Cody Finke, cofounder and CEO of Brimstone, was a high schooler in Seattle when he saw An Inconvenient Truth. Staring at the glacial peak of Mount Rainier, he thought that, absent serious interventions, “That thing’s going to melt.”
The eye-opener inspired Finke to launch a school composting program and cemented his resolve to develop meaningful climate solutions. As a doctoral student at California Institute of Technology, he invented a solar-powered sewage treatment device that generated hydrogen and electricity. But he realized its “techno-economics” — the cost of implementation — would limit its global impact.
Ultimately, Finke discovered that decarbonizing cement — the main ingredient in concrete, one of the planet’s most consumed resources — could make a serious dent in fighting climate change. Conventional production, which accounts for nearly 8 percent of global carbon emissions, is notoriously dirty: 1,500-degree F kilns fire limestone, a carbon-heavy rock, by incinerating cheap fuels like coal and used tires. The resulting clinker is mixed with supplementary cementitious materials, or SCM — industry-speak for fly ash or flag, both byproducts of burning yet more coal or forging steel — to create cement.
Finke found that calcium silicate, a mineral found in basalt and other common rocks, contains both the clinker and SCM — yet none of the carbon. The firing process also leaves behind magnesium, which permanently sequesters CO2. Brimstone’s cement is chemically and physically identical to industry standards, he says, but carbon negative — and it will be cheaper once mass-produced, a winning techno-economic proposition.
The 4-year old company plans to build a pilot plant outside of Reno, Nevada, and Finke recently met Bill Gates, whose Breakthrough Energy Ventures is a major investor. As they bonded over wastewater and climate issues, Finke recalls Gates telling him with a laugh, “Either we’re both right or both really wrong, but we’re definitely in good company.”
