Nation-wide blackout a wake-up call that ‘sustainable’ wind and solar energy cannot sustain a modern electrical network
By Bjorn Lomborg, Wall Street Journal, June 03, 2025
When a grid failure plunged 55 million people in Spain and Portugal into darkness at the end of April, 2025, it should have been a wake-up call on green energy. Climate activists promised that solar and wind power were the future of cheap, dependable electricity. The massive half-day blackout shows otherwise. The nature of solar and wind generation makes grids that rely on them more prone to collapse—an issue that’s particularly expensive to ameliorate.
Te data have long shown that environmentalists’ vision of cheap, reliable solar and wind energy was a mirage. The International Energy Agency’s latest cost data continue to underscore this: Consumers and businesses in countries with almost no solar and wind on average paid 11 U.S. cents for a kilowatt hour of electricity in 2023, but costs rise by more than 4 cents for every 10% increase in the portion of a nation’s power generation that’s covered by solar and wind. Green countries such as Germany pay 34 cents, more than 2.5 times the average U.S. rate and nearly four times China’s.
Prices are high in no small part because solar and wind require a duplicate backup energy system, often fossil-fuel driven, for when the sun doesn’t shine or the wind doesn’t blow. The Iberian blackout shows that the reliability issues and costs of solar and wind are worse than even this sort of data indicates.
Wind and solar lack inertia needed to resist changes in frequency
Grids need to stay on a very stable frequency—generally 50 Hertz in Europe—or else you get blackouts. Fossil-fuel, hydro and nuclear generation all solve this problem naturally because they generate energy by powering massive spinning turbines. The inertia of these heavy rotating masses resists changes in speed and hence frequency, so that when sudden demand swings would otherwise drop or hike grid frequency, the turbines work as immense buffers.
But wind and solar don’t power such heavy turbines to generate energy. It’s possible to make up for this with cutting-edge technology such as advanced inverters or synthetic inertia. But many solar and wind farms haven’t undergone these expensive upgrades. If a grid dominated by those two power sources gets off frequency, a blackout is more likely than in a system that relies on other energy sources.
Spain has been forcing its grid to rely more on unstable renewables. The country has pursued an aggressive green policy, including a commitment it adopted in 2021 to achieve “net zero” emissions by 2050.
The share of solar and wind as a source of Spain’s electricity production went from less than 23% in 2015 to more than 43% last year. The government wants its total share of renewables to hit 81% in the next five years—even as it’s phasing out nuclear generation.
Just a week prior to the blackout, Spain bragged that for the first time, renewables delivered 100% of its electricity, though only for a period of minutes around 11:15 a.m. When it collapsed, the Iberian grid was powered by 74% renewable energy, with 55% coming from solar. It went down under the bright noon sun.
When the Iberian grid frequency started faltering on April 28, the grid’s high proportion of solar and wind generation couldn’t stabilize it. This isn’t speculation; it’s physics. As the electricity supply across Spain collapsed, Portugal was pulled along, because the two countries are tightly interconnected through the Iberian electricity network.
Spain in denial about grid instability
Madrid had been warned. The parent company of Spain’s grid operator admitted in February: “The high penetration of renewable generation without the necessary technical capabilities in place to keep them operating properly in the event of a disturbance . . . can cause power generation outages, which could be severe.”
Yet the Spanish government is still in denial. Even while admitting that he didn’t know the April blackout’s cause, Prime Minister Pedro Sánchez insisted that there was “no empirical evidence” that renewables were to blame and that Spain is “not going to deviate a single millimeter” from its green energy ambitions.
Even while admitting that he didn’t know the April blackout’s cause, Prime Minister Pedro Sánchez insisted that there was “no empirical evidence” that renewables were to blame and that Spain is “not going to deviate a single millimeter” from its green energy ambitions.
Unless the country—and its neighbors—are comfortable with an increased risk of blackouts, this will require expensive upgrades. A new Reuters report written with an eye to the Iberian blackout finds that for Europe as a whole this would cost trillions of dollars in infrastructure updates. It’s possible that European politicians can talk voters into eating that cost. It’ll be impossible for India or nations in Africa to follow suit.
That may be unwelcome news to Mr. Sánchez, but even a prime minister can’t overcome physics. Spain’s commitment to solar and wind is forcing the country onto an unreliable, costly, more black-out-prone system. A common-sense approach would hold off on a sprint for carbon reductions and instead put money toward research into actually reliable, affordable green energy.
Unfortunately for Spain and those countries unlucky enough to be nearby, the Spanish energy system—as one Spanish politician put it— “is being managed with an enormous ideological bias.”
Bjorn Lomborg is president of the Copenhagen Consensus, a visiting fellow at Stanford University’s Hoover Institution and author of “Best Things First.”