Heat Batteries: The Quiet Engine of Green Industry

Most companies chasing “net-zero by 2050” hit the same wall: industrial heat. You can electrify cars and offices, but you can’t run a cement kiln at 1,400°C with good intentions and a few rooftop panels.

Here’s the thing about heavy industry: heat is the real carbon problem. It’s roughly half of industrial energy use worldwide, and most of it still comes from burning fossil fuels. That’s why Rondo Energy’s new 33MWh industrial heat battery in Thailand isn’t just another storage project – it’s a live example of how green technology and smart energy storage can finally start cutting emissions where they’re hardest to tackle.

This post looks at what Rondo and SCG Cleanergy have actually built, why industrial thermal energy storage matters, and how heat batteries fit into the wider green technology story – especially if you’re running or advising an energy‑intensive business in 2025.

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What Rondo’s Thailand Project Really Proves

Rondo Energy’s 33MWh Heat Battery at SCG’s cement plant in Saraburi, Thailand, is more than a regional first. It quietly answers three questions every industrial decision-maker asks about new green tech: Does it work? Does it scale? Is it local?

What was deployed?
Rondo and SCG Cleanergy have brought online Southeast Asia’s first industrial thermal battery energy storage system at an operating cement plant. Key points:

• Capacity: 33MWh of stored thermal energy
• Application: Cement manufacturing, one of the most energy- and carbon-intensive industries on the planet
• Integration: Tied into the plant’s existing heat recovery system
• Output: Superheated steam powering a steam turbine – delivering both process heat and electricity inside the facility

Instead of just storing electricity like a lithium-ion battery, the Rondo Heat Battery (RHB):

1. Takes in low-cost or surplus electricity (from the grid or renewables)
2. Stores it as high-temperature heat in specially engineered bricks or similar refractories
3. Releases that heat on demand as superheated steam or hot air for industrial processes

At Saraburi, the RHB acts as an add-on to the existing heat recovery turbine, boosting power output and providing a controllable clean heat source. It’s not replacing the plant overnight – it’s improving and decarbonising what’s already there. That’s a smart decarbonisation approach most plants can actually live with.

Why this matters for Southeast Asia
SCG and Rondo manufactured the system entirely in Thailand, using local supply chains. That’s huge for two reasons:

• It builds local capability instead of importing every component
• It proves these systems can be replicated across the region without waiting on foreign factories or long lead times

For a region with aggressive manufacturing growth and rising energy demand, this isn’t a demo – it’s a template.

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How Industrial Heat Batteries Work (And Why They Beat Fossil Boilers)

Industrial heat batteries are simple in concept: turn cheap or renewable electricity into very hot, storable heat, then deliver it exactly when your process needs it.

The Rondo model in plain language

Rondo’s Heat Battery works roughly like this:

1. Charge phase

   • Use electricity (ideally cheap, off‑peak, or directly from solar/wind) to run electric heaters.
   • Those heaters warm up stacks of refractory bricks or similar materials to temperatures up to ~1,000°C in existing systems, and designs can reach higher.

2. Storage phase

   • The hot bricks simply sit and hold heat, with very low energy loss thanks to insulation.
   • No complex chemistry. No rare metals. Just high‑temperature materials doing their job.

3. Discharge phase

   • When the plant needs heat, air or another working fluid is pushed through the hot bricks.
   • That stream turns into superheated air or steam, which can:
     • Feed a turbine (as in the SCG plant), or
     • Go straight into kilns, dryers, or other high‑temperature processes.

The reality is simpler than most people expect. There’s no exotic physics, just good thermal engineering and control.

Why this beats traditional fossil heat

Compared to a gas- or coal-fired boiler or kiln, a mature industrial heat battery offers:

• Major emissions reduction
  When charged from renewables or low-carbon grid power, you’re effectively swapping combustion for stored green electricity.

• Cost stability
  You can charge the battery when electricity is cheap (for example, midday solar peaks or nighttime wind) and use that stored heat when power prices or fossil fuel costs are high.

• High temperatures
  Rondo’s early commercial systems already hit 1,000°C, and the tech is being pushed toward temperatures suitable for cement, steel, and chemicals.

• Longevity and simplicity
  No degradation curves like lithium-ion. The core materials are bricks and steel. Maintenance is more like a furnace than a battery pack.

When you put this in the context of green technology more broadly, industrial heat batteries are one of the few storage technologies directly matching how heavy industry actually consumes energy: as heat, not just electrons.

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Why Cement, Steel, and Chemicals Need Thermal Storage

If you’re serious about industrial decarbonisation, you eventually end up staring at the same pie chart: cement, steel, and chemicals collectively account for a huge slice of global CO₂ emissions because they need extreme heat.

The industrial heat problem

Processes like:

• Clinker formation in cement: >1,400°C
• Steelmaking: often >1,500°C
• High-temperature chemical reactions: 500–1,200°C

are all incredibly hard to electrify with standard approaches. Direct electric heating is possible in some cases, but it’s often:

• Expensive
• Disruptive to retrofit
• Dependent on a constant supply of cheap clean electricity, which most grids can’t guarantee year‑round yet

Thermal battery systems bridge that gap by smoothing out intermittent renewables into a dependable industrial heat supply.

