Evaluation of hydrogeologic conditions for groundwater heat pumps: analysis with data from national groundwater monitoring stations

Abstract

Groundwater can be used as an alternative renewable and clean energy source for space heating and cooling. Hydrogeologic conditions of Korea were evaluated for application of groundwater heat pumps (GWHPs), especially for open-loop system. Groundwater data obtained from the national groundwater monitoring stations (NGMSs) were used for the purpose. Temperatures of shallow and deep groundwaters are between 1.2–25.8°C and their annual variations are mostly within 10°C. Especially the small amplitude of variation for deep groundwaters can facilitate design and maintenance of groundwater heat pumps. Groundwater levels for shallow and deep wells are located at average 4.79–6.07 m below ground surface. The shallow water levels are most promising for groundwater heat pumps, which reduces pumping costs. A large number of monitoring wells showed a good well yield exceeding a requirement for 3 RT heat pumps for small residential purposes but a limited application is expected for large commercial uses with the single well. Some proportions of shallow and deep groundwaters exhibited scaling and corrosion potentials in respect to hardness, pH, electrical conductivity, total dissolved solids, bicarbonate and chloride. Each relevant parameter was separately evaluated in this study but the parameters are closely correlated. Thus for more detailed and quantitative examination of water quality conditions for GWHPs, integrated and extensive chemical analysis of groundwaters are essentially required.