Cement is ubiquitous in our world, from our buildings, to our bridges, to our roads. Factor in that cement is responsible for eight percent of global CO₂ emissions, and it becomes clear that decarbonizing this material is a critical step in decarbonizing the global economy.

But no single solution for zero-carbon cement has come forward other than post-combustion carbon capture—until Sublime Systems. 

“Sublime Systems decarbonizes one of the hardest-to-decarbonize sectors,” says Joe Hicken, Sublime’s Head of Policy. “We’re replacing today’s cement with high-performance, low-embodied-carbon cement.”

Cement’s CO₂ emissions stem from its manufacturing process. First, cement uses limestone as a raw material, and breaking down limestone releases CO₂ that’s contained within it. Second, the raw materials are heated in a fossil-fuel-powered kiln, which requires temperatures of 1500°C. 

Sublime pioneers an electrochemical process that replaces the kiln and works at ambient temperatures. Sublime’s technology is on track to reduce over 90 percent of cement’s CO₂ emissions, Hicken says. Today, this technology cuts about 60 percent of cement’s carbon emissions.

Reducing cement’s CO₂ emissions by 60 percent is a feat that would already represent a massive leap in decarbonization when deployed at scale. The 90 percent reduction will be achieved through using other raw materials that don’t release CO₂ when broken down compared with limestone. 

Sublime’s cement can be a “total replacement” for current cement uses and will be cost-competitive at scale, according to the startup. The startup’s primary commercialization pathway is to run its own cement-producing plants, though it anticipates that there will be a demand for licensing its technology down the road.

Sublime spun out of MIT in 2020, and was founded by CEO Leah Ellis and Chief Scientist Professor Yet-Ming Chiang. Ellis, who is heavily involved in the Greentown community, serves on Greentown’s Board of Directors as a Community Board Member. 

The 25-person startup has doubled its team in the past year, and intends to double again soon. In addition to team growth, Hicken explains, Sublime is focused on maintaining the momentum that it’s developed in Greentown’s labs.

“The technology is scientifically derisked, and I think this is one of those great success stories for Greentown Labs,” he says. “We were fundamentally able to test the performance of the product in the wet lab and prototyping lab so rigorously that now it’s a function of maintaining that momentum as we grow out of the lab space and start producing the product to test with customers.”

The Greentown team is thoroughly impressed with Sublime’s progress, and has been thrilled to see Sublime hitting its technical milestones even faster than the startup anticipated. 

“Seeing startups like Sublime making big leaps personally gives me hope that we can solve climate change,” says Greg Ralich, Greentown’s senior director of lab and member resources. “We are excited to watch this team grow, work collaboratively, and continue to check off prototyping milestones.”