Thailand’s First Heat Battery Powers an SCG Cement Plant
Thailand’s First Heat Battery Powers an SCG Cement Plant
Cement and clean energy don’t usually appear in the same sentence. Making cement is hot, dirty work, and the industry has long been treated as nearly impossible to decarbonize. So when a Thai cement plant became the launch site for a brand-new kind of battery, it was worth a closer look. The technology isn’t a lithium pack. It stores electricity as heat — in ordinary bricks — and gives it back as steam.
What did SCG and Rondo just switch on in Saraburi?
On November 13, 2025, SCG Cleanergy and Rondo Energy commissioned a 33 MWh heat battery at an SCG cement plant in Saraburi province — the first industrial heat battery in Southeast Asia. The system charges from the grid and a nearby floating solar farm, then delivers 2.3 MW of continuous steam to drive a turbine and generate round-the-clock power for cement production.
What makes it a genuine first? According to Rondo Energy, it’s the world’s first heat battery installed at a cement plant, and the only one anywhere delivering high-pressure steam for electric power generation. The unit was built in just eight months, as reported by Energy-Storage.News.
It’s also the first unit on Rondo’s new modular platform, which scales from this 33 MWh size up to more than 1 GWh. That matters for replication. If a configuration works in Saraburi, the same building blocks can be stacked far larger elsewhere — a point the companies stressed at the ribbon-cutting.
How does a “brick-and-wire” heat battery actually work?
A heat battery stores electricity as high-temperature heat inside stacked firebricks, then releases that heat on demand as hot air or steam. Electric resistance wires warm the bricks to over 1,000°C when cheap renewable power is available. Air blown through the glowing stack picks up the heat and carries it out as superheated steam — a remarkably simple idea.
The appeal is the materials. Rondo’s storage medium is just brick and wire — common, proven, and incapable of catching fire, exploding, or leaking anything toxic. That’s a sharp contrast to chemical batteries. This form of thermal energy storage also runs at very high round-trip efficiency: Rondo reports above 97% for its commercial systems, as detailed by Electrek.
Why does that efficiency number matter so much? Because the whole point is to soak up surplus solar and wind when it’s abundant and cheap, hold it for hours, and hand it back as steady industrial heat. Lose too much in the round trip and the economics collapse. Brick stores heat well, so very little is wasted between charge and discharge.
The timing is the clever part. Power prices and solar output swing through the day. So the battery charges when power is cheapest — and the cheapest power of all is the plant’s own solar. Once those floating panels are paid off, the midday electricity they generate is essentially free, give or take maintenance. The battery soaks up that surplus and releases it as steady heat long after dark, shifting the plant off costly peak grid power without changing how it runs.
Why is cement so hard to clean up — and why Saraburi?
Cement is one of the world’s most stubborn climate problems, and Thailand’s footprint is concentrated in one place. The country’s cement sector emitted about 24.5 million tonnes of CO₂ in 2022 — close to 10% of Thailand’s total emissions, according to Reccessary. Saraburi alone accounts for roughly 80% of national cement production capacity.
That makes Saraburi the country’s second-highest carbon-emitting province after Bangkok, as TheReporterAsia notes. The trouble is the heat. Cement kilns need process temperatures near 1,400°C, and much of cement’s CO₂ comes from the chemistry of limestone itself, not just the fuel. A heat battery doesn’t fix that chemistry.
What it can do is clean up the electricity and steam side of the plant. By turning intermittent solar into firm, 24-hour steam and power, the Saraburi unit cuts fossil fuel burned for that slice of the operation. It’s a meaningful start, not a total solution — and the industry is honest about the distinction. Thailand’s cement makers have adopted a 2050 net-zero roadmap targeting 17.5 million tonnes by 2030.
Where does Thailand’s unit fit in Rondo’s global rollout?
The Saraburi battery sits in the middle of Rondo’s short but fast-growing deployment record. Rondo’s first commercial unit — a modest 2 MWh system — started up at the Calgren biorefinery in California back in March 2023, per Business Wire. Two and a half years later, the technology had scaled more than fiftyfold.
Just weeks before the Thai launch, Rondo powered up a 100 MWh battery — the world’s largest — at a Holmes Western Oil facility in California, running purely on an on-site 20 MW solar array, as covered by pv magazine. The Saraburi project’s significance isn’t raw size, then. It’s the first to pair the technology with cement, and the first in this region.
What does this mean for Thailand’s industrial decarbonization?
Saraburi was chosen for a reason: it’s the centerpiece of Thailand’s flagship low-carbon experiment. The “Saraburi Sandbox” aims to turn the province into the country’s first low-carbon city, with a target to cut 5 million tonnes of CO₂-equivalent by 2027 from a 2019 baseline of roughly 22.1 million tonnes, according to Nation Thailand. The heat battery is one visible proof point inside that wider renewable energy policy effort.
It also fits SCG’s own targets. The group has committed to Net Zero Cement and Concrete by 2050 and already runs its kilns on up to 48% alternative fuels instead of coal. Firm, clean steam from stored solar slots neatly into that transition.
Could the same approach spread beyond cement? The technology is industry-agnostic — it delivers heat, and heat is what most factories actually buy. Thailand’s food processors, chemical makers, and pulp mills all burn fuel for steam at temperatures a heat battery can comfortably reach. Each one is a candidate to firm up the country’s growing solar output the same way SCG just did, turning daytime panels into round-the-clock process heat.
One honest caveat: neither SCG nor Rondo has disclosed the installation cost, so the per-tonne economics aren’t yet public. And the unit doesn’t touch the kiln’s core chemistry. Still, the model travels well. Any heat-hungry industry — food processing, chemicals, paper — could use the same brick-and-wire approach to firm up renewable power. For a region racing to industrialize without locking in emissions, that’s a quietly important lesson from a cement town an hour north of Bangkok.
Frequently Asked Questions
What is a heat battery?
A heat battery stores electricity as high-temperature heat rather than as a chemical charge. Rondo’s design uses electric wires to heat stacked firebricks above 1,000°C, then blows air through them to release the energy as hot air or steam. It’s a form of thermal energy storage built from cheap, fireproof materials.
How big is the SCG Saraburi heat battery?
The Saraburi unit holds 33 MWh of thermal energy and delivers 2.3 MW of continuous steam. It charges from the grid and a nearby floating solar farm, then drives a steam turbine to generate round-the-clock power for cement production. Rondo built it in about eight months.
Does the heat battery replace fossil fuels at the cement plant entirely?
No. It cleans up the electricity and steam side of the plant by storing renewable power as firm heat. But cement kilns need roughly 1,400°C process heat, and much of cement’s CO₂ comes from limestone chemistry itself. The battery addresses part of the footprint, not all of it.
How is the heat battery charged?
It draws surplus electricity from the grid and from a floating solar farm beside the plant. The system is designed to charge when renewable power is cheap and plentiful, store that energy as heat in firebricks, and discharge it as steady steam whenever the cement plant needs it — day or night.
How does a heat battery compare to a lithium-ion battery?
Lithium-ion stores electricity and gives back electricity. A heat battery stores electricity as heat and gives back heat or steam, which suits industry directly. It uses brick and wire instead of scarce metals, can’t catch fire or leak, and runs above 97% round-trip efficiency for heat delivery.
Are there other heat battery projects in Southeast Asia?
The SCG Saraburi unit is the first industrial heat battery in Southeast Asia, commissioned in November 2025. Rondo’s other deployments are in the United States, including a 2 MWh system in California from 2023 and a 100 MWh battery — the world’s largest — that started up there in October 2025.