Spain Extends Almaraz Nuclear Plant Operations as Energy Security Reshapes the Phase-Out Debate

Spain has decided to keep the Almaraz nuclear power plant operating until June 2030, delaying the first major step in the country’s planned nuclear phase-out and signalling how energy security is increasingly influencing Madrid’s approach to nuclear power. The decision, published in Spain’s official gazette on August 14, extends the operating life of both reactors while leaving the broader plan to phase out the country’s nuclear fleet by 2035 intact.

Almaraz had been scheduled to become the first Spanish nuclear plant to close, with Unit I due to stop operating in November 2027 and Unit II in October 2028. The new authorisation keeps both units running until June 8, 2030, effectively adding around two and a half years to Unit I and nearly two years to Unit II. The extension was requested by the plant’s owners, Iberdrola, Endesa and Naturgy, after they argued that changing energy-market conditions justified reconsidering the original timetable.

The decision does not amount to a reversal of Spain’s nuclear policy. The government continues to envisage a gradual closure of the remaining reactors, with the national phase-out scheduled to be completed by 2035. Almaraz is therefore becoming an exception within the existing timetable rather than the beginning of a formally announced new nuclear strategy. Yet the decision is significant precisely because it shows that the timetable is no longer being treated as immune to changing conditions in the electricity system.

Gas volatility is changing the calculation

The immediate backdrop is a European energy market in which security of supply has become harder to separate from the question of generation capacity. Spain has invested heavily in renewable power, but the rapid expansion of wind and solar does not eliminate the need for reliable electricity generation when renewable output falls. The government has argued that maintaining Almaraz can reduce exposure to volatile gas prices while having only a limited effect on the expansion of renewables. Spanish authorities estimate that keeping the plant open would modestly reduce the amount of renewable generation expected in 2030 and lower the use of gas-fired power plants.

That distinction matters for Spain’s energy transition. Nuclear power is not being presented as an alternative to renewables, but as a source of firm generation that can operate alongside them. The decision therefore reflects a broader European dilemma: governments are trying to accelerate decarbonisation while simultaneously ensuring that electricity systems remain capable of meeting demand through periods when weather-dependent generation is insufficient.

The argument has gained additional weight since the major Iberian blackout of April 2025. The incident intensified scrutiny of the stability of the Spanish and Portuguese electricity systems and prompted renewed debate over the role of nuclear and gas generation in maintaining system resilience. Nuclear operators and industry representatives have argued that nuclear plants provide system inertia and stability that can complement a power system increasingly dominated by variable renewable sources.

Almaraz became a test of Spain’s nuclear policy

The extension has been under consideration for months. In October 2025, the three companies operating Almaraz formally requested permission to continue running both units until June 2030. The request was subsequently sent to Spain’s Nuclear Safety Council, which carried out the technical assessment required before the government could make its decision.

In July, the Nuclear Safety Council issued a favourable assessment, subject to additional safety conditions. The regulator concluded that the two reactors could continue operating until 2030 from a nuclear-safety perspective, while requiring measures including sufficient staffing for safety-related functions during the extended operating period. The final decision was then left to the government.

The distinction between technical safety and economic policy has been important throughout the process. The regulator assessed whether the reactors could continue operating safely; questions over the economic viability of the plant and the wider energy strategy remained political decisions. That separation allowed the government to extend Almaraz without formally abandoning the wider nuclear phase-out.

For the companies involved, however, the economics remain central. Spain’s nuclear operators have previously argued that the fiscal burden imposed on nuclear generation makes continued operation increasingly difficult, particularly when plants face high costs related to taxation, spent-fuel management and decommissioning. The Almaraz case has therefore also exposed the tension between a government seeking to maintain its long-term energy strategy and operators deciding whether individual reactors remain commercially viable.

A wider European shift

Spain’s decision fits into a broader European reassessment of nuclear power. Across the continent, governments that once expected ageing reactors to disappear from the electricity mix are increasingly weighing the costs of closing plants against the costs of replacing their output.

The calculation has become more complicated since the energy crisis that followed the full-scale Russian invasion of Ukraine. Europe has sought to reduce its dependence on imported fossil fuels while electricity demand is expected to rise because of electrification, industrial reshoring, digital infrastructure and data centres. At the same time, renewable capacity is expanding rapidly, but grids, storage and interconnection infrastructure are struggling to keep pace.

For Spain, the question is particularly consequential because nuclear power still represents a substantial part of the country’s electricity system. Nuclear plants generated around one-fifth of Spain’s net electricity production in 2024, making nuclear the country’s second-largest source of electricity generation that year.

Keeping Almaraz online until 2030 gives Madrid additional time to expand renewable generation, storage and grid infrastructure before removing one of its major sources of continuous low-carbon electricity. It also reduces the immediate amount of generation that would otherwise need to be replaced by a combination of renewables, storage and thermal power.

The decision nevertheless leaves Spain with a difficult long-term question. If Almaraz can safely and reliably operate beyond its original closure dates, policymakers will have to weigh whether the same logic should apply to other reactors as their shutdown dates approach. Extending every plant would undermine the existing phase-out strategy, while closing plants regardless of changing market and system conditions could increase pressure on gas generation and the electricity grid.