ESREE Energy raises undisclosed funding from ReGACY Innovation Group to scale gravel-based thermal energy storage
What's the deal? Tokyo-based ESREE EnergyDealroom has a profile for this one. Try Dealroom →, a startup developing gravel-based thermal energy storage, has received an investment from ReGACY Innovation GroupDealroom has a profile for this one. Try Dealroom →. The exact funding amount was not disclosed.
ESREE Energy converts surplus renewable electricity into heat stored in gravel, targeting industrial processes that require temperatures around 200°C. It has already built a 1kWh prototype storage unit as part of an accelerator programme in Takehara, Hiroshima Prefecture.
The startup was selected through "Takehara DX," an accelerator programme run by ReGACY that pairs startups with the small coastal city to solve local challenges and spur new industries. ReGACY said it will take an active role in coordinating partnerships among ESREE Energy, the city, local businesses, and nearby universities.
Why now? Roughly 50% of the world's final energy consumption comes from heat, yet decarbonising industrial heat has lagged far behind the electrification of power grids. Japan's industrial sector, which relies heavily on mid-to-low-temperature processes, faces growing pressure to find viable green alternatives.
Solar power curtailment is also rising across Japan, creating cheap surplus electricity during daytime hours — exactly the input ESREE Energy's system is designed to absorb and store for round-the-clock steam generation.
What could go wrong? The technology is still at proof-of-concept stage. Scaling from a 1kWh demo unit to the 1,000kWh systems the company is targeting for commercial deployment is a significant engineering leap. ReGACY executive Tateo Okeya acknowledged that technical hurdles and difficult business models have prevented breakthrough services in this space for years.
Commercialisation also depends on persuading local industrial operators to adopt an unproven system — a notoriously slow process in Japan's conservative manufacturing sector.
The signal: Industrial heat accounts for roughly half of global energy consumption yet remains one of the hardest sectors to decarbonise, leaving a vast market with few clean solutions. ReGACY's bet — as a corporate investor that channels startups into municipal accelerator programmes — illustrates an emerging Japanese model in which rural cities serve as live testbeds for early-stage deep tech, lowering the barrier to first deployments that pure venture capital rarely underwrites.
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