(Bloomberg) -- France’s nuclear power plants were generating at the highest level in nearly a year, providing temporary relief in Europe’s fight to save natural gas this winter. 

The nation had 45 reactors online on Friday, producing as much as 45,360 megawatts, according to grid operator RTE. That’s the highest since Feb. 11 last year, but about 12% lower than the average of the past five years. 

That surge in output is likely to be short-lived though as fresh maintenance this month is likely to curb generation to historically low levels for this time of year. How much of France’s nuclear fleet can return to service and stay in operation will be crucial for Europe’s energy security with flows of Russian gas now mostly halted. 

Eight reactors are due to be taken off the system for maintenance this month, grid operator RTE said last month. As temperatures dip and German wind power output is poised to plunge in the coming days, they will be sorely missed and likely drive increased use of coal and gas plants. 

Output from the fleet slumped to the lowest in more than three decades last year. As a result, carbon emissions in the European Union rose 3% last year according to Ember, despite a record-setting deployment of new solar capacity.

Improved French nuclear output, along with stronger hydropower and more renewables, could help Europe cut fossil fuel power by as much as 43% this year, compared with last year, according to BloombergNEF.

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