Earlier this week, two low-carbon cement startups unveiled new partnerships with data-center developers and operators, which are looking at ways to curb the tech sector’s ballooning climate impact.
The separate announcements from Sublime Systems and Brimstone are a striking example of how businesses are pressing ahead with efforts to decarbonize essential polluting industries like cement making — even as the Trump administration guts federal programs meant to kick-start U.S. manufacturing of cleaner construction materials.
Both companies are developing novel ways of producing cement that don’t cook the planet in the process. Cement — the gluey powder mixed with sand, gravel, and water to form concrete — is responsible for roughly 8% of global carbon dioxide emissions. Nearly all cement is made today by heating carbon-rich limestone in fossil-fuel-burning kilns.
Sublime, an MIT spinout, said on Tuesday that it completed a “pilot pour” of its fossil-fuel-free cement at a data center campus in northern Virginia owned by Stack Infrastructure. Sublime’s approach involves electrically charging a bath of chemicals and calcium silicate rocks. In Virginia, the startup and its partners used the cement to make seven cubic yards of concrete mix, which was then spread over a high-traffic loading dock.
Demonstration projects like these are key to convincing the inherently cautious construction industry to embrace new approaches. “It gives us a proof point to then [do] larger-scale deployments in a few years,” Cory Waltrip, Sublime’s director of business development and strategy, told Canary Media.
Those future deployments could include facilities run by Microsoft. The tech giant recently signed a binding deal to purchase up to 622,500 metric tons of Sublime’s cement products — enough to build roughly 30 professional football stadiums — from the startup’s forthcoming manufacturing facilities. The agreement marks a massive step up for Sublime, which can currently make just 250 metric tons of cement per year at its pilot plant in Somerville, Massachusetts.
Brimstone, for its part, also announced on Tuesday that it signed a commercial agreement with Amazon. The deal allows Amazon, valued at $2 trillion, to reserve future supplies of Brimstone’s low-carbon cement, though the partners declined to provide more specific details.
Oakland, California–based Brimstone sources carbon-free rocks instead of limestone, then pulverizes those rocks and adds chemical agents to leach out valuable minerals. Certain compounds are heated in a rotary kiln to make industry-standard cement. What remains can be used as supplementary cementitious materials — which help bulk up cement mixes — or to make a key component of aluminum.
Cody Finke, Brimstone’s co-founder and CEO, said Amazon began testing Brimstone’s products about a year ago and found they worked just as well as the conventional materials used in Amazon’s buildings. Amazon will get its supply from Brimstone’s $378 million commercial demonstration plant, which is slated to be operating by the end of the decade, Finke said.
The announcements send an important signal that private-sector demand isn’t waning for cleaner construction products — despite the White House abandoning strategies and rescinding funding for using greener cement, steel, glass, and other materials in public buildings, roads, and bridges.