Abstract
In recent years, geothermal energy use from low-temperature sandstone reservoirs has sharply increased. Nonetheless, the injection of heat-depleted geothermal fluids has not been an easy task because of well/formation damage and operational/economic issues. Sønderborg geothermal plant is a case example of heat-mining from a low-temperature reservoir. It is in the northeast of Sønderborg towards Augustenborg Fjord. The present work takes into consideration the regional and local geology of the Sønderborg area, construction of the wells, field experience and water chemistry. The main issues of the geothermal plant appear to be related to the construction of the wells and reinjection of the heat-depleted brine. Our water chemistry analysis and PHREEQC simulations indicate that geothermal brine was saturated with respect to carbonate and barite minerals. The excess of Ca2+ and SO42− ions could have led to the formation and precipitation of carbonate and sulfate scales. Moreover, the increment of iron concentration over time could suggest the ingress of oxygen and pitting corrosion due to the presence of halide ions.
Highlights
The Sønderborg geothermal plant is one of three plants (Thisted, Margretheholm, Sønderborg) in Denmark [1], located northeast of Sønderborg towards AugustenborgFjord [2]
The geothermal fluid is extracted with an average temperature of around 48 ◦ C and a salinity of 15% to produce heat which is distributed to the district heating system [5]
Those values indicate that basically, all sand present in Gassum formation constitutes potential reservoir sand that is displayed as different zones: upper sandstone (USd), lower sandstone (LSd) and shale (Sh)
Summary
The Sønderborg geothermal plant is one of three plants (Thisted, Margretheholm, Sønderborg) in Denmark [1], located northeast of Sønderborg towards Augustenborg. The geothermal fluid is extracted with an average temperature of around 48 ◦ C and a salinity of 15% to produce heat which is distributed to the district heating system [5] This plant was designed to produce up to 12 MW from the geothermal fluid using adsorption heat pumps [1], which are powered by a boiler unit with two woodchip fired boilers. At the beginning of the project, the CO2 emissions were reduced from 58,000 to 4800 tons annually, which is more than 90% if we consider woodchips as a CO2 neutral This huge reduction in the climate gas emissions from the district heating production could support the Sønderborg municipality’s ambitious goal of CO2 neutrality by 2029 [6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
