Rotating blackouts may continue affecting parts of Indonesia in coming months, as the nation’s electricity system is expected to further weaken, with supply from new power plants failing to meet rising demand and older plants reportedly being shut down. 

According to data from the Energy and Mineral Resources Ministry’s directorate general for electricity, the additional supply from plants newly built by state-owned electricity firm PLN and independent power producers stood at 1,491 megawatts as of October this year, less than half of a target to have additional 3,868 MW installed in the full year of 2015. Given the low supply, some areas have reported experiencing supply deficits. 

Figures from the electricity office as of Oct. 28 showed that of the total 23 power systems in the archipelago, 11 systems produced lower than expected supply; another nine, meanwhile, are in a critical state, with reserve margins so low that they could be shut down if a main power plant experiences difficulties. Only three electricity systems are in a normal state, with sufficient reserves, namely the Ambon, East Nusa Tenggara and Ternate-Maluku power systems.

“We are trying to prevent the normal electricity systems from falling into a critical or deficit state, even though we have many other ongoing projects that need to completed all at once,” said Alihuddin Sitompul, director of the directorate’s electricity development program.

According to Alihuddin, the development of certain plants is expecting delays that may lead to the completion date being pushed further back. Indonesia’s rising population and economic growth is creating rocketing demand for electricity, demand supposed to be catered for by new power plants. 

Alihuddin said, however, that new plants would not necessarily resolve supply deficits, since aging plants also presented a challenge. 

“We are currently pushing our power plants to the limits of their operation in order to catch up with growing demand. We have to rest [some of] the plants. Yet, that simply means that the supply will become a nagging concern,” Alihuddin explained.

The country’s total power installed capacity stood at 53,535 MW as of October. The electrification ratio reached 86.39 percent nationally.

Concerns mounted when the Java-Bali electricity system reached a historic peak of 24,258 MW last week. The system now has around 30,000 MW in electricity installed capacity, of which the net capacity is approximately 27,000 MW. 

The reserve margin in the Java-Bali system is now less than 1,000 MW, according to PLN acting head for corporate communications Bambang Dwiyanto. 

“Our reserve margin is very limited now. However, we are still able to manage it, as Cirata and Saguling are now in partial operation while problems at Paiton and Suralaya have been resolved,” Bambang said of the existing power plants. 

Java-Bali’s electricity reserve margin was in deficit in late October, following disruptions at a number of large coal-fired steam power plants (PLTU), such as Paiton and Suralaya, as well as idle hydro electricpower plants (PLTA) running out of water to generate power.

An ideal electricity reserve margin should be maintained at 30 percent of the total peak demand.