MIT spinout cooks zero-emission cement that could slash 4 gigatons CO2 yearly

MIT spinout Sublime Systems researchers realized that the Romans had cracked the code centuries ago. Their cement was durable, and it didn’t require these extreme temperatures for production. So, the team considered how they could replicate the Romans’ success with modern technology.

“Romans couldn’t go to those obscene temperatures, but they’ve proven their cement is hard and durable, and we now have 2,000 years of innovation to get that cement to meet the criteria we expect out of modern cement,” said Leah Ellis, Sublime co-founder and CEO.

Sublime Systems developed a solution that works by harnessing the power of electrochemistry. They’ve created a process that replaces the energy-intensive kiln with a low-temperature, electricity-driven reaction.

Sublime’s electrochemical process

Cement manufacturing contributes roughly 7% of global human-caused CO₂ emissions.

Portland cement’s massive carbon footprint stems largely from limestone, which is composed of almost 50% carbon dioxide. The intense heat needed to convert limestone into lime liberates nearly all this carbon and contributes significantly to overall emissions.

Sublime’s electrochemical process makes cement without using high heat or limestone.

“Cement enabled civilization as we know it today, but now it needs to be reinvented. Cement creates about 4 gigatons of emissions a year, and by 2050 that’s projected to become 6 gigatons a year. I think of what we’re doing as technically a very feasible way of decreasing those 4 gigatons of cement emissions as soon as possible,” said Yet-Ming Chiang, founder of the startup. 

Sublime’s process uses electrochemistry to convert abundant calcium silicate rocks into cement ingredients at room temperature.

The process yields reactive calcium and silicates, which are then dried and combined to form Sublime’s cement.

Interestingly, the final product matches Portland cement in strength and structure, meeting industry standards for construction use.

Startup’s plant to come up in 2026

Sublime Systems has achieved a major milestone by successfully using its cement in Boston’s largest net-zero commercial building. This sustainable building project in the Seaport district incorporated 3 tons of Sublime cement in its construction in May.

The company is currently building a large-scale manufacturing facility in Holyoke, Massachusetts, designed to produce 30,000 tons of cement per year. The plant is projected to begin operations as early as 2026.

“The Holyoke plant is designed to be a module that we can repeat to get to a million-ton-per-year plant. That will allow us to eliminate scale-up risk so we can deploy simultaneously all over the world,” Ellis said in the press release. 

There has been rapid research and development ongoing to make construction materials eco-friendly. Just recently, University of Tokyo researchers made strong bricks using used concrete and adding trapped carbon dioxide. Interestingly, these bricks could be used to make buildings and pavements.