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Maguire: Europe's dispatchable energy woes are worsened by a new hydro power hit

The mix of power generated in Europe is likely to become dirtier this summer, after a prolonged dry spell has depleted the reservoirs and reduced hydro-electricity production.

The hydro dams of Europe are the third largest electricity generator in Europe after nuclear and natural gas plants. Their annual production peaks just before summer, as spring rains and snowmelt recharge dams and rivers systems.

This network of run-of river hydro plants and reservoirs is typically used to generate so-called dispatchable energy, which can then be discharged by grid operators on demand in order to balance the system's power needs.

Ember data shows that a persistent drought this year has reduced hydroelectricity production by 13% in the first five month of 2025 compared to the previous year. This is the lowest May level since 2017.

The shortfall in hydro power has forced utilities to use other sources of dispatchable energy, including coal and natural gas plants. These may have to be used at higher levels this summer, if hydro production remains stunted.

HIGH & DRY

The hydro problem this year has been exacerbated by the below-normal snow coverage in Europe's Alps.

A model of the snow-fed generation potential by LSEG estimated that the output of the Alps is about a third lower than the long-term mean so far this season.

LSEG data indicates that the Danube Catchment Area, one of Europe's major river-fed hydro systems, has also suffered from a lack of spring rains, with production generation potential over 60% below average.

HYDRO HIT

According to Ember, the combination of precipitation and snowfall below average has resulted in a 13% decrease in the cumulative production of hydro-powered energy from January to May 2024 compared to the same period in 2024.

The 71 Terawatt Hours (TWh), or the amount of electricity produced by Europe's hydroelectric plants, was the lowest output for May in the last three years. It was also 11 TWh below the total production of the same month one year earlier.

The hydroelectricity output from January to May this year was 48.5 TWh lower than in the same period of 2024. This has reduced the hydropower's share in Europe's electricity production mix to 16.7%, down from 19% in the same months of 2024.

FOSSIL FIX

In order to offset the decline in hydro-generation, and a 36 TWh reduction in cumulative output of Europe's wind farm so far this season, European power companies have been forced to increase fossil fuel generation.

Ember data show that the output of gas-fired power stations was 31 TWh or 7% higher than January to May 2024, and coal-fired plant output was 12.5TWh or 5% higher.

If hydro production is constrained and power demand stays at the same level, European utilities will need to increase coal and gas plant output.

The output of Europe's nuclear reactors could also be increased to compensate for the decline in hydroelectric plants.

However, the regional nuclear power production could be limited if river temperatures in the region rise during potential heatwaves. This would reduce their ability as a cooling water source for reactors.

This means that Europe's gas- and coalfired power stations will remain the main source of dispatchable energy through the summer. Especially if the dry weather conditions of this year continue.

These are the opinions of a columnist who writes for.

(source: Reuters)