Globally, over the past few decades, there has been a rapid increase in the use of ground source heat pump (GSHP) systems for heating and cooling purposes. Although these systems are more energy efficient than conventional air source heat pump systems, their association with potential groundwater contamination risks, e.g., the leakage of heat exchanger fluids like glycol, is a major concern. In this study, HYDRUS software was used to simulate the transportation of fluids from such systems into an aquifer. To better understand the transport environment, a geological survey was conducted and a > 50 m deep observation well was dug close to the GSHP installation site. To determine the physical properties of the soil, core samples were collected and analyzed; to determine the flow rate of the groundwater as well as the hydrological properties of the aquifer, measurements were conducted using a velocimeter that was installed in the borehole of the observation well. A laboratory column containing aquifer soil was used to determine drainage breakthrough curves. The hydrological parameters of the soil and the solute were used for the simulation under a virtual groundwater environment. The flow of groundwater resulted in the dispersion of the contaminant from its source, and its concentration was significantly reduced owing to degradation presumedly by biological activity. Additionally, two methods for the elimination of the contaminant from aquifers (enforced biodegradation and decontamination by pumping) were identified.
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This research was supported by grants from Core Research for Evolutionary Science and Technology (CREST) which is funded by the Japan Science and Technology Agency (JST). It was also partially supported by KAKENHI from the Japanese Society for the Promotion of Science (Grant number 18K05895). The authors deeply appreciate Dr. Takeshi Saito for providing guidance and analyzing the chemicals in groundwater and Dr. Ayako Funabiki for supporting the geological survey. The authors also appreciate Dr. Toshiko Komatsu, Dr. Takato Takemura, and Dr. Shoichiro Hamamoto for providing valuable counsel regarding this research project. Finally, the authors also appreciate Mr. Hiromu Muto and Mr. Hirokiyo Minamino for supporting the sampling and analysis of groundwater and soil samples.
This research was supported by grants from Core Research for Evolutionary Science and Technology (CREST) which is funded by the Japan Science and Technology Agency (JST). It was also partially supported by KAKENHI from the Japanese Society for the Promotion of Science (Grant number 18K05895).
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Moritani, S., Saito, H., Win, P.W. et al. Assessment of potential groundwater contamination by ground source heat pump operation using solute transport models. Int J Energy Environ Eng (2020). https://doi.org/10.1007/s40095-020-00360-2
- Confined aquifer
- Breakthrough curve
- HYDRUS simulation
- Ground source heat pump