Voltage, not adjectives: what the final report on the Iberian blackout requires engineering to say out loud

Television debated semantics, but thermodynamics set the rules.

The final ENTSO-E report on the Iberian blackout of 28 April 2025 — whose decisive events were concentrated on the Spanish side — closed the debate of euphemisms with the coldness of facts.

It was not a question of «intermittent» or «variable» energy: it was a failure of system services — and the responsibility cuts across dogma, in either direction.

In my article I dissect the document and set out what the media debate keeps stifling:

1️⃣ Exoneration and Enforceability: the report exonerates the «colour» of the electron — the problem was not renewables, it was voltage control, whatever the technology. What failed was enforceability: the gap between the voltage and reactive-power support that some system users were supposed to provide and what they actually delivered in real time. It is not about absolving some and condemning others by nature, but about requiring everyone — fossil, renewable or storage — to deliver the contracted system service.

2️⃣ The Right Quantity: the collapse was one of voltage stability. And here I am more incisive than the current debate — inertia was not the root cause; it was excessive voltage and reactive-power control. The grid is not measured in inertia alone: it is measured in short-circuit power, in reactive-power capacity and in the deterministic firmness of voltage control.

3️⃣ The Cyber-Physical Risk (the next problem, not this one): let it be clear — the blackout of 28 April had no cyber cause, and the report does not address one. But what it does not say is what worries me next: rotating steel cannot be updated or switched off remotely; inverters — necessary and already mandatory — open a new cyber-physical surface. In a firmware monoculture, they become a systemic Single Point of Failure (SPOF) — a critical risk in the light of the NIS 2 Directive. This is my own extrapolation, not a conclusion of the panel; but it is the omission that engineering must put on the table before the next event.

4️⃣ The Symmetry of the Lei REI (Integral Energy Responsibility Act): whoever introduces variability must internalise its stabilisation — and the principle is symmetrical and measurable. Reactive power not provided is a quantifiable breach of contract, owed by whoever it may be, fossil or renewable. Where engineering ends and value judgement begins — externalities, CO₂, exposure to fuel —, I say so with the boundary marked, so that physics is not confused with politics.

The answer is a hybrid system designed by engineering, not by slogan. We do not need more «electricity in powder».

«Physics does not stand for election. Thermodynamics does not accept adjectives. And cybersecurity does not accept monocultures.»

Gaspar do Amaral

Methodological note

What this page is. A translation of the post the author published on LinkedIn on 14 June 2026 to present his article on the final ENTSO-E report; the Portuguese version is on this site. The post has no calculations of its own.

Terms. The Lei REI (Integral Energy Responsibility Act) is the author's own proposal and keeps its Portuguese name. «Electricity in powder» (eletricidade em pó) is the author's image for energy treated as a commodity detached from the physics of the grid.

Changes of form, not of content. The final line of the original, with the shortened link to the full article, and the hashtags were left out; the closing sentence is shown as a quotation.

Gaspar do Amaral · Original in Portuguese of 14 June 2026, published on this site; translation issued on 30 October 2026 · Figures and tables © Aprecisa.com · AI-assisted

How to cite: Gaspar do Amaral (2026). Tensão, não adjetivos: o que o relatório final do apagão ibérico exige que a engenharia diga em voz alta. Zenodo. https://doi.org/10.5281/zenodo.23814390 · Permanent archive on Zenodo.