Rondo’s scaling story shows the trajectory

The Thailand project isn’t happening in isolation. It follows a clear scale‑up path:

• 2MWh pilot: Initial commercial deployment proved that the system could hit 1,000°C and operate reliably.
• 100MWh California project: Built for Holmes Western Oil Corporation, delivering continuous steam from off‑grid solar – showing it can provide 24/7 industrial heat with no grid connection.
• 100MWh system for Heineken in Portugal: Will charge directly from a ground-mounted solar PV plant at the Vialonga Brewery and Malting Plant – clean heat for food and beverage, not just heavy industry.
• 90GWh gigafactory ramp-up: Rondo is planning manufacturing capacity on a scale that lines up with mass-market industrial adoption, not niche pilots.

The Thai cement plant sits right in the middle of that story: large enough to be commercial, integrated enough to be replicable.

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Why Southeast Asia Is a Hotspot for Heat Batteries

Southeast Asia is quickly becoming one of the most interesting regions for industrial green technology. The Rondo–SCG project hits several strategic trends at once.

Strong manufacturing, rising climate pressure

The region has:

• Large cement, steel, and manufacturing sectors
• Rapidly growing electricity demand
• National climate commitments that now have real teeth in policy and finance

Thermal energy storage plugs into this reality because it:

• Lets industries grow without simply scaling fossil fuel use
• Uses local manufacturing and supply chains, as seen in Thailand
• Offers a way to use regional solar and wind resources more effectively for industry

Policy and finance tailwinds

At events like the Energy Storage Summit Asia 2025, one theme kept coming up: batteries alone won’t decarbonise everything. Grid-scale lithium systems are great for balancing supply and demand, but they’re not the right tool for every job.

Industrial heat batteries:

• Sit behind the meter at factories
• Directly displace fossil consumption
• Can be financed as infrastructure with clear, measurable fuel savings

For energy buyers and sustainability leaders in the region, this is attractive because it ties decarbonisation to hard numbers: fuel costs avoided, tonnes of CO₂ reduced per year, and predictable payback periods.

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Practical Steps for Companies Considering Industrial Heat Storage

If you’re responsible for decarbonisation, operations, or strategy in an energy-intensive business, heat batteries might sound promising but abstract. Here’s how to turn this into a concrete roadmap.

1. Map your heat loads, not just your electricity use

Most energy audits obsess over kWh of electricity. For industrial decarbonisation, you need a temperature‑resolved heat map of your processes:

• What temperature ranges do you operate at (e.g., 120°C, 250°C, 600°C, 1,000°C+)?
• Which loads are continuous vs. batch?
• Where are you already doing waste heat recovery?

Thermal storage works best where you have consistent, high-temperature needs and some flexibility about when exactly you deliver the heat.

2. Identify where renewables can feed a heat battery

Ask questions like:

• Do you have land or rooftop space for dedicated solar PV or wind?
• Are you in a market with significant off-peak price spreads?
• Could you sign a PPA for cheap green electricity and route it into a thermal storage system?

You’re looking for situations where electricity is cheap or clean at specific times, but your heat demand doesn’t line up perfectly with that profile. That mismatch is exactly what a heat battery exploits.

3. Start with brownfield integrations, not “rip and replace”

One of the smartest aspects of the SCG project is that it works alongside an existing heat recovery system and turbine. For most plants, that’s a more realistic first step than rebuilding your entire thermal system.

Good early candidates include:

• Boosting existing steam systems
• Supplying preheating stages
• Serving processes with moderate retrofit complexity

You get emissions reductions and operational experience without betting the entire plant on one new technology.

4. Use digital tools and AI to optimise operations

This is where the “Green Technology” series theme really shows up. AI and advanced analytics can:

• Predict electricity price curves and renewable output
• Optimise charge/discharge cycles of your heat battery
• Coordinate with other assets like chillers, boilers, and on-site generation

I’ve found that the biggest wins often come not from the hardware alone, but from smart control strategies that continuously adapt to market prices, weather, and production schedules. That’s where AI earns its keep.

5. Build a phased decarbonisation plan

Industrial decarbonisation is a marathon. A realistic plan might look like:

1. Year 1–2: Detailed heat mapping, feasibility studies, and pilot projects on smaller loads.
2. Year 3–5: First large-scale heat battery integrated with existing waste heat and renewables.
3. Year 5–10: Expansion to more processes, potential fossil phase‑down, integration with green hydrogen or other low‑carbon fuels where needed.

Heat batteries are one of the few tools that can show meaningful reductions in Scope 1 emissions in this decade, which is exactly what regulators, investors, and customers are increasingly demanding.

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Where Heat Batteries Fit in the Bigger Green Technology Picture

Green technology isn’t just about shiny solar panels or EVs anymore. The next wave is about deep decarbonisation of industry, and that requires:

• Smart energy storage that matches how factories actually use energy
• Advanced AI and control systems to orchestrate complex energy flows
• Flexible financing and policy frameworks that reward real emissions cuts

Rondo’s projects in Thailand, California, and Europe show that industrial heat batteries are ready to move from slide decks into factories. They’re not a silver bullet, but they are one of the few proven ways to convert intermittent clean electricity into the high‑temperature heat that cement, steel, chemicals, and food & beverage depend on.

For businesses, the question isn’t whether thermal energy storage will matter – it’s how soon your competitors will start using it to cut fuel costs and emissions while positioning themselves as credible climate leaders.

If you’re already exploring solar, wind, or battery storage, the next logical step is simple: put your heat loads on the table and ask where an industrial heat battery could replace fossil fuel combustion. That’s where green technology stops being a CSR line and starts rewriting your cost structure – and your carbon footprint – at the same time.