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University of Minnesota Aquifer Thermal Energy Storage (ATES) project report on the first long-term cycle

Technical Report ·
DOI:https://doi.org/10.2172/10103375· OSTI ID:10103375
 [1]
  1. Minnesota Geological Survey, St. Paul, MN (United States)
The technical feasibility of high-temperature (>100{degrees}C) aquifer thermal energy storage (IOTAS) in a deep, confined aquifer was tested in a series of experimental cycles at the University of Minnesota`s St. Paul field test facility (FTF). This report describes the additions to the FTF for the long-term cycles and the details of the first long-term cycle (LT1) that was conducted from November 1984 through May 1985. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic aspects of LT1 are reported. The permits for long-term cycles required the addition of a monitoring well 30.5 m from the storage well for monitoring near the edge of the thermally affected area and allowed the addition of a cation-exchange water softener to enable continuous operation during the injection phase. Approximately 62% of the 9.47 GWh of energy added to the 9.21 {times} 10{sup 4} m{sup 3} of ground water stored in the aquifer LT1 was recovered. Ion-exchange water softening of the heated and stored ground water prevented scaling in the system heat exchangers and the storage well and changed the major-ion chemistry of the stored water. Temperatures at the storage horizons in site monitoring wells reached as high as 108{degrees}C during the injection phase of LT1. Following heat recovery, temperatures were <30{degrees}C at the same locations. Less permeable horizons underwent slow temperature changes. No thermal or chemical effects were observed at the remote monitoring site. 25 refs.
Research Organization:
Pacific Northwest Lab., Richland, WA (United States); Minnesota Geological Survey, St. Paul, MN (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
AC06-76RL01830
OSTI ID:
10103375
Report Number(s):
PNL--7817; ON: DE92004699
Country of Publication:
United States
Language:
English