Geothermal fluid chemistry and human health

Abstract

Several effects on the environment arising from the utilization of geothermal resources may affect human health. (1) Human surroundings: changes in noise level, local climate, and landscape. (2) Water pollution: hot water geothermal fields emit large quantities of saline fluids which contain fluoride, boron, arsenic, and minor amounts of other heavy metals. Heavy metal sulphide precipitates form from some geothermal waters and collect in river sediments. Processing of geothermal waters to remove heavy metals may be necessary. Sulphide, boron, ammonia, and mercury may also enter local waters from geothermal steam condensates. (3) Air pollution: emission of CO 2 and H 2S from geothermal power stations in some extreme cases may approach the outputs from similar-sized coal-fired stations. Sulphide emission can be controlled by chemical processing of condensate and waste gases. Mercury from geothermal steam is unlikely to cause local levels in air to rise by more than 1 ppb. The significant environmental problems from geothermal development are capable of technical solution but add significantly to the cost of geothermal power.