On April 28, 2025, Spain, Portugal and Southwest France experienced a historical blackout. Just past midday on the 28th, Spain’s power supply dropped 60% with an abrupt loss of 15 gigawatts of electricity. It took almost 23 hours for the electricity grid to be declared back to normal, and it was brought back online by electricity transfers from France and Morocco, and contributions from gas and hydropower.
Right before the outage, Spain’s power grid was running on 60.64% solar, 12% wind and 11.6% nuclear. As the specific cause of the outage remains unknown, many people are blaming it on Spain’s overreliance on renewable energy. According to Red Eléctrica, Spain’s grid operator, almost 57% of the country’s electricity in 2024 was generated from renewable sources, and 20% was generated by nuclear power plants. However, both Spanish Prime Minister Pedro Sánchez and Red Eléctrica have indicated that the use of green energy is not the cause of the blackout.
A major concern with primarily running on green energy is that electricity grids were not designed to be fueled that way. Renewable sources often don’t supply the same constant flow of energy that gas-powered plants do, and these fluctuations can be difficult to manage when the grid was designed based on a more steady power supply. This means that grid updates need to be done as countries transition to more renewable energy to ensure that electricity supply can be modulated and the grid isn’t overloaded.
Spain has a goal that by 2030, 81% of its electricity will be from renewable sources. In 2019, a plan was approved by the Spanish government to “decommission the country’s remaining nuclear reactors between 2027 and 2035”, as they continue to move towards renewable energy. Some are opposed to this switch, with nuclear lobby groups insisting that nuclear energy would help provide stability to the grid that renewables do not. But would having more nuclear energy have prevented the April outage? According to Sánchez, there is currently no “empirical evidence” that having more nuclear energy would have stopped the outage, and the four nuclear facilities that were running on April 28 were all shut down once the blackout occurred to ensure they didn’t overheat.
Nuclear is a zero-carbon energy source, but it generates radioactive waste that is challenging to safely dispose of. This makes it a controversial energy source as although some believe it is the key to helping reduce greenhouse gas emissions, it is not a perfect solution. Sánchez stated that “his government would not ‘deviate a single millimeter’ from its energy transition plans” after facing criticism after the blackout about moving away from nuclear energy. Other European countries, like Denmark, are investigating using small modular reactors to complement their renewable energy sources, instead of traditional nuclear power plants.
Spain's 23-hour blackout raised questions about renewable energy, but the government's response was telling. Despite facing criticism and calls to slow down their green transition, Spanish officials remain commited to their plan.