In late November 2023, in a remote area of Devon, England, workers at RheEnergise began creating a unique energy storage solution. They mixed a light brown powder with water to form a special fluid, designed to store energy more efficiently. This innovative fluid is intended to be 2.5 times denser than water, enabling a new approach to pumped hydro energy storage.
According to Stephen Crosher, CEO and co-founder of RheEnergise, the process is hands-on, requiring careful blending to ensure the mineral-based fluid flows smoothly. The company’s demonstration system, located at a china clay mine near Plymouth, utilizes this mixture to generate electricity by driving turbines as it moves through angled pipes connecting an upper reservoir to a lower one, situated 80 meters below.
This project represents a modern twist on a traditional technology that dates back to the late 19th century. While pumped hydro energy storage was initially developed to complement fossil fuel plants, it has recently seen renewed interest as a means to balance the growing amounts of variable renewable energy sources like wind and solar. The technology allows for rapid adjustments to electricity supply, filling gaps in generation or absorbing surplus energy almost instantaneously.
The Economic Impact of Pumped Hydro
In the UK alone, it’s estimated that over £1 billion (approximately $1.32 billion) was lost in 2023 due to the shutdown of wind turbines, prompted by insufficient energy demand. This highlights the potential of pumped hydro plants to mitigate energy waste by storing excess power for future use. Traditional pumped hydro projects often require significant investments and infrastructure, which can be a barrier to development.
RheEnergise’s denser fluid allows for a more compact energy storage solution, significantly reducing the need for large reservoirs and high elevations. Crosher claims there are approximately 6,500 suitable sites for their technology in the UK alone, compared to only 20 to 25 locations ideal for conventional pumped hydro. If successful, RheEnergise could unlock hundreds of thousands of potential sites globally.
The company announced that it generated its first power from the demonstration system in March 2024. If the results continue to meet expectations, a commercial-scale project with a capacity of 10 megawatts (MW) could be operational by 2028.
A Global Perspective on Pumped Hydro
RheEnergise is not an isolated example; the global pumped hydro sector is witnessing significant growth. According to the International Hydropower Association (IHA), around 600 gigawatts (GW) of pumped hydro projects are currently in development, with 8.4 GW added in 2023 alone. A notable example is the 3.6 GW facility in Fengning, China, the largest pumped hydro plant by capacity worldwide. Such facilities are essential for managing large-scale energy demands.
In central Germany, the Goldisthal pumped hydro power station connects a reservoir containing approximately 12 million cubic meters of water to a lower reservoir with nearly 19 million cubic meters. The facility can provide 1.06 GW of electricity for up to nine hours and can switch rapidly between energy generation and storage modes. This operational flexibility is becoming increasingly crucial as renewable energy sources fluctuate.
As the demand for energy storage solutions rises, research indicates that countries around the world possess geographies suitable for pumped hydro. A recent report by Rosie Madge from Energy Systems Catapult evaluated 11 countries for their suitability in pumped hydro and other long-term storage technologies. While countries like Denmark and the Netherlands scored lower due to their flat landscapes, others, including the UK, Australia, and China, exhibited strong potential for high-density pumped hydro.
In Australia, the ambitious Snowy 2.0 project is currently under construction, aiming to expand an existing pumped hydro system with a projected capacity of 350 GWh upon completion. However, the project has faced numerous challenges, including delays and cost overruns. The final estimate for Snowy 2.0 has ballooned to between AUD $15 billion and AUD $18 billion, well above the original AUD $2 billion projection.
Despite these challenges, experts like Andrew Blakers of the Australian National University affirm the long-term value of pumped hydro, highlighting its potential to deliver cost-effective energy storage solutions over a 150-year lifespan.
As the world continues to grapple with the demands of energy transition, the evolution of pumped hydro technologies is critical. While traditional large-scale projects will remain significant, companies like RheEnergise are pioneering faster, more flexible solutions that could address the pressing need for efficient energy storage in the face of climate change.
