Endesa and Iberdrola stand as the two dominant owners of Spain’s nuclear power plants. Both energy groups are partners and share ownership in nearly every facility. The majority stakes shift between each plant, with one company or the other holding the controlling share depending on the installation. Taken together, the two groups exert a comparable influence on Spain’s nuclear market. Yet their visions for the future of the reactors do not align, and recent developments have once again underscored their divergence.
A mid-path between necessity and opportunity, in recent weeks it has become clear that Endesa favors keeping the nuclear fleet running as long as possible, extending beyond the originally planned lifetimes. Iberdrola, by contrast, is prepared to comply with the government timeline and phase out each plant according to a staged shutdown between 2027 and 2035, terminating all reactors by the nationwide blackout. This clash mirrors a similar dispute five years after a sector-wide agreement with the government to set clear shutdown dates and manage decommissioning.
Divergent visions
Intellectually, Endesa’s chief executive José Bogas has argued in favor of extending nuclear lifetimes, noting that both companies have their faults. In a recent media briefing tied to Endesa’s annual results, Bogas said the company would propose to regulators and to the government that the plants be allowed to run longer, and added that Endesa would try to persuade authorities to extend operating licenses if feasible. He emphasized that he did not know what other operators would do, signaling a split among peers.
Iberdrola’s leadership has signaled a different sentiment. The company’s president Ignacio Sánchez Galán stressed that a formal closure protocol exists, reflecting the government’s agreement to shut down plants by 2035. Iberdrola intends to honor the signed plan and maintain the agreed schedule, arguing that it is essential to respect the commitments already made.
Galán also indicated that extending reactor lifetimes could be technically possible, but would require massive new investments. Any extension would hinge on regulatory changes that ensure the plants remain financially viable. If there is adequate compensation to cover additional costs, the company would study the case. For the moment, however, Iberdrola plans to adhere to the signed framework.
Both companies’ positions align with their broader business models. Iberdrola operates as a highly international group, with Spain representing a shrinking share of its overall footprint. In Spain, it maintains substantial renewable capacity and hydroelectric plants. Endesa, by contrast, concentrates its activity in Spain and Portugal and relies more heavily on nuclear generation to meet its needs, giving it a stronger stake in keeping plants online.
Meanwhile, Naturgy remains the third-largest electricity supplier and the top gas operator in the Spanish market. It holds minor stakes in several nuclear plants and has historically steered away from advocating lifetime extensions for reactors. Naturgy’s president, Francisco Reynés, has recently reiterated that electricity security remains intact even if all nuclear plants close on schedule, thanks to the growth of renewables and the stable output from gas-fired plants, where Naturgy is a leading operator.
The different sensitivities around nuclear maintenance emerge at a moment when all the plant owners are united in opposing the government’s planned increase in charges to fund decommissioning and waste management. The Nuclear Forum, a trade association that groups Iberdrola, Endesa, Naturgy, and EDP, is maneuvering to curb the proposed tax increase and to push for a comprehensive fiscal reform of the sector’s obligations. It has filed petitions with the court to challenge the government’s nuclear waste plan to build seven dedicated waste sites and to pause the project to have a single central nuclear waste repository in Villar de Cañas, Cuenca.
Endesa has majority stakes in Ascó II and Vandellós II and runs Ascó I solo. Iberdrola is the principal shareholder at Almaraz I and II, and holds stakes in Trillo while fully controlling Cofrentes. Naturgy possesses small minority interests in Almaraz and Trillo, and EDP also participates in Trillo. Despite the distribution of majority stakes, decisions at the plants are taken through joint arrangements that require unanimity among the participating companies. A tacit understanding effectively gives the lead to the plant’s largest shareholder, but the legal requirement is that plant board decisions be made unanimously. This rule has in the past produced gridlock when Iberdrola and Endesa disagreed on how far to extend plant lifetimes.
For years, the two giants clashed over whether to close Spain’s nuclear plants. After tense negotiations about reviving the Garoña plant and renewing licenses for other reactors, a government-sector-wide accord was reached five years ago. It represented a nuclear peace, close to expiration of the window to file license renewal requests for Almaraz and Vandellós.
In March 2019, the government and Enresa, the state company responsible for radioactive waste management and plant dismantling, agreed with Endesa, Iberdrola, Naturgy, and EDP on a staged shutdown calendar from 2027 to 2035 for all reactors. Endesa secured a lifeline to extend plant lifetimes beyond the then-40-year reference, averaging about 46 years of operation before closure. Iberdrola obtained a clear regulatory framework and, later, guarantees about the maximum investments that would be injected into some plants as part of separate agreements with Endesa.
The planned sequence of closures includes Almaraz I in 2027, Almaraz II in 2028, Ascó I in 2030, Cofrentes in 2030, Ascó II in 2032, Vandellós II in 2035, and Trillo in 2035. The anticipated closure of Almaraz, where Iberdrola holds a majority, is considered likely given the tight window for extending its life, which would require making decisions within the year to allow time for shutdown arrangements and necessary investments. Endesa, meanwhile, seems determined to push back the closures of the remaining plants, especially Vandellós and Ascó in Catalonia where it holds the majority stake.
As the debate continues, the industry remains focused on balancing energy security, regulatory outcomes, and the economic realities of extending reactor lifetimes. The shared challenge is clear: align commercial interests with public policy while ensuring a reliable, affordable energy supply for households and industry across Spain and the broader Iberian market.