Summary

• Epyr has raised €15m in Series A financing led by SlateVC to expand thermal energy storage for industrial steam production.
• Its operating installation at WEPA's Troyes paper mill reportedly supplies up to a quarter of the site's steam requirements.
• A planned 35MWh system at Papeco represents the next commercial project, with the economics dependent on electricity prices, system performance and financing arrangements.

French energy technology company Epyr has raised €15 million to expand industrial thermal energy storage, moving towards larger installations after commissioning a system that supplies part of the steam required by a working paper mill in Troyes.

The Series A financing, announced on 13 October, was led by SlateVC, with existing investors AENU, Daphni, OVNI Capital, WEPA Ventures and Aurum Impact participating. Epyr plans to use the capital to develop and deliver further industrial projects, beginning with a recently announced 35MWh installation at French paper manufacturer Papeco.

Rather than storing electricity for subsequent conversion back into electrical power, Epyr’s technology converts electricity into heat and retains that energy for use when an industrial process requires steam. The arrangement allows electricity consumption to be shifted towards periods when prices are favourable, while factories continue receiving heat according to their production requirements.

The approach addresses a substantial cost consideration for industries that rely on natural gas to generate process heat. Electrification can reduce dependence on fossil fuel combustion, but manufacturers need confidence that the resulting supply will remain reliable and commercially competitive across changing electricity and gas prices.

Separating electricity purchases from heat demand

Epyr’s system uses electrical resistance heating to warm air, which transfers energy into a high-temperature storage medium made from firebricks. Once charged, the storage unit releases heat when required by the industrial process, allowing steam production to continue without consuming electricity at the same rate throughout the day.

The technology is designed around differences between when electricity is economically attractive to purchase and when factories require energy. Renewable generation can produce periods of relatively low wholesale electricity prices, particularly when wind or solar output is strong in relation to demand.

Storing energy during those periods may reduce the cost of producing industrial heat, provided the system has sufficient capacity to serve its intended workload. The financial outcome also depends on charging efficiency, heat losses, network costs and the amount of time for which stored energy can support production.

For a manufacturer operating continuously, the ability to avoid electricity consumption during expensive hours can be valuable. However, a storage unit must be sized to match the site’s thermal demand, and the system may require additional charging capacity if inexpensive electricity is available only for limited periods.

The equipment must also integrate with existing steam production and distribution infrastructure. Pressure, temperature and the rate at which heat can be delivered all determine whether stored energy can replace gas-fired production during normal operation.

These engineering requirements differ between industrial sites. A paper mill with relatively stable steam demand may offer different operating conditions from a food processing facility where production patterns change during the day, while sites with limited electrical network capacity may face additional costs before installing equipment.

Epyr combines the technology with system integration and energy management services. Its offer can also include third-party financing through a Heat-as-a-Service arrangement, under which the industrial customer purchases delivered heat rather than necessarily financing every part of the installation directly.

Such agreements may reduce the initial capital required from manufacturers, although they replace some upfront expenditure with continuing contractual commitments. The resulting economics depend on the price of delivered heat, operating responsibilities, equipment availability and how electricity market risks are allocated between the parties.

The company’s financing announcement does not disclose the prices agreed with customers or provide independently verified comparisons between the cost of stored electrical heat and conventional gas-fired steam production. Its assertion that the technology can be competitive therefore remains dependent on project-specific circumstances.

WEPA provides an operating reference

Epyr’s existing installation is located at WEPA Group’s paper mill in Troyes, France, where the company commissioned an industrial thermal storage system earlier in 2026. The installation was formally inaugurated in May after development and construction that Epyr says took less than six months.

The project received public support through France 2030, administered by the French environment and energy agency ADEME. It therefore combines private industrial investment with government backing intended to advance technologies that could reduce emissions from industrial production.

After approximately three months of commercial operation, Epyr reported that its system was supplying around a quarter of the plant’s steam requirements. The company has also described the installation as contributing up to 25% of the site’s demand, providing a useful indication of scale without establishing that the proportion is maintained under every operating condition.

WEPA’s participation provides evidence that the technology can be integrated into a working manufacturing environment. The project has moved beyond a laboratory demonstration, and the customer has publicly confirmed the installation’s operation without disruption to its production during commissioning.

Nevertheless, the published information does not include a complete independent assessment of availability, thermal efficiency or the actual cost of delivered steam over a representative operating period. Those measurements would be needed to compare the installation fully with alternative methods of industrial heat production.

Epyr says the Troyes system also participates in reserve markets operated by French electricity transmission system operator RTE. By adjusting electricity consumption in response to power system requirements, a thermal storage unit may provide useful flexibility while continuing to meet the factory’s demand from stored energy.

Participation in such services can create additional value, but the associated revenue depends on market rules, eligibility and actual operating conditions. The company has not disclosed earnings from the arrangement, making it premature to include reserve market income as an established contribution to the project’s financial performance.

Papeco will test a larger deployment

Epyr’s next announced project is at Papeco’s paper mill in Orval-sur-Sienne, where it has been selected to deliver a 35MWh thermal storage installation. The scheme is intended to replace natural gas consumption at the site, with Energy Pool supporting the project from its study phase towards operation.

The 35MWh figure describes the amount of energy the system is designed to store, rather than the electrical power required for charging or the instantaneous rate at which heat can be delivered. Those separate characteristics determine how the equipment can operate within the factory’s energy requirements.

Although the project is planned to replace the site’s gas consumption, that outcome has not yet been demonstrated in commercial operation. The final contribution will depend on successful construction, commissioning and integration with Papeco’s existing production equipment.

A larger installation may improve the range of electricity market conditions under which stored heat can be used, provided the charging system and network connection support the required operating schedule. It may also introduce additional installation and financing costs, so storage capacity alone cannot establish the economics of the project.

Epyr is concentrating on industrial steam applications in paper manufacturing, food and beverage production, and chemicals, where a recurring heat requirement can create opportunities for thermal storage. The company’s ability to expand beyond its existing reference will depend on identifying sites with suitable electricity access, operating requirements and commercial conditions.

The financing comes as European manufacturers face pressure to reduce emissions while maintaining internationally competitive production costs. Electrification can offer an alternative to direct fossil fuel combustion, but low-carbon electricity availability and the cost of connecting industrial sites remain important constraints on deployment.

With a functioning installation at WEPA and a larger project planned at Papeco, Epyr has evidence of initial industrial adoption and a defined route towards further deployment. The €15 million investment supports that expansion, while subsequent projects will need to demonstrate whether reliable operation and favourable energy purchasing can deliver competitive heat costs across different factories.