Efficient borehole energy storage system for high-story buildings

In this paper, a seasonal solar energy storage system using boreholes which can be applicable to large facilities including high-story buildings was proposed. The proposed system provides space heating/cooling energy for the high-story buildings. The three-dimensional computer simulations were carried out for this borehole system in which vertical boreholes as deep as 100 meters are drilled in the ground. The system recovers the heat generated by the space cooling and refrigeration counters utilized in the summer season. During the summer months, this excess heat is used for charging a heat store (borehole unit), and during the winter season, the heat extracted from the borehole unit and solar thermal energy collected by the solar collector are used to heat the high-story buildings. Then, the winter cold energy is stored and utilized as a cold energy source in the summer. The thermal performance including transient isotherms in the borehole unit, long-term variation of average temperature of the unit for charging and discharging processes was clarified in detail. Moreover, effects of CO/sub 2/ reduction by the proposed system on urban warming were suggested.