QUEZON CITY, January 11, 2024 – Residents of Panay, the sixth largest island in the Philippines covering the provinces of Aklan, Antique, Capiz, and Iloilo, and parts of Guimaras experienced large-scale blackouts from January 2 to 5 caused by the tripping of major coal-fired power plants. 

Local governments and business groups from Panay and Guimaras islands have called for an investigation, demanding accountability from the National Grid Corporation of the Philippines (NGCP), Department of Energy (DOE), and Energy Regulatory Commission (ERC) to address the incident. At the Senate energy committee hearing on January 10, Iloilo City Mayor Jerry Treñas also cited that the four-day blackouts resulted in an estimated PHP 2 billion worth of economic losses

In response, the Energy Policy Team of the Institute for Climate and Sustainable Cities (ICSC) examined the factors that resulted in the large-scale power outages and highlighted the importance of distributed and flexible power generation in preventing another island-wide blackout.

Overview of power generation in Panay Island

The overall capacity of existing power plants in Panay Island is 780 megawatts (MW), distributed across coal (454MW), diesel (263MW), and renewable energy sources, particularly solar (5.7MW), wind (36MW), run-of-the-river hydropower (8.1MW), and biomass (15MW). Considering this breakdown, the capacities of renewable energy (RE) plants mentioned are very limited while diesel power plants are only used for peaking purposes. 

Panay is still heavily reliant on power generation coming from coal, specifically the four major coal-fired power plants in the island: Panay Energy Development Corp. (PEDC) 1 providing 83.7MW, PEDC 2 with 83.7MW, PEDC 3 with 150MW, and Palm Concepcion Power Corporation (PCPC) with 135MW. Collectively, these coal plants contribute 454.4MW of power to the island’s total installed capacity. 

Panay’s demand fluctuates between 500MW during peak periods and 300MW in off-peak periods. Under normal operating conditions, the four large coal-fired power plants, combined with smaller RE and diesel plants, can meet the island’s demand. The total dispatchable capacity on the Panay sub-grid (a combination of coal, diesel, and biomass) is 730.4MW, which is well above the grid’s reserve requirements – indicating a normal grid status. While diesel has a high dispatchable capacity on paper, its actual operational capacity can significantly differ based on real-world operating conditions, since these are peaker power plants.

It is crucial to note that the Panay sub-grid is situated at the end-of-the-line or the tail-end of the transmission grid in Visayas, connected only through a submarine cable from Negros. In cases where additional capacity is required to meet Panay’s demand and there is excess generation in Negros, the Panay demand can still be satisfied. At the same time, Panay also has the capability to export its excess power generation to Negros.

Analyzing Panay blackouts from January 2 to 5, 2024

Before the January 2 incident, PEDC 3 was undergoing a planned maintenance shutdown as stipulated in the Grid Operating and Maintenance Program (GOMP), reducing the reserve capacity of the grid to 580.4MW (under the assumption that all diesel plants are available at full capacity). This would have brought the grid to yellow alert status had it not been for its transmission link with Negros. No alert level was raised before January 2 since the reserve deficiency could still be met using the transmission link. The normal status for the Visayas grid before the tripping of PEDC 1 was indicated in the market operator’s advisory logs.

However, at 12:06PM on January 2, PEDC 1 (83.7MW) tripped and was disconnected from the grid, resulting in only 309MW of actual in-island generation––composed of PEDC 2 at 83.7MW (full capacity), PCPC at 150MW (full capacity), and all diesel plants at 76MW (out of 263MW). Because of this incident, in-island generation fell below Panay’s demand requirement of 450MW. This should have triggered the red alert status on the Panay sub-grid internally: after the tripping of PEDC 1, the island was already operating at sub-par condition, largely depending on the remaining two coal-fired power plants in operation at the time, as well as the Negros-Panay transmission link.

The Visayas grid was still in normal operating condition according to the market operator’s advisory logs after tripping of PEDC 1, as the available generating capacity of the Visayas grid as a whole was still sufficient at the time. However, due to transmission bottlenecks between the islands in Visayas, the normal status might not be applicable to the individual sub-island groups, especially to Panay Island at the tail-end of the network.

From 12:06PM to 2:19PM, the Panay sub-grid should have been at red alert status, since total in-island generation was already less than the demand requirement, and any further disturbance could further push the system into the brink of its operation. At this point, a smart move should have been to conduct manual load dropping, as even though the system can still meet the demand requirements and the voltage and power quality were still normal as stated by NGCP, the reserves were already depleted. In addition, the Panay sub-grid at the time was largely dependent on its two remaining coal-fired power plants that have 150MW and 83.7MW in capacity, a significant capacity that no longer has a reserve to back it up  in the event of another disturbance.

At 2:19PM, another system disturbance occurred when the two remaining in-island plants PEDC 2 and PCPC tripped, significantly disrupting the supply-demand balance of the Visayas grid. Also, since the transmission link between Panay and Negros was limited, and Negros might not have had excess power to transport to Panay at the time, there was a significant lack of power generation in the entire Panay sub-grid, triggering an island-wide black-out.

The total system blackout occurred because there was not enough power generation to meet the demand in Panay Island, as all four large coal-fired power plants became unavailable. While the incident was mainly a power generation problem, more issues came up that, if addressed, could have prevented the island-wide blackout. Had NGCP implemented manual load dropping in the 2-hour window, to which the red alert status should have been declared in the whole island, rotating power outages could have significantly reduced the load demand requirements in Panay. If this were the case, even with the subsequent tripping of PEDC 2 and PCPC, the remaining power sources would have been able to shoulder the reduced load demand requirements.

Moving forward: Preventing another island-wide blackout

Given the recent blackouts in Panay, a reevaluation of the island’s energy mix and grid resilience measures is imperative. This can include exploring advanced energy storage technologies, enhancing grid interconnections, and strategically integrating renewable energy sources to diversify the island’s energy portfolio.

NGCP currently categorizes the normal, yellow, and red alert levels per island cluster: Luzon, Visayas, and Mindanao in particular, which underscores the need for more granular monitoring of reserve requirements per sub-grid, especially in Visayas, where each island exhibits a distinct energy mix and infrastructure conditions

The situation was further complicated by the limited transmission capacity links between islands – had the red alert status been properly raised in Panay Island during the 2-hour window, manual load dropping would have been triggered in response. However, since the reserve requirements were viewed holistically based on the Visayas perspective, the yellow alert status was raised instead over the grid, and the nuances in the operation of the Panay sub-grid, being the tail-end of the network, were overlooked.

The Panay Island blackouts underscore the urgent need for more distributed and flexible generation in the country. Since the island is heavily dependent on a few centralized coal-fired power plants, any disturbance can have disastrous effects on the entire sub-grid. Generation and grid planning must evolve to embrace more distributed sources to ensure grid stability, reducing reliance on a few power plants. Through distributed generation, power generation becomes more resilient, less susceptible to single-point failures, and adaptable to variable demand conditions. A diversified mix of energy sources, including renewables and other distributed technologies, can contribute to a more robust and reliable energy infrastructure, leading to more affordable, reliable, and secure power for Filipinos.

ABOUT
The Institute for Climate and Sustainable Cities is a climate and energy policy group based in the Philippines that promotes climate resilience and low-carbon development.

CONTACT
Sanaf Marcelo, ICSC: media@icsc.ngo, +63 968 886 3466, +63 917 149 5649

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