Dieng Geothermal Project: Risk Assessment for the Decision on 60 MW Expansion

Abstract

Dieng is one of the prospected geothermal fields in Indonesia with an estimated field development potential at 350 MW. At present, one 60 MW power plant unit has been installed and the current production is around 46 MW. Dieng geothermal power plant is owned and operated by PT Geo Dipa Energi (Geo Dipa), a state owned company. Geo Dipa is implementing a phase development for the field. Unit 1 has been in operation since 1998 and now Geo Dipa plans to add another 60 MW, Unit 2. The Unit 2 project is still in feasibility stage and the feasibility study is currently being updated. In the development of Unit 2, there are risks that need to be considered before a decision can be made. Therefore, in this paper, the risks associated with Unit 2 project are identified and appropriate mitigation actions are listed. The key risks are identified as resources and technical risks which are related to scaling and corrosion in production wells, turbine and Fluid Collection and Reinjection System (FCRS). To mitigate the scaling, methods such as hot water reinjection, pH modification, inhibitors, cold water injection and retention tank have to be studied further. Several environmental issues are also considered as extreme risks and should be mitigated prior to a decision on the Unit 2 project.