Central Java government: Mount Ungaran geothermal potential stands at 55 MW
The Central Java Provincial Government has stated that geothermal development at Mount Ungaran in Semarang Regency has the potential to generate up to 55 megawatts (MW) of electricity from a power plant.
Head of the New and Renewable Energy (EBT) Division at the Central Java Energy and Mineral Resources Office, Dwi Suryono, said in Semarang on Wednesday that the area spans 29,800 hectares and is estimated to contribute 4-5 percent of the total renewable energy mix in Central Java.
To harness the geothermal energy, he said, drilling to a depth of 1,900-2,200 metres is expected to be required.
However, he cautioned that drilling would not be carried out in arbitrary locations, but rather based on geothermal potential identified through prior research.
If geothermal resources are found as expected and the permitting stages proceed smoothly, he continued, the geothermal power plant, with an investment value of US$300 million, will commence operations in 2031.
“To prove the existence of geothermal potential, drilling needs to be carried out. However, all permitting phases must of course be fulfilled. If the timeline is met, drilling will be conducted at the end of 2028 or early 2029,” he said.
If sufficient geothermal resources are found, he said, infrastructure will be built and commercial operation date (COD) will be achieved in 2031 to generate electricity, which will be transmitted to the interconnected Java, Madura and Bali grid system.
He also confirmed that the geothermal exploration plan in the Mount Ungaran area, located in Semarang Regency and bordering Kendal, will undergo a rigorous process, from environmental permits to public hearings involving local communities.
Following the issuance of Minister of Energy and Mineral Resources Decree Number 134.TK/EK.04/MEMBPE/2026, he said, the process remains lengthy before reaching the drilling and geothermal mining stages.
Through that decree, he said, the Ministry of Energy and Mineral Resources delegated the Geothermal Working Area (WKP) to PT PLN Persero.
Furthermore, there are permitting stages that must be passed, such as KKPR (Spatial Utilisation Activity Suitability) and PPKH (Forest Area Use Approval).
Beyond that, the project must also obtain an environmental permit or Amdal (Environmental Impact Analysis).
“Of course, permits already obtained do not mean activities can commence immediately. There are also forums within the environmental permit process, public hearings inviting relevant parties such as stakeholders, the community and NGOs,” he said.
Dwi added that the renewable energy mix in Central Java has currently reached 22.3 percent, exceeding the 2025 Regional Energy General Plan (RUED) target of 21.32 percent.
Not only at Mount Ungaran, he said, geothermal renewable energy potential in Central Java stretches from Dieng, Baturraden, Guci, Umbul Telomoyo and Jenawi.
“Dieng is already operating at 70 MW, with phase two of 55 MW in progress. In Jenawi there has been no further activity, in Umbul Telomoyo socialisation has been carried out, Baturraden is still off, and Guci is also still off,” he said.