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Gene Nelson, Ph.D.'s avatar

Thank you for your follow-up analysis. The lack of thermal generation on the morning of April 28, 2025 was a preventable problem which GreenNUKE will be discussing in an upcoming article.

The principle of lowest cost dispatch apparently kept a pair of available nuclear power reactors offline. The reason is Spain-specific. The Socialist government devised a unique tax on reliable and abundant nuclear power as a method to subsidize the low-quality unreliable power from solar and wind. This Spanish tax was ideologically-driven instead of being based on scientific and engineering principles. This Spanish tax needlessly made reliable nuclear power reactors more expensive, so two reactors Almaraz I (1,011 MW) and Cofrentes (1,064 MW) weren't dispatched in the day-ahead market. Nuclear power reactors tend to supply the greatest amount of synchronous grid inertia (SGI) to a power grid to stabilize frequency, as nuclear power plants reduce the rate of change of frequency in response to perturbations (they damp out frequency oscillations.) However, nuclear power reactors require considerable time to come online as a consequence of the large thermal inertia.

Monitoring the post April 28, 2025 Red Eléctrica (REE) supply information at mid-day shows the grid operator has learned an important lesson. There is significantly more CCGT and nuclear power being dispatched at mid-day to assure sufficient SGI. However, the official reports fail to mention the unique Spanish tax (impuesto) on nuclear power. Politics is the likely cause.

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For additional details, please see GreenNUKE's July 8, 2025 article "The Spanish Version of the 'Duck Curve' is a real killer - This curve underscores the problem of insufficient synchronous grid inertia in Spain on April 28, 2025."

https://greennuke.substack.com/p/the-spanish-version-of-the-duck-curve

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Ed Reid's avatar

"The first principle is that you must not fool yourself and you are the easiest person to fool."

Richard P. Feynman

The parties involved in the Iberian blackout would do well to keep that in mind.

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