Epyr raises €15M Series A to electrify industrial heat

Paris-based Epyr has raised a €15M Series A led by SlateVC, with AENU, Daphni, WEPA Ventures and OVNI Capital returning and Aurum Impact joining, to roll out its firebrick heat batteries across European industry.

European industry still burns gas for most of its process heat – and yet the cheapest energy on the continent is now the electricity we throw away at midday. A Paris team just raised €15M on the gap between those two facts, announced on 13 October 2026. Below, I lay out the round, the machine behind it, the market it compounds in, and the pattern worth watching.

Eighteen months from pre-seed to Series A

The round is €15M, Epyr’s first priced round since its €3M pre-seed of February 2025. SlateVC leads – the Paris climate investor that announced a €132M first close for its inaugural growth fund in February 2026, betting on industrial efficiency rather than green premium. AENU and Daphni, which co-led the pre-seed, increase their stakes; WEPA Ventures and OVNI Capital return; Aurum Impact joins the table.

The money goes into the next wave of industrial projects, starting with a 35 MWh unit at paper producer Papeco’s site in Orval-sur-Sienne, Normandy – a deployment Papeco describes as the largest thermal energy storage project in France, supported by Energy Pool and designed to replace the site’s entire natural gas consumption. From there, Epyr targets the steam-hungry trio of paper, food and beverage, and chemicals.

“In France, there have already been more hours with zero or negative electricity prices this year than in 2025,” said co-founders Léa Dardenne and Bastien Oggeri in the announcement. “That electricity is the cheapest, cleanest energy source European industry has.”

Firebricks against a gas bill

Epyr was founded by Dardenne, a former Boston Consulting Group partner specialised in energy, and Oggeri, a co-founder of insect farming scale-up Innovafeed. The product is almost provocatively simple: when electricity is cheap, smart controls run electric resistors that heat air; the air heats firebricks; the bricks hold the energy until the factory needs it back as hot air or steam. Epyr sells the whole package – hardware, integration, energy management, optional third-party financing – as Heat-as-a-Service, and the unit can balance the grid on the side.

The proof sits in Troyes. Epyr’s unit at WEPA Group’s paper mill there – France’s first industrial thermal energy storage installation – was built and commissioned in under six months, inaugurated in May 2026, and now covers up to a quarter of the site’s steam needs. Note who returned for the Series A: WEPA Ventures, the customer’s own investment arm. “Together with Epyr, we have shown that innovative energy solutions can be implemented quickly and successfully in an industrial environment,” said Andreas Krengel, member of WEPA’s management board, in the announcement.

A $5bn storage layer under a fifth of global energy

Industrial heat accounts for roughly 20% of global energy consumption, overwhelmingly fossil-fired and gas-dominated in Europe, per the figures Epyr cites in its announcement. SlateVC’s co-founder Sébastien Léger sizes the electrification of European industrial heat at €100bn in the same release. The storage layer underneath is smaller but compounding: the global thermal energy storage market was worth $5.0bn in 2023 and is forecast to reach $10.9bn by 2030, an 11.7% CAGR from 2024 to 2030, with Europe already the largest regional market (Grand View Research, 2024-2030 outlook).

Against our own fundraising data, €15M sits exactly where French industrial energy hardware is pricing this month: VoltR raised €22M to industrialise second life batteries last week, and 1KOMMA5° landed €70M for the consumer side of the same electrification story two days ago. The capital is moving down the stack, from software to firebricks.

Wasted electrons are becoming a business model

So what does a paper mill in Troyes tell us about European venture? That the renewables overbuild has quietly created a new raw material: the negative-price hour. France has more of them this year than in all of 2025, by the founders’ own count, and every one of them is margin for whoever can soak up the surplus and sell it back as heat, flexibility or storage. The companies we cover keep converging on that arbitrage from different directions – batteries, virtual power plants, now bricks.

The good news is that this is one race where Europe’s handicaps are the moat. Our gas is expensive, our grids are congested, our midday power is often free – exactly the spread a thermal battery monetises, and one that no team in Texas wakes up needing to solve this badly. What to watch now: whether Heat-as-a-Service contracts scale faster than equipment sales, and whether the next deployments stay in paper or jump to food and chemicals, where the steam bills are just as brutal.

Europe does not need to invent cheap clean energy – at midday, we already have it. The opportunity is storing it until the afternoon shift clocks in, and Epyr just raised €15M on exactly that premise. Watch where the next firebrick lands!