Yellow alert exposes vulnerability of power system

The yellow alert raised by the National Grid Corporation of the Philippines on Thursday highlights a lingering weakness of the energy sector – too much reliance of a few large power plants away from the ideal decentralized, diversified and flexible power system.

The international energy thinktank Institute for Climate and Sustainable Cities (ICSC) said the country’s energy sector remains baseload-centric and relies on large power plants, making the grid more exposed to disruptions that affect Filipino households and businesses across the country.

According to NGCP, the yellow alert in Luzon was due to the forced outage of 35 power plants while 14 were running on derated capacities, thus leaving 5137.2 MW unavailable to the grid.

The agency said that between 4 and 10 p.m., the power generation capacity was only 12,223MW while the demand was nearing that capacity at 11,966MW.

Among the power plants that tripped were the Excellent Energy Resources, Inc. (EERI) 1, 2, and 3 Plants, which have a combined capacity of 1,262 MW, and Ilijan Block A and B Plants, which have a combined capacity of 1,200 MW. The power plants are both liquefied natural gas (LNG) plants utilizing the same LNG terminal and experienced unplanned outages simultaneously on 16 April, at around 3:00 p.m.

These power plants tripped while Magat 1, 2, 3, and 4 hydro plants were unavailable due to scheduled maintenance operations.

ICSC said that while their outages on LNG plants only spanned a few hours and have since been resolved, they still highlight the vulnerability of the energy system overly reliant on a few large facilities.

ICSC has constantly emphasized that relying heavily on only a few large power plants makes the energy system less flexible and unreliable. “Even short-term outages or plants operating below normal capacity can quickly reduce available reserves and affect grid stability,” ICSC said.

In addition, while multiple plants were cited to have been operating at derated capacity, the biggest contributors to the supply issues are Sual 1 (235 MW available out of 647 MW) and Sual 2 (300 MW available out of 647 MW) – both running at less than half of their dependable capacity at the time and have further reduced effective supply during that time.

On the Visayas grid, ICSC said the event on 16 April also exposed the vulnerability of the grid due to its reliance on high-voltage direct current imports from Luzon and Mindanao.

“The Visayas grid, already operating on net negative reserves, felt the ripple effect of outages and derations in Luzon—its primary source of imported power,” ICSC stated.

Way out of the cycle

ICSC said that to break the cycle alert, the country must move towards a more decentralized, diversified, and flexible power system, where the outage of a single facility does not put the entire grid at risk.

The group said that central to this energy transition is expanding the share of indigenous renewable energy, such as geothermal, hydropower, solar, and wind, supported by energy storage systems.

“Renewables strengthen energy security, improve system resilience, and reduce exposure to volatile global fuel markets,” ICSC said.

“Heavy reliance on imported LNG continues to tie domestic electricity prices to global fuel price shocks and geopolitical disruptions, unlike indigenous RE sources that have no fuel costs and help moderate electricity prices in the Wholesale Electricity Spot Market (WESM),” it added.

With the country’s archipelagic geography and exposure to extreme weather, the group said power generation must also be geographically distributed.

“A more decentralized system allows communities to reduce reliance on a few large plants –– improving local reliability, self-sufficiency, and reducing the risk of power supply disruptions brought by outages, disasters, or other physical shocks,” the think-tank said.

“A system built on diversified, distributed and flexible resources minimizes single points of failure, and it provides a more stable foundation for affordable, reliable, and secure electricity for all Filipinos,” it said.