Iberdrola and Endesa defend the operation of their plants during last year's blackout as investigations by regulators continue.

The CEOs of Iberdrola Spain and Endesa defended their companies' power plant operations during last year's unprecedented blackout that affected the Iberian Peninsula. They appeared before a parliamentary inquiry to answer lawmakers' questions, following the CNMC's investigations into major energy firms for alleged serious violations related to the April 28 outage.

Mario Ruiz-Tagle of Iberdrola Spain noted that while the CNMC identified unusual behaviors at several of their power plants, it did not directly connect these to the blackout. He stated that once Iberdrola receives more information from the CNMC, "we will be able to know what we're accused of and defend ourselves."

Endesa's CEO, Jose Bogas, asserted that his company's power plants met voltage control responsibilities that day. He argued that the grid operator REE should have activated more synchronous generation, increased hydropower capacity, or utilized combined-cycle gas plants. Bogas believes REE was primarily responsible for the incident due to its delayed reaction, although not entirely to blame, as it had the necessary tools to avert the crisis.

Ruiz-Tagle shared this perspective, stating that REE should have operated with broader safety margins and failed to respond promptly, exacerbating the issue with its voltage control measures. The CNMC is currently investigating REE for "very serious infringements" that could result in fines of up to 60 million euros ($70.7 million), citing examples of breaching protocols that led to unjustified power supply interruptions affecting safety.

REE contended that earlier reports indicated the blackout was the result of multiple factors and provided technical evidence showing that there was no breach on their part that could be deemed a determining cause. A report by ENTSO-E's expert panel did not pin blame on any single entity, concluding that the blackout stemmed from a mix of factors such as oscillations, voltage gaps, and uneven stabilization capabilities. Bogas criticized ENTSO-E's report for its shortcomings and claimed it overlooked significant issues, also noting a conflict of interest since REE was part of the organization.