What Caused The Blackout On The Iberian Peninsular? It’s Complicated.

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On November 9, 1965, much of eastern Canada, New England, New York, and Pennsylvania went dark. The Great Blackout lasted up to 13 hours and forever disrupted the idea that our electric power supply would always be there when we needed it. What caused it was a question that took many months to answer. Finally, an explanation emerged. According to Wikipedia, the cause of the failure was the setting of a protective relay on one of the transmission lines from the Sir Adam Beck Hydroelectric Power Station No. 2 in Queenston, Ontario, near Niagara Falls, which was set to trip if other protective equipment deep within the Ontario Hydro system failed to operate properly.

On a particularly cold November evening, power demands for heating, lighting, and cooking were pushing the electrical system to near its peak capacity. Transmission lines heading into southern Ontario were heavily loaded. The safety relay had been mis-programmed, and it did what it had been instructed to do — disconnect when certain conditions were met. At 5:16 PM, a small variation of power originating from the Robert Moses generating plant in Lewiston, NY, caused the relay to trip, disabling a main power line heading into Southern Ontario.

Instantly, the load that was flowing on the tripped line redistributed to the other lines, causing them to become overloaded. Their own protective relays, which were also designed to protect the lines from overload, tripped as well, isolating Beck Station from all of southern Ontario. With nowhere else to go, the excess load from Beck Station was redirected east, over the interconnected lines into New York state, overloading them as well, and isolating the power generated in the Niagara region from the rest of the interconnected grid. The Beck generators, with no outlet for their power, were automatically shut down to prevent damage.

The blackout became the basis for the first episode of a TV series by historian James Burke called Connections. It begins with Burke at the top of the World Trade Center decades before September 11, 2001, which gives the show an eerie sense of foreshadowing. As the episode progresses, Burke explores how access to abundant electrical energy can set the stage for enormous social stress if that energy suddenly becomes unavailable.

If you are not familiar with Connections, you have missed out on one of the pivotal moments in television history. It is all available on YouTube and highly recommended viewing. CleanTechnica readers, who are all well above average, will find the series especially rewarding. Many years ago, while visiting Colonial Williamsburg, I discovered the staff there were all James Burke aficionados who thought of him with special reverence.

The Blackout On The Iberian Peninsular

Last week, great swaths of Spain and Portugal went dark. Both nations have strongly supported wind and solar resources over the past decade, and so, naturally, the first thought in everyone’s mind — especially those who do not live on the Iberian Peninsula — was that renewables were the cause of the grid failure.

On May 2, 2025, The Breakthrough Institute published a blog post entitled “It’s Okay to Notice When Solar and Wind Fail.” What it basically said is that renewables are fundamentally different that thermal generators. Unfortunately, the Spanish and Portuguese grid is based on the Westinghouse model, which has served the world well but which is optimized for the kinds of spinning reserves from coal, methane, and nuclear thermal generators that have been prevalent during the last century.

The problem, it says, is that Spain and Portugal have been slow to transition to the control structures a grid supplied with large quantities of renewable energy requires, mostly because they were reluctant to spend the money that would be needed to make that happen. Sharp-eyed readers will recall that when Texas was whacked by a severe winter storm a few years ago, many of its wind turbines failed because they iced up. (More important in that case, though, was that natural gas power plants failed.)

There are systems available to keep wind turbines from freezing. In fact, wind turbines are used to provide electricity to research stations in Antarctica. But the equipment to keep them from icing up costs money, and the Texas grid operator — ERCOT — places a premium of the cheapest possible technology. It turns out that cheaper is not always better. Despite that perfectly logical explanation, however, people still insist the problem in Texas was too much renewable energy. To counter the scourge of renewables, the Texas legislature wants to require developers of new renewable resources to build backup thermal generation as well so Texas will never again be victimized by an abundance of renewables.

This blackout in Spain and Portugal is not the inevitable outcome of running an electricity system with substantial amounts of wind and solar power, The Breakthrough Institute says. Rather, it is exactly what one would expect from the type of energy transition attempted by the Spanish government — breakneck deployment of renewables coupled with a failure to ensure enough spinning generator capacity to maintain stabilizing grid inertia despite knowing the risks and ignoring warnings from grid operators. The result was an under-investment in grid capabilities that could compensate for renewable energy’s unique technical risks to reliability.

