A series of plant breakdowns pushed the Luzon grid to a critical yellow alert on 16 April, but Department of Energy (DoE) data showed that Prime Infrastructure Capital Inc.’s natural gas facilities played a crucial role in stabilizing the system.

The government data showed that as the system reeled from the sudden loss of supply, oil-fired plants providing ancillary services were quickly dispatched to stabilize grid frequency. These included Limay CCGT, TMO Navotas, Bulacan Power Gen (Trans-Asia), Ingrid, and Subic.

In addition to the Bauang oil plants, natural gas and coal-fired facilities were also ramped up later in the day to meet demand.

Prime Infra’s gas plants, operated by subsidiary Prime CoreGen, ran at about 95 percent capacity, helping cushion the impact on the grid. These facilities include the 1,000-megawatt (MW) Sta. Rita plant, the 450-MW San Gabriel plant, and the 97-MW Avion plant.

The disruption began when several major generation units, including Ilijan Blocks A and B and Excellent Energy Resources Inc. (EERI) Units 1, 2 and 3, tripped offline.

Fifteen plants suffered forced outages, while 13 operated at reduced capacity, resulting in a 679.2 megawatt (MW) shortfall, according to the National Grid Corporation of the Philippines (NGCP).

Fragile grid amid RE

In response, Energy Secretary Sharon Garin directed the operators of the affected facilities to restore them immediately.

An energy expert said that when the power grid flashes yellow or red during the scorching summer months, the public invariably points the finger at failing fossil fuel plants but this oversimplified narrative obscures the structural drivers of grid fragility.

The more complex reality involves the seasonal depletion of hydroelectric reservoirs and the daily, uncounted disappearance of solar power at sunset, which are quietly stressing grid reserve margins. Rather than being the sole culprits of system failure, fossil fuel plants in general are under immense pressure.

The yellow alert was driven by the tripping of gas plants that serve more than just baseload but also provide the mid-merit and, more importantly, the flexible peaking power requirements of the grid, which work in conjunction with the inherent drawbacks of variable and intermittent renewable energy.

To effectively transition, the grid will need massive energy storage, both short and long-duration, to effectively “load shift” large quantities of energy from when there is excess to when it will be needed. Currently, this vital load-shifting and balancing role is played by present flexible, dispatchable fossil fuel plants.

First of the year

The outages pushed Luzon into its first yellow alert of the year, as demand peaked at 11,966 MW against an available capacity of just 12,223 MW.

At the time, 35 power plants were on forced outage, while 14 others were operating at reduced capacity, leaving over 5,100 MW unavailable.

The grid operator attributed the tight supply to outages in key Batangas gas plants and limited hydroelectric generation. A yellow alert is issued when reserves fall below the required contingency level.

The situation extended beyond Luzon, with the Visayas grid also placed under a one-hour yellow alert later in the evening. Available capacity there stood at 2,597 MW, only slightly above the demand of 2,368 MW, partly due to reduced power imports from Luzon.

Despite the strain, the system stabilized relatively quickly. Manila Electric Co. reported that power was restored after a brief imbalance lasting 10 to 15 minutes.

The DoE said it remains on heightened monitoring and has instructed the NGCP, along with generation companies and system operators, to accelerate the restoration of offline units to prevent further disruptions.