- ENGIE reaches final close on the latest stage in its pumped storage hydro assets replanting programme in North Wales, supporting jobs, skills and clean energy
- Delivering on its long-term investment commitments in Wales and across the UK, the company is pursuing its strategy to be the best transition utility
In North Wales, ENGIE has reached a significant step in its £1billion investment programme at the Dinorwig and Ffestiniog pumped storage hydro stations through First Hydro Company, a 75:25 joint venture between ENGIE and La Caisse. These sites have long played a vital role in the local communities and across the region, with Dinorwig opening in 1984 and Ffestiniog in 1964.
The investment for the next stage of this programme has been approved by the ENGIE board and La Caisse. This will enable the first two units at Dinorwig to be replanted in a c.£300 million project, with units expected to reach commercial operation in 2028 and 2029. During this period, the remaining 4 units in Dinorwig will remain fully operational.
Located around 500 metres beneath the mountain, the works will see major components replaced in Dinorwig, including turbine and generator shafts of around 160 tonnes and generator motor rotors of up to 460 tonnes. The cavern itself is large enough to house St Paul’s Cathedral, and the station can generate up to 1,800MW of power, enough to supply around 1.5 million homes at peak output.
This investment will support a highly skilled workforce in North Wales, with peak construction activity expected to involve more than 250 people. The project will draw on local expertise alongside national and international supply chains, creating opportunities for Welsh businesses and workers.
The announcement follows the company’s recent agreement to acquire UK Power Networks, one of the UK’s largest electricity distribution companies, a 6,500 strong, best-in-class, organisation serving 8.5 million customers across London, the South East and East of England. The deal, expected to complete by mid-2026, is widely seen as transformational in scale and strategic importance.
Miya Paolucci, UK CEO of ENGIE, said: “Wales plays a central role in ENGIE’s UK strategy. Reaching financial close on this latest tranche of our pumped hydro investment demonstrates our long-term confidence in these vital assets and in the role flexible storage will play in delivering a secure, low carbon power system.”
Dinorwig is Europe’s largest and fastest-acting pumped storage station, capable of reaching full output in just 30 seconds. Water from Marchlyn Mawr runs through high-pressure tunnels to generate electricity within the underground power station, before being released at Llyn Peris.
As a key part of the local community over the last 40 years, the power station continues to work closely with surrounding communities, including participation in the Llyn Padarn Forum, engagement with schools, and support for local initiatives through its donations and sponsorship activities.
ENGIE is also strengthening the talent pipeline in North Wales working with Bangor and Wrexham universities, collaborating with Ambition Wales and the North Wales skills portal. This includes participation in local careers events – notably the GradCon Cymru 2026 on the 31 March, where ENGIE will be meeting students to showcase career opportunities in the energy transition. This year, four new apprentices and two new graduates will join the business, as ENGIE continues to invest in skills development and future career pathways.
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Notes to editors
- ENGIE announced on the 25 February 2026, the signing of an agreement to acquire 100% of UK Power Networks (UKPN), the best-in-class electricity distributor in the UK, for an equity value of £10.5 billion.
- The enterprise value of the company (at 100%) stands at £15.8 billion, corresponding, for the regulated activities, to a multiple of c.1.5x the estimated Regulated Asset Value (RAV) as of end-March 2026 and an estimated 2027 EBITDA multiple of c.10x, including the additional contribution of unregulated assets.
- First Hydro Company have invested £250m since 2017 on the replanting of Ffestiniog and some early works in Dinorwig.
- The two pumped storage hydro plants are the UK’s leading provider of power storage and flexibility, with 2.1GW of installed capacity in total.
- Two of the six turbine‑generator sets will undergo full mechanical and electrical replacement. A unit refers to one complete generating set, comprising one reversible pump‑turbine (used both to generate electricity and to pump water back uphill), one motor‑generator, and its associated shaft, rotor, control systems and auxiliary equipment. Each unit can operate independently of the others.
- They represent 5% of the UK’s total installed power generation capacity and 74% of the UK’s pumped storage hydro capacity.
A Welsh translation of this Press Release is available upon request.
ENGIE Press contact:
Alanna Rooney
Tel. UK: 07739072404
Email : Alanna.Rooney@engie.com / UKmediaenquiries@engie.com
