The Physics Behind the Spanish Blackout

As I wrote in these pages in January, the data have long shown that environmentalists’ vision of cheap, reliable solar and wind energy is 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 paid, on average, 11 cents/kWh in 2023; but at 10% W/S costs increase to 15 c/kWh; at 20% W/S, 19 c/kWh; at 30%, 23 c/kWh, etc.

Adding tens of millions of illegal, unskilled, not-integrated misfits, from all-over is no help;

Prices are high in no small part because unreliable 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 unreliable solar and wind are much worse..

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 unreliable 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 expensive advanced inverters or synthetic inertia.

But many unreliable solar and wind systems haven’t undergone these expensive upgrades.

If a grid dominated by those two power sources deviates from its standard frequency, a blackout is far more likely than in a system that relies on traditional energy sources.

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 unreliable 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 unreliable renewables to hit 81% in the next five years—even as it’s phasing out nuclear generation.

That is beyond insane, as it was and still is in dysfunctional California, after frequent blackouts and massive battery fires.

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 the grid collapsed, it was powered by 74% unreliable renewables, with 55% coming from solar.

When the Iberian grid frequency started faltering on April 28, the grid’s high proportion of unreliable solar and wind generation couldn’t stabilize it.

Analysis of Spain’s April 2025 Blackout: Causes, Low-Inertia Grid Risks, and Protection Solutions

As the electricity supply across Spain collapsed, Portugal was pulled along, because the two countries are tightly interconnected through the Iberian electricity network.

Madrid had been warned. The parent company of Spain’s grid operator admitted in February: “The high penetration of unreliable renewables 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.”

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 unreliable renewables were to blame and that Spain is “not going to deviate a single millimeter” from its green energy ambitions.

That fellow is about as smart/technically savvy as dysfunctional Governor Newscum of California

Unless Spain—and its neighbors—are comfortable with an increased risk of blackouts, this will require expensive upgrades.

It’s possible that European politicians can talk voters into eating that cost.

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.”

Mr. Lomborg is president of the Copenhagen Consensus, a visiting fellow at Stanford University’s Hoover Institution and author of “Best Things First.”

Analysis of Spain’s April 2025 Blackout: Causes, Low-Inertia Grid Risks, and Protection Solutions

On April 28th, 2025, Spain experienced a massive electrical blackout that affected the entire Iberian Peninsula, disrupting electricity supply across Spain and its interconnections with Portugal and France. According to Red Eléctrica de España (REE), the event was triggered by a sudden loss of 15 GW of generation within just five seconds at 12:33 PM, representing approximately 60% of the system’s online generation at that moment (REE, Preliminary Event Report, April 2025).

This rapid imbalance between generation and demand led to an immediate frequency drop and the activation of automatic protection systems across the grid. Official data shows a dramatic decline in recorded demand from 26,968 MW to under 13,000 MW within minutes (REE, Demand Graph, 28/04/2025). Full restoration of service extended into the early hours of April 29th.

This incident marks one of the most significant electric grid collapses in Spain in recent decades.

An electrical power system must maintain a continuous real-time balance between generation and demand. Any instantaneous mismatch directly impacts the system’s frequency, with Europe’s nominal frequency set at 50 Hz.

The system’s ability to resist sudden frequency deviations depends on its inertial response, traditionally provided by synchronous generators (nuclear, thermal, large hydro plants) whose spinning masses store kinetic energy. These rotating masses act as a natural buffer, slowing down the rate of frequency change after a disturbance.

In low-inertia systems, frequency variations occur much more rapidly, leaving less time for operators or automated systems to react and correct imbalances.

At 12:30 PM on April 28th, 2025, according to REE data, Spain’s generation mix was as follows:

This generation profile reflects a system highly reliant on non-synchronous generation, particularly solar PV connected via power electronic inverters. Unlike synchronous machines, inverters do not contribute natural rotational inertia since they lack a physical spinning mass coupled to the grid frequency.

Moreover, with only 4.82% of generation from combined cycle gas turbines and minimal participation from other synchronous generators, the system’s ability to provide kinetic energy reserves was critically low at the time. Synchronous generators are vital because their spinning rotors can release or absorb kinetic energy following a disturbance, reducing the rate of change of frequency (RoCoF, or df/dtdf/dtdf/dt).

