Factories heated by stored renewable heat

How far away are factories heated by stored renewable heat?

Heat stores made of sand, bricks or carbon blocks now run at several sites. Rondo has a 33 MWh unit supplying steam at a Thai cement plant and a 100 MWh unit at a California oil facility. Tata Steel is testing a 20 MWh unit at its Jamshedpur steelworks, and Antora has commissioned a 5 GWh multi-day store at a South Dakota biofuels plant. Most figures come from the companies involved. The sources reviewed include no independently measured, multi-year operating data, and none gives the cost of a project.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREPilots

Close. Early pilots are running in the real world.

Several stores of 20 to 100 MWh now run beside industrial plants, and a 5 GWh multi-day store has been commissioned. The base is still a handful of sites. The figures are mostly reported by the companies, the sources reviewed hold no independent multi-year data, and the 100-hour sand design has only been tested at 100 kW for 10 hours. That places the field at pilot, past the prototype stage but short of widespread use.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: Factories heated by stored renewable heat Unlocked Being researched Locked
  1. 2022Thermal energy storagePilot and early commercial Unlocked.
  1. 2024100-hour sand storage at pilot scaleIn progress Being researched.
  2. 2025One-year steel plant trialIn progress Being researched.
  3. 2025Sand battery supplying district heat at 100 MWh scaleDone Unlocked.
  4. 2025Heat battery running beside gas boilers at an oil facilityDone Unlocked.
  5. 2025Heat battery supplying steam to a cement plantDone Unlocked.
  6. 2026Multi-day store commissioned at a biofuels plantIn progress Being researched.
  7. Date not recordedFull-scale 100-hour sand siloNot started Locked.
  8. Date not recordedIndependent multi-year operating dataNot started Locked.
  1. GoalFactories heated by stored renewable heatGoalRequires: Thermal energy storage, Sand battery supplying district heat at 100 MWh scale, Heat battery supplying steam to a cement plant, Heat battery running beside gas boilers at an oil facility, One-year steel plant trial, Multi-day store commissioned at a biofuels plant, 100-hour sand storage at pilot scale, Full-scale 100-hour sand silo, Independent multi-year operating data. Locked.

The road so far

3 of 8 steps done, 3 in progress.

  1. Done · 11 Jun 2025Sand battery supplying district heat at 100 MWh scale

    Polar Night Energy and the operator Loviisan Lämpö commissioned a unit at Pornainen, Finland, rated at 1 MW thermal with 100 MWh of storage. It supplies a district heating network, not an industrial process. The announcement says the battery could cover almost a month of summer heat demand and close to a week in winter. The operator's expected cut of about 160 tonnes of CO2 equivalent a year is a projection. Efficiency and project cost were not disclosed. [1]

  2. Done · Nov 2025Heat battery supplying steam to a cement plant

    Rondo Energy reports that a 33 MWh system at SCG's cement plant in Saraburi, Thailand, is operating. It supplies 2.3 MW of continuous steam, which drives a turbine to make electricity, and is charged from the grid and a nearby floating solar farm. The company says it was built in eight months and that the project is economical. These are company statements. No efficiency or cost figure is given. [2]

  3. Done · Oct 2025Heat battery running beside gas boilers at an oil facility

    A 100 MWh Rondo unit at the Holmes Western oil facility in California has entered daily automatic operation, according to Rondo. It is charged by 20 MW of on-site solar, stores heat above 1000 °C, and works alongside gas-fired boilers, so it does not replace them. Rondo claims a round-trip efficiency above 97%. No project cost or contract value is stated. [3]

  4. In progress · May 2025One-year steel plant trial

    Kraftblock's 20 MWh heat battery at Tata Steel's Jamshedpur plant has run since May 2025 as a one-year test. It stores waste heat from sinter cooling at up to 500 °C, with charging up to 1.5 MW and discharge up to 1.8 MW. Kraftblock says the technology can reach 1300 °C. The projected 22,000 tonnes of CO2 a year is the company's own projection. No cost or efficiency figure is given, and the article mentions no independent confirmation. [4]

  5. In progress · May 2026Multi-day store commissioned at a biofuels plant

    Antora and POET have commissioned a store described as 5 gigawatt-hours at POET's Big Stone City plant in South Dakota. The figure comes from the joint POET and Antora announcement. Excess wind power is stored as heat in carbon blocks, which can supply process heat or be turned back into electricity. The project went from construction to delivery in under 12 months. Full operation is expected later in 2026. Temperatures, output in MW and project cost have not been published. [5]

