CO2 emissions and heat flow through soil, fumaroles, and steam heated mud pools at the Reykjanes geothermal area, SW Iceland

• Published in: Applied Geochemistry
• Main Authors: Fridriksson, T., Kristjansson, R., Armannsson, H., Margretardottir, E., Olafsdottir, S., Chiodini, G.
• Other Authors: Fridriksson, T.; Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Kristjansson, R.; Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Armannsson, H.; Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Margretardottir, E.; Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Olafsdottir, S.; Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia, Iceland GeoSurvey, Grensa´ svegi 9, 108 Reykjavı´k, Iceland, Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2006
• Subjects: geothermal; emissions; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases; Reykjanes; Iceland
• Online Access: http://hdl.handle.net/2122/2680; https://doi.org/10.1016/j.apgeochem.2006.04.006

Carbon dioxide emissions and heat flow through soil, steam vents and fractures, and steam heated mud pools were determined in the Reykjanes geothermal area, SW Iceland. Soil diffuse degassing of CO2 was quantified by soil flux measurements on a 600 m by 375 m rectangular grid using a portable closed chamber soil flux meter and the resulting data were analyzed by both a graphical statistical method and sequential Gaussian simulations. The soil temperature was measured in each node of the grid and used to evaluate the heat flow. The heat flow data were also analyzed by sequential Gaussian simulations. Heat flow from steam vents and fractures was determined by quantifying the amount of steam emitted from the vents by direct measurements of steam flow rate. The heat loss from the steam heated mud pools was determined by quantifying the rate of heat loss from the pools by evaporation, convection, and radiation. The steam flow rate into the pools was calculated from the observed heat loss from the pools, assuming that steam flow was the only mechanism of heat transport into the pool. The CO2 emissions from the steam vents and mud pools were determined by multiplying the steam flow rate from the respective sources by the representative CO2 concentration of steam in the Reykjanes area. The observed rates of CO2 emissions through soil, steam vents, and steam heated mud pools amounted to 13.5 ± 1.7, 0.23 ± 0.05, and 0.13 ± 0.03 tons per day, respectively. The heat flow through soil, steam vents, and mud pools was 16.9 ± 1.4, 2.2 ± 0.4, and 1.2 ± 0.1 MW, respectively. Heat loss from the geothermal reservoir, inferred from the CO2 emissions through the soil amounts to 130 ± 16 MW of thermal energy. The discrepancy between the observed heat loss and the heat loss inferred from the CO2 emissions is attributed to steam condensation in the subsurface due to interactions with cold ground water. These results demonstrate that soil diffuse degassing can be a more reliable proxy for heat loss from geothermal systems than soil ...