WASHINGTON — Leah Ellis is not worried about building demand for the low-carbon process she has developed for making cement. The CEO of Massachusetts-based Sublime Systems says she has a healthy pipeline of prospective customers waiting to buy the company’s product, made with an electrolyzer powered by wind and solar, rather than the traditional, high-heat, high-emission kiln.
“The demand for low-carbon cement is phenomenal,” Ellis said during an interview at Wednesday’s Clean Industrial Summit, sponsored by the Clean Air Task Force and ClearPath Foundation, both nonprofits focused on reducing greenhouse gas emissions. Sublime has a pilot plant up and running in Somerville, Mass., and potential customers are often more interested in how much of the company’s high-performance cement they can get than the price.
“They do ask about price, but I think it’s just not one of the first questions that people ask me,” she said. “Understand, you’re not just buying a ton of cement; you’re also buying the carbon avoidance.”
Ellis was just one of the startup executives at the summit, talking about the potentially game-changing technologies they are bringing to market, all aimed at upending conventional wisdom about heavy industry and its notoriously hard-to-abate greenhouse gas emissions.
Antora Energy, a California based startup, has developed a thermal storage technology that allows wind and solar energy to be stored at high temperatures — as high as 1,500 degrees Celsius — to provide heat for industrial processes. The company is targeting steel and cement as early markets, said CEO Andrew Ponec.
“This product has the potential to strike right in the heart of industrial emissions,” Ponec said. “It can serve almost every industry at any temperature range that’s used widely [and] any geography that has wind and solar at scale.”
The company’s investors include the Bill Gates-funded Breakthrough Energy Ventures, Lowercarbon Capital and Shell Ventures.
Historically dependent on carbon-intensive processes, heavy industry — including cement, iron and steel, and petrochemicals — accounts for 23% of U.S. greenhouse gas emissions, according to EPA. While transportation (28%) and electric power (25%) are the country’s top emitters today, industrial emissions are projected to jump into the No. 1 spot by 2035, according to the Rhodium Group.
The Department of Energy has made industrial decarbonization a priority, with a series of reports and funding opportunities, such as the Industrial Heat Shot, which is supporting research into new technologies that can cut industrial heat emissions by 85% by 2035.
Early research-and-development funds from DOE’s Advanced Research Projects Agency-Energy (ARPA-E) were essential for both Sublime and Antora, their CEOs said.
But, while promising, these new technologies may not be able to scale fast enough to meet the decarbonization goals of industrial giants such as Cemex, a multinational cement company with plants in seven states in the U.S., said Jerae Carlson, the company’s senior vice president for sustainability, communications and public affairs.
What’s technically feasible may not be economically feasible for “each and every one of our operations,” she said. And the new technologies like Sublime’s and Antora’s may take a long time to scale.
Efficiency, Electrification and Carbon Capture
Many companies in the industrial sector have committed to cutting emissions and reaching net zero by 2050, but David Crane, DOE’s under secretary for infrastructure, says that’s not fast enough.
Crane said most of these businesses are approaching decarbonization with a four-step strategy. Efficiency and electrification are first and second, respectively, both over the next decade, followed by efforts to tackle industrial process heat in the mid-2030s and 2040s and some form of carbon sequestration for any residual emissions.
Crane is also focused on industrial process heat. “Our goal is to break that third step, which is where government can play a role because it’s the hardest step to change the mentality of both producers and buyers,” he said. “If you think you have to wait around till 2035, you won’t be a leader in your industry.
“The federal government is going to use every power at its disposal” to push industrial decarbonization forward, he said, from DOE programs, such as its $7 billion initiative to stand up regional green hydrogen hubs, to procurement.
“The government directly or indirectly pays for 50% of the cement used in the United States,” Crane said. “Now, how do you translate that into sending a market signal that we want green cement? That’s something we’re still working on.”
Melissa Carey, head of climate policy and government affairs for Holcim, a building materials multinational, acknowledged her company’s decarbonization strategy hews closely to Crane’s description.
