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.
Enter Greentown member Sublime Systems.
Sublime Systems pioneers an electrochemical process to create low-carbon cement without a fossil-fuel-powered kiln. Its material functions as a drop-in replacement for traditional, ready-mix concrete and enables a 90 percent reduction in greenhouse gas emissions.
If this sounds like a game changer, it is—and the manufacturing and buildings sectors are taking notice. In 2024 alone, Sublime Systems deployed its cement in its first commercial construction project, Boston’s largest net-zero-carbon office building that’s leased by Greentown partner Amazon; announced a sale of 2,000 tons of cement to Vineyard Offshore, the parent company of Greentown partner Vineyard Wind; signed an MOU with Microsoft; and brought in new investments from the U.S. Department of Energy’s Office of Clean Energy Demonstrations and Greentown partner Holcim.
But how does a novel technology like Sublime Systems’ get ready for this level of commercial deployment? Hardware-oriented climatetech solutions need lab space, equipment, patient capital, and more to get from a working prototype to a fully realized product that can be produced at scale.
In the four years since Sublime Systems spun out of MIT and became a Greentown member, it’s seen immense growth by every metric—going from its first gram of cement to a 250-ton-per-year pilot plant, from two founders to a team of more than 85, and from $0 raised to over $200M. As a startup that’s needed access to co-located prototyping lab, wet lab, machinery, and office space, its footprint at Greentown has grown accordingly, taking as much as 3,800+ square feet of prototyping space—including for its pilot plant—and four wet lab benches. It’s also tapped into Greentown’s networks of corporate partners, investors, and software and business resources.
The Sublime Systems team worked tirelessly in Greentown’s labs to rapidly progress through stages critical for any materials-science startup: bench-scale iteration, product testing, and pilot-system production. Greentown’s operations team supported Sublime Systems’ impressive innovations by meeting its chemical, electricity, space, safety, and hazardous-waste requirements—applying its expertise from supporting more than 575 climatetech startups to anticipate the startup’s needs, help embed safety into the process and product, and offer hands-on support throughout.
“Greentown Labs is a place where it’s very easy to start a science or technology-based company,” says Leah Ellis, CEO and Co-founder of Sublime Systems. “You go there, two co-founders with a PowerPoint, and they take care of everything so you can grow from two to 30 people easily. The founders don’t have to worry about facilities, waste management, permitting, working with the fire department, providing training for their employees or even providing coffee for them. Everything is taken care of. It’s like a full-service hotel for startups where someone does your laundry and brings you breakfast, so you can just focus on what matters the most.”
Sublime System is rapidly becoming a major player in the climatetech industry and an economic driver for the Commonwealth of Massachusetts, as it builds a low-carbon cement plant in Holyoke, MA that will be capable of producing 30,000 metric tons of cement per year. The facility will bring about 70 jobs to the region.
Join us in looking back at Sublime Systems’ growth and key milestones over the past four years!
Q1 2020
Major 2020 milestones:
- January 2020: Became a Greentown member
- January 2020: Received an award of nearly $500k from ARPA-E
- March 2020: Spun out of MIT
- Received funding from Azolla Ventures, the U.S. Department of Energy (DOE), The Engine, and Lowercarbon Capital
Q1 2021
A year of growth
- Sublime spent the year hard at work in the wet lab and prototyping lab, de-risking its technology, growing its team, and working to identify potential partners
Q1 2022
MAJOR 2022 MILESTONES:
- February 2022: Received a $3.6M ARPA-E award
- December 2022: Commissioned pilot plant at Greentown to produce 100 metric tons of cement per year
- August 2022:
“The technology is scientifically derisked, and I think this is one of those great success stories for Greentown Labs. 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.”
—Joe Hicken, VP of Business Development and Policy at Sublime Systems
Q1 2023
Major 2023 milestones:
- January 2023: Raised a $40M Series A, with Greentown partner Siam Cement Group (SCG) as a lead investor
- September 2023: Received ASTM C1157 designation, ensuring its concrete’s compliance with major U.S. and international building codes for construction projects
- November 2023: Announced it would open a low-carbon cement plant in Holyoke, MA capable of producing 30,000 metric tons of cement per year, bringing about 70 jobs to the region
- November 2023: Received a life-cycle assessment from Climate Earth validating that its cement manufacturing process enables a 90 percent reduction in greenhouse gas emissions
- December 2023: Increased its Greentown pilot plant capacity to 250 metric tons of cement per year
Q1 2024
Major 2024 milestones:
- January 2024: Received $6.69M in funding from the DOE’s Industrial Efficiency and Decarbonization Office (IEDO)
- March 2024: Selected for an up-to $87M investment from the DOE’s Office of Clean Energy Demonstrations (OCED) and $2.5M from the Massachusetts Clean Energy Center
- March 2024: Named to TIME Magazine’s list of America’s Top GreenTech Companies of 2024, along with 20 other Greentown members and alumni
- May 2024: Deployed its cement in its first commercial construction project, Boston’s largest net-zero-carbon office leased by Greentown partner Amazon
- July 2024: Announced a sale of 2,000 tons of cement to Vineyard Offshore, the parent company of Greentown partner Vineyard Wind
- September 2024: Received $75M in investments from global building materials leaders Holcim—a Greentown partner—and CRH. These partnerships involve Sublime Systems providing its cement to both corporates through offtake agreements; Holcim and CRH supporting the building of Sublime Systems’s first commercial manufacturing facility; and Sublime Systems collaborating with each of the companies to co-develop future facilities to scale and commercialize its technology.
- September 2024: Signed an MOU with Microsoft for the purchase of environmental attribute certificates generated from the cement produced at Sublime’s first commercial facilities
Q4 2024
“The Greentown Labs wet lab space allowed the then-three-person Sublime Systems R&D team to test their ideas and grow their technology into a combined R&D and engineering team of more than 40 people. The Greentown wet lab was home to the company’s first chemical process reactors, which were built into the fume hoods for safe and contained operation. Sublime Systems’s researchers used these early reactors to not only produce novel cementitious materials, but to tune their operating conditions and optimize their product for the highest performance. Overall, the work performed in the Greentown wet lab allowed Sublime Systems’s process to grow from a fume hood to a 1,500-square-foot pilot plant space in Greentown’s prototyping space that produces 100x the product, and soon to be a first-commercial manufacturing facility in Holyoke, MA! The facilities in the Greentown wet lab, and the drive of their talented R&D team, allowed research to hit the ground running and make groundbreaking progress without the headache or cost of building out basic lab facilities.”
All photos courtesy of Sublime Systems, unless otherwise noted.
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