobody’s done that before. We think we’re there,” he said. Terra CO2’s first large-scale plant will be something of a test on that front. Today, the company runs different samples of silicates through its pilot plant and subjects the output to examination via X-ray diffraction and test mixes of concrete in its lab to ensure the SCM product can meet ASTM specifications, he said.
“If that goes well, we’ll take a full truckload to our pilot plant and make a full batch,” he said. “Usually it’s our potential customers who want to check it in their labs, pour concrete with it.”
Terra CO2 has raised about $61 million in venture capital to date, with investors including U.K.-based mining firm Rio Tinto, the venture arm of U.S.-based homebuilder Lennar Corp. and Bill Gates–founded Breakthrough Energy Ventures. BEV is a big backer of low-carbon cement, with investments in Brimstone Energy, CarbonCure, Ecocem and Solidia as well as Terra CO2.
Other approaches that promise a completely zero-carbon replacement for Portland cement are in a more experimental phase and would require retooling the cement industry to bring to scale. Some examples include startups such as Sublime Systems and Chement, which are developing electrochemical processes to replace the high-heat methods used to make cement. More esoteric concepts include using living organisms to “grow” cement.
“A lot of the other emerging technologies, they’re scientists trying to work out of labs and eventually commercialize,” Yearsley said. He sees future promise in that kind of work, but with their outsized emissions, the concrete and cement industries also need technologies that can provide guaranteed emissions reductions — right now.