Preliminary geothermal environmental impact assessment for the Torfajökull area, central S-Iceland

Abstract

The Torfajökull high-temperature area is located within the Torfajökull central volcanic complex in South Iceland. This complex contains anomalously abundant acid volcanics. A large ring structure, probably related to a caldera subsidence, encircles the complex. The geothermal manifestations cover an area of about 140 km2. They are almost entirely located within the ring structure. Natural output has been estimated to be equivalent to 190-930 kg/s of steam. Basaltic intrusions underlying the silica rocks may be the heat source for the geothermal reservoir. The geothermal manifestations are mostly steaming ground but steam-heated water of the bicarbonate and the acid sulphate type is common in the area. A preliminary review is carried out on possible environmental effects due to drilling in the area in order to decide how to carry out an environmental impact assessment (EIA) and disclose key impacts. In this study, an attempt has been made to identify the likely impact of geothermal exploration, drilling and operations, and potential mitigating measures. As environmentally more advantageous, the result of this study suggests that detailed studies be carried out on the water supply for drilling, on how to get rid of effluent water, and on the monitoring of gas emissions to the atmosphere during drilling operations, as well as a detailed assessment of the biology of the area.