Summary:

Pumped hydro storage works like a water battery - using excess power to pump water uphill to a reservoir when electricity is cheap, then releasing it through turbines to generate power when needed, typically achieving 70-85% round-trip efficiency. Pumped hydro storage dominates the grid-scale energy storage landscape, with 160 GW of installed capacity representing about 80% of global storage. This dwarfs other technologies like lithium-ion batteries (30 GW) and thermal storage (6 GW combined). 60 new projects are under construction with capacity projected to reach 240 GW by 2030. Most installations range from 100 MW to over 1000 MW in size, offering the large-scale, long-duration storage capabilities crucial for grid stability. But pumped hydro storage can only be deployed where there are natural elevation differences like mountains limiting deployment. But what if, you didn’t need mountains. Where we’re going we don’t need mountains.

Key Takeaways:

1. Underground Data Center Synergy One of the most fascinating aspects is how GPHS facilities can be multi-purposed. The underground infrastructure created for pumped hydro can also house data centers, which benefit from naturally cooler underground temperatures. This multi-use approach significantly improves the economics by sharing infrastructure costs across different revenue streams. It's a clever way to make the technology more commercially viable while solving multiple problems at once.
2. The Nuclear Connection There's an unexpected symbiotic relationship between nuclear power and pumped hydro storage. While they might seem like competitors in the energy space, pumped hydro has "always been a friend to nuclear" because nuclear plants need balancing services. This reveals how different clean energy technologies can complement rather than compete with each other. Interestingly, in terms of grid reliability metrics (derating factor), long-duration storage ranks higher than nuclear power for security of supply.
3. Geographic Flexibility vs Traditional Constraints While traditional pumped hydro is limited to locations with mountains, GPHS can be placed almost anywhere with suitable geology. This geographic flexibility allows for strategic placement near population centers and grid infrastructure, potentially transforming energy storage from a geography-dependent to a geology-dependent solution. The caveat about salt caverns being unsuitable (because "it would just become salty water") shows how the technology still has specific geological requirements, just different ones from traditional pumped hydro.

Interview:

Morning Peep, what is Traditional Pumped Hydro Storage (PHS) and what is it used for?

Pumped Hydro Storage is currently the most mature and widespread form of large-scale energy storage, accounting for over 90% of utility-scale storage globally with about 160 GW of capacity. Traditional PHS requires natural topographical features, typically mountains, to create the necessary height difference between two water reservoirs. Water is pumped to the higher reservoir when electricity is cheap or abundant, and released through turbines to generate electricity when needed. Major users include China, Japan, the US, and Europe. It's primarily used for storing large amounts of energy over long periods, helping balance the grid and integrate renewable energy sources.

What is Geotechnical Pumped Hydro Storage (GPHS) and how does it differ?

GPHS is an innovative approach that removes the need for natural topographical features like mountains. Instead, it utilizes underground reservoirs to create the necessary height difference. Our company, Zero Terrain, enables PHS in regions without traditional environmental prerequisites by using the Earth's crust for lower reservoirs and surface water bodies for upper reservoirs. This approach has several advantages: reduced environmental impact, lower CO2 emissions, and decreased land use compared to traditional PHS. There's also potential additional income from selling excavated rock. The key innovation is that we can implement pumped hydro storage in locations where it wasn't previously possible due to topographical constraints.

Can you explain how you see the market bifurcating between short-term and long-term duration storage technologies?

There is already a very clear distinction between short-term and long-term storage, not just technology-wise, but because of the needs. Short duration storage focuses on two aspects: providing system services (like frequency regulation) and maintaining renewable energy producers' business model by increasing the capture price for wind and solar operators. When it comes to long duration storage, there are two additional important features. First, it replaces the need for fossil fuels, particularly gas. It efficiently replaces gas-fired power needs on the market, thus reducing costs and energy bills for consumers. Second is security of supply - it effectively replaces the need for fossil fuel-based energy generation. In the UK and Poland, long duration energy storage assets are more valued than gas turbines. The derating factor, which is key for security of supply, is somewhat higher for long duration storage compared to gas plants. Nuclear is far below both gas and long duration energy storage in this regard. Both short and long duration storage are needed, but I'm convinced that pumped hydro storage will play an even bigger role than today in long duration storage.

What geological conditions do you require for GPHS?