Under these conditions, any sudden imbalance would result in much faster and deeper frequency deviations, increasing the likelihood of triggering protective disconnections (Bollen, Understanding Power Quality Problems, IEEE Press, 2000).

In this scenario, a significant and abrupt load loss (such as a major industrial zone, a large city, or even an international export interconnection) caused an immediate generation surplus.

This surplus led to a frequency increase (f>50Hzf > 50 Hzf>50Hz). In a high-inertia grid, this rise would have been dampened by kinetic energy absorption from synchronous generators. However, in a low-inertia system, the rate of frequency rise (df/dtdf/dtdf/dt) is much higher, quickly triggering overfrequency protection systems, typically set between 50.2 Hz and 51 Hz in European grids.

These protections disconnect generation to reduce frequency. But if the response is uncoordinated or excessive, too much generation is disconnected → frequency drops below nominal → underfrequency protections activate → cascading shutdown → total collapse.

Key electrical parameter: crossing of overfrequency protection thresholds (>50.5 Hz) causing widespread automatic generation disconnections.

Alternatively, the initiating event could have been a sudden generation disconnection, such as:

The resulting deficit caused frequency to drop (f<50Hzf < 50 Hzf<50Hz). In a low-inertia system, this drop was rapid and steep. When frequency fell below underfrequency protection thresholds (typically 49.5 Hz to 49 Hz), underfrequency load shedding (UFLS) was activated to disconnect load and rebalance the system.

However, if the initial generation loss was too large, or if UFLS responses were insufficient or delayed, frequency continued to decline, causing further protection trips and a cascading blackout.

Key electrical parameter: rapid rate of frequency decline (df/dt) exceeding UFLS capacity to stabilize the system.

Example: The 2006 European blackout originated from a planned line disconnection in Germany that unintentionally isolated large regions, cascading across the grid (UCTE Final Report, 2007).

5.2. Possible causes of sudden generation disconnection (underfrequency scenario)

Example: In the 2016 South Australia blackout, multiple transmission line faults combined with inverter-based wind farm protections led to a rapid cascade of generation loss and system collapse (AEMO, Black System Report, 2017).

Regardless of the initiating cause, this blackout highlights the need for modernizing grid operation under high non-synchronous generation. Solutions include:

In addition to grid-scale measures, enhancing the reliability and responsiveness of protection systems (relays) is critical. Many of the protection failures or delayed actions in both hypotheses could be mitigated by more rigorous, scenario-based relay testing.

A key solution is to implement routine and scenario-driven testing of protective relays, including under-frequency, over-frequency, and load-shedding schemes, using advanced relay test equipment capable of simulating dynamic grid conditions.

By validating protection responses under varying rates of frequency change (df/dtdf/dtdf/dt) and multi-event scenarios, utilities can:

Such testing practices improve the system’s capacity to contain localized disturbances and prevent cascading failures, especially in grids dominated by inverter-based resources.

Spain’s April 28th, 2025 blackout underscores the vulnerability of modern low-inertia power systems to both overfrequency and underfrequency events. Both hypotheses—a sudden load loss leading to overfrequency, or a sudden generation loss causing underfrequency—are technically plausible and reveal critical challenges in protection, coordination, and inertia management.

The energy transition demands not only increasing renewable generation but also reinforcing system stability through improved protections, synthetic inertia, fast-response reserves, and enhanced testing protocols to ensure a secure and resilient grid.

Over-reliance on Unreliable Wind/Solar Makes Widespread Blackout Nightmares More Likely

Imagine taking the subway to work when the train comes to a sudden halt halfway between scheduled stops. You pull out your smartphone to go online and see what the problem is, but you have no reception – no cell signal, no internet.

Hours later, rescue workers arrive to extract you and your fellow passengers from the stalled train.

You make your way to the street in hopes of taking a taxi or an Uber.

But without your phone apps and with credit card machines inoperable, you are forced to search for an ATM – only to discover those aren’t working, either.

You soon realize that everyone else is in the same predicament.

Hospitals operating on emergency backup systems.

People trapped inside elevators.

Traffic snarled due to inoperable stoplights.

Gas station pumps not functioning.

Airport terminals closed.

