Energetic Efficiency of a Deep Borehole Heat Exchanger Adapted from a Freezing Borehole Based on a Long-Term Thermal Response Test

Abstract

This paper describes the characteristics of a thermal response test and presents the results of the test conducted on a borehole at the freezing shaft in Poland. Freezing boreholes are temporary boreholes created to facilitate other geological work, especially for large-diameter mine shafts or other boreholes. Due to their nature, they are abandoned after the necessary work around the mine shaft is completed. The economical point of view suggests that, after their use as freezing boreholes, they should be used for heating if possible. In this paper, the authors aim to suggest that they can be utilized as borehole heat exchangers. Large numbers of freezing boreholes sit idle across the globe while they could be used as a renewable energy source, so creating a new way to obtain heating power in the future should be popularized. The paper includes a description of the implementation method of the thermal response test and the results of the test on a sample freezing borehole intended for abandonment. The test results were interpreted, and the key parameters of the borehole heat exchanger based on the freezing borehole were determined to be satisfactory. The possibilities of other borehole uses are also described.

Keywords

• geothermal energy
• thermal response test
• borehole heat exchangers
• deep borehole heat exchangers
• mine shafts
• freezing boreholes