French startup Epyr raises €15M following successful industrial heat storage deployment

French industrial energy startup Epyr has closed a €15 million Series A led by SlateVC. Existing backers AENU and Daphni followed on, alongside WEPA Ventures, OVNI Capital and Aurum Impact. The bet is simple: if factories can get high-temperature heat from electricity for less than from gas, the switch finally starts to make sense.

That timing looks better than it used to. Industrial heat accounts for roughly 20% of global energy use, and in Europe it still mostly comes from burning fossil fuels, especially natural gas. Epyr says the market is shifting because fossil fuels remain costly and volatile after repeated crises, while renewable power can be very cheap when supply is high and demand is low.

Epyr’s answer is thermal storage. During low-price hours, electric resistors heat air, which then warms firebricks that hold the energy at high temperature until it is needed as industrial heat. The company packages that as Heat-as-a-Service, handling the technology, system integration, energy management and, when necessary, third-party financing.

The startup already has a working reference. In May 2026, it inaugurated its first installation at WEPA Group’s paper mill in Troyes, where the system was built and commissioned in less than six months and now covers up to 25% of the site’s steam needs. WEPA says the project proved both the technology and the partnership.

And there is a bigger job lined up. Epyr has been selected for a 35 MWh storage unit at Papeco’s Orval-sur-Sienne site, which is set to become France’s largest thermal energy storage project. That system is meant to replace all of the site’s natural gas use, with Energy Pool supporting the rollout from studies to operations. Epyr says more deployments are coming, focused on paper, food and beverage, and chemicals.