Europe’s biggest-ever blackout flipped the switch on a hard truth: the clean energy transition is only as strong as the grid behind it. Fortunately, there’s no shortage of ways to shore it up, and we've got you covered.
A shock to the system
Last week, Europe experienced its largest power outage in history when cascading grid failures on the Iberian Peninsula caused a mass blackout, affecting about 55m people for more than 12 hours until power was restored. Blackouts like this one are rare in Europe, but they’re not unprecedented — and increasingly, they are symptoms of a deeper problem: power grid infrastructure needs more investment to ensure a reliable, safe, clean energy transition.
What happened
We’re still in the dark about the exact cause of the blackout, and the full picture won’t come into focus for weeks or even months. Here’s what we understand today:
- In southwest Spain, two generators, and likely a third, went offline in quick succession immediately before the blackout, according to Bloomberg. (The Conversation also has a look at what was going on with the different sources of power generation in the region at the time, although it’s still unclear which generators, whether fossil or renewable, went out.)
- Electricity demand (or "load") suddenly exceeded supply (generation), causing a mismatch on the grid. This imbalance led to a drop in system frequency. Under normal conditions, the grid’s “inertia” — provided by the spinning mass of traditional generators like gas, coal, or hydro turbines — helps resist such changes. But when inertia is low, the grid becomes more vulnerable to rapid fluctuations in frequency, which destabilizes it and makes it more prone to cascading disturbances.
- Once the Iberian grid’s frequency dropped outside of normal levels, for safety reasons, the interconnector between Spain and France’s network was disconnected. Overall, about 15GW in Spain and 5GW in Portugal were disconnected, and outages across the region persisted for up to nearly a day.
Thankfully, in that time, hydro plants and international links with France and Morocco helped restore supply, while interconnections restarted. While authorities have ruled out a cyberattack, the underlying cause remains under investigation by a new expert panel convened by authorities and grid operators.
Why it matters
The Iberian blackout is a flashing warning light on the dashboard of the energy transition. While Spain and Portugal have raced ahead on renewables — Spain generated a record 56% of its electricity from clean sources in 2024 — the grid they rely on was built for a different era. Centralized fossil fuel plants (which provide sources of inertia) are giving way to distributed wind and solar. Power no longer flows in a straight line from plant to plug. It's a multidirectional, decentralized web.
But the grid hasn’t caught up. Interconnectivity still lags across the Iberian Peninsula, even though the EU has set high targets. That isolation may have magnified the disruption last week. And the grid’s physical backbone — lines, substations, software — remains alarmingly underfunded. Europe is facing a $2tn investment shortfall to modernize its electricity network by 2050.
The Iberian blackout exposed structural gaps in Europe’s grid preparedness — but it also offered a preview of where solutions lie. For instance, there’s no clean energy transition without transmission. That means doubling down on storage, advanced grid technologies, and distributed energy resources that can absorb shocks and bounce back quickly. It also means unlocking regional coordination to expand interconnection. All this can help future-proof both the nuts and bolts, and bits and bytes, behind the grid.
What’s next
Grid tech
- Boost interconnection ASAP. The Iberian Peninsula is functionally a grid island, with just 3% interconnection relative to its installed capacity, well below the EU’s 15% target by 2030. That isolation amplifies the impact of local disturbances. The planned Bay of Biscay interconnector will help…starting in 2028.
- Until then, use dynamic line rating to do more with the transmission we’ve got. Dynamic line rating (which increases transmission capacity by replacing conservative, blanket assumptions with real-time data) could unlock additional capacity on Spain’s existing connections. This worked for Belgian transmission system operator Elia in the 2010s, which managed to ride through a wave of nuclear shutdowns with the help of Ampacimon’s tech.
Inertia
- New sources of low-carbon inertia to slow down grid destabilization. Grids need new sources of inertia to replace the spinning generators of conventional (and fossil-fueled) power plants. Fortunately, there are plenty of options for inertia without emissions:
- Synchronous condensers: retrofitted turbines that spin without generating power, mimicking the inertia of fossil plants. Already deployed in parts of Australia and the UK.
- Long-duration energy storage (LDES): technologies like compressed air, liquid air, liquid CO2, and thermal storage have spinning generators that provide inertia during discharge.
- Reduce the need for inertia in the first place. The faster power can be rebalanced after a fault, the less inertia the system needs. That’s where short-duration storage comes in. Unfortunately, Spain and Portugal have limited grid-scale battery capacity, leaving them exposed to frequency dips.
Resilience
- Level up broader grid resilience tools. The blackout wasn’t just a generation issue — it was a system coordination failure. Smarter grid tech can make the difference next time:
- Distributed Energy Resource Management Systems (DERMS) and Virtual Power Plants (VPPs) can orchestrate behind-the-meter solar, batteries, EVs, and other flexible resources to help balance the grid dynamically.
- Microgrids can island from the grid during outages and continue serving critical infrastructure.
- Don’t forget the forecast — weather data matters. As climate change intensifies heatwaves, storms, and droughts, grid operators need better forecasting to stay ahead of risk. Real-time weather-informed grid operations (e.g. DLR, wildfire risk models) are increasingly essential. Today, energy traders also rely on weather signals to balance supply and demand — and the NOAA budget cuts currently being proposed could jeopardize access to key forecasting data across the US and allied systems.
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