Electrolyzer-assisted cement production method draws $40M in venture capital 

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Sources: Sublime Systems, Somerville, Mass.; CMCM staff

Sublime Systems has closed a Series A funding round to support commercialization of technology that replaces the most energy- and fossil fuel-intensive aspects of portland cement production. The company derives a portland cement alternative from a variety of graded, abundantly available calcium and silicate sources using electrolysis. Its electrolyzer assemblies run at ambient temperature, thereby avoiding the carbon dioxide emissions tied to conventional cement plant kilns’ calcining and clinkering phases (1,000°C to 1,500°C). Sublime Systems’ pilot production indicates a 70 percent reduction in CO2 emissions versus conventional cement milling.

The use of electrolysis positions Sublime as the first company to produce cement through a process that eliminates emissions from limestone calcining and the fossil fuel combustion attending high temperature kiln operation. The filter tanks shown here separate solids from electrolytes.

Leading the $40 million funding round is climate-tech focused Lowercarbon Capital, followed by existing investors The Engine and Energy Impact Partners, plus Southeast Asia market leader Siam Cement Group. Sublime Systems will use the capital to ramp up production at its pilot plant, potentially to 40,000 tons/year capacity by 2025; build its technical team; conduct product testing; and, advance new customer or partner commitments.

“We have successfully demonstrated the viability and scalability of our approach and we are able to produce cement with the same or better strength, slump, and durability than today’s portland cement,” says Sublime CEO and Co-Founder Dr. Leah Ellis. “The support of our talented team and capital from our investors will enable us to operate our pilot facility, secure advance offtake agreements and work toward producing our low-carbon cement at scale.” Unlike new process developers that rely on carbon capture and sequestration to remove COfrom production, she adds, Sublime produces an economical cement with both low embodied COand low embodied energy. 

“Sublime’s technology has cracked the code for low-carbon cement,” observes Lowercarbon Capital Founding and General Partner Clay Dumas. “Sublime’s decarbonized cement offers many advantages over competitors not only for emissions reduction potential, but also for ability to deploy. The team has a clear path towards commercialization and is set up to execute and scale.”

“Sublime is the first company we’ve seen whose approach has the potential to decarbonize the entire process of creating cement,” affirms Siam Cement Global Investment Director Deep Technology Tim McCaffery. “We are committed to decarbonizing production as fast as possible, proud to be working with such an innovative team [and] eager to see Sublime Systems progress from pilot to commercial scale.”  

Sublime was spun-out of the Massachusetts Institute of Technology in 2020, Professor Yet-Ming Chiang joining Dr. Ellis as co-founder. To date, the company has concentrated on developing its low-carbon cement, validating its manufacturing process at the pilot scale, and gauging buyer demand.  —  www.sublime-systems.com