Pumped Thermal Energy: the Overlooked Storage Solution with Alexis Dole (SynchroStor)

As the grid decarbonises, our need for flexible, affordable, and longer-duration energy storage is growing fast. But are we overlooking some of the best tools for the job?

Whilst lithium-ion and pumped hydro dominate the energy storage conversation, thermal energy storage offers a low-cost, scalable alternative that could complement renewables at massive scale.

Explore how pumped thermal energy storage works, what makes it commercially compelling, and why it deserves more attention in the conversation around grid flexibility and net zero. In this episode, Alexis Dole, CTO at SynchroStor, joins Quentin. Over the course of the conversation they discuss:

• What sets thermal energy storage apart from alternatives like lithium-ion and pumped hydro.
• Why Synchrostor is betting on crushed rock and heat cycles over batteries.
• The storage challenge: balancing duration, cost, efficiency, and scale.
• How to design storage for real-world flexibility - not just peak shaving.
• Why the market undervalues long-duration storage and how that’s starting to shift.

About our Guest

Alexis Dole is Chief Technology Officer at Synchrostor, a UK-based company developing pumped thermal energy storage solutions. With a background in mechanical and energy systems engineering, Alexis leads the development of novel long-duration storage technologies designed to integrate clean energy more effectively into the grid. For more information on SynchrStore - head to their website.

About Modo Energy

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