Leah Ellis and Yet-Ming Chiang
Photo courtesy The Engine
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.
Leah Ellis, CEO of Sublime Systems
Photo courtesy Summer Camerlo, Sublime Systems
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.”
Ellis has always been curious. “I grew up pretty nerdy, I guess, reading a lot of books,” she said. “I always had that thirst for knowledge and a sense of adventure.”
She also grew up in a religious household. Her father is an Orthodox Jewish rabbi from Texas, her mother grew up on a sheep farm in South Africa, and the two met when they were both in Israel. “Jerusalem has more than enough rabbis. So he moved to eastern Canada, where they don’t have a lot of rabbis,” Ellis told CNBC of her father’s move. Her family celebrated and encouraged having a robust intellectual life.
Leah Ellis, CEO of Sublime Systems, works in the cement lab.
Photo courtesy Leah Ellis
Ellis and one of her two younger sisters ended up getting their doctorates in chemistry.
“Both of us realize that chemistry is a very creative subject; it’s also a very difficult subject. And I think we both sort of gravitate to things that are challenging,” Ellis told CNBC.
When mastered, chemistry can be used to effect change. “It has a lot of creative power to make things happen in the real world,” Ellis said. “It’s almost like magic. If you work really hard on it, you can create things that make the world a better place.”
Battery scientists and cement producers have not historically worked together. “Cement typically sits in civil engineering, and battery science normally sits in chemistry or physics,” Ellis said. “They don’t go to the same conferences.”
But with Sublime Systems, Ellis and Chiang are bringing those two fields together.
That framework of using electrochemistry to drive reactions that once happened with very hot fossil fuel-powered reactions is not exclusive to cement.
“It’s a huge tool. I don’t think Sublime is the only one that’s applying electrochemistry to clean tech. I think the best way we have to get around fossil fuels is to use electrons,” Ellis told CNBC.
“The electrochemical way is often more efficient,” she said. “Heating things up to make them go is often not as efficient as electrochemistry, which is a bit more surgical, a bit more efficient — or at least can be more efficient with the right processes.”
That fundamental energy efficiency is why Chiang is confident in their solution.
“Decarbonizing cement production is going to be a very tough task. There will be numerous approaches, all of which have challenges and most of which deserve to be tested,” Chiang told CNBC. “I prefer to face our challenges because we see a pathway to complete decarbonization at cost parity with today’s cement while consuming the least amount of energy. In the long run, the lowest-energy process usually wins.”
Yet-Ming Chiang, professor of materials science and engineering at Massachusetts Institute of Technology, speaks during the 2016 IHS CERAWeek conference in Houston, Texas, Feb. 26, 2016.
Bloomberg | Bloomberg | Getty Images
“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.
Sublime completed its pilot plant at the end of 2022 and spent a few months on quality control measures. Now, Ellis is focused on getting the product to partners, and the company hopes to do its first construction project by the end of the year. The next step is to go from the 100-ton pilot plant to a 30,000-ton-per-year demonstration plant.
While Sublime is just getting ramped up, Ellis knows speed is essential in the race to decarbonize. “My mission is to have a swift and massive impact on climate change,” she told CNBC in Boston.
Leah Ellis bikes in Africa.
Photo courtesy Scott Carmichael
It’s an audacious goal, and while Ellis has credentialed chemistry chops, this is her first time being the boss of a company.
“I suppose I am aware of my age. And I’m also humble about that. I’m a first-time founder. I’m a first-time CEO,” Ellis told CNBC. “I figure things out as I do them. And I’m really lucky to have great mentors and support and people who believe in me, and, I think, who recognize the fact that I have a lot of energy, and I have a lot of passion. And I’m going to work as hard as I can for as long as I can to make this happen.”
Ellis knows how to keep herself going, too. She makes sure she gets good sleep and she stays active. She’s run seven marathons. She’s a cycler, and once cycled across Africa in about four months with a group, a trip that averaged out to riding more than 60 miles a day. She also participates in a “fitness cult” that climbs the Harvard stadium stairs every Sunday.
“I’m not a fast runner at all. I’m not a fast cyclist either,” Ellis told CNBC. “I just know how to toe that effort line to just like maintain the same effort for a very long time, and to keep my own spirits up.”
For Chiang, building solutions keeps him moving forward.
“It’s been about 15 years since the words ‘climate change’ entered the lexicon. It’s been a gift, and very energizing, to have potentially impactful solutions to pursue, as opposed to sitting and fretting,” Chiang told CNBC.
“I believe climate change has pushed all of us into an extremely fertile, creative period that will be looked back on as a true renaissance. After all, we’re trying to re-invent the technological tools of the industrial revolution. There’s no shortage of great problems to work on! And time is short.”