- Two 315 MW generating units will be replaced by the end of the decade under the first phase awarded to GE Vernova.
- The wider six-unit programme is intended to extend Dinorwig’s operating life by at least 25 years.
- Modernising an asset with established reservoirs, civil works and a grid connection could provide lower-risk flexibility while Britain develops new long-duration storage.
First Hydro Company has selected GE Vernova to replace two generating units at the 1.8 GW Dinorwig pumped-storage power station, beginning the equipment phase of a modernisation process intended to keep the North Wales facility operating for at least another 25 years.
The contract covers two 315 MW units and associated electrical, mechanical and control systems. Installation is expected to be completed by the end of the decade, according to a joint announcement by the companies.
The wider programme will eventually replace all six generating units and upgrade supporting infrastructure at the more than 40 year-old site. The contract value was not disclosed.
First Hydro is owned by ENGIE and La Caisse, with respective stakes of 75% and 25%. ENGIE UK chief executive Delphine Cherel-Sparham described the award as “an important milestone in our long-term investment programme at Dinorwig”.
GE Vernova will supply upgraded pump turbines and motor generators alongside embedded components, control equipment and low and medium-voltage electrical systems. Physical model testing of the revised turbine design has already been completed at the company’s hydropower laboratory in Grenoble.
Dinorwig can provide 1,320 MW within 12 seconds of leaving standby and reach its full 1,800 MW output in less than a minute. The plant can therefore respond to sudden losses of generation or unexpected demand substantially faster than most thermal power stations.
Its role has evolved since construction. Dinorwig was originally designed partly to absorb overnight output from large nuclear stations before meeting predictable morning and evening demand peaks. It is now increasingly used to balance variable wind and solar generation, provide reserves and help manage short-duration system disturbances.
Together, Dinorwig and First Hydro’s Ffestiniog station provide approximately 2.1 GW of capacity, representing nearly three quarters of Britain’s existing pumped-storage fleet. The concentration gives the assets considerable system value, but also makes their continued availability strategically important.
Route to resilience
Britain currently has only about 2.8 GW of operational long-duration electricity storage (LDES), all provided by pumped hydro. Ofgem has provisionally selected 16 new projects for support through its cap-and-floor regime, covering pumped storage, compressed air, lithium-ion batteries and flow batteries. Final investment and construction will still take several years.
Modernising Dinorwig offers a different route to increasing resilience. The reservoirs, tunnels, powerhouse and grid connection already exist, avoiding many of the planning, civil engineering and connection risks faced by new projects. Extending the life of those assets could deliver dependable capacity before some proposed storage schemes reach operation.
The programme will still require careful execution. Each unit must be removed from service for replacement work while sufficient capacity remains available to the system. Older civil structures and equipment interfaces can also present risks that are difficult to identify until work begins.
New technology will not make Dinorwig an unlimited energy resource. Like every pumped-storage plant, it must use electricity to pump water back to its upper reservoir and has a finite discharge duration. Its strength is the combination of scale, speed, storage and an established operating history.
The modernisation is therefore best viewed as complementary to new construction. Britain will need additional LDES as renewable generation expands, but preserving existing capacity is likely to be faster and less risky than attempting to replace it.
The economic case cannot be evaluated fully because neither the contract price nor the expected future revenue arrangements have been disclosed. Nevertheless, the decision underlines a broader policy lesson: extending the life of proven flexibility assets can be as important as procuring new megawatts.
Dinorwig’s value lies not simply in producing power, but in being able to deliver it almost immediately when the wider system is under pressure.
