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One of the most promising low-carbon cement startups, Sublime Systems, has hit a major roadblock in its efforts to scale up production.
The startup said this week that it had laid off about two-thirds of its workforce, having already paused construction in December on its forthcoming commercial-scale facility in Holyoke, Massachusetts. The actions were in response to the Trump administration clawing back an $87 million award last year from the Department of Energy’s now mostly gutted Office of Clean Energy Demonstrations.
The grant, which was meant to help Sublime build the Holyoke manufacturing plant, was swept up in the administration’s broader rollback of billions of dollars in previously awarded funding for projects that curb carbon emissions from industrial facilities.
Ever since then, ​“the company has faced compounding challenges in assembling the capital stack required to scale our operations,” a Sublime spokesperson said on Thursday in an email to Canary Media. Sublime said its project had been expected to create hundreds of direct and indirect jobs in the region.
Sublime, an MIT spinout, has raised over $200 million in total funding, including the federal grant. The six-year-old company is part of a bigger global push to develop novel ways of making cement, without producing planet-warming pollution in the process.
Traditional cement — which is 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 as hot as molten lava.
Sublime’s approach is very different. It involves electrically charging a bath of chemicals and calcium silicate rocks. In March 2024, the Biden administration awarded Sublime and other producers a collective $1.5 billion to slash the carbon impact of cement, as part of a larger $6 billion investment in industrial decarbonization projects.
Before this week’s layoffs, Sublime employed as many as 90 people, and it was making progress around proving its technology and securing key customers, including Microsoft.
Last summer, Sublime completed a ​“pilot pour” of its low-carbon cement at a data center campus in northern Virginia owned by Stack Infrastructure. And in May, Microsoft 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.
This week’s setback casts doubt on Sublime’s ability to supply Microsoft with that cement, as Bloomberg first reported. The tech giant declined to comment directly on how Sublime’s layoffs might affect Microsoft’s own goals to reduce carbon emissions from infrastructure projects.
However, Microsoft ​“remains committed to advancing low‑carbon building materials and continues to work with Sublime and a range of partners to support our long‑term sustainability goals,” a spokesperson said by email.
Microsoft has also invested in the clean-cement startup Fortera to support construction of that firm’s 400,000-ton-per-year facility. And it’s partnering with RMI and the Center for Green Market Activation to develop a system enabling companies to purchase ​“environmental attribute certificates” that represent the emissions reductions provided by cleaner cement and concrete — without actually buying the physical product.
Sublime said it continues to see ​“strong customer demand and industry backing” and is sticking to its goal of building the first electrochemical cement plants in the United States and Europe by 2030. The startup added that it remains in talks with the Department of Energy to try to restore its award and resume construction on its Holyoke facility.
“Sublime remains strong and well-positioned to continue to attract capital, commercialize its technology and meet market demand,” the company said.
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