Environmental effects of geothermal energy utilizations: A case study of the Seferihisar geothermal system, İzmir, Türkiye

Geothermal resources are often regarded as environmentally friendly and sustainable resources. They are utilized for different purposes, including energy generation, thermal tourism and greenhouse cultivation. The utilization type depends on the temperature, chemical characteristics and the flow rates of available geothermal resources. In long-term applications, there is a need for research and monitoring process to assess environmental consequences. Also, supervised use of the resource is crucial for both the geothermal system and its environment, as there is a possibility of unpleasant impacts on the environment, as chemical pollution, subsidence, and thermal effects in cases of improper use of geothermal resources. In Seferihisar, current consumption types of geothermal energy are consisting of a geothermal power plant with an installed capacity of 12 Mwe and a few primitive spas. In the Tuzla geothermal field, the geothermal waters ascending to the surface cause the deposition of travertine, where sea water interference to the geothermal system is clearly observed and supported by XRD analysis of the sample collected from the Tuzla travertine. Seismic activities as earthquakes, affect the surface manifestations of the SGS. The temperature measurement values obtained from Tuzla and Doğanbey are higher than the values recorded prior to the installation of the geothermal power plant. The operation of the geothermal power plant has caused the nearby hot springs to dry up and has ceased travertine deposition in the Cumalı geothermal field. The annual mean values of NO₂ and SO₂ for the region are lower than the National threshold value and European Union Countries’ threshold value.