The City of Idaho Springs, located about fifty kilometers west of Denver in the foothills of the Rockies, used to flourish in the mining industry but now attracts tourists with its historic downtown and a hot spring, which produces geothermal fluid at 48 degrees Celsius. In the 1920s, Colorado School of Mines purchased one of the abandoned mines north of the city, Edgar Mine and has been using the mine for mining and earth systems education and research. The purpose of this paper is to propose heat pump systems using thermal resources in Idaho Springs. Edgar Mine can be used to store cold groundwater, which would be consumed in summer to cool down a condenser. Hot geothermal fluid would be transported from a hot spring to residential areas and consumed in winter to heat up an evaporator. In this way, the heat pump systems can work efficiently throughout the year. In addition, hot geothermal fluid can melt snow from pedestrian pavement areas and reduce snowplow activities in the historic downtown. The authors investigated the temperature environment inside Edgar Mine and performed heat transfer analyses. The preliminary results show the surface temperature of the rock mass inside Edgar Mine reaches a maximum of 12 degrees Celsius, which indicates the mine is relatively cool. Thus, the mine would be suitable for cold thermal energy storage (CTES). Heat transfer analyses show the proposed systems can achieve a higher coefficient of performance than ground-source heat pump (GSHP) systems, which is already superior to conventional air-source heat pump (ASHP) systems. Many places in the world don’t fully utilize locally available thermal resources. The authors hope this case study can serve as an example of local consumption of locally produced energy. If communities start utilizing economically viable local energy in a socially and environmentally responsible manner, it will have global implications to sustainable development.

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