What a forced outage means when a coal plant runs 24 hours

By Francis Allan L. Angelo

The Visayas grid hit red alert for a second straight day on Friday, Sept. 4. The main culprits were exactly the same as the day before: the unavailability of Therma Visayas Inc. (TVI) Unit 1 in Toledo City, Cebu, and Panay Energy Development Corp. (PEDC) Unit 3 right here in Barangay Ingore, La Paz, Iloilo City.

The situation deteriorated rapidly. By 2 p.m., the National Grid Corporation of the Philippines (NGCP) reported available capacity at 2,076 megawatts (MW) against a peak demand of 2,506 MW—a glaring gap of 430 MW. The red alert expanded into a grueling nine-hour stretch from 1 p.m. to 10 p.m. The threat of manual load dropping loomed over Iloilo, Guimaras, Antique, Aklan, Capiz, and Negros, compounded by zero power imports from Mindanao.

The grid was already limping. Leyte-A geothermal dropped 60 MW after a line tripped. Multiple other units were unavailable.

But the entry for Cebu Energy Development Corp. (CEDC) deserves heavy scrutiny. According to information shared with us, Unit 1 of the Toledo City coal plant completed its maintenance ahead of schedule on Friday. It had previously gone on forced outage, prompting the operator to move up its preventive maintenance. Yet, by 2 p.m. Friday, NGCP listed it as tripped again. Did it fully synchronize, or did it trip on startup? NGCP and the operator need to answer that.

Beyond Friday’s numbers lies a severe, systemic backlog. NGCP data shows 12 plants on forced outage in September. Six have been down since August, one since July, and others since 2025, 2024, 2023 – and incredibly, one since 2021. Add 16 plants running below capacity, and a massive 972.6 MW is currently stripped from the grid.

TVI 1 and PEDC 3 are repeat cases. Both were flagged during the major May outages. PEDC 3 briefly returned in July, only to be isolated a day later when a transmission line tripped. By Sept. 3, it was back on forced outage.

We need to dissect the mechanics of these failures because accountability starts there.

A 150-MW baseload coal unit like PEDC 3 is designed to run nonstop for months. But running 24/7 consumes the plant’s service life. Inside the boiler, steel tubes endure extreme heat, pressure, and corrosion. Downstream, turbines spin at 3,600 RPM, degrading bearings and seals by the hour.

Without strict, scheduled maintenance – which requires cooling the unit and running ultrasonic inspections – boiler tubes leak. Fouled condensers burn more coal for less power. That is when a plant is “derated”: still online, but crippled. Furthermore, emergency protection systems can seize up if they are never tested, making a running plant more dangerous than an offline one.

This is the key difference to know when reading an NGCP alert. A planned outage is coordinated, provisioned with spare parts, and timed for low-demand months. A forced outage happens at the worst possible time, with no safety net, and can stretch for months if major components fail.

When NGCP reports plants on forced outage for years, it is no longer just bad luck. It means maintenance was deferred, repairs failed, or the plants are simply too old to remain reliable. Each of those failures has an owner.

Panay urgently needs new capacity as PEDC has projected that baseload and demand are now almost at a level.

But new plants are years away. Our only immediate fix is to run existing plants exactly as designed – maintained on schedule and repaired properly.

NGCP issues the alerts. But the Department of Energy and the Energy Regulatory Commission can compel operators to publish the maintenance records behind them. Until they do, the public will keep treating red alerts like bad weather, instead of what they truly are: the consequences of human decisions.