Geothermal HVAC - PCM Seasonal Energy Storage

Geothermal heat pump systems have proven energy savings potential, but currently possess only a small percentage of the overall heating, ventilation and air conditioning market in the United States. The single most important market barrier to the widespread implementation of geothermal heat pump systems is their high installation cost, which is preventing geothermal heat pump systems from realizing a potential of 3.7 quads in primary energy savings. This problem is being addressed by combining materials with a high thermal storage capacity known as phase change materials with a specific type of geothermal heat pump system called a borehole energy storage system. Implementing phase change materials into a borehole thermal energy storage system will reduce the amount of drilling that will be required, which ultimately lowers the high installation cost of the system. The overall approach involves identifying the method of incorporating phase change materials into the borehole thermal energy storage system that will result in the largest net installation cost reduction. In Phase I, a test apparatus will be constructed that will allow for the rapid testing of borehole thermal energy storage systems that are integrated with phase change materials. Performance testing will be conducted for a variety of different phase change materials. Ultimately, a decision matrix will be created that will highlight the specific borehole thermal energy storage system with phase change materials that will yield the highest degree of commercialization potential. If this project is carried over into Phase II or Phase III and beyond, a commercial product will be developed that has instant applicability to all geothermal heat pump systems. The commercialized product will provide a cost effective means to introduce phase change materials into a geothermal heat pump system while requiring no special installation experience on behalf of the installers.