Two years ago, we brought our readers news about the Joule Hive thermal battery from Electrified Thermal Solutions. ETS is an MIT spin-off that began researching the benefits of electrified firebrick more than 12 years ago. Here’s why that is important.
About 20 percent of all energy consumed globally each year is used to create what is known as process heat. We are not talking about pasteurizing milk here, people. We are talking about the kind of heat you need to make steel, aluminum, and cement. Until the advent of the Joule Hive technology from ETS, it was simply not possible to obtain the enormous heat needed for such operations using electricity. Only burning fossil fuels — either methane or coal — would do. Of course, that meant the carbon emissions from making those products were significant.
What ETS figured out was how to make firebricks that conduct electricity by rearranging their chemistry to include more metallic oxides. “There’s no exotic metals in here, there’s nothing that’ll burn out,” co-founder Daniel Stack told Inside Climate News.
As electrons pass through the modified firebricks, they can heat up to 1800º C — hot enough to make steel, cement, or even steam to run a traditional electricity generating station. The process is 95 percent efficient and is a great way to put excess renewable energy to productive use.
ETS stacks the firebrick inside an elevator-sized insulated enclosure it calls a Joule Hive that can store the heat for up to three days. The company says their Joule Hive is the first heating element that can electrify the economic sectors that require the highest temperatures — steel, cement, glass, and chemicals. They are also the hardest industries to abate their climate emissions.
Commercial Viability
Startups all suffer from the same challenge — can the technology be made commercially viable outside the laboratory? In a press release on September 15, 2026, Electrified Thermal Solutions announced that Holcim — one of the largest cement companies in the world — has completed the installation of two Joule Hive thermal batteries at one of its production facilities. Daniel Stack called the project “a step change in what’s been done to actually electrify cement and concrete production.”
The announcement comes on the heels of the first commercial-scale Joule Hive at Southwest Research Institute in San Antonio, which has now logged more than 1,000 hours of operation. That testing provided the proof of concept verification needed to move ahead with the Holcim project. With cement responsible for roughly eight percent of global CO₂ emissions, electrifying kiln heat with firebricks charged on clean power is one of the most direct paths to cleaner concrete, the company said.
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Making Cement Takes A Lot Of Heat
Cement production is among the hardest of all industrial processes to electrify. Process temperatures regularly exceed what conventional electric heating can reach, which has left combustion as the default source of heat for the sector. “For Holcim, the agreement extends work already underway to decarbonize its highest-temperature operations,” their press release says. “For Electrified Thermal, it adds a third global industrial partner to a customer base built specifically around sectors, including cement, steel and chemicals, where electric alternatives to combustion have not previously existed.”
“Electrifying high-temperature industrial heat is one of the advanced technologies we are incorporating in our decarbonization strategy, and this deployment allows us to evaluate its potential,” said Ram Muthu, the head of operational excellence at Holcim. “Working with Electrified Thermal gives us a path to accelerate decarbonization as part of our industry-shaping sustainability road map.”
CleanTechnica readers will immediately notice that burning fossil fuels is only part of the carbon dioxide emissions associated with making cement. The other part is the carbon dioxide released when that heat is used to convert limestone into cement. Another MIT spin-off — Sublime Systems — is greatly reducing carbon emissions from that part of the cement-making process.
“Holcim’s decision to deploy our technology validates years of work to bring electrified heat to high-temperature industrial-scale applications that no other technology or company can achieve,” said Daniel Stack, CEO of Electrified Thermal Solutions. “This agreement follows the recent turn-on and successful 1,000+ hours of operation of our commercial demonstration system and shows that global industrial producers are ready to move this technology from demonstration to deployment. We look forward to expanding this relationship with Holcim over time.” Going forward, Holcim will be an investment partner to ETS.
First ETS Installation In Kentucky
In 2024, Ashland, a specialty chemical manufacturer based in Wilmington, Delaware, was awarded up to $35 million in a matching grant from the Department of Energy to fund the first commercial deployment of the Joule Hive thermal batteries at its ISP Chemicals plant in Calvert City, Kentucky. That facility requires large volumes of high temperature steam to run its operations, which is exactly the sort of process heat the new technology is designed to supply.
Curt Jawdy, a senior manager with the Tennessee Valley Authority, a partner on the grant and the local electric utility for Calvert City, said the company’s ability to charge its thermal batteries during off-peak hours allows industrial facilities to decarbonize without placing greater strain on the utility’s electric grid.
“Simpler is always better,” he said. “The fact that the brick is also the heating element, and you just supply electricity to the brick itself, simplifies the system significantly.” The project will eventually replace methane fired boilers at the Calvert City plant. Air blown through the Joule Hive batteries will heat water to generate the required steam.
The project would reduce greenhouse gas emissions associated with steam generation at the plant by nearly 70 percent, according to the DOE. In 2022, Ashland released 72,000 tons of carbon dioxide from burning methane at the plant — equal to the annual greenhouse gas emissions of 17,000 automobiles.That’s a significant source of climate pollution in a town of 2,500 people, according to the EPA.
ETS points out that steam is what drives most conventional generating stations. Its Joule Hive technology can easily create the high temperature steam those facilities need, which would allow them to pivot away from the traditional fuels they use today — methane and coal.
The more you look, the more opportunities appear to exist for Joule Hive technology.
