The renewable energy firm has appointed global hydropower technology supplier ANDRITZ as the main contractor for the Cruachan upgrade project.

ANDRITZ Hydro is a supplier of electromechanical equipment and services for hydropower stations and has installed around 470 gigawatts of capacity during its more than 180 years of operations.

The £80m project will see the generating capacity of two of the plant’s four units increased by a combined 40 MWs to raise the facility’s total generating capacity to 480 MWs. The units were commissioned in 1965 and contain parts, including their turbines, which are now more than 50 years old.

Drax’s interim COO, Penny Small, said: “Pumped storage hydro is vital to the UK’s energy security, it’s a technology which works in partnership with renewables.

“These plants play a critical role in stabilising the electricity system, helping to balance supply and demand through storing excess power. When wind turbines are generating more power than we need, Cruachan steps in to store the renewable electricity so it doesn’t go to waste.

“By investing in Cruachan today, Drax is ensuring the power station can play an even bigger role in the energy system of tomorrow. We look forward to working with our contracting partners to deliver this exciting project.”

Dominik Fust, managing director at ANDRITZ HYDRO Germany, said: “We are proud to have been entrusted with the refurbishment of the Cruachan Pump Storage Power Plant.

“This project aligns with our mission to contribute to the global transition toward sustainable energy generation.”

The major upgrade to the two units will improve their operability and reliability, lengthening their lifespan. Drax’s investment is underpinned by the award of 15-year capacity market agreement worth around £221m.

Pumped storage plants act like giant water batteries by using reversible turbines to pump water from a lower reservoir to an upper reservoir which stores excess power from sources such as wind farms when supply outstrips demand. These same turbines are then reversed to bring the stored water back through the plant to generate power when the country needs it.

The Cruachan upgrade project is separate to Drax’s plan to build a new 600 MW pumped storage power station adjacent to the existing Cruachan facility. A study by trade body Scottish Renewables estimated that the project could create and support up to 1,100 jobs.