Brimstone to Produce the World’s First Carbon-Negative Portland Cement

Breakthrough Energy Ventures and DCVC co-lead a $55 Million Series A round to pilot a process to make carbon-negative Portland Cement at industrial scales.

New investors include Amazon through its Climate Pledge Fund and Fifth Wall Climate Tech

Brimstone makes ordinary Portland Cement, chemically and physically identical to conventionally manufactured cement, but without releasing CO₂. At scale, Brimstone’s breakthrough will produce cement at or below market prices, solving the problems of both emissions and scarcity of raw materials, and without increasing cost or risk for customers. At scale, Brimstone’s process will be able to supply organizations and governments that want to construct new buildings or replace aging infrastructure but want to use tried and true building materials at an affordable price while also sequestering carbon.

Ordinary Portland Cement—the binder in concrete—is the key structural material in buildings. Cement production is also responsible for around 7.5% of global CO₂ emissions or 5.5% of global greenhouse gas emissions, about the same as the CO₂ produced by all cars world-wide. Brimstone has developed a novel process for making Ordinary Portland Cement that eliminates these emissions.

Cody Finke, the co-founder and CEO of Brimstone, commented, "What sets Brimstone apart in the space is that we are building a new process to make Portland Cement carbon-negative, which will be both lower cost and produce the exact same material trusted by builders for 150 years.”

The founders created Brimstone on the belief that reducing CO₂ emissions quickly enough to mitigate the worst impacts of climate change requires making cement differently without changing the final product and without relying on versions of carbon sequestration that only add cost. Traditionally, cement has been made from heating limestone (CaCO₃) in a high temperature kiln such that it emits its embedded CO₂, thereby producing lime (CaO). Brimstone has developed a process that makes Ordinary Portland Cement but sources lime from calcium silicate rocks, which have no embedded CO₂, instead of limestone. This new process also produces magnesium species as a waste product, which passively absorb CO₂, making the Brimstone process net carbon-negative regardless of the fuel source used in the kiln.

“Cement is a miracle material that lets us build the infrastructure that is the foundation of our society and economy. It also happens to be a significant contributor to CO₂ emissions during production,” said Carmichael Roberts of Breakthrough Energy Ventures. “Not only has Brimstone figured out a way to eliminate the emissions in that process – their innovation creates an opportunity where our built environment could be a net sink for carbon. This means that the buildings and bridges that we build with carbon-negative Brimstone Portland Cement can be a part of the climate solution instead of the intractable liability they are today.”

“Brimstone has discovered how to produce carbon-negative ordinary Portland Cement—by far and away the most common kind of cement, used in concrete worldwide, but today is responsible for around 7.5% of greenhouse emissions,” said Rachel Slaybaugh, a Principal at DCVC. “We’re excited to continue to back the company as it scales this cost-effective Deep Tech breakthrough that can prevent gigatons of emissions annually.”

“Brimstone’s unique approach to reducing carbon emissions resulting from cement production will be an important step forward not only within the construction industry, but broadly in the fight against climate change,” stated Kara Hurst, Vice President of Worldwide Sustainability at Amazon. “We will continue to invest in innovative, forward-looking companies like Brimstone, whose work will help Amazon reach its Climate Pledge goal of reaching net-zero carbon by 2040.”

Brimstone will use this fundraise to build a pilot plant capable of making the first building-scale Ordinary Portland Cement ever made from a calcium silicate rock. Brimstone is actively hiring chemical engineers and people experienced in the cement industry who want to decarbonize it.

“Concrete is the most used material on the planet, and cement is one of the largest contributors to global CO₂ emissions,” said Greg Smithies, Fifth Wall partner and co-lead of the Climate Tech Investment team. “If the planet is to get to zero-carbon on any sort of meaningful timeline, we cannot get there unless we fix cement’s CO₂ problem. Brimstone is the only company in the world that can make cost-competitive zero-carbon cement. It’s truly a game-changer.“

In addition to building a pilot plant, Brimstone has initiated its partner program and is engaging cement companies, architects, structural engineering firms, and concrete companies and other organizations who want to joint venture on a plant or directly buy industrial quantities of cement. Through its First Builders initiative, this coalition of industry players and early adopters will get early access as Brimstone begins to scale. Contact [email protected] to participate.

Brimstone’s series A financing is co-led by existing investors Breakthrough Energy Ventures (BEV) and DCVC with participation from other existing investors, including Collaborative Fund and AccelR8. New investors include Amazon’s Climate Pledge Fund and Fifth Wall Climate Tech whose limited partners represent the global real estate industry. Other investors include Impact Science Ventures, S2G Ventures, Gatemore Capital Management, Osage University Partners, and SystemIQ.