Renewable Grids Are Different

“Wind and solar power can contribute meaningfully to large, modern electric grids. But their benefits to the power system — modularity and low marginal costs — have to be balanced against their shortcomings such as intermittency, the need for large amounts of land, and specific transmission requirements. Most solar and wind farms operating today use simpler equipment that are vulnerable to unexpected shifts in frequency and do not provide spinning or synthetic inertia that can compensate for grid frequency fluctuations.”

Running a power system mostly on wind and solar may be theoretically possible, but has yet to be demonstrated on any large grid in the world, the report says. “Doing so would require a number of ‘grid-enhancing’ solutions that are only just beginning to enter operational service at scale today. Installing ‘grid forming’ inverters that let solar, wind, and batteries regulate grid frequency and voltage strengthens the grid compared to currently common ‘grid following’ inverters that cannot adjust to grid fluctuations.

“A sufficiently large fleet of charged battery systems can also automatically release power in response to loss of generation from one or more power plants, maintaining grid frequency and the balance of supply and demand until reserve generators can come online. Ancillary supporting equipment such as synchronous condensers and static synchronous compensators can similarly provide necessary frequency support to correct for grid fluctuations. Engineers are also devoting increasing attention towards optimizing the parameter tolerances for grid following inverters and other systems so assets don’t disconnect from the power grid unless truly necessary.”

“The Iberian outage emphasizes the importance of large scale investments in grid enhancing equipment and reliability that occur alongside significant penetration of wind and solar onto the power grid,” The Breakthrough Institute claims. “Ideally, those investments should be made before connecting new renewable energy sources to the grid, not afterwards.” An IEA report in 2021 stated the issue clearly. “To achieve a high share of renewables, the first step is to develop a new way for [inverters] to operate when they start dominating the system.”

A Preventable Blackout

This week’s blackout appears to have been made worse by exactly what experts have been worried about. Large unexpected frequency anomalies likely triggered a protective automated shutdown of a sizable fraction of Spain’s solar plants, aggravating a large-scale supply/demand imbalance, a worsening frequency excursion, and a total grid collapse. Inertia from spinning turbines usually helps resist sudden grid frequency fluctuations, but relatively little spinning generator capacity was operating at the time of the recent grid disruption.

In a recent interview for Heatmap, Bri-Mathias Hodge captured the essence of the problem, arguing that “the entire stability paradigm of the power grid was built around this idea of synchronous machines. And we’re moving toward one that’s more based on the inverters, but we’re not there yet.”

The Breakthrough Institute report offers this conclusion: “For too long, climate and clean energy advocates have conditioned themselves to roll their eyes at any commentary suggesting that grid-following wind, solar, and storage cannot do literally everything, everywhere, at all times. Even basic and fundamentally true observations like ‘the sun doesn’t always shine and the wind doesn’t always blow’ have drawn dismissive mockery from some climate hawks. That the Spanish grid collapsed under a bright sun just a half hour past midday fundamentally challenges platitudes that we have already solved the integration challenges of wind and solar power. It is not only okay to admit that wind and solar cannot do everything, it is precisely what this moment needs.”

Is it fair to say that renewables played a role in the blackout on the Iberian peninsular last week? Yes, it is. Is it fair to say that the blackout occurred because of the renewables? No, it is not. A grid is a very complex thing and most of us do not fully understand what makes one work properly. The accusations about how renewables crashed the grid started almost as soon as the lights went out as clueless people reached for the most convenient explanation for why the grid failed.

In a social media world, misinformation and disinformation spread wildly, with those who start pointing fingers and hurling accusations first being rewarded with the title of “influencers,” whatever that means. In a prior time, we would have just dismissed them as big-mouths and know-it-alls, but in the upside down world of anti-social media, they become instant authorities. It’s good to remember that coincidence is not the same as causation, and diagnosing a failure is often a complex task that can take days, weeks, or months to complete.

Mistakes are the best teachers … if we are willing to learn from them. If The Breakthrough Institute is correct, there is much yet to learn about managing grids that have lots of renewable energy flowing through their wires. We need to calm down, stop pointing fingers, and figure out how to do better — unless you are in Texas, in which case all actions that smack of sanity are immediately discounted as products of a woke mind virus. Our best hope is that the know-nothing approach of the typical Texas politician does not infect rational and careful analysis by those situated outside the borders of the Lone Brain Cell State.