People in darkened homes desperately searching for candles and battery-operated radios to learn what’s happening.

On April 28, the residents of Spain, Portugal and parts of France didn’t have to try to imagine this nightmare scenario.

They found themselves prisoners of it for hours when an unprecedented blackout impacted at least 55 million people after the Iberian Peninsula electric grid system failed.

The outage, described as one of the worst ever in Europe, “disrupted businesses, hospitals, transit systems, cellular networks and other critical infrastructure,” according to the France 24 news channel.

Many news agencies, particularly in the U.S., insisted for days that it was too early to say what caused the massive blackout.

Others, though, acknowledged the obvious.

The Reuters news agency reported early on, “Redeia, which owns Red Electrica, warned in February in its annual report that it faced a risk of ‘disconnections due to the high penetration of renewables without the technical capacities necessary for an adequate response in the face of disturbances.’”

While many observers did their best to point fingers at alternative causes, others were more straightforward in identifying the culprit.

Raúl Bajo Buenestado is a non-resident energy scholar at Rice University’s Baker Institute for Public Policy in Houston.

He received a Fulbright scholarship as a graduate student and a grant for young researchers from Spain’s Ministry of Education, and received his Ph.D. in economics from Rice.

Currently, he is “primarily working on the generation investment incentives and capacity markets in the electricity sector. He also conducts research on gasoline retail markets,” according to his online biography.

After studying the April 28 blackout data, Buenestado authored a commentary concluding that mere minutes prior to the grid collapse, “renewable sources accounted for 78% of electricity generation in the Iberian Peninsula grid system, with solar alone contributing nearly 60%.

By contrast, conventional technologies, such as gas-fired and nuclear power plants, comprised only around 15% of the total generation mix.

This configuration is not unusual in Spain or Portugal, where high shares of renewable generation are common, particularly during sunny and windy days.”

Buenestado added, “What sets April 28 apart, however, is that, according to Spain’s national electricity grid operator (Red Eléctrica de España), two consecutive generation loss events occurred in southwestern Spain, involving large solar installations.” It is likely the DC to AC rectifiers failed.

Buenestado noted that “the risk of large-scale blackouts in electricity systems with high shares of renewable energy is well-established.

However, the Iberian blackout of April 28 brings these long-recognized vulnerabilities into sharp focus.”

He explained that unlike conventional power plants, solar and wind installations “depend on a stable grid to function correctly and cannot autonomously support grid stability during disturbances.”

Any energy systems analyst would know Spain/Portugal-like blackout problems would eventually happen, before a single W/S system were connected to the grid, but naive, woke, technically illiterate enviros do not want to listen to the pros. All wind/solar/battery nonsense must be stopped dead by taking away the generous subsidies.
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The More W/S Electricity on the Grid, the Less the CO2 Reduction/kWh, due to Inefficiencies

Analysis of 2013 data of the island Irish grid showed the CCGT fleet operating at about 50% without wind; at 45.58%, with 17% wind.
At higher W%, the CCGT fleet operates at lesser efficiencies (high Btu/kWh, high CO2/kWh), until no CO2 is reduced.
Fortunately, Brussels paid for major connections to the much larger UK and French grids.

