The Mindanao grid was placed under red and yellow alert on September 2 as available generation fell below projected peak demand, according to the National Grid Corporation of the Philippines (NGCP). The grid operator reported an available capacity of 2,526 megawatts (MW) against a projected peak demand of 2,545 MW, leaving a 19-MW gap.
NGCP placed the grid under yellow alert from 1 p.m. to 4 p.m. and from 5 p.m. to 8 p.m., and raised the alert to red from noon to 1 p.m., from 4 p.m. to 5 p.m., and from 8 p.m. to 9 p.m.
A yellow alert is issued when the power supply is technically sufficient to meet consumer demand, but the available operating margin falls short of the grid’s required backup contingency in case of further technical disruptions. A red alert indicates that the supply is insufficient to meet demand and the operating margin is insufficient to meet the grid's contingency reserve requirement.
The alerts followed a yellow alert declared on September 1, when NGCP reported 2,555 MW of available capacity against a projected peak demand of 2,450 MW.
NGCP attributed the extended alerts to the unavailability of Mindanao’s large coal plants, including GNPower Kauswagan (GNPK) Units 1 and 2 and Therma South Inc. Unit 2 (TSI 2). The operator also cited a significant increase in the region’s demand forecast and a decrease in available generation.
Local distribution utilities implemented rotational power interruptions, causing localized blackouts in Region 9 (Zamboanga Peninsula) and the Bangsamoro Autonomous Region in Muslim Mindanao (BARMM). Local electric cooperatives across these regions initiated scheduled power shedding to manage the supply deficit.
A separate advisory reported that available capacity had dropped to 2,517 MW against a peak demand of 2,376 MW. A total of 804.1 MW was stripped from the transmission system due to 20 plants on forced outage for the month, including the emergency shutdowns of TSI 2 on August 29 and GNPK 1 on August 30, alongside the ongoing unavailability of GNPK 2 and other facilities running at reduced capacities.
A sudden 106-MW surge in localized demand outpaced the active backup supply, prompting immediate manual load-dropping measures to prevent a broader system collapse.
Grid data indicates that the bulk of the unavailable capacity stems from the sudden loss of major generating units, including large coal-fired facilities that form the baseload of the Mindanao grid.
NGCP said it is closely monitoring the situation and coordinating with power generation companies. The operator urged consumers to practice energy conservation and to monitor announcements from local utilities.