An overview of carbon dioxide emissions from Icelandic geothermal areas

The origin of CO2 in fluids from Icelandic high-temperature geothermal systems is predominantly magmatic. Emissions from producing areas have risen with increased production. Abnormal rises have been recorded due to magmatic activity and the onset of boiling due to increase in production. Natural flow is predominantly through soil but to a small extent via steam vents and steam heated pools. The extent of natural steam flow varies considerably between areas, apparently due to the formation of carbonate deposits (mainly calcite) in relatively cool liquid dominated aquifers at shallow depths, where these are present. The CO2 concentration of fluids from aquifers at higher temperatures apparently decreases with temperature and is for instance very low (< 1000 ppm) in fluid from IDDP-1, Krafla where the source temperature is 450 degrees C.