| Pumped storage
and deployment of a ‘push’ system to place logging tools in horizontal boreholes. “Our team has considerable experience in using them on horizontal boreholes up to about 40m in length. However, these were up to around 280m so the magnitude of the task could not be underestimated.” He added: “There were other challenges – notably in designing a push system for the raised boreholes up to 22m in length – but a manual arrangement using customised tubular push rods was engineered, which worked successfully. “The work environment was noisy at times with the inevitable dripping water on sensitive equipment such as laptops, though together we resolved all these issues. “The geophysical logging campaign we undertook formed a vital component of the overall ground investigation, providing high-quality calibrated data, not attainable by other means, at centimetre resolution in the boreholes.”
New ways to use water As discussions at a recent webinar hosted by the
International Hydropower Association highlighted, other technologies need to be able to step up to provide deep storage in locations where conventional pumped storage is unable to.
Gavin O’Leary is the Head of Electricity Storage Policy at the Department for Energy Security and Net Zero (DESNZ). Explaining that although the UK has 2.8GW of Long Duration Energy Storage (LDES) capacity installed in the form traditional pumped storage across four sites, he said: “We have not found the right model in a privatised electricity grid to incentivise development of storage.” And that’s why the country has gone over four decades without adding to its stockpile of long duration storage. Admitting that although pumped hydro is established and “we know it works and is efficient”, O’Leary says the problem is “it takes a long time to build”.
“Construction is expensive and uncertain, and is something investors have not been willing to finance on a purely merchant basis so far,” he added. Although alternatives to pumped hydro “might be
quicker to build in principle and might be as, or even more, efficient and have other advantages”, O’Leary says it’s just not deployed in the same gigawatt scale anywhere. So as it’s uncertain you’re taking a leap into the unknown, and this means risk. And if you have risk, he added, risk means LDES is not being built and that’s a problem. The need for long duration flexibility is high and rising. The UK government’s Clean Power 2030 Action Plan sets out what needs to be done to achieve its goal of eliminating reliance on fossil fuel burning in the power grid by
2030.This means aiming for 4-6GW of long duration storage by end of the decade, and looking at 11-15GW by 2050. And these were, according to O’Leary, “really some quite substantial numbers we need to get to”. “Given our historical dependence on pumped hydro which has many virtues but has long build times and geographical immobility, we are always interested in things that are quicker to build and can be built in wide variety of places. This will give us, Ofgem and the national energy system operator more tools to build the storage we need, wherever it’s needed,” he added.
Scalable solution Stephen Crosher is the CEO of RheEnergise, a
company that is developing High-Density Hydro. Based on traditional pumped hydro storage, it claims to be solving the challenges the technology faces, such as lack of sites, environmental and social issues around flooding valleys, water abstraction, the time taken to consent and construct, plus distances from generation or demand. RheEnergise’s solution is a form of gravitational
energy storage that pumps proprietary fluid uphill. And with the LDES market predicted to be US$4billion by 2040, with rapid scaling and exponential growth, Crosher says there is a “huge demand for solutions to solve the problems”. With capacities ranging from 10-500MW, RheEnergise says it has a pipeline of projects in over 25 countries, with MOUs with utilities and developers. High Density Hydro, the company believes, is a scalable pumped storage solution for the future. And as it doesn’t need to abstract water in the same way as conventional schemes, it can be built in arid locations such as Texas where the demand for electrical power is set to grow by 50% in next five or so years. Such markets, Crosher says, will be a huge opportunity for them especially when the impacts of climate change and declining rainfall are taken into consideration. Although they’re “looking for small hills and not mountains” for prospective project sites, Crosher admits that elevation can be a prohibiting factor. Consequently in the UK, flatter areas such as East Anglia, along with other countries such as The Netherlands, won’t provide favourable conditions. However a small hill or mine or mine shaft will suffice. In fact, he said the company is currently assessing a 280m mine shaft in Wales.
Above: SSE has submitted a planning application to convert the Sloy Power Station into a new pumped storage scheme
References
https://british-hydro.org/ bha-news/scottish-parliament- psh-bha/
New ways to use water - Innovation in the energy storage space. IHA Webinar. 7/5/2025.
https://www.hydropower. org/events/new-ways-to-use- water---innovation-in-the- energy-storage-space
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