Author: Dr. Nenad Končar, M.Sc.Eng.

Date: May 2, 2025

After the historic power grid failure that affected almost the entire Iberian Peninsula on April 28, the president of the Spanish transmission system operator, Red Eléctrica, Beatriz Corredor, addressed the public with a message: “It won't happen again.”
It was a statement that, understandably, was intended to instill confidence in the system and its experts. But how can we interpret this statement from a technical perspective?

Rapid Response – A Reason for Praise

Red Eléctrica indeed demonstrated a high level of operational readiness. By 4 a.m. the following day, 100% of substations were back online.
This is an exceptional technical and organizational achievement and should not be underestimated.
In complex and interconnected power systems, recovery speed is crucial — and Spain passed that test.

But What Do We Actually Know About the Cause?

In the same address, the REE president emphasized that the cause of the failure has not yet been determined.
If we do not know exactly what caused the cascading outage, then — with due respect — the statement “it won’t happen again” is more of an expression of hope than a fact-based assurance.
As one of the world’s leading experts on grid stability once said: “Zero risk does not exist.”

The Role of Oscillations and Reduced Inertia

Data released by independent grid monitors show that voltage oscillations of increasing amplitude occurred in the hours leading up to the outage.
This is often a sign of declining grid inertia — the physical stability provided by large synchronous generators.
As Europe transitions to renewable energy, that natural stability decreases, and the need for active regulation increases.

Can We Do More?

Yes. Instead of relying solely on hope, the technical community increasingly advocates for:

• Decentralized storage systems,
• Battery plants with black-start capability,
• Grid-forming inverters that simulate the behavior of traditional generators.
  These technologies represent the new line of defense — not against renewables themselves, but against their operational challenges.

“It Won’t Happen Again” with Proven Technical Solutions

Long-term grid security is based on investments in technologies that can respond quickly, flexibly, and predictably.
The statement “it won’t happen again” will best be validated if it is accompanied by concrete measures.
Because the future of the grid cannot be secured by statements — but it can be secured by technology.

From System Restart to Long-Term Resilience – Lessons and Solutions After April 28

Author: Dr. Nenad Končar, M.Sc.Eng.
Date: May 2, 2025

What We Know – And What We (Still) Don’t Know
Three days after the largest power grid collapse in the history of the Iberian Peninsula, the causes are still not officially confirmed. However, reactions have already started:

• Red Eléctrica claims it was not a cyberattack,
• BBC and Reuters report on technical instability and low grid inertia,
• pv magazine points out that renewable sources were not the cause, but the lack of flexibility contributed to the spread of the outage.

What Actually Happened?
In just a few seconds, 15 GW "disappeared" from the grid.
Consequences:

• More than 50 million people without electricity,
• Cities in lockdown, hospitals running on emergency diesel generators,
• Telecoms on the brink of collapse (Vodafone survived with 70% redundancy),
• Air and rail transport in chaos.

How Was Spain “Reignited”?
The power return process took 6 to 10 hours – some sources say even longer.
Experts from Euronews and DW explained that it involved a black-start procedure, a complex process without which the recovery would have taken days.
Where microgrids and battery backups operated – everything worked seamlessly.

Solution: Decentralized Resilience Through Batteries
All relevant sources, from Bloomberg analysts to Grid Engineering associations, agree on one thing:
Strong battery storage systems are key to future stability.

Why?

• They provide an immediate response to frequency changes,
• They deliver artificial inertia and voltage balance,
• They act as standalone power sources for microgrids and critical infrastructure,
• They enable black-start without waiting for external support.

What Does Adriadiesel Offer?
As one of the leading regional providers of battery storage systems, we offer:

• Containerized units (1.5 MWh) with smart inverters and climate control,
• Scalable solutions up to 600 units per region,
• Second-life batteries from electric vehicles – sustainable and cost-effective,
• Systems already prepared for grid-forming and islanding operation.

What’s Next?
Spain may eventually reveal the cause.
But Europe must answer how to prevent consequences next time.
The key question is no longer what went wrong but what was not ready.

Contact
Adriadiesel collaborates with utilities, cities, and private operators:

• for resilience planning,
• for urgent battery system implementation,
• and for the transition to a 21st-century smart grid.
  Contact: This email address is being protected from spambots. You need JavaScript enabled to view it.

The energy of the future is not just green – it must be resilient.
Time for smart systems before another blackout strikes.