“We do efficiency. We do carbon capture. We plant trees,” Carey said. “It’s unfortunate but true, in a sense, because we know what we need to do. We need to be able to do it faster.”
The key roadblocks to Holcim’s decarbonization plans are what Carey called “enabling conditions.” The company has ordered 200 of Ford’s F-150 Lightning electric pickup trucks but so far has received only one.
Reviewing plans for carbon capture at the company’s largest cement plant, Carey recalled asking, “How much does the timeline depends on funding and technology availability? And the answer was ‘completely.’
“If we can’t get more transmission built, then we can’t get more renewable energy,” she said. “We have 13 cement plants and zero pipelines right now to connect any captured CO2 to storage. … Where we’re really focused now is having later plans on trying to spur some of these enabling conditions so that we can do what we want to do as fast as possible.”
Cemex is looking to alternative fuels — such as bioenergy and renewable natural gas — to power its high-temperature kilns, Carlson said. With plants that operate 24/7 at high temperatures, the company would like to tap into waste streams as a source for bioenergy that can meet its need for tightly scheduled operation.
But, Carlson said, “the regulations around waste management here in the U.S. are not nearly as cohesive at a rural level, and then you also have to deal with state and local issues.”
While “focusing heavily” on carbon capture, Cemex’s “goals for 2050 … do not rely on known, proven, viable strategies right now,” she said. “We know we’re going to have to rely on innovations that we haven’t even conceived of yet.”
The steel industry has already cut its emissions, with a heavy reliance on the use of recycled steel as feedstock for steel production. “About 70% of the steel made in the United States is actually made through a recycling process,” said Kevin Dempsey, CEO of the American Iron and Steel Institute, an industry trade group.
Companies also are shifting from coal to natural gas to produce the high heat needed for purifying iron ore, a key step in making steel, and looking forward to possibly moving to clean hydrogen, when it becomes available, he said.
At the same time, Dempsey cautioned, “there’s not going to be a single way to get to [net] zero. All our companies are significantly committed to get to zero … but they’re pursuing a variety of paths, because our industry is very competitive.
The upside is that customer demand has become a major spur for innovation. “Frankly, demonstrating you can produce a clean product that can meet your customers’ needs is really one of the most significant driving forces in the steel market today,” he said.
‘Turn off the Tap’
As with steel, the quest for carbon-free cement is also drawing multiple innovators and new technologies. The industry has long been seen as one of the hardest sectors to decarbonize, with its reliance on a raw material, limestone and a high-heat process. Worldwide cement accounts for about 8% of all CO2 emissions.
At California-based Brimstone, CEO Cody Finke and his team have developed a chemical process for making cement from calcium silicate rock, a carbon-free rock that, Finke said, is 100 times more abundant than the limestone used to make most cement. The process also produces magnesium, which can passively absorb CO2, making Brimstone’s cement potentially carbon negative.
The company’s goal is to manufacture Portland cement, a building industry standard, that is both cost-competitive and carbon-free. Brimstone’s cement was recently certified to meet a key industry standard for Portland cement, ASTM C150.
To earn industry acceptance and scale quickly, “you need to use the [industry] structure that exists out there, existing trade unions and builders who know how to deal with the material,” Finke said. “If I have the option to build that building with the material we trust, the same material that we’ve always been building buildings out of … it’s hard to take the risk to build with a new material, even if the new material may be as good.”
Finke also said Brimstone’s process can be used “across a broad range of energy scenarios” and can be completely electrified. All of the cement the company has produced to date has been powered by electricity, he said.
Sublime is going another route, also using calcium silicate rock but producing cement that meets another ASTM standard, C1157, which is performance-based, CEO Ellis said. The standard is just as rigorous as C150 and has increasing acceptance across the industry, she argued.
When mixed with water, Sublime’s cement “sets and hardens to make the same concrete we’ve be using for millennia, but it’s not made in a kiln,” she said.
