While a comprehensive investigation will take weeks to complete, today’s massive power outages across Spain and Portugal present compelling evidence of the inherent vulnerability in renewable-heavy grids and likely offer a stark lesson in the dangers of sacrificing grid stability on the altar of green energy. While officials scramble to restore power to millions and politicians inevitably deflect blame, the catastrophic failure aligns perfectly with warnings that power grid experts have been sounding for years: systems with high penetrations of solar and wind generation have diminished mechanical inertia and are inherently vulnerable to collapse.

The inertia problem nobody wants to discuss

Spain’s electrical grid, once a model of reliability, has undergone a radical transformation over the past decade. Conventional power plants with massive spinning turbines – the kind that naturally resist frequency changes and provide crucial stability – have been systematically replaced with weather-dependent solar panels and wind turbines that contribute virtually no inertia to the system.

The result? A grid that may function adequately under ideal conditions but remains perilously susceptible to rapid destabilization when faced with disturbances.

Anatomy of a collapse

Initial reports from Spain grid operator Red Eléctrica indicate that ‘oscillations’ in the network triggered the cascade of failures. This technical language obscures a simpler truth: the system likely lacked sufficient physical inertia to withstand a relatively routine disturbance.

The data reveals the shocking speed and scale of the collapse. Real-time generation data shows that before the blackout, Spain’s grid was operating with an extremely renewables-heavy mix, including 18,068 MW from solar PV (by far the largest contributor at approximately 54% of domestic generation) and 3,643 MW from wind. By contrast, conventional synchronous generation sources provided minimal output: nuclear at 3,388 MW, hydro at 3,171 MW, and combined cycle at just 1,633 MW.

After the collapse, the generation mix shifted dramatically as operators struggled to restore the system. Total demand dropped from ~27 GW to just ~16 GW. Interestingly, nuclear generation disappeared completely from the generation stack, confirming that these plants – typically considered the most reliable part of the generation fleet – were forced to disconnect entirely during the event. Solar PV output fell by more than half to 8,236 MW, while other sources like wind and hydro saw similar reductions.

What is system inertia and why does it matter?

System inertia is the inherent resistance to sudden frequency changes provided by the kinetic energy stored in rotating masses of conventional power plants. When a disturbance occurs, this inertia automatically slows the rate of frequency change, giving operators crucial seconds to respond. Consider the difference between a heavily ballasted ship and a lightweight vessel in rough seas. The former can absorb massive waves without capsizing, while the latter remains dangerously vulnerable to sudden squalls.

Power system engineers have been warning about the high penetration of renewables and the inertia-related risk for years. The European Network of Transmission System Operators for Electricity (ENTSO-E) has been sounding increasingly urgent alarms about declining system inertia. Their studies methodically demonstrate that as renewable generation increases, the reduction in rotating mass weakens the grid’s natural ability to resist frequency disturbances and they’ve identified a critical vulnerability: when renewable generation dominates the mix, the resulting low rotating mass and insufficient inertia create conditions where frequency disturbances can accelerate rapidly – precisely the pre-failure conditions that existed in Spain’s grid before today’s collapse. Indeed, these conditions mirror the vulnerabilities observed in previous European events, such as the 2021 Iberian Peninsula separation.

Lessons for Britain

British grid operators have been highlighting nearly identical concerns. The National Grid ESO’s 2023 ‘Operability Strategy Report’ explicitly identifies that Britain’s system inertia declined by around 40% between 2009 and 2021, creating reduced resistance to frequency changes and making the grid more vulnerable to disturbances. The report further acknowledges that operating to an inertia threshold is increasingly challenging as renewable penetration grows – a warning that recent events in Spain make even more urgent.

As our nation races down the same dangerous path – systematically closing reliable coal and gas plants while becoming increasingly dependent on weather-contingent generation – green energy advocates inside and outside of government will inevitably blame extraordinary circumstances when failures occur, refusing to acknowledge the underlying vulnerability regarding system stability created by dismantling conventional generation capacity. For years, many renewable advocates have dismissed these warnings, claiming that clever electronics and battery systems can provide ‘synthetic inertia’ to replace what’s lost. However, multiple studies have shown this to be untrue.

The path forward

A sensible approach to any energy transition would be to prioritize maintaining adequate system inertia through a mix of conventional generation. New technologies must be carefully tested and validated before widespread deployment. Grid stability isn’t merely a technical detail; it’s the foundation of our civilization.

Unfortunately, Britain’s headlong rush toward a renewables-dominated grid is being led by Energy Secretary Ed Miliband, whose economic illiteracy regarding energy markets is rivaled only by his magical thinking on power system fundamentals. Such delusion is nothing new in the energy sector. Enron’s spectacular collapse came after years of selling ‘innovative’ energy products that analysts and governments lapped up but that were, in reality, elaborate financial illusions. Today’s renewable alchemy represents the next iteration of energy-related magical thinking – insisting, contrary to all engineering evidence, that a grid built on wind and solar can match the reliability and resilience of conventional generation. Like all magical thinking, this too collides with the immutable laws of physics.

This week, millions of Spaniards learned this lesson the hard way, trapped in elevators, stranded on trains, and left without basic services. The economic toll of the Spanish blackout will be huge. With the outages affecting much of Spain and Portugal for several hours (at the time of writing the system is only partially restored and could take days to fully recover), the total economic damage will likely reach into the tens of billions of euros.

Britain faces a stark choice: acknowledge the physical realities of electrical systems and maintain adequate conventional generation or continue the current ideologically-driven path toward likely system collapse.

Stop Press: The power cuts across Spain and Portugal were likely caused by failures at solar farms, the grid operator REE has said. It has identified two incidents of power generation loss, probably from solar plants, in the country’s south-west, which caused instability in the electric system and led to a breakdown of its interconnection with France.