A Case Study of the Iberian Grid
Did over-reliance on renewables cause the Spain-Portugal blackout?
On April 28, 2025, Spain and Portugal suffered one of the most severe blackouts in their recent history, with cascading impacts extending briefly into parts of southern France and Andorra. The disruption began around 12:30 PM local time, halting transportation systems, severing mobile and internet communications, affecting hospitals, and causing widespread public disruption across the Iberian Peninsula.
According to the Portuguese prime minister, Luís Montenegro, the root cause of the blackout originated in Spain. Portugal’s transmission operator, REN, reported that a “rare atmospheric phenomenon”, specifically extreme temperature variations in the Spanish interior, triggered anomalous oscillations in the 400 kV very high voltage lines. This event, known in the industry as “induced atmospheric vibration”, disrupted the stability of the interconnected European grid. The oscillations led to synchronization failures between regional systems, causing the frequency of the network to drop below the 50Hz standard, and resulting in cascading disconnections of power plants, including one in France. Though power restoration efforts were rapid, the incident exposed significant vulnerabilities in the grid's ability to handle extreme atmospheric conditions.
Energy Transition and System Fragility
Today, most OECD governments, along with many other nations, are deeply committed to an accelerated energy transition. Driven by the urgency of climate change, industrial policy, and economic modernization goals, there is a strong push to shift from fossil fuels to renewable energy systems, particularly solar and wind. Ambitious targets for clean energy deployment are now widespread across Europe, North America, and parts of Asia.
However, as the Spain–Portugal blackout demonstrates, transitioning energy systems involves more than simply replacing generation sources. It fundamentally reshapes the architecture and physics of power grids. Without careful attention to the dynamic stability, reliability, and structural resilience of new systems, the risk is going to be two-fold: slower transition and occasional catastrophic failures. Governments and system operators must recognize that in a future dominated by inverter-based resources and weather-dependent generation, grid resilience must be designed explicitly and not assumed as a passive byproduct.
In recognition of these challenges, a significant amount of research and development is underway worldwide to innovate solutions for renewable energy generation and grid stability. Institutions such as the International Energy Agency (IEA), national laboratories, universities, and private companies have intensified their focus on technologies that can make high-renewables systems cleaner and fundamentally more resilient.
For this post, I present some of the top technologies identified by the IEA’s Energy Technology Perspectives 2024 report, which highlights manufacturing and grid integration priorities, as well as some of the other sources that presents cutting-edge control strategies and frequency stability innovations specific to wind-heavy grids. My goal here is to assess, against the real-world failure seen in the Spain–Portugal blackout, whether these technologies (if they had been deployed) could have mitigated or prevented the cascading outage. In doing so, we apply a structured evaluation grounded in both technical realism and energy security principles.
Technology Evaluation Against the Spain–Portugal Blackout
To evaluate how modern renewable and grid technologies could have impacted the 2025 Spain–Portugal blackout, we must consider both the technical behavior of each solution and how it would have interacted with the specific disturbance dynamics. Namely, the recent rapid frequency collapse initiated by atmospheric-induced transmission line oscillations. Here I evaluate six advanced relevant technologies:
Technology 1) Wind + DFIG-ES Controls for Turning Wind Farms into Grid Stabilizers
Modern wind farms equipped with Doubly-Fed Induction Generators (DFIG) already provide reactive power control. However, coupling them with onsite energy storage (ES) enhances their ability even further to deliver synthetic inertia and fast frequency response. These are two capabilities crucial during sudden system disturbances.
Had Spain and Portugal’s wind fleets been equipped with large scale DFIG-ES systems as described in the sources I’ve listed, they could have intervened within milliseconds as the frequency dipped. Fast energy injection from wind farms would have counteracted the frequency instability early, potentially halting or delaying the cascading plant disconnections that followed. In DFIG-ES hybrid systems, small, targeted bursts of stored energy can supply critical active power precisely during the window where traditional generators and slower grid services cannot react. Widespread deployment of DFIG-ES systems would have provided a frontline defense against the rapid decline triggered by atmospheric-induced conductor oscillations.
Technology 2) Grid-Forming Inverters for Establishing Localized Grid Resilience
Traditional inverters in solar PV and battery systems are grid-following. They rely on an existing voltage and frequency reference to operate. Grid-forming inverters, by contrast, can create those references themselves. They effectively simulate the behavior of synchronous machines, maintaining stable voltage and frequency even as the broader system destabilizes.
The IEA report highlights grid-forming inverters as indispensable for future high-renewables systems. In the context of the Iberian blackout, a more widespread presence of grid-forming inverters would have enabled localized microgrid stabilization. Rather than entire national grids collapsing in synchrony, sections of the system could have held together, forming resilient islands capable of autonomous operation until central coordination was restored. Grid-forming inverter deployment could have dramatically contained the extent of the blackout.
Technology 3) Flexible Kinetic Energy Release for Tapping Wind Turbines' Hidden Reserves
Wind turbines inherently store kinetic energy in their rotating blades. Traditionally, this energy is lost during disturbances. Flexible kinetic energy release mechanisms enable turbines to strategically extract and inject this stored energy during frequency drops. In the Iberian blackout, controlled release of this kinetic reserve could have blunted the speed and depth of the frequency decline. Even modest contributions from turbines across Spain and Portugal would have cumulatively provided critical inertia-like behavior exactly when needed. This technique is especially powerful because it requires no additional hardware, only smarter control software and coordination protocols. Flexible kinetic control represents a near-term, cost-effective method for enhancing system resilience without major infrastructure upgrades.
