Environmental and human health impacts of geothermal exploitation in China and mitigation strategies

Exploitation of the vast reserve of geothermal energy for power generation and direct use has been elevated to the top of China's energy agenda, while the environmental impacts and human health risk have received little attention. This review systematically summarizes the environmental and human health impacts of geothermal utilization in China, and identifies the key technologies and policy measures that can be implemented to mitigate them. Geothermal fluids are typically enriched with a range of dissolved species and non-condensable gases, which originate from magma degassing and/or water-rock interaction under high temperature and pressure, and often low pH conditions in the reservoirs, and their releases could pollute local surface water, groundwater, soil, and air, and adversely affect biodiversity. The toxic elements (primarily As and F) could negatively impact the health of people living in geothermal areas through contaminated surface water, groundwater, and food crops. Among the gaseous pollutants, hydrogen sulfide often poses the most significant health concern, while radon might pose potentially significant radiological risk to the workers of geothermal spa and hot spring facilities. Improper disposal of the geothermal wastes enriched with natural radionuclides might elevate the radiation exposure of workers at geothermal facilities and people living in their vicinity. To minimize the potential environmental impacts and human health risk from large-scale expansion of geothermal exploitation, heat-extraction-only technologies should be promoted, while geothermal facilities should actively adopt pollution control and prevention measures. Government regulation and supervision can further ensure the negative environmental and human health impacts are adequately mitigated.