Geothermal Explorations on the Slate Formation of Taiwan

Abstract

Currently, over 90% operated geothermal power plants are distributed in the volcanic-or magmatic intrusion-related geological systems. Only a few cases are done in metamorphic terranes, especially on the slate formation. Taiwan is located at the ring of fire and is famous for the young orogenic belt, which has wide distributions of rapid uplifting terranes with few active volcanoes. The metamorphic rocks, for example, schist and slate formations with high geothermal gradients, are occurring in the major mountain range. This chapter introduces the techniques or methods we used for geothermal exploration in the slate formation of the Chingshui geothermal field of Taiwan, where a 3-MW pilot geothermal power plant had been installed in 1983 and operated for 12 years.

Integrating Stable Isotopes with Mean Residence Time Estimation to Characterize Groundwater Circulation in a Metamorphic Geothermal Field in Yilan, Taiwan

“…All surface data lie along the regional meteoric water line, indicating all surface water is highly related to local precipitation in the study area. Song and Lu (2018) [2] reported the same close relationship between thermal water and the local meteoric water line in the nearby thermal field, the Chingshui geothermal field. However, the characteristic of ITH03 is similar to that of surface water.…”

“…The more than 2‰ shift clearly indicates some interaction mechanism occurred during the circulation. Song and Lu (2018) [2] reported a 3‰ in δ 18 O from the MWL in the nearby Chinshui geothermal field and interpreted it as slow fluid-rock interaction in terms of low permeability of the slate host rocks. We argue this slow fluid-rock interaction could have happened in the study area.…”

“…It is a well-known fact that more than 90% of currently operating geothermal power fields are located in volcanic or magmatic intrusion-related geologic systems [1,2]. The Chingshui and Tuchen geothermal fields in Taiwan are among few metamorphic geothermal fields existing in the world.…”

“…The exploration of geothermal resources in Taiwan can be traced back to the 1970s. A 3-MWe geothermal energy power plant was constructed in Chingshui, Yilan in 1981, but it was forced to shut down due to the deterioration of efficiency in the early 1990s [1,2], mainly due to scaling issues. In 1985, a 260 kWe dual-cycle power generation test system was built in the Tuchen geothermal area to make full use of the thermal energy of the geothermal fluid.…”

“…The study area, the Tuchen geothermal field (Figure 1), is located in the Slate Belt of the northern Central Range of Taiwan, which mostly comprises tight formations that are characterized by low primary porosity [2,5,6]. Thus, the mechanism of how water circulates and bring underground heat to the surface critically affects the duration of the operation of a geothermal field in the metamorphic region [5].…”