Lessons from the Iberian blackout: The starfish and the spider

Introduction

On Monday, April 28, Spain, large parts of Portugal and an area in Southern France suddenly were in the dark due to a massive power failure. According to the Spanish prime minister, the blackout was a result of 15 GW of power capacity suddenly "gone missing" for five seconds. While it is unclear what exactly caused the 15 GW to disappear, utilities will need to learn from it, as it could happen in any country. Several probable causes have been mentioned. For now, Spanish and Portuguese authorities seem to rule out that the blackout was the result of a cyberattack. One possibility points to the Spanish-French interconnection line between Figueres, Spain, and Perpignan, France; another suggests overproduction of solar; and a third hints at a rare natural phenomenon called induced atmospheric vibration. Large differences in temperature and high humidity may cause transmission lines to vibrate and disrupt the 50-hertz frequency of the grid. The loss of power resulted in a cascading effect, taking out substations and shutting down generation capacity.

The Take

The outdated view of the power grid as a one- or even bidirectional system no longer reflects today's energy reality. With the rise of distributed energy resources, the grid must evolve into an omnidirectional system where energy flows dynamically across a decentralized network. This transformation is best illustrated by the "starfish and spider" analogy — moving from a centralized, utility-centric model (the spider) to a resilient, adaptive system with distributed intelligence (the starfish). Enabling lateral movement of energy and data across the grid enhances flexibility, resilience and self-recovery, making the grid better equipped to handle modern energy demands and disruptions.

Context

Both Portugal and Spain have invested heavily in the expansion of solar power generation. According to grid operator Red Eléctrica de España (REE), Spain installed 6.6 GW of new photovoltaic (PV) systems in 2024, for a total of 32,043 MW, just overtaking the total capacity of wind power (32,007 MW). In 2024 solar generated as much as 44,520 GWh, which represents 17% of the country's total electricity production. Renewable energy now makes up 66% of Spain's total generation capacity.

Similarly, Portugal installed a record 1.77 GW of solar in 2024, bringing the cumulative installed PV capacity to 5.66 GW, as it works toward a revised 20.8 GW target by 2030. According to the International Energy Association, oil, natural gas and biofuels contributed roughly 31% to the energy mix in 2023, with 30% generated by hydro, 27% by wind and 11% by solar.

The high penetration of renewables, or decentralized energy resources (DERs), leads to net congestion. Exhibitors at the 2023 Lisbon Energy Summit already pointed out that, although Portugal and the entire Iberian Peninsula have enormous potential for renewable energy generation, it runs into grid constraints as it tries to scale. Although the ambition to add gigawatts of renewable energy is sky high, most grid-scale solar farm construction projects are suffering from delays as the grid runs out of capacity to add more intermittent energy resources.

Universal root cause

While the energy mix may differ in various countries, many experience the same challenges in maintaining grid stability. One of the key challenges is the energy transition to more sustainable sources of energy. While thermal power plants provide a stable base load that brings inertia to the grid, DERs do not provide that inertia, or residual energy in rotating generators, that can keep the grid going when generation capacity suddenly falls away. As the outage occurred just after noon, the percentage of renewable energy was high, leading to low inertia. While the vibration of the high-voltage transmission lines may have tripped the system, the problem translates to the distribution net. The amount of DERs that feed power back into the grid causes congestion. The capacity of power that can be delivered to the end user is reduced as the capacity is needed to bring power from the DERs upstream into the grid. According to a 2024 study by S&P Global Market Intelligence 451 Research and Eaton Corp., 58% of utilities see the medium-voltage grid as their biggest challenge, followed by the low-voltage grid (41%). Many countries are facing congestion issues, sometimes resulting in utilities needing to curtail solar PV or EV charging infrastructure, and in some countries it leads to long waiting lists for new connections, or even a moratorium on new datacenter permits. Wherever the grid is full, relatively small incidents can cascade and cause wide blackouts. Especially in Europe, where the grid is highly interconnected from Portugal to Estonia, these blackouts can cross borders.

Grid-forming versus grid-following technology

Most of the power was restored within 24 hours. According to REE, most of the grid has been restarted by importing power from France and Morocco to the regions of Basque, Catalonia and Andalusia, which provided the necessary power to bring its own generation capacity back online, particularly hydro power. These, in turn, could begin to provide the other regions with power. The lesson is that we are too dependent on grid-following inverters (i.e., power-generation facilities that need power to power up). DERs such as solar and wind, as well as grid-scale energy storage systems (batteries), are much more technologically advanced than thermal power plants. When operated in isolation in a microgrid, these can restart a part of the grid in seconds when equipped with grid-forming inverters.

The starfish and the spider, and the changing architecture of the grid

The global energy landscape is undergoing a significant transformation. Driven by the need for sustainability and resilience, decentralized energy resources are increasingly being integrated into the grid. These resources not only help meet the growing demand for electricity, but also diversify the supply mix. At the same time, the demand side is evolving due to the widespread adoption of energy storage systems, electric vehicle (EV) charging infrastructure, and smart technologies in homes and businesses. These developments are contributing to new, dynamic and less predictable patterns of energy consumption.

Moreover, utilities are under pressure from multiple fronts: organic population growth, the electrification of transportation and industrial sectors, and the surge in electricity demand from energy-intensive facilities like datacenters. These shifts are fundamentally altering how electricity is generated, distributed and consumed. The result is a transition from a traditional, linear, centralized power grid to a multidirectional, decentralized energy ecosystem.

This transformation introduces complexities that go beyond simply upgrading existing infrastructure for reliability. Grid expansion and modernization now require a holistic redesign, shifting the operational focus toward the "grid edge" — the point where energy consumers, producers and prosumers interact with the network. At this edge, real-time energy balancing becomes essential, requiring sophisticated digital tools, automation and secure data exchange. As decentralized assets like rooftop solar, batteries and EVs proliferate, utilities must integrate vast volumes of real-time data to maintain stability and optimize performance.

The conventional view of the grid as a one-way or even bidirectional system is no longer sufficient. Today's grid functions in an omnidirectional manner, with energy flowing in many directions depending on where and when it is generated and needed. This requires a fundamentally new way of thinking about grid architecture, planning and management.

The future of energy lies at the grid edge. Here, distributed energy resources combine with advanced technologies and digital platforms to form a responsive, resilient energy ecosystem. This shift strengthens the grid's resilience by reducing dependence on centralized generation and enabling localized energy production through microgrids. Such decentralization enhances energy security, mitigates risks from cyber threats and ensures grid functionality during disruptions like extreme weather events.

To build a grid that is not only resilient but antifragile — capable of improving in the face of stress — requires distributed intelligence. Grid-forming inverters, automated systems, and predictive analytics will be critical in maintaining stability, enabling fast recovery and managing intermittency from renewables. These changes demand an end-to-end approach that considers the effects of new technologies on both upstream generation and downstream distribution.

An apt analogy for this transformation is "the starfish and the spider," from Rod Beckstrom and Ori Brafman's 2006 book on decentralized organizations. The traditional utility-centric grid resembles a spider, vulnerable when its central control is compromised. In contrast, the new decentralized grid mirrors a starfish — with a distributed neural system capable of regeneration and adaptation. Embracing this antifragile model is essential for building the grid of the future.