Iberian Blackout Raises Concerns Over Renewables-Heavy Power Grids

The incident is ‘a lesson in trigger events and systemic risk, both of which are exaggerated by renewables,’ says analyst Andy Mayer.

Customers dine in a restaurant illuminated by a generator during a blackout in Barcelona, Spain, dated April 28, 2025. Emilio Morenatti/AP Photo

For one day in the sunny Iberian Peninsula, the lights went off, in what has been described as the worst blackout in living memory in Europe.

With power now restored, authorities are probing the root cause, but energy analysts say that the region’s heavy reliance on intermittent renewables may have enabled the grid collapse.

The core issue is grid frequency, a 50Hz “heartbeat” that must stay balanced and is fundamental to how electricity travels through the grid.

To keep the frequency stable, the grid needs an unwavering force of power, something the industry refers to as “inertia.”

Fossil fuel oil and gas-fired stations and nuclear power plants have traditionally enabled the decades-old grid to keep a consistent frequency.

However, the rapid increase in renewables and their variable output can effectively throw the rest of the grid out of balance, analysts say.

An unexplained fault on April 28 led to widespread power cuts across Spain, Portugal, and parts of southern France.

The disturbance caused the France–Spain interconnector to trip, instantly isolating the two networks.

Red Eléctrica de España (REE) said on April 30 that there had already been two significant “disconnection events,” or interruptions in power, earlier on the same day.

“The Iberian incident is a lesson in trigger events and systemic risk, both of which are exaggerated by renewables,” Andy Mayer, COO and energy analyst at the free market think tank Institute of Economic Affairs, told The Epoch Times by email.

Since adopting its Climate Change and Energy Transition Law in May 2021, Spain has pledged climate neutrality by 2050, with a complete nuclear phase-out by 2035.

The first reactor is slated to close in 2027, envisioning a grid powered almost exclusively by wind and solar.

At an April 29 briefing, REE system-operations chief Eduardo Prieto acknowledged a “major loss of generation” in southwestern Spain, possibly caused by solar, but cautioned that investigations were ongoing.

However, a day later, REE president Beatriz Corredor Cadena, a former Socialist minister, flatly rejected any link between solar dependence and the blackout, saying that renewables today operate “as reliably as conventional generators.”

Socialist Prime Minister Pedro Sanchez also denied there was a problem of excessive reliance on renewable energy.

A young couple stands on a wall looking at the sky at a viewpoint overlooking Lisbon during a nationwide power outage, dated April 28, 2025. Armando Franca/AP Photo

In its annual report posted in February, REE, which is 20 percent owned by the state and the rest is in private hands, had warned about the loss of firm generation performance due to the phasing out of traditional power plants.

“The closure of conventional generation plants such as coal, combined cycle, and nuclear (in response to regulatory requirements) leads to a reduction in the firm generation and balancing capacities of the electricity system, as well as its strength and inertia,” it said.

Inertia is the stored kinetic energy of the system’s giant spinning metal turbines.

In large power plants, these steel turbines weigh hundreds of tonnes and span several metres, spinning at 3,000 rpm in a 50 Hz system to stabilize frequency by resisting sudden speed changes.

“This increases the risk of operational incidents that could affect supply and damage the company’s reputation. This carries a risk over a short to medium-term horizon,” REE said.

“It affects both own operations and those of customers and users,” it added.

‘Ideological Approach’

Analysts begged to differ with the hesitancy to blame renewables.

Mayer said that wind and solar power are intermittent and weather-dependent.

And every day carries “an elevated risk of a power cut over conventional generation from gas, coal or nuclear,” he said.

According to Mayer, renewables are more difficult to connect to the grid and more distributed, requiring more equipment and creating more points of failure.

He said that such sources lack inertia, which means when they fail, “they fail fast and hard.”

“A sudden loss of power in turn can push the rest of the grid out of balance, triggering relays designed to stop  ‘oscillation events’ from damaging equipment,” he said.

“Consequently, there is higher risk of a trigger event, and a higher risk of a systemic cascade in a renewables-rich power grid. That’s what just happened in Spain and Portugal,” he said.

He added that there are solutions called “inertia services” like flywheels—which are machines that can continuously accelerate and decelerate to balance electrical supply and demand—so the grid can be tuned to the right frequency.

He added that batteries and grid-forming inverters can also reduce renewables risk, but these add to the cost of deployment.

While electricity was restored to most of Spain and Portugal early on Tuesday, European leaders will be keen to give assurances it won’t happen again.

Mayer said that all national grids with renewables “are aware of this problem, but the policy incentives are wrong.”

He criticized that most governments have taken an “ideological approach” to achieving net zero by setting renewable capacity targets and not delivered output targets.

He said this has led to sometimes “useless over-supply, in the wrong places, without concomitant investment in grid security.”

“The disaster to avoid is ploughing on with net zero regardless, and hoping consumers and industry will bear the already high cost or forgive the occasional day of darkness,” he said.

“Any government not carefully reviewing which path they’re on after this week should be mindful that those that lose power, lose power,” he added.

Energy expert David Turver told The Epoch Times by email that he thinks the countries with high wind and solar penetration are “most vulnerable.”

He said that France’s 50GW of nuclear power stations will provide considerable inertia, along with Germany’s coal-fired power plants.

“The way to generate synthetic inertia is through batteries and possibly flywheels. All very expensive,” he added.

‘First Total Blackout’

In a Cinco Días opinion piece on April 29, Jordi Sevilla, who served as REE’s chair until 2020, said that the government is moving too quickly to retire nuclear power plants, arguing that they are crucial for supplying stable output needed to smooth the ups and downs of intermittent renewables.

“This is the first total blackout ever experienced in Spain. It is also the first time that non-synchronous technologies have provided the majority of our electricity,” Sevilla said.

He said that under current technology, the grid must maintain a “synchronous backup capacity” of hydroelectric, gas, or nuclear, which can be called upon when solar and wind are insufficient, either because of their “intermittency [there may be no sun or wind] or because they lack the synchronism needed for generator stability.”

Spain’s unified high-voltage transmission grid was unified in 1985, with more than 10,000 km of lines. Today, the network spans roughly 45,000 km.

Substation equipment, including transformers, is often built for multi-decade operations, up to 40 years.

Not all of Spain’s substation gear has been swept away in a single upgrade to ready itself for mass net-zero electrification, but there is an ongoing, multi-billion-euro modernization program.

Spain’s renewable capacity has also almost doubled in the past five years, according to a March report by Aurora Energy Research.

Adopting the country’s grid infrastructure to net zero will be pricey, considering that the EU’s electricity demand is expected to more than double by 2050.

Last month, the European Court of Auditors warned that the current pace of planned grid investments was insufficient for future electricity demand and the energy transition.

They said that if grid operators keep investing at today’s pace, they’ll spend 1.8 trillion euros ($2.06 trillion) by 2050, which is below the 1.9 trillion to 2.2 trillion euros the European Commission says is needed.