Carbon-Negative Cement by Brimstone: Pioneering Sustainability in Construction

Brimstone, an Oakland-based company, recently announced that it received third-party certification approving that its carbon-negative cement is structurally and chemically the same as regular cement. The company claims it to be the first carbon-neutral or carbon-negative cement meeting the building requirement.

The cement industry is responsible for about a twelfth of global carbon dioxide (CO2) emissions, which makes it one of the major carbon-emitting industries of the world. Decarbonising the sector would play a critical role in reducing net global Greenhouse Gas (GHG) emissions. As per the International Energy Agency report, annual CO2 intensity declines of about 4 per cent through to 2030 are required for the sector to get on track with the Net Zero Emissions by 2050 (NZE) Scenario.

The 35-person start-up, Brimstone, uses carbon-free silicate rock instead of baking limestone. In the conventional process, Limestone is baked in a kiln at incredibly high temperatures, which produces calcium oxide and carbon dioxide. This way, not only do the fossil fuels used to heat to kiln give off carbon dioxide, the chemical reaction at the heart of cement manufacturing releases the climate-warming gas, too.

This is not the case with Brimstone’s way of cement manufacturing. Chemically extracting calcium oxide from silicate does not release carbon dioxide. The carbon-negative phenomenon can be seen here by the fact that magnesium, a byproduct of the process, can absorb CO2 from the atmosphere. The firm claims that its product meets the same standards as regular cement.

Brimstone’s product met one of the most commonly used standards in the business, known as ASTM C150.
The green cement is still away from full-fledged commercialization with the company planning to build a pilot plant near Reno, Nev., before constructing a commercial-scale factory.

Cody Finke, the CEO of Brimstone, pointed out that concrete remains a significant climate concern, receiving comparably less attention and funding when compared to emissions from automobiles or power plants.

He emphasized, “Concrete poses a substantial climate challenge that has garnered remarkably little attention from the research and development community.”

Brimstone so far raised about $60 million, including $500,000 from the federal government’s Advanced Research Projects Agency-Energy. The investors include Amazon’s Climate Pledge Fund and Bill Gates-founded Breakthrough Energy Ventures.