THE National Grid Corp. of the Philippines (NGCP) and the Independent Electricity Market Operator of the Philippines, Inc. (IEMOP) separately raised concerns yesterday about power supply in May.

“The worst-case projections (are) not good,” NGCP Spokesperson Cynthia P. Alabanza told reporters in a briefing Thursday.

She said the “usage habits” in the Luzon, Visayas and Mindanao grids have been changing as observed by NGCP. Power demand in Luzon usually peaks in May, the hottest month of the year. During the day, demand is highest at 2 p.m., the hottest hour of the day.

This year, power demand is expected to peak at 12,285 megawatts (MW) in Luzon in May, 2,419 MW in Visayas also in May, and 2,278 MW in Mindanao in November, according to the NGCP. Thin electricity supply is expected between April to June even with an expected 700 MW capacity from new power plants.

The NGCP said the Luzon grid needs around 4% of peak demand or around 491 MW in regulating power to stabilize the grid. It also needs to maintain a reserve equivalent to the largest plant online, usually equivalent to 647 MW, as contingency power to support the grid in case of an emergency power plant shutdown.

Should the net operating margin fall below these numbers, NGCP issues a yellow alert. If the power supply falls below the system peak demand, it issues a red alert, which means rotating power interruptions may be implemented to protect the integrity of the power grid.

“Normally, Luzon and Visayas, which are interconnected, can help each other,” Ms. Alabanza said, referring to the two grids exporting power to each other because their power demand peaks at different hours of the day.

Visayas and Mindanao used to register peak power demand during the day at 7 p.m., and in November to December over the course of the year. The grids in Luzon and the Visayas are interconnected, while the Visayas are expected to be linked to Mindanao by year’s end.

However, Ms. Alabanza said heaviest usage in Cebu and Visayas has shifted towards the dry season, and at 2 p.m. during the day.

“Why is that of concern to NGCP? Because then nag-aagawan na sila (the grids are competing) for the same resources at the same time,” she said.

Separately, Robinson P. Descanzo, IEMOP chief operating officer and head of trading operations, said in a briefing Thursday that May and June could be the worst period for power supply this year.

He said after Easter, which this year falls on the second week of April, power supply will be “barely enough” to cover the requirements of the system. But in May to June, supply is expected to be insufficient to cover the system’s reserve requirement.

The deficiency could give rise to a new round of yellow and red alert notices during these months.

Mr. Descanzo said the worst-case scenario would be when power plants go on forced outage in May or June. He said if 1,200 MW is lost because of unscheduled shutdowns, the average electricity prices at the spot market could jump to as high as P5.50 per kilowatt-hour (kWh) in May and P6.00 per kWh in June.

The estimated increase compares with the low prices seen in January and February at P3.03 per kWh and P3.47 per kWh, respectively.

Ms. Alabanza said the deficiency “underlines the need for more investment in new power plants.” She said the fastest to be built are solar farms whose power supply is intermittent.

“The ones that are baseload tend to be longer in coming,” she said.

Mr. Descanzo only one big power plant is expected to come online this year — the first 668 MW unit of GNPower Dinginin Ltd. Co. in Bataan, which is set for launch in June.

“After Dinginin walang papasok na baseload na malalaki (After Diningin, no big baseload power plant will come online),” he said. — Victor V. Saulon