Indonesia's state-owned electricity utility PT Perusahaan Listrik Negara (PLN) is planning a major retrofit of its coal-fired power plants (CFPPs) on Java island to enable them to burn low-CV coal, a strategic shift aimed at aligning the country's power generation fleet with a domestic coal market increasingly dominated by lower-rank material, a top executive said on July 2.

PLN President Director Darmawan Prasodjo said the majority of CFPPs in the Java grid were originally engineered to utilize mid-to-high CV coal. However, supplies of these grades are becoming increasingly constrained, making technical adjustments to the plants necessary.

The executive described the modifications as a long-term solution to the growing mismatch between power plant specifications and the changing profile of national coal production. Recent years have seen Indonesian output increasingly tilt toward low-CV coal, while reserves of mid- and high-CV grades have steadily dwindled.

This structural supply trend poses a potential risk to fuel security for CFPPs, especially in the Java system, which serves as the backbone of the nation's electricity supply. Beyond expanding the range of usable coal, the retrofit initiative is also designed to reduce PLN's dependence on specific coal grades and optimize the use of domestic coal production.

Darmawan noted that the recent supply disruption served as a critical wake-up call. The scarcity of mid- to high-CV coal had hampered operations at several CFPPs, leading to rolling blackouts in parts of Java.

As an immediate stopgap measure, PLN has secured additional supplies of coal with a calorific value above 4,500 kcal/kg. The additional supply is expected to reach around 1.8 million tonnes by July 2026, with an estimated further 3 million tonnes to be added between August and December 2026, according to the president director.

Darmawan emphasized that these extra volumes have bolstered the reliability of the Java electricity system while the company awaits the implementation of the retrofit programs at a number of power plants. He reaffirmed that the modification strategy is a cornerstone of PLN's efforts to maintain grid reliability amidst the evolving landscape of national coal quality, ensuring the plants can continue to operate even as low-calorie coal increasingly dominates the domestic market.