PLN Modifies Coal Mills at Power Plants to Boost Electricity Reliability
PT PLN (Persero) is performing modifications on several Steam Power Plants (PLTU) to prevent the recurrence of electricity blackout incidents.
The company is conducting retrofits, or technical adjustments, on existing power units to enable them to consume low-caloric coal.
President Director of PLN, Darmawan Prasodjo, revealed that this effort is a response to the declining trend in the production of medium and high-caloric coal (4,500 kcal/kg and above). Meanwhile, the current larger supply trend consists of low-caloric coal.
At least two power plants have undergone retrofitting, namely PLTU Suralaya 6 and 7, with the possibility of continuing to other power plants.
“We have completed the retrofit of PLTU Suralaya 6 and 7 by modifying their mills. Following the success of the retrofit at Suralaya 6 and 7, we are now conducting feasibility studies (KKP) across all PT PLN (Persero) power plants,” he stated during a Hearing Meeting (RDP) with Commission XII of the Indonesian House of Representatives (DPR RI), as reported on Friday (3/7/2026).
Through the modification of these coal grinding devices, the Suralaya power plants are now capable of using low-rank coal in the range of 4,100 to 4,300 kcal/kg. Previously, these units required higher caloric specifications, specifically at the 4,600 to 4,800 kcal/kg level.
“Because the supply of high and medium-caloric coal is thinning every day, we are performing adjustments to our power plants with the goal of ensuring such incidents do not recur,” he said.
In addition to machine adjustments, PLN is optimising power plant operations during low-load periods between 00:00 and 06:00 WIB. The excess power generated during these hours is stored in a Battery Energy Storage System (BESS) with a capacity of 4 Gigawatt hours (GWh) or equivalent to 500 Megawatts (MW) to strengthen power reserves.
“This improves system reliability, as there is capacity in underutilised power plants that can be optimised to capture energy,” he explained.
The company ensured that the electricity condition, particularly on Java Island, has returned to stability. PLN is committed to continuously maintaining system reliability 24 hours a day to support public activities and sustainable national economic growth.
“The electricity system condition, especially in Java, has had no more rotating blackouts since 21 June 2026. We are working together to maintain and improve this through our system reliability strengthening programme,” he concluded.