Sublime Systems co-founders making the ‘electric vehicle of cement’

While Leah Ellis was earning her doctorate at Dalhousie University in Nova Scotia, she was part of a team that did battery research for Tesla. After she graduated, her budding career took an unusual turn.

“I could have gotten an easier job with my background in battery materials — a lot of my colleagues go work for Tesla or Apple. I could have done that, … and I would have made more money at first,” Ellis, 33, told CNBC by phone Wednesday.

Instead, Ellis applied for and won a prestigious Banting Postdoctoral Fellowship that granted her two years’ salary to work with whomever she wanted.

Ellis took her Ph.D. in electrochemistry and went to work for Yet-Ming Chiang, a renowned material sciences professor at Massachusetts Institute of Technology who is also a serial clean-tech entrepreneur. Chiang co-founded companies such as American Superconductor Corporation, A123 Systems, Desktop Metal, Form Energy and 24M Technologies.

Now Ellis is working to scale up a new climate-conscious process of making cement, one powered with electrochemistry instead of fossil fuel-powered heat.

Making cement using electrochemistry was Chiang’s idea, Ellis told CNBC in Boston at the end of May. Ellis said she worked with Chiang in 2018, just after he had started Form Energy, a long-duration battery company, and he was thinking about the abundant intermittent energy that was being generated by renewable energy sources such as wind.

“Sometimes people will pay you to take energy off their hands,” Ellis told CNBC. “Instead of putting that energy in a battery, what if we can use this extra low-cost renewable energy to make something that would otherwise be very carbon-intensive? And then the first on the list of things that are carbon-intensive — it’s cement.”

Cement is a necessary ingredient in concrete, which is the cornerstone of global construction and infrastructure, because it’s cheap, strong and durable. Four billion metric tons, which is the equivalent of 50,000 fully loaded airplanes, of cement is produced each year, according to a 2023 report from management consulting company McKinsey. The value of the market was $323 billion in 2021 and is expected to reach $459 billion by 2028, according to SkyQuest Technology Consulting.

Cement powder is conventionally made by crushing raw materials, including limestone and clay, mixing with ingredients such as iron and fly ash, and putting it all into a kiln that heats the ingredients up to about 2,700 degrees Fahrenheit. That process of making cement generates approximately 8% of global carbon dioxide emissions, which are a leading cause of global warming.

When Chiang had the idea to electrify cement manufacturing, he turned to Ellis. “He’s super busy, so he was like, ‘Go off and figure it out,'” Ellis told CNBC.

So she did.

In 2020, Ellis and Chiang co-founded Sublime Systems to refine and scale up the electrochemical process they created for making cement.

Sublime has raised $50 million from some leading clean-tech investors, including Chris Sacca’s LowerCarbon Capital and Boston-based, MIT spin-out venture firm The Engine; from Siam Cement Group, a leading cement and building materials company in Asia; and via a couple of grants from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy, or ARPA-E, program.

Ellis likes to describe what they’re doing as developing the “electric vehicle of cement making.” An electric vehicle replaces a combustion engine with an electric motor, and that’s what Sublime Systems does in the cement-making process.

“I think for the layperson, it’s easiest for them to understand how we take that high-temperature, fossil-driven process and replace it with something that is powered by electrons. And we’re using electrons to push these chemical reactions,” Ellis told CNBC by phone Wednesday. “That happens at an ambient temperature below the boiling point of water,” she said, and that is a critical differentiator.

Ellis said she didn’t know much about cement when Chiang bade her to go figure out how to make low-carbon cement. She started by reading Wikipedia, and then textbooks. Then she worked with another Ph.D. student doing research that was later published in scientific journal articles on the topic. That led to the concept for what Sublime is doing now, and she’s continued to refine that concept ever since.

“And basically just haven’t stopped,” Ellis told CNBC. “It’s been five years.”

“On the whole, the industry is highly motivated to go green,” Mark Mutter, the founder of Jamcem Consulting, an independent cement industry consultancy, told CNBC. Motivations to go green are highest for producers located in parts of the world such as Europe, where there is a price on carbon dioxide emissions at around 80 euros (almost $88) per metric ton. That’s “a big financial penalty for producers and it gives them an incentive to invest” in green cement tech, Mutter told CNBC.

That’s one reason investors are putting money behind Sublime.

“Customers are lining up to partner with Sublime because they can supply fossil-free cement at a time when the rest of the industry are all struggling to hit emissions targets and comply with carbon tariffs,” Clay Dumas, partner at LowerCarbon Capital, told CNBC.

“For Lowercarbon, their omnipresence and medieval production techniques are precisely the qualities that make building materials such an irresistible opportunity,” Dumas told CNBC.

Some cement producers are looking at carbon capture technologies as a way to manage their greenhouse gas emissions. But “this is highly costly, and in some respects is just business as usual and burying the problem for future generations,” Mutter told CNBC.

Sublime is making clean cement without the expensive additive of carbon capture and storage technologies, which is attractive because it keeps costs low, said Katie Rae, CEO at The Engine. “Producing decarbonized cement directly, rather than doing carbon capture, drives both energy efficiency and eventual cost parity,” Rae told CNBC. 

Dumas said Sublime has “the most elegant chemistry, which runs on electricity at ambient temperatures while emitting zero carbon. That means they have no need for big ovens or costly CO2-capture systems that would drive up capex.”

Siam Cement Group looks at thousands of companies and makes only “a few” investments a year, Timothy McCaffery, a venture investor at SCG, told CNBC. For SCG, what’s attractive about Sublime is that it avoids the complicated and expensive carbon capture technology and works with existing infrastructure.

“We have seen that Sublime Systems could disrupt the industry. The company produces a cement at room temperature that can drop into the existing ready mix supply chain and meets American Society for Testing and Materials standards,” McCaffery told CNBC. American Society for Testing and Materials is the body that creates test standards and protocols that manufacturers use to test their materials against.