This report introduces Aquifer Thermal Energy Storage (ATES) systems, which utilize
renewable geothermal energy. Beneath our feet lies plenty of groundwater stored unused. When
compared with the outside air temperature, groundwater is warmer in the winter and cooler in the
summer, and therefore is of high value as a heat source or heat sink (cold source). Mitsubishi
Heavy Industries Thermal Systems, Ltd. has constructed a heat/cold source system for
heating/cooling by using a centrifugal chiller and aquifers with a very low flow of groundwater.
The system is comprised of (1) the centrifugal chiller, (2) pumping wells, (3) cold/hot water pumps,
and (4) the heat exchanger. Currently in test operation at the time of report publication (April
2017), the system has achieved a coefficient of performance (COP) of 4.77 while heating in the
winter with an average outside air wet-bulb temperature (WBT) of 0.15°C.
