The Visayas grid will be placed under red and yellow alerts on Thursday due to limited power supply, the National Grid Corp. of the Philippines (NGCP) said.

Based on NGCP’s 8 a.m. update, a red alert is scheduled from 6 p.m. to 8 p.m., while yellow alerts are expected from 2 p.m. to 6 p.m. and from 8 p.m. to 9 p.m.

The grid has an available capacity of 2,283 megawatts (MW) against a peak demand forecast of 2,360 MW, resulting in a supply shortfall of 77 MW.

NGCP said several power plants are unavailable or operating below their full capacities, limiting the power supply available to the grid.

Six plants were placed on forced outage in August, while additional plants have been unavailable since previous months and years. Another 13 plants are operating at derated capacities, bringing the total unavailable capacity to 903.2 MW.

NGCP attributed the alert declarations to the unavailability of large coal-fired power plants TVI 1, TVI 2 and CEDC 1, limited power imports from Mindanao due to the maintenance outage of GNPK 2 and emergency shutdown of GNPK 1 following a boiler tube leak, and high forecasted system demand.

The red alert indicates that the grid has insufficient power reserves to meet demand and the required contingency reserve, while a yellow alert means reserves are lower than the prescribed level.

NGCP said it continues to monitor the power situation as demand rises and generating units remain unavailable.