The Potential of Atedai Geothermal Field Based on Geological Geochemical an Geophysical Studies, Lomblen Island East Nusatenggara

Abstract

From the preliminary geological, geochemical and geophysical studies, the potential of Atedai Geothermal field estimated between 30 to 40 MWe. The potential of the energy resources more than enough to fulfill electricity demand of 1266 km square of the island with population about 86 000 people. The thermal features in this area associated with post volcanic activity and controlled by a couple near parallel NE-SW faults. The geothermal discharge consists of hot spring, hot ground, fumarole and altered rock. The hot spring mostly near neutral pH bicarbonate type water. Only two springs with low pH sulfate type. The spring temperature about 40oC while the fumarole temperature up to 98oC. Alteration type is argillite to advanced argillite with altered minerals including Kaolinite, Halloysite, Alunite, Smectite, Dyckite and Phyropillite. Those minerals analyzed by using Portable Infrared Minerals Analyzer (PIMA). The geochemical soil survey data shows that there are two areas of anomaly for Hg (Mercury). The maximum Hg contents up to 2522 ppb. From electrical resistivity data, there are three areas of low resistivity (less than 10 Ohm). The areas are Watu Wawer (14.5 km2), Wolo Kebingin (0.25 km2) and Waru (1.5 km2). The thickness of the low resistivity area is about 600 to 650 m.