The company’s pilot plant has recently expanded its capacity from 100 tons of cement per year to 250, Ellis said. The first shipments of cement are being sent to customers for field testing.
Responding to Carlson’s comments on scalability, Ellis said the next steps will be to “optimize” the demo plant and then scale, to produce tens of thousands of tons of low-carbon cement per year as soon as 2025 and up to 1 million tons by 2027 or early 2028.
The cement’s strongest selling point will be its carbon-avoidance, as opposed to the carbon capture used by Brimstone and the multinationals, she said.
“We have to do everything as fast as possible to bend the curve of CO2 emissions,” she said. “I think of CO2 emissions as a leak from a tap, and you have water spilling out onto the floor. And in my opinion, the first thing you do is turn off the tap … avoiding the source of the emissions.”
Opening New Markets
As Antora CEO Ponec says, tackling industrial process heat lies at the heart of industrial decarbonization, and multiple solutions will likely be needed. But he and others emphasized that new technologies should not be forced on the market.
Nuclear developer X-energy decided to go small with its 80-MW small modular reactor (SMR), the Xe-100. Benjamin Reinke, director of global business development, said the design provides a flexible solution with both electricity and super high temperatures for process heat.
The company is one of two being funded through DOE’s Advanced Reactor Demonstration Program, with $1.1 billion to stand up its first reactors this decade; the other is the Bill Gates-founded TerraPower.
X-energy had originally partnered with Energy Northwest, a public power provider in Washington state, for its first deployment, but it announced in March it would instead be working with Dow Chemical, providing process heat and electricity to one of the company’s plants on the Texas Gulf Coast.
The Xe-100 is a high-temperature, gas-cooled reactor, which uses small “pebbles” of graphite-covered nuclear fuel and can produce steam for high-heat industrial processes, with temperatures of 750 C, or close to 1,400 degrees Fahrenheit.
Reinke said the Xe-100 can turn its power level up or down, like a natural gas peaker plant, and can be expanded as needed. For Dow, the company is planning to install four of its SMRs. It is also still working with Energy Northwest and recently signed a joint agreement to develop up to 12 reactors for a site near the utility’s Columbia nuclear reactor in central Washington. (See X-energy, Energy Northwest to Develop up to 12 SMR Nukes.)
“Two years ago, we thought for sure that the largest utilities in America would be the first to adopt advanced nuclear at [scale] because they had the most experience operating nuclear reactors,” Reinke said. “Today, what we’re seeing is that investors’ [environmental, social and governance] goals and requirements at various companies and their customers are driving a lot of heavy industry to decarbonize faster than many utilities have in their own projections. …
“We’re opening up a new market,” he said. “It changes the total addressable market for us and for many of our competitors … but we’re also leveraging that for additional learning and the ability to de-risk new technology coming to market.”
Ponec said Antora’s process has also been market driven.
“We were really looking for what would have the biggest impact,” Ponec said. Looking at industrial heat, he said, combining “that need to decarbonize with the incredibly low cost of variable renewable energy is so tantalizing. It was clear that renewables could do the job, if not for the variability.”
Finding a solution to that problem led to the development of the company’s carbon-based thermal storage technology, he said. “The way our system works is you take electricity from wind and solar when it’s available; you run that through resistive heating elements, just like a twister coil, to heat up carbon blocks to a very high temperatures, white hot, about 1,500 degrees; and then you continuously extract that … heat as steam.”
Further, he said, the materials in the storage unit are inexpensive and domestically sourced. “There aren’t a lot of barriers to scaling this up to the massive scale we need for rapid decarbonization,” he said.
The company has completed construction of a pilot plant and hopes to have its first systems online by 2025, he said.
While not naming names, Ponec said potential customers are looking at Antora’s combination of cheap renewables and thermal storage as a lower-cost source of industrial heat than natural gas by 2030. “At the point that you can start saying … you can beat the cost of … natural gas over a 10-year contract, that opens a market that is extraordinarily large,” he said.
