Assessment of Geothermal Potential in Kepahiang District Using the Magnetotelluric Method for Renewable Energy Development

Abstract

Indonesia, located on the Pacific Ring of Fire, has 147 volcanoes, with 76 still active, creating optimal conditions for geothermal energy development. Kepahiang Regency in Bengkulu Province is particularly promising for geothermal exploration, evidenced by hot springs, fumaroles, and other geothermal phenomena. This study aims to enhance subsurface analysis through a detailed Magnetotelluric (MT) survey, utilizing 17 strategically placed stations near geothermal manifestations and fault zones. The MT method is highly effective for deep geothermal resource exploration, as it measures natural geomagnetic field variations to assess subsurface electrical resistivity. Data were collected over 16 hours at different frequencies (128 Hz, 1024 Hz, 4096 Hz) and analyzed using MAPROS, ZONDMT1D, and ZONDMT2D software, producing detailed subsurface resistivity models. The results identified low-resistivity zones at various depths, indicating potential geothermal reservoirs with hot fluids and thermally altered stones. Notably, the measurements revealed a heat source in the upper layer with a resistivity of over 350 ohm-m, and at point 3L1, the presence of a cap rock beneath the manifestation at a depth of 1-2 km with a resistivity of 0.7-1.6 ohm-m. Below this cap rock, a hot rock layer with a resistivity exceeding 350 ohm-m was detected. These findings highlight promising targets for further exploration, including directional drilling to confirm the presence and feasibility of geothermal resources. Developing geothermal energy in Kepahiang could offer a sustainable energy source, reduce fossil fuel dependence, and support regional economic growth by creating jobs and lowering greenhouse gas emissions.