Grid-scale storage takes shape in Wales

Successful geotechnical investigations at Glyn Rhonwy – the proposed site for Britain’s first new grid-scale electricity storage scheme for more than 30 years – have taken the development another step closer to its planned commissioning in 2019.

Analysis of 19 boreholes to depths up to 130 metres, along with samples of material taken from multiple surface excavations, confirm the geology at the site near Llanberis, clearing the way for developer Snowdonia Pumped Hydro (SPH) to begin discussions with potential contractors for the construction phase.

SPH wants to turn the disused Glyn Rhonwy slate quarries into a 99.9MW pumped hydro-electricity storage (PHES) facility, with an operational lifetime of 125 years or more. The scheme which was designed in consultation with AECOM, Gwynedd Council, Cadw, Countryside Council for Wales and Natural Resources Wales, already has planning permission at an output of 49.9MW. An application to increase the output to 99.9MW is currently considered by the Planning Inspectorate.   

When commissioned, water will be pumped to an upper reservoir at times of high electricity supply and low demand then be released back through turbines to a lower reservoir to re-generate electricity when supply is low and demand high.

SPH chairman Peter Taylor said: “Britain cannot afford to continue using its renewables in such a costly and wasteful way and will have to embark on a big expansion of grid-scale storage. Our Glyn Rhonwy scheme is right there at the moment of change with a blueprint for how that can be achieved through the use of brownfield land.”

He explained that the proposed facility could play an important role in balancing the UK’s electricity grid as the percentage of intermittent renewables such as wind and solar power continues to grow.

Speaking before Christmas, Mr Taylor added: “We think there is also great potential for other non-traditional sites such as coastal areas and existing fresh water reservoirs to play a key role in solving this UK-wide problem.”

Because Britain has insufficient grid-scale storage, the National Grid cannot capture all the excess power generated by renewables for later use, and as result households and industry are having to pay – through their electricity bills – more every year to renewables operators to stop generation when the wind blows too hard.

Unless Britain builds more grid scale storage, these avoidable constraint payments could reach £2.7bn a year if Britain builds all of the wind farms currently in planning, according to Imperial College London. The storage deficit also means that polluting gas power stations and diesel generators must be kept on stand-by for when the wind drops or stops altogether.


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