(Bloomberg) -- Electricite de France SA’s UK unit plans to extend the operating lives of four of its reactors that offer stable electricity just as intermittent sources take a larger share of the nation’s generation mix. 

The stations, equivalent to 4.6 gigawatts of capacity, will undergo inspections and need regulatory approval to continue running, according to a company statement on Tuesday. The decision on whether to extend operations is expected this year, EDF said. 

The nation is increasingly relying on wind and solar to meet demand but needs back up power when output from those sources drop significantly. EDF’s current fleet of five nuclear plants is scheduled to shrink to just three by the end of 2026. Last year, output slumped to the lowest in more than four decades last year. 

UK Nuclear Output Slumps to 42-Year Low in Threat to Net Zero

Hartlepool and Heysham 1 are scheduled to shut in 2026 while Heysham 2 and Torness power stations are due to generate until March 2028. The four reactors use so-called advanced gas-cooled technology to operate. 

“These AGR lifetimes will be reviewed again by the end of 2024 and the ambition is to generate beyond these current forecasts,” EDF said in a statement.

The company is also considering a 20-year life extension for Sizewell B, from 2035-2055. A decision would be made in 2025.

The firm is also building Hinkley Point C — the nation’s the first nuclear project in more than three decades. Startup of its two reactors is due in 2027 and 2028, though the utility has warned that may be pushed back by more than a year. A financing deal for Sizewell C, another development, is being worked out with government and private investors.

“While lifetime extensions will help in the short term, they won’t address the medium and long-term issues of a fleet getting close to retirement – what we now need is for the government to get Sizewell C to a final investment decision swiftly,” said Tom Greatrex, chief executive officer of the Nuclear Industry Association. 

EDF also plans to invest a further £1.3billion ($1.7 billion) in its five UK units over the 2024-26 period. 

(Updates with industry group comment in eighth paragraph.)

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