  6. In progress · Jul 2024100-hour sand storage at pilot scale

    The US National Renewable Energy Laboratory (NREL) started a demonstration in July 2024 of sand heated to about 1200 °C by electric resistance heaters. The pilot runs at 100 kW for 10 hours. The target design is 100 hours of storage. [6]

  7. Not startedFull-scale 100-hour sand silo

    NREL describes a commercial silo for 100 hours of storage, up to 70 metres tall and 20 metres in diameter, storing and discharging hundreds of MW. This is a design described in the article, not a built unit. The sources reviewed describe no built silo of this size and give no delivery date for one. [6]

  8. Not startedIndependent multi-year operating data

    The sources reviewed contain no independently measured, multi-year record of heat delivered, heat lost or running cost from any industrial store. Such a record would show whether the operator figures hold over a full cycle of seasons and maintenance.

Why it matters

Many factories use fuel to make high-temperature heat for drying, cooking and making materials. If cheap stored heat can replace that fuel, factories could use renewable power when it is plentiful and cut fossil gas use. That would change how industrial sites are supplied and how much they depend on gas.

What stands in the way

  • Most performance and cost figures come from the companies that sell or run the systems. No independent multi-year operating data is in the sources reviewed.
  • Costs are not disclosed for the industrial projects reviewed, so there is no verified price for delivered process heat to compare with gas.
  • Multi-day storage at industrial scale has not been shown. NREL's 100-hour design has only been tested at 100 kW for 10 hours.
  • Efficiency figures are not like-for-like. Heat-in to heat-out figures above 97% cannot be compared with electricity-in to electricity-out figures of about 50 to 52% from modelling.
  • Heat must reach the temperature a process needs. Sites need heat exchangers and steam or heat delivery systems matched to each process, and these add cost and complexity.
  • Insulated stores lose heat over time. NREL reports about 1% a day for an insulated silo, so duration depends on insulation design.
  • The Holmes Western unit runs alongside gas boilers, so it shows integration with existing fuel, not a full replacement for it.

Published forecasts

What others have predicted. These are their estimates, not ours.

WhoForecastTimeframeMade
John O'Donnell (CEO, Rondo Energy)In its November 2022 launch release, Rondo's CEO said the company looked forward to first installations in 2023, and the release said it had begun commercial deliveries. The release named no customer. [7]202316 Nov 2022

Signals to watch

  • Tata Steel's decision on expanding the Jamshedpur test after its full year of operation, and any published heat delivered and efficiency figures.
  • POET's Big Stone City store reaching full operation later in 2026, with output, temperature and cost figures published.
  • Independent measurements of heat delivered, heat lost and running cost from at least one industrial store over several seasons.
  • NREL's results from the 10-hour pilot and any move to a larger 100-hour demonstration.
  • Published cost per MWh of delivered process heat, compared with gas-fired boilers, for a named project.
  • The US Department of Energy award negotiated with Diageo North America, which the pv magazine article says is not finalised.

Sources

  1. company announcement
    World's Largest Sand Battery Now in Operation
    Polar Night Energy, 11 Jun 2025.
  2. news
    Rondo Energy brings Southeast Asia's first industrial heat battery online in Thailand
    Tristan Rayner. ESS News, 21 Nov 2025.
  3. news
    Rondo Energy's 100 MWh heat battery powered by 20 MW of onsite solar
    William Driscoll. pv magazine USA, 17 Oct 2025.
  4. news
    Global giant Tata Steel is using a heat battery to curb emissions
    Maria Gallucci. Canary Media, 27 Feb 2026.
  5. news
    A huge 5 GWh thermal energy storage system is now delivering power to a South Dakota biofuels facility
    Sean Wolfe. Renewable Energy World, 20 May 2026.
  6. news
    Long-duration thermal energy storage in sand begins NREL demo
    Susan Kraemer. SolarPACES, 18 Sept 2024.
  7. company announcement
    Product launch: the Rondo Heat Battery (RHB), providing the world's lowest-cost, zero-carbon industrial heat
    Rondo Energy, 16 Nov 2022.

Last reviewed 21 Oct 2026.