As a result, most of the ups and downs of wind output disappeared in the noise of the large grids.
https://www.windtaskforce.org/profiles/blogs/fuel-and-co2-reduction...
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Expensive Wind/Solar Systems
The over-taxed, over-regulated taxpayers and ratepayers are paying at very high rates, c/kWh, for: 1) electricity, and 2) Heat Pump heating/cooling, and 3) EV driving.
There is no way such high-cost electricity would increase standards of living and increase the GDP.
Businesses and skilled people would move to low-energy-cost states.
These businesses and people are tired of paying for:
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1) Highly subsidized, expensive W/S systems that disturb the grid with weather-dependent, variable, intermittent electricity, which has caused expensive brownouts/blackouts, as in Spain/Portugal, California, Texas, New England, etc., and many other places, over the years.
2) Grid expansion to connect all these far-flung wind/solar systems to the grid,
3) Grid reinforcements to ensure the grids do not crash during periods with higher levels of W/S power
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Here are some operational realities of W/S systems that are at the core of their problems:
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Synchronous Rotational Inertia, SRI, Stabilizes the Grid
Closing down traditional plants (nuclear, gas, coal, hydro), with rotating generators that provide SRI, de-stabilizes the grid; a death sentence for the grid.
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Wind/solar systems provide ZERO SRI to help stabilize the grid, because their variable outputs are digitized, then reconstituted into an artificial sine wave with the same phase and frequency as the grid.
Super expensive battery systems provide ZERO SRI.
Battery systems can provide virtual inertia, at very high c/kWh, by means of their back-end DC to AC power electronics (which failed in Spain/Portugal), which can quickly counteract voltage/frequency drops for a short time.
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Connections Between Grids
Almost all grids have connections to other grids for import and export purposes.
About 50% of such connections are high-voltage, direct-current lines, HVDC
Such DC connections transfer power, but transfer ZERO SRI to other grids.
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Reactive Power
No AC grid can function without positive reactive power; say power factor of 0.8
Wind/solar systems take reactive power FROM the grid; say power factor of -0.8
All traditional power plants are automatically set up to provide positive reactive power TO the grid.
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Synchronous Condenser Systems
The weather-dependent, variable/intermittent, wind/solar feed-ins to the grid often create transmission faults.
Those faults are often minimized with synchronous condenser systems that provide positive reactive power TO the grid.

Blackouts
In case of too much W/S power, it needs to be curtailed.
Owners usually get paid for what they could have produced.
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In case of too little W/S power or a W/S outage, reliable, quick-reacting CCGT plants, in Hot Synchronous Standby, HSS, mode, would provide:
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1)) Instant SRI to the grid for "ride-through" to give switches time to switch, and
2) Provide power to the grid, within seconds, to counteract voltage/frequency drops due to W/S outages, 24/7/365; if battery systems were used, they would be empty after a few hours, with no prospect of a black grid to refill them.
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Spain/Portugal would have needed about 10,000 MW of CCGT plants in HSS mode to avoid its recent blackout.
They would operate at 50% output throughout the year, and quickly provide up to 5000 MW, in case of a W/S outage.
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Black Start Procedure for a 100 MW CCGT Power Plant
Initial Power Source: The on-site auxiliary generator is started. It provides power to critical plant systems, including control, safety, and communication systems.
Plant Startup: The auxiliary generator then powers the CCGT plant's essential systems. This includes cooling systems, fuel handling systems, and starting the gas turbine.
Connecting to the Grid: After the CCGT plant is spinning at 3600 rpm at the same phase and frequency as the grid, it can be connected to the grid to supply power to its section of the grid. That section powers another power plant, etc., until all sections are up and running. Only then, grid-destabilizing W/S systems are connected.

Before President Trump reversed the previous administration’s war on fossil fuels, President Biden had committed the U.S. to reaching “100% clean electricity” by 2035 – a goal that seriously imperiled our own infrastructure.

Biden’s corresponding attacks on affordable and reliable energy sources like natural gas were idiotic and unpopular.

Likewise, Spain is “currently aiming to phase out fossil fuel and nuclear generation in favor of renewables,” with a goal of renewables comprising 74% of total output by 2030, under the plan.

The insistence on replacing affordable, dependable energy with more expensive and unreliable alternatives is both idiotic and impractical.

Natural gas remains the most cost-effective, reliable and increasingly clean fuel choice in the world.

Despite the Spanish government’s anti-fossil fuel rhetoric, the U.S. recently became the main supplier of liquefied natural gas to Spain.

Much of Europe – mimicking extremist climate change rhetoric – publicly decries America’s continued production and use of traditional energy, while simultaneously gobbling it up.

Will the disaster of April 28 make European leaders think twice about abandoning our most reliable energy sources? Hardly.

Following the devastating blackout, Spanish Prime Minister Pedro Sanchez said his government would not “deviate a single millimeter” from its plans to transition to so-called renewables; he is totally woke, like PM Starmer of the UK, which has achieved the highest household electricity rates, c/kWh, in Europe, along with a stagnant GDP, and stagnant real wages.

It is worth noting, oil and gas powered diesel-generators were used to gradually restore the grid from Black Start conditions, and restore electricity to about 50 million people in Spain, Portugal and parts of France.

The Physics Behind the Spanish Blackout

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