Classification of geothermal resources in Indonesia by applying exergy concept

Indonesia is well-known for its reputation for possessing the world's largest geothermal potential, which has been characterized by high temperature geothermal resources' concentration. The geothermal energy potential of Indonesia has been estimated to be 28,617 MW, which is about 40% of the world's geothermal potential. However, only about 4.5% is being utilized as electrical energy supply in this country. This paper comprises the Indonesian geothermal resources, based on their capability of doing work and efficiency. In this study, currently operating geothermal power plants in Indonesia have been classified, based on the exergy concept and the Specific Exergy Index (SExI). The results of SExI values show that nine geothermal fields are classified as high exergy resource with their SExI values exceeding 0.5, and two remaining power plants with SExI values between 0.05 and 0.5 are classified as medium geothermal resources.