Technology 4) Battery Energy Storage Systems (BESS) as Ultrafast Stabilizers
Grid-connected battery storage can provide instantaneous frequency regulation, absorbing or injecting power orders of magnitude faster than mechanical plants can ramp. In the Spain–Portugal incident, utility-scale and co-located battery arrays would have been capable of cushioning the initial frequency sag and slowing the rate of RoCoF (Rate of Change of Frequency). The IEA’s projections show energy storage deployment growing rapidly but unevenly. Had a greater proportion of Spain and Portugal’s grids been buffered by BESS assets, it is highly plausible that frequency deviations could have been arrested before protective relays disconnected generators, fragmenting the grid. Batteries would have offered critical first-response inertia and buying precious seconds for larger grid interventions.
Technology 5) AI-Based Short-Term Forecasting, Useful, But Not for Physical Disturbances
We are all 100% certain that AI is going to solve all our problems. Well, while some of these machine learning models intelligence like time-series neural nets have been significantly improving forecasting, I don’t see how having advanced ML would have helped in this scenario. WD-LSTM models combining wavelet decomposition and deep learning, has helped short-term forecasting for wind and solar variability. This technology is fundamentally forecasting generation patterns, but not predicting rare physical infrastructure phenomena.
The atmospheric-induced oscillations that triggered the Iberian blackout are mechanical effects on transmission lines, unrelated to renewable generation volatility. No level of AI forecast accuracy would have anticipated conductor oscillations of this type.
Technology 6) Regional Fast-Acting RoCoF Detection for Critical Early Warning System
The rate at which frequency changes during a disturbance (RoCoF) is a key indicator of grid stability. Traditional systems monitor RoCoF globally, however, fast regional probabilistic RoCoF detection allows localized intervention before instability becomes systemic.
Application of this technology to the Spain–Portugal blackout, advanced regional RoCoF systems could have detected anomalous frequency behavior early, isolated affected sections of the grid, and prevented propagation across national borders. Fast-acting regional RoCoF control would have transformed a continental-scale event into a localized disturbance, maintaining power for large areas even if faulted zones had to island temporarily.
Final Synthesis
In 2015, the Baixas–Santa Llogaia HVDC interconnector between France and Spain was inaugurated, offering 2,800 MW of transmission capacity and aiming to end Iberia’s historical energy isolation. Yet, despite this active link and further plans like the Gulf of Biscay interconnector (still delayed and now expected by 2026) the effective interconnection capacity remains among the lowest in Europe relative to national load. Spain’s interconnection ratio, at approximately 5–10% of peak demand, still falls below the EU's 10% target, limiting its ability to exchange electricity dynamically during crises. France’s robust nuclear fleet makes it a reliable energy stabilizer option, but cross-border bottlenecks, technical constraints, and political frictions have left critical gaps exposed.
The 2025 Iberian blackout was triggered by a rare transmission disturbance, not by over-reliance on renewable generation. However, the evolving grid architecture increasingly dominated by inverter-based resources lacked sufficient dynamic resilience to absorb the shock, allowing a local disturbance to cascade into a continental event. This shows that renewable systems’ physical and operational resilience cannot be taken for granted. Many governments have decided that decarbonization and electrification are essential goals, and the shift away from traditional synchronous machines with their natural inertia and stability margins exposes grids to new, less intuitive failure modes. Rare events such as atmospheric-induced conductor oscillations, can cascade into systemic failures if the architecture of grid resilience is not deliberately reengineered.
In this post I try to show how some of the vulnerabilities exposed in this incident could have been substantially mitigated, if not outright prevented, by deploying a set of well-researched but not yet fully scaled technologies. Specifically, fast-response dynamic controls such as DFIG-ES hybrid systems, flexible kinetic energy release from wind turbines, grid-forming inverter technology, utility-scale battery storage, and regional RoCoF detection could have collectively absorbed and isolated the atmospheric disturbance before it triggered a frequency collapse and widespread plant disconnections.
Resilience at the operational timescale which means seconds and sub-seconds must be distinguished from supply chain or daily dispatch optimization. This blackout is a great case study to show that dynamic, fast-acting grid stabilization technologies must be deployed in parallel with renewable generation scaling. The next generation of energy policy must recognize that operational reliability as an engineering function is more important that energy generation source statistics.
Sources:
International Energy Agency (IEA). (2024). Energy Technology Perspectives 2024: Manufacturing for Net Zero. Paris: International Energy Agency. Retrieved from https://www.iea.org/reports/energy-technology-perspectives-2024
Meegahapola, L., & Bu, S. (2021). “Wind Power Integration into Power Systems: Stability and Control Aspects”. Energies, 14(12), 3680.
Chen, J., Yuan, T., Li, X., Li, W., & Wang, X. (2023). Research on coordinated control strategy of DFIG-ES system based on fuzzy control. Energies, 16(12), 4770.