What just a few months ago seemed like a chimera—seeing overflowing reservoirs in the middle of winter—has become an overwhelming reality after the passage of successive Atlantic fronts. But the water that has fallen on the peninsula has not only alleviated the drought; has generated such an excess of energy supply that the electrical system has had to do without its traditional “base load”: nuclear energy. The data confirms that, faced with the push of water and wind, the atom has lost its place in the market.
A change of scenery. According to data from the Peninsular Hydrological Bulletinthe water reserve in Spain has skyrocketed to 77.3% of its total capacity, storing 43,341 hm³ of water. This represents an increase of 10.1% in a single week, a figure that illustrates the volume of rainfall. To understand the magnitude of this data, just look back: in this same week in 2025, the reserve was at 58.13%. Even more impressive is the comparison with the average of the last 10 years, which stands at 53.6%. That is, today we have 13,000 cubic hectometers more water than the historical average for the decade.
The situation is such that the focus has shifted from scarcity to security. In Andalusia, where red notices have been activated, reservoirs are functioning as the last line of defense. The system has been doing “flood lamination” work (water retention to avoid floods), especially in the Guadalquivir and Genil basin, where dams such as Iznájar or El Tranco are crucial to contain the flow before it reaches cities like Seville.
The great battery of Spain is full. The impact goes far beyond the visible. Reservoirs are not just liquid stores, they are giant batteries, and right now they are more charged than ever. As detailed in the Hydrological Bulletin in your energy sectionSpain currently stores 16,184 GWh of hydroelectric energy, the largest amount ever recorded at this time. If we compare this figure with the same week of the previous year (13,825 GWh), the jump is notable: today we have 117.1% of the energy we had a year ago.
This massive injection of cheap electricity has saturated the seams of the Iberian market. The supply of renewable energy has been so high that interconnections have not been able to cope. According to expert Joaquín Coronado on your LinkedIn profilethe combination of rain and high wind production in Portugal caused the saturation of the interconnection between both countries. With electricity unable to flow freely, the market disengaged: while in Spain prices were sinking due to the sun and water, in Portugal they skyrocketed during peak hours due to technical restrictions. The physical network is suffering to manage such an avalanche of green electrons.
The nuclear “no home”. The direct consequence of this renewable surplus is that nuclear energy is no longer competitive in this scenario. The thesis is clear: there is plenty of installed power when the weather is favorable.
According to market datathe pressure from renewables has expelled 1.5 GW of nuclear power. On the one hand, Almaraz unit II had to reduce load. On the other hand, the Trillo Nuclear Power Plant was completely disconnected from the grid on Sunday, February 8. The confirmation comes from the headquarters itself. In his informative noteTrillo managers acknowledge that the plant stopped on a scheduled basis because “it was not compatible with the electricity market nor was it required by the System Operator.” Although they assure that the plant is technically perfect, they point to an economic reason: with prices sunk by storms and “high taxation”, operating the nuclear plant costs them.
The underlying debate: why keep what is left over? This episode of “nuclear blackout” comes in the middle of the debate over the extension of the Almaraz plant, whose owners are requesting to extend its useful life beyond 2027. A new report from Greenpeaceprepared by the Rey Juan Carlos University and the UPC, warns that artificially keeping nuclear operational is a stopper for the ecological transition. What happened this week in Trillo reinforces his conclusions:
- Technical feasibility: The study ensures that in the period 2028-2029, Almaraz’s energy could be replaced by 96.4% by renewables.
- Economic cost: According to The Jumpextending Almaraz would cost consumers an additional 3,831 million euros and would stop green investments worth 26,129 million.
- Emissions: The report indicates that the extension would generate millions of tons of extra CO2 by discouraging the installation of new clean power.
The market ruling. This episode is not a meteorological anecdote, it is confirmation of a change in structural cycle. The February storm has functioned as a stress test for the electrical system and the result is clear: in a marginalist market, water and wind physically displace nuclear power. The data supports that this is already a trend, not an exception. According to closing figures for 2025 published by Five Daysin Iberdrola’s generation mix in Spain, hydroelectric energy (33.3%) already surpassed nuclear energy (33.2%) in total production last year.
What happened this week in Trillo is the real-time demonstration of that statistic. With Spain’s “battery” charged to 77% and the wind turbines spinning, the rigidity of the nuclear park becomes an economic barrier. The market’s conclusion is, today, unappealable: we have so much water that nuclear power is no longer essential.
Xataka | When Spain embraced wind energy, it did not have a problem: it would be too windy.
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