Integrating Geophysical and Geochemical Insights for Geothermal Resource Evaluation in Taiwan's Ruilin-Hongye Region

The Ruilin-Hongye region in Hualien County, Taiwan, represents a promising site for the development of non-volcanic geothermal energy resources. This study adopts an integrated approach, combining geological, geophysical, and geochemical analyses to assess geothermal potential and delineate reservoir characteristics. The region is located within the Yuli Belt, a complex metamorphic zone dominated by quartz-mica schists with interspersed mafic rock bodies. Geophysical surveys, particularly magnetotelluric (MT) surveys, have identified four shallow geothermal reservoirs at depths ranging from several hundred meters to approximately 1.5 kilometers. These reservoirs are distinguished by fractured and permeable rock formations, facilitating efficient hydrothermal fluid storage and circulation, which are crucial for geothermal energy development.Geochemical analyses indicate a favorable thermal gradient across the region, supported by recharge from meteoric waters and groundwater inflow along local fault and fracture networks. Borehole temperature profiles combined with simulation data suggest that the reservoirs could support a generation capacity of approximately 14 MWe, positioning the area as a viable candidate for geothermal power production. The study also developed a conceptual 3D geological model, offering a detailed subsurface map that highlights high-potential zones and enables more targeted exploration and drilling strategies.Our findings contribute to Taiwan’s renewable energy goals by demonstrating the feasibility of non-volcanic geothermal systems as a clean and sustainable energy source. This research underscores the importance of integrating geophysical and geochemical data to accurately characterize subsurface conditions, reduce exploration uncertainties, and optimize resource extraction. Future work should prioritize additional drilling and comprehensive monitoring to confirm production capacity and refine the development model, potentially advancing the role of non-volcanic geothermal systems in Taiwan's energy portfolio. By using such integrated methodologies, this study aims to mitigate development risks and enhance the efficiency of geothermal energy projects. Keywords: Hualien, non-volcanic geothermal, Reservoir characteristics, Resource evaluation