ESDM Addresses Geothermal Development in Mount Ungaran
The Ministry of Energy and Mineral Resources (ESDM) has emphasised that the development of the Geothermal Power Plant (PLTP) within the Mount Ungaran Geothermal Working Area, spanning Semarang and Kendal Regencies in Central Java, will be carried out gradually. The process will prioritise technical studies, safety, environmental protection, and the preservation of cultural heritage sites, including the Gedong Songo Temple.
ESDM Ministry Spokesperson Dwi Anggia stated that the project is currently in the exploration and feasibility study phase, meaning several stages remain to be completed. “Every stage must be based on data, technical studies, environmental aspects, licensing, and social considerations of the community. Exploration is conducted to ensure geothermal potential while assessing development feasibility,” Anggia noted in a written statement on Wednesday.
According to the 2025-2034 Electricity Supply Business Plan (RUPTL), the Mount Ungaran PLTP is planned to have a capacity of approximately 55 MW, with an operational target of 2031. To reach the construction stage, developers must first gain certainty regarding the characteristics and potential of the reservoir through a series of research and exploration efforts.
Anggia explained that exploration drilling is conducted based on geological and geophysical studies to understand subsurface conditions and determine reservoir targets. Surface drilling locations do not always sit directly above the geothermal source. “With directional drilling technology, drilling can be directed from specific points towards the target reservoir underground. Therefore, well location determination is based on technical data and studies, not solely on the surface position of the geothermal source,” she explained.
In its implementation, the preservation of the Gedong Songo Temple is a critical consideration. A 2019 social mapping study by Diponegoro University identified a zoning system comprising core, buffer, and development zones. Geothermal development must adhere to these boundaries and regulations to ensure the cultural heritage site remains protected.
“The protection of cultural heritage is a vital component that must be addressed throughout the entire development process. Every planned activity must refer to the applicable zoning regulations and preservation principles,” said Anggia.
Regarding the land footprint, the Ministry noted that the area used for the 55 MW PLTP will occupy less than 1% of the total geothermal working area. During the drilling phase, land requirements are also relatively limited and determined by technical studies, field conditions, and spatial planning regulations.
Water and environmental aspects are also subject to scrutiny before moving to subsequent stages. The government ensures that water needs, potential impacts on the environment and community, and management measures will be assessed during the environmental licensing process.
Concurrently, social mapping is being conducted to understand the conditions of the surrounding communities, including land use, environment, and spatial planning. This approach is necessary so that development plans can consider the area’s conditions comprehensively and involve the community from the early stages.
“Geothermal development is not just about drilling and power generation. There are social, environmental, spatial, licensing, safety, and cultural preservation aspects that must be integrated,” Anggi emphasised.
The development of the Mount Ungaran PLTP is a long-term process. The Ungaran Working Area has been established since 2007, and development has progressed through various stages, including geoscience studies, well location determination, licensing, exploration drilling, feasibility studies, and eventually construction and operation.
The results of the exploration will serve as the primary basis for determining development feasibility. If exploration shows a reservoir potential that meets technical and economic criteria, and all environmental, safety, and licensing requirements are met, the project may proceed to the next development stage.
Experience from geothermal developments in other parts of Indonesia shows that geothermal energy utilisation can coexist with other regional functions. The Dieng experience serves as a relevant lesson for Mount Ungaran, where geothermal development operates alongside areas of geological, biodiversity, cultural, and tourism value, as well as agricultural activities. Geothermal facilities in that area function alongside community activities and tourism, including cultural events.
In the context of Mount Ungaran, a similar approach can serve as a foundation to build synergy between energy development and the potential for nature and geological tourism, cultural preservation, agriculture, the environment, and community activities in the surrounding area.