Geothermal energy in Indonesia is located along a volcanic arc, and is distributed and related to the tectonic setting of Indonesia. Most geothermal power plants are located along this volcanic arc at the flank of in-active volcanoes. The total install capacity of these geothermal power plants has reached 2318 MW, which is now the second largest geothermal capacity in the world.

A few exploration or production wells are located in un-stable volcanic areas, which has led to the blowouts of wells and the release of volcanic gases. The instability of the rock masses is caused by hydrothermal clay and the porous structure of the primary rock, which was intensively altered. The altered rock is affected by the hydrothermal processes, including the acidity of the volcanic gases. Acidity changes the petro physical properties. The physical alteration of the rock gradually causes a transformation of the hydrothermal system structure, which leads to changes in its hydrodynamic and temperature regimes.

Gases are dangerous and often overlooked hazards in volcanic and geothermal regions. The effects of gases from geothermal areas may cause asphyxiation, respiratory diseases, and skin burns. The hazards mostly stem from CO2, H2S, CO, SO2, and other minor gases. New cases of gas hazards have involved the death of five people and more than 40 victims of anxiety and headaches. Volcanic gases may cause blowouts during geothermal drilling. Monitoring systems are being developed to mitigate such risks due to volcanic gases. Other geothermal hazards are landslides, phreatic eruptions, and earthquakes.

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