14th August 2024

The world is in a climate emergency. Higher levels of clean, renewable energy are urgently required, a flexible and secure energy system is necessary with more and different types of energy storage solutions needing to be deployed. As a developer of a pioneering form of storage, we are asked a multitude of questions about our high-density long duration energy storage (LDES) solution.

Our scalable HD Hydro solution can be built quickly, is cost-competitive with other forms of LDES, and has less environmental impacts than large-scale hydro. Our R&D work has been extensive and exhaustive, has been independently validated (by the UK National Engineering Laboratory, academics and different arms of the UK Government), and our R&D continues. We will take valuable lessons from our demonstrator project that is currently under construction in SW England.

Here are the facts about our High-Density Hydro® solution and why it will play such an important role in enabling the energy transition across the globe:

• The energy transition requires a 100x increase in the rate of long-duration energy storage [1]. The status quo will not work, and new solutions are required to solve the problem of scaling to large volumes, quickly and globally. 

• Conventional pumped hydro storage (PHS) makes up more than 95% of all legacy energy storage [2]. But as good as conventional pumped hydro is, it is unable to scale to the required volumes. This ultimately comes down to site constraints: the overwhelming majority of PHS is open-loop and requires a river or water course, a sufficiently high mountain, and a natural alpine valley that can be dammed to form a reservoir. The most current industry statistics [3] confirm that conventional PHS cannot scale; only a handful of projects are under development globally with development times exceeding a decade.

• High-Density Hydro solves these site constraint limitations. A closed-loop design removes the need for significant water course and alpine valleys [4]. And the high-density fluid gives a 2.5x decrease in system size (on a like-for-like basis). 

• RheEnergise has developed a high-density fluid for High-Density Hydro applications. It has a density 2.5x that of water, low viscosity, the required stability, low abrasion/erosion, non-toxic (as tested by third party labs [5]).

• We regularly run our high-density fluid in test rigs at our 15,000sq ft R&D facility in Montreal, through pipes, valves, pumps and turbines. The various parts of a full-size system have been under test over the last three years and the knowledge gained has fed into the completed design of our demonstration project which is now being built in SW England.

• Our High-Density Hydro solution won the UK Government’s “Longer Duration Energy Storage” competition [6], as part of which it has undergone intense scrutiny from the UK Department of Energy Security and Net Zero.

• Our solution is being developed in close cooperation with the established global hydro industry [7].

• The strong validation of winning the “Longer Duration Energy Storage” competition is echoed by customers, with a weighted commercial project pipeline of over £500m and signed commercial agreements in Chile [8], UK [9], Australia and the US.

• Respected international energy industry research organisation Bloomberg NEF surveyed LDES technologies and concluded that the lowest cost solutions were “novel pumped hydro storage”, which includes High-Density Hydro [10].

• Our flow rate is comparable to water; we have proven field test results validated by academics at the University of Exeter [11] and industry partners [7].

• The deployment of our technology does not require tunnelling into the mountain/hillside as our projects will be significantly smaller-scale than conventional pumped hydro. For a typical project, penstock (pipes and cut and cover excavation) are only 12% of the total project cost. For a 20MW RheEnergise project, the penstock diameter is between 1 and 1.6m. Volumetrically - everything (pipes, valves, turbo machinery) is ~60% smaller. This leads to cost savings, not cost increases.

• In comparison to a PHS water project, HD Hydro is ~60% smaller volumetrically. Everything is ~60% smaller volumetrically - the storage reservoirs, the pipes, the valves, the turbo machinery, the power-house footprint, etc.

• When considering the costs of a PHS project approx. 65% to 70% of the cost is the civil engineering costs, therefore a 60% reduction in volumes of civil engineering work represents a significant saving in overall project construction costs. These civil engineering cost savings offset the cost of the fluid, leading to comparable best in class economics, but with the advantage of scalability (more sites and faster build times). RheEnergise has worked with a global engineering consultancy, and supply chain economists to estimate project investment CAPEX, and even at a much smaller scale systems, the $/kWh is comparable to conventional pumped Hydro and one of the most cost competitive of all novel LDES solutions under development (BloombergNEF [10]). 

• The world needs energy storage that can be scaled rapidly and globally, and there are orders of magnitude more sites at 200m, than at 500m. So a project site with only 40% of the elevation needed for the same performance, HD Hydro will aide the energy transition where there is an urgent need for scalability. Scalability is vital without having to resort to new transmission infrastructure, which is costly, and has decade-long development timescales. RheEnergise offers a scalable solution whilst maintaining best in class economics of conventional pumped hydro.

We have the support of our investors, our business partners, government agencies, academics and energy industry professionals. The onus is now with us to have our demonstrator project enter operation within the next few months and thereafter to deploy our first commercial scale project.  This is firmly in our sights. 

References

[1] McKinsey & Co Report with LDES Council - Net-zero power - Long duration energy storage for a renewable grid - November 2021 

[2] [3] Pumped Hydro Storage database

[4] Australian National University - https://re100.eng.anu.edu.au/global/

[5] Toxicity tests carried out by Blue Frog Scientific, Chemex and Socotec

[6] Press release - RheEnergise awarded £8.25m UK Government contract to build its first advanced long duration hydro energy storage system - 28th November 2022

[7] Reports, work and analysis carried out by: Cost Models: Mott Macdonald (Global Engineering Consultancy), Computational Fluid Dynamics: TUV-NEL (National Engineering Laboratory - UK), Formulation Science: University of Greenwich - Formulation Science Department, and Turbine R&D: Energy Revolution Services.

[8] Press Release - RheEnergise Signs MOU with Leading Chilean Utility Colbun to Develop Long Duration Energy Storage Projects in Chile - 14th November 2023

[9] Press Release - Mercia Power Response and RheEnergise Working Together to Build Long Duration Energy Storage - 16th August 2023

[10] BloombergNEF - Lithium-Ion Batteries are set to Face Competition from Novel Tech for Long-Duration Storage: BloombergNEF Research - 30th May 2024

[11] University of Exeter - Cambourne School of Mines