Abstract

An Oblique Subduction of the Indo-Australian plate beneath the Eurasian plate has led to extensive distribution of Volcanism and major faulting in Sumatera. The combination of shallow magmatic heatsources and fault-enhanced permeability provides South Sumatera with one of the largest concentration of geothermal prospects in Indonesia. The prospects are mostly concentrated along a major zone of crustal weakness created by the northwest-southeast trending Sumatera fault system.

PERTAMINA geological surveys have currently identified at least 18 geothermal prospects which are classified as hot water dominated geothermal systems. The systems are manifested by major fumarolic areas, boiling hotsprings, thermally altered ground and turbid hot pools associated with pleistocene to recent andesitic-rhyolitic volcanic centres.

Presently PERTAMINA has estimated a total resource potential of approximately 2725 megawatts taken from 10 high enthalpy geothermal prospects and five prospects had been surveyed in detail which provide South Sumatera with an estimated possible reserve potential of approximately 1080 megawatts.

South Sumatera is experiencing rapid growth rate of electricity demand with an annual rate of about 20%. Approximately 1450 megawatts are required to be generated to meet the projected electrical demand in year 2003. Besides for local industrial and household consumption, it is possible to transmit electricity generated in South Sumatera to Java where high electricity market exists.

To meet the rapidly increasing electrical demand in South Sumatera, the exploration and exploitation of the geothermal resources are receiving increasing-government support. PERTAMINA plans to develop Ulubelu and Lumutbalai geothermal prospects to generate a total of 140 megawatts by using 20 megawatt turbine units. The first 40 megawatts are expected to be commercially available in year 1998. PERTAMINA offers other Statutory Bodies including Private Sector to contribute in geothermal energy development of other prospects in South Sumatera.