Puerto Rico Blackouts Widen After Costa Sur Plant Fails

By Elena Vázquez Ortiz

Puerto Rico's grid buckled again this week. Over 240,000 households sat in the dark Wednesday night, and by 8:20 p.m. LUMA Energy's own outage tracker put the number above 243,000 — a figure the company warned could still climb before the night was over. The trigger was blunt and mechanical. Unit 5 at the Costa Sur power plant, operated by Genera PR, tripped offline at 5:45 p.m., forcing an automatic load shed across the island. LUMA had already been bracing for trouble. A roughly 300-megawatt generation shortfall was expected heading into peak evening demand. Then Costa Sur 5 quit, and the shortfall got worse. "We already expected a generation deficit that would force outages, but the sudden loss of Costa Sur's Unit 5 is what's driving the load shedding we're seeing right now," LUMA spokesperson Hugo Sorrentini said by phone. He added that rolling blackouts would continue, rotating between neighborhoods, until more generation comes back online. The numbers behind that statement are not reassuring. Genera PR's own generation dashboard showed 2,417 megawatts of available capacity Wednesday evening against an operational reserve of just 77 megawatts — a razor-thin margin for an island grid that has little room for error even on a calm day. Costa Sur sat dark. EcoEléctrica, a privately owned plant in Peñuelas, was running at only half capacity after one of its units, CT1, shut down that morning at 11:23 a.m. because of what the company described, preliminarily, as a voltage regulator failure. The hardest-hit regions told their own story of geographic spread rather than a single overloaded pocket. Arecibo led with more than 44,000 customers without service, followed by Mayagüez at over 42,000, Bayamón near 38,500, Ponce close to 36,000, San Juan around 35,000, Caguas near 35,000, and Carolina at roughly 13,000. This is not an isolated bad night. It's the latest turn in a generation crisis that has been building since July 16, when Costa Sur's Unit 5 first went down abruptly — attributed at the time to a boiler problem, according to Puerto Rico's energy czar, Josué Colón. Hours later that same evening, Unit 6 at the same plant also dropped offline, an event Colón initially described as an "explosion" in the switchyard that distributes the unit's output onto LUMA's lines. LUMA has disputed that characterization, denying any explosion occurred. Whatever the precise mechanics, Colón said the damage sustained during the restart and synchronization process the following day would keep Unit 6 out of service for at least two weeks. Crews did manage some recovery. Iván Báez, Genera PR's vice president of government and public affairs, said the two other units that had been down since July 16 — Palo Seco's Unit 4 and San Juan plant's Unit 7 — were successfully reincorporated into the grid. Costa Sur's Unit 5 itself was restarted Wednesday after repairs, only to fail again hours later. "We're working to bring the unit back online within the next two hours," Báez said Wednesday evening, adding that the cause of the renewed failure remains under investigation. Unit 6, he said, will likely stay offline at least until next week. The timing is not incidental. This is peak Caribbean summer, when air conditioning load pushes demand to its highest points of the year, and it's precisely the season LUMA has spent months publicly promising to prepare for — through transformer upgrades, insulator replacements, and a customer battery-sharing program designed to ease exactly this kind of strain. None of that infrastructure work stops an aging generation unit from failing at the worst possible hour. There's a broader fight unfolding in the background, too. Puerto Rico's fiscal oversight board has asked for a pause in the process to contract new permanent power generation for the island — a request that, if honored, could push out the timeline for the kind of modern baseload capacity many argue the grid desperately needs. For residents watching their lights flicker off again this week, that debate over long-term contracts probably feels distant. What matters more immediately is whether Costa Sur's units stay lit through the next heat wave, and whether Genera PR and LUMA can explain why a plant central to the island's power supply keeps failing at the moments Puerto Rico can least afford it.