Indonesia’s captive coal plants generate 134 TWh in 2025

Output reached 58% of grid-connected coal generation.

Indonesia’s captive coal power plants generated an estimated 134 terawatt-hours (TWh) of electricity in 2025, equivalent to 58% of the country’s 233 TWh of grid-connected coal generation, according to Ember.

The estimate was about 30 TWh higher than the captive coal generation reported in Indonesia’s Handbook of Energy and Economic Statistics (HEESI) 2025, underscoring gaps in tracking electricity generation from captive power facilities.

Ember estimated total captive power generation at more than 161 TWh in 2025, compared with over 144 TWh reported by HEESI.

The analysis also estimated that fossil-fuel captive power produced around 135 million tonnes of carbon dioxide emissions.

Nickel processing accounted for more than 81 TWh of captive electricity demand in 2025, with more than 94% supplied by coal.

“Most smelting plants are situated in Sulawesi and North Maluku—remote regions with limited access to the national power grid,” Ember said.

Coal use also extends beyond nickel. Aluminium plants generated an estimated 12.2 TWh from captive power in 2025, whilst pulp and paper accounted for 22 TWh and multi-industry industrial parks for 13.5 TWh.

Ember said some industries could provide earlier opportunities to reduce captive coal use.

“Meanwhile, pulp and paper already meet 20% of its captive demand without coal through combined heat and power systems from black liquor and wood waste, and palm oil mills run largely on their fruit bunches and kernel shells,” it added.

Renewables supplied around 10% of captive electricity demand in 2025, with hydropower providing almost 4 TWh to the aluminium sector.

Solar paired with battery storage could provide another pathway for replacing captive coal, Ember said.

The analysis identified more than 490 gigawatt-peak of on-site solar potential and around 70 gigawatt-hours of captive solar generation in the pulp and paper industry.

Ember said stronger facility-level reporting would be needed to accurately track captive generation and associated emissions, as applying a common capacity factor across different industries could result in systematic errors.

The organisation also linked better captive-power data to Indonesia’s industrial competitiveness as carbon-related trade measures, including the European Union’s Carbon Border Adjustment Mechanism, increasingly affect exporters.

“Data rigour for captive power is more than an accounting task,” Ember said, arguing that more granular reporting could support carbon-market development and improve tracking of Indonesia’s decarbonisation efforts.