Léa Dardenne and Bastien Oggeri did not set out to build a battery. Their machine is closer to a kiln with a memory.
Epyr, the Paris company they founded in 2024, electrifies industrial heat. When power is cheap, its controls run electric resistors that heat air. The air heats a stack of firebricks. The bricks hold the heat, then hand it back as steam or hot air when a factory needs it. No flame. No gas line.
The pair raised €15 million in an oversubscribed Series A on October 13, led by SlateVC. AENU and Daphni, who backed the company at pre-seed, doubled down. WEPA Ventures returned. So did OVNI Capital. Aurum Impact joined.
It is Epyr's first priced round since a €3 million pre-seed in February 2025, and it takes total funding to €18 million.
Why heat is the harder half
Industrial heat is roughly 20% of global energy consumption, and in Europe it still comes mostly from burning natural gas. Dardenne, a former Boston Consulting Group partner, and Oggeri, who co-founded the insect-farming scale-up Innovafeed, are betting on a spread that Europe owns and Texas does not.
French power prices now fall to zero, or below it, at midday when wind and solar oversupply the grid. The founders say France logged more zero- or negative-price hours this year than in all of 2025. A factory that can absorb that cheap power and store it as heat turns a market quirk into a margin.
SlateVC co-founder Sébastien Léger puts the European market for electrified industrial heat at €100 billion. The storage layer underneath is smaller and compounding: the global thermal energy storage market was worth $5.0 billion in 2023 and is forecast to reach $10.9 billion by 2030, an 11.7% annual pace, per Grand View Research.
What the Troyes mill proved
Epyr's reference plant sits at WEPA Group's paper mill in Troyes, in northeastern France. It was designed, built and commissioned in under six months, and went live in May 2026. After three months of operation it covered about a quarter of the site's steam demand — a customer measurement, not a company projection.
The detail that matters sits in the cap table. WEPA Ventures, the mill owner's investment arm, returned for the Series A. The buyer is also a backer.
Epyr is not alone in chasing industrial heat. As we wrote in August, when Antora raised its Series C, and again in September on turning waste heat into power, the heat factories run on is becoming a venture category of its own.
The €15 million does not buy a factory
Epyr sells Heat-as-a-Service: hardware, system integration, energy management, and third-party financing where a client wants it. The model shifts the upfront cost and keeps Epyr in the operating loop.
The next project is the real test. Papeco, an independent French papermaker, selected Epyr for a 35 MWh unit at Orval-sur-Sienne in Normandy. If it works as designed, it will replace all of the site's natural gas. Energy Pool, a French flexibility operator, will run it, and ADEME supports the project under the France 2030 programme.
Papeco says the switch avoids 3,000 tonnes of CO2 a year. That is a project claim. The unit is not yet commissioned, and Epyr has not shown it can repeat the WEPA result at larger scale with a new customer.
€15M Series A · €18M raised total
35 MWh Papeco unit, full gas replacement
~25% of WEPA Troyes steam demand
20% of global energy consumption is industrial heat
What has to be true
Three things decide whether this compounds. Cheap midday power has to stay cheap and keep arriving in predictable blocks. Firebricks have to hold up over years of thermal cycling without losing capacity. And Heat-as-a-Service has to produce repeat customers, because one-off equipment sales do not build much of a business.
Epyr is prioritising paper, food and beverage, and chemicals. Those three industries run on steam, buy gas at industrial scale and price every therm. The gas boiler is the incumbent, and the pitch is arithmetic: a firebrick that buys at noon costs less than a flame that burns around the clock.