Most factories are powered by burning fossil fuels to produce the cheap, scorching-hot steam needed to make everything from steel and cement to potato chips and soda.
Their access to cheap fossil fuels that can instantly burn to sky-high temperatures is why industrial heat is one of the hardest sectors to decarbonize. But thermal battery startups are inching closer to disrupting that centuries-old model, now that at least six companies are actively testing their technology in the U.S., Europe, and Thailand. The latest is Electrified Thermal Solutions, which last month fired up its first commercial-scale project at a research institute in San Antonio.
The company said its firebrick system can store 20 megawatt-hours of heat at up to 1,800 degrees Celsius — ideal temperatures for making cement, steel, chemicals, and glass. Bricks made of metal oxides are stacked inside a steel container and directly charged via the grid, then discharge hot gas to industrial furnaces, boilers, and kilns.
Thermal batteries’ ability to charge up when renewable generation is plentiful and electricity costs are low is what makes them such a promising technology, several industry experts told Latitude Media. This is because the main barrier to industrial electrification is that per unit of energy, fossil fuels are often cheaper than electricity.
“If thermal batteries can selectively buy cheaper electricity, it could cut the cost of reliable, electrical heating in half or by one-third,” Jeffrey Rissman, senior director of industry at Energy Innovation, a nonpartisan think tank. He noted that ETS’ batteries store about as much energy as is consumed by 695 U.S. households on an average day; the ETS site also pitches the technology for grid storage.
Buying the dip
In certain regions of the U.S. and Europe, wholesale electricity prices regularly hit zero dollars or lower. That’s true in states like Texas and California, where there is an abundance of solar and wind power midday.
ETS’s battery system, called Joule Hive, takes advantage of the price dips, according to CEO and co-founder Daniel Stack. This can save manufacturers money and reduce greenhouse gas emissions by avoiding burning fossil fuels onsite.
Industrial heat accounts for aboutone-fifth of global energy consumption, with 89% generated by burning fossil fuels, according to the International Energy Agency. These processes also account for about 15% of global emissions — equivalent to the annual emissions of the U.S. and India combined.
ETS hasn’t deployed its system at an industrial site yet, but backers include major cement and steel companies including Holcim and ArcelorMittal; the latter invested in September, and also agreed to explore pilot projects.
Stack said ETS expects to deliver its first units to customers by early 2027.
“We’re working with industrial companies now, who like to see things working well before they can 10x a technology,” Stack said. “I think before the end of the decade, you’re going to see really large deployments tackling some of the hardest-to-abate industries.”
Scaling up
Other thermal battery companies including Antora, Brenmiller, Kraftblock, Kyoto Group, and Rondo Energy also have commercial operations underway. Rondo Energy launched its first project in 2023 at a biofuels refinery in California, and has since announced the world’s largest thermal heat battery powered by an onsite array of solar panels at an oilfield in the state. A Heineken brewery in Portugal and a cement plant in Thailand are also partnering with Rondo Energy.
John O’Donnell, chief innovation officer at Rondo, told Latitude Media in October that each project helped pave the way for the next. The unit at Holmes Western Oil proved Rondo’s battery works at 100 MWh scale, and facilitated the construction of its thermal batteries in Europe.
For more on Rondo Energy’s heat batteries, listen to John O’Donnell’s interview on The Green Blueprint podcast:
Stack of ETS similarly said that in order to scale, “we just need to keep building.” A single ETS’ system produces just a few megawatts of power, but they’re designed to be modular; many Joule Hive containers could be built on one site. An integrated steel plant might need a gigawatt of power, Stack said, so the company plans to build larger systems that deliver several hundred megawatts of power from one “dual-optimatal battery.”
“What larger systems let you do is hold more energy and more power while cutting down on the costs of raw materials per unit of energy and power,” Stack said. “That’s an advantage.”
Right now, thermal batteries aren’t completely replacing fossil fuels at manufacturing sites, clarified Ruth Checknoff, senior project and research director at the Renewable Thermal Collaborative, which acts as a convener of battery startups and potential customers.
“We see a common trend where the end users will maintain their existing boilers as backup, but only use them if there’s scheduled maintenance to the new electrified technology,” Checknoff said. “But thermal batteries truly do have the potential to fully decarbonize industry.”
The Renewable Thermal Collaborate is advocating for Congress to change the Federal Power Act to enable faster adoption of thermal batteries. The law currently doesn’t allow thermal battery operators selling heat to industrial customers to buy electricity at wholesale prices. Instead, companies are going state by state and utility by utility to negotiate special rates that mimic those of the wholesale market.
“It’s a bit burdensome to these solutions providers, when a key part of their business case is being able to access that cheap electricity,” Checknoff said. “So that’s a really key piece.”
