Key Takeaways
- Edinburgh-based Exergy3 has raised €11.4 million (around £10 million) in seed funding to scale its ultra‑high temperature thermal energy storage technology for industrial heat.
- The round is led by Axeleo Capital, with participation from Bayern Kapital, Kibo Invest, and existing backers Scottish Enterprise, Zero Carbon Capital, and Old College Capital.
- Exergy3’s system converts curtailed or negative-priced renewable electricity into high-temperature process heat, tackling industrial decarbonisation, grid balancing, and energy security in one platform.
- The company plans to move rapidly from pilot projects to commercial deployment, targeting heavy industry which accounts for over 20% of global energy consumption.
Quick Recap
Edinburgh-based clean heat startup Exergy3 has closed a €11.4 million seed round to commercialise its ultra‑high temperature thermal energy storage systems that convert surplus renewable power into industrial heat.
The funding, equivalent to roughly £10 million, was announced via EU-Startups on social media and confirmed by accompanying investor and university statements. The capital will help Exergy3 scale from pilots to full commercial rollouts, targeting energy‑intensive industries across Europe.
Turning wasted renewables into industrial heat
Exergy3, a University of Edinburgh spinout, has developed modular thermal energy storage systems that convert curtailed or negative-priced renewable electricity into heat stored at ultra‑high temperatures, above 1,000 degrees Celsius. This heat can be dispatched on demand for energy‑intensive processes, effectively transforming wasted wind or solar generation into firm, low‑carbon industrial heat and easing pressure on overloaded grids.
The €11.4 million seed round is led by French investor Axeleo Capital’s Article 9 Green Tech Industry fund, joined by Bavaria‑based Bayern Kapital and Singapore‑based Kibo Invest, alongside existing investors Scottish Enterprise, Zero Carbon Capital and Old College Capital.
CEO Markus Rondé frames the opportunity as solving “two sides of the same problem,” linking industries’ need for reliable high‑temperature heat with the growing volumes of renewable generation that are currently curtailed. Exergy3 will deploy the capital to scale manufacturing, expand its team and move quickly from demonstration sites, such as distillery applications, to larger commercial installations.
Why this matters in the energy transition?
Industrial heat remains one of the hardest parts of the energy system to decarbonise, since many processes require continuous temperatures that are still largely supplied by fossil fuels. At the same time, as wind and solar capacity grow, grid operators are curtailing increasing amounts of clean power that could otherwise displace fossil energy if stored effectively.
Technologies like Exergy3’s high‑temperature thermal batteries aim to bridge this gap by storing surplus electricity as heat at a fraction of the cost of conventional electrochemical batteries, particularly for multi‑hour or daily applications. The market for long‑duration and thermal storage is heating up, with players such as Fourth Power and other thermal battery developers also targeting grid‑scale and industrial customers using ultra‑high temperature storage media.
Exergy3’s focus on directly supplying industrial process heat, rather than converting back to electricity, positions it squarely in the emerging “heat‑as‑a‑service” segment of climate hardware. If it can prove reliability and cost competitiveness at scale, the company could become a key enabler of Europe’s decarbonisation and energy security goals.
Competitive landscape
For context, here is a comparison between Exergy3 and two relevant thermal storage peers, Rondo Energy and Fourth Power, both of which also focus on high‑temperature storage for industrial and grid applications. (Values are indicative, based on public descriptions of capabilities rather than strict like‑for‑like pricing disclosures.)
Industrial thermal storage snapshot
| Feature/Metric | Exergy3 (news subject) | Rondo Energy | Fourth Power |
| Primary focus | Surplus renewables to high‑temperature industrial heat | Industrial heat from intermittent renewables | Grid and industrial power via thermal battery |
| Typical temperature range | >1,000°C ultra‑high temperature storage | Up to ~1,000°C class thermal bricks (public claims) | 1,900–2,400°C thermal battery system |
| Context window (use case span) | Multi‑hour to daily industrial processes, grid balancing | Multi‑hour to daily industrial processes | 10–100+ hours grid‑oriented storage duration |
| Pricing per MWh stored** | Targeting low‑cost heat below fossil alternatives | Markets storage as lower cost than fuel alternatives | Aims for storage cost below lithium‑ion at grid scale |
| Multimodal support (heat vs power) | Heat only (industrial process heat) | Primarily heat, potential for power via add‑ons | Heat plus conversion back to electricity |
| Agentic capabilities (smart control) | Dispatchable heat integrated with grid signals under development | Smart controls for charging during low‑cost periods | Advanced controls to stack storage modules and durations |
While Exergy3 appears strongest where customers want direct, low‑carbon industrial heat at very high temperatures, Fourth Power is pushing the envelope on duration and flexibility by converting stored heat back into electricity for grids and power‑hungry infrastructure. Rondo‑style systems meanwhile may retain an edge in more mature deployments today, particularly where customers already view thermal bricks as a proven retrofit solution for existing boilers and process lines.
Sci-Tech Today’s Takeaway
In my experience, rounds like this signal that investors are becoming far more comfortable backing heavy climate hardware at seed stage when the pathway to revenue is tied to clear industrial pain points and grid constraints. I think this is a big deal because Exergy3 is not just another storage play; it directly monetises curtailed renewables and converts them into a revenue‑generating, fossil‑displacing heat stream for factories.
From a funding perspective, a €11.4 million seed round, led by a specialist Article 9 fund and flanked by public and international climate investors, looks decidedly bullish for adoption if the team executes on commercial rollouts. I generally prefer models that tie climate impact to clear cost savings, and Exergy3 seems to sit exactly at that intersection, positioning this raise as a strong vote of confidence in thermal storage as a core pillar of the next energy system.
