Civil works |
Re-planting Welsh power plants
£1 billion is being invested in two Welsh pumped storage plants to ensure their continued operation for at least another 25 years
A £1 BILLION REFURBISHMENT PROGRAMME is underway to extend the life of Dinorwig and Ffestiniog pumped storage power plants in Wales. With 2.1GW of installed capacity the two facilities are the UK’s leading providers of power storage and flexibility, representing 5% of total installed power generation capacity and 74% of the UK’s pumped storage hydro capacity. Electric utility company ENGIE owns 75% of the plants via First Hydro Company, a 75:25 joint venture with Canadian investment group CDPQ. With both plants now reaching the end of their operational lives, preparations for refurbishment at Dinorwig pumped storage station have begun – hot on the tail of a nine-year refurbishment at Ffestiniog. ENGIE says that such ‘re-planting’ could see the complete refurbishment of up to all six generating units at Dinorwig – a final investment decision is still to be made on the number of units to replace – while the re-planting at Ffestiniog is set to be completed by July 2026. The complexity and the scale of engineering
involved, along with the necessity to keep the plant available to serve the electricity system, explains why the re-planting project for Dinorwig will take up to ten years. The programme involves replacement of the main inlet valves which are among some of the largest in the world, weighing in at over 160 tonnes. With full drain down of the station and detailed inspections of the water shafts required, all of this necessitate specialist technology, bespoke lifting systems, and expert contractors. Indeed the valves themselves were modelled
at a reduced scale in a lab and designed as fully working scale models to drive efficiencies. AI was used to optimise and improve the infrastructure and technology. These valves are now waiting to be installed at Dinorwig station, where engineers will lathe and fine tune the seal on site for up to two weeks.
Switched on
Above: View from the top of Dinorwig former slate quarry, site of the pumped storage project in Snowdonia, North Wales, UK
Right: Ffestiniog power plant in Wales. © David Pimborough /
Shutterstock.com
34 | August 2025 |
www.waterpowermagazine.com
Earlier in the year, National Grid switched on new high voltage electricity cables as part of its Dinorwig to Pentir project, a scheme that will help futureproof vital infrastructure carrying clean electricity from ENGIE’s Dinorwig power station.
Since autumn 2021, National Grid has been upgrading the 12km connection between its 400kV Dinorwig substation which sits inside the same mountain as the power station, and its 400kV Pentir substation. Engineers from National Grid, and contractors Morgan Sindall Infrastructure and Siemens Energy,
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