Yes, creating an underground heat reservoir to store heat from summer and use it to heat a house during winter can be a sensible and efficient solution. This concept is often referred to as seasonal thermal energy storage (STES) or seasonal heat storage.
Geothermal systems, which utilize the Earth's natural heat, are already an effective way to heat and cool buildings. However, they typically operate on a continuous basis and extract heat from the ground as needed. STES takes this a step further by allowing excess heat to be stored during the warmer months and used when heating is required in colder months.
Here's how it generally works:
Heat Collection: During summer, when the ambient air and ground temperatures are higher, heat is collected from the geothermal system or other sources such as solar thermal collectors or waste heat from industrial processes. This excess heat is transferred to a thermal storage medium, such as water, which is then circulated into the underground reservoir.
Heat Storage: The underground reservoir serves as a thermal storage bank, acting as a buffer to store the collected heat for an extended period. The reservoir is typically located at a sufficient depth where the natural ground temperature remains relatively constant throughout the year.
Heat Retrieval: When winter arrives and heating is required, the stored heat is retrieved from the underground reservoir. The heated water or other heat transfer fluid is circulated back into the geothermal system or a heat exchanger, where it transfers its heat to the house's heating system, providing warmth during the colder months.
By utilizing STES, homeowners can take advantage of excess heat during the summer and avoid relying solely on the geothermal system's continuous operation, which can potentially reduce energy consumption and operating costs. Additionally, it helps optimize the use of renewable energy sources, such as solar thermal energy, by storing the surplus energy for later use.
It's worth noting that implementing an underground heat reservoir for STES requires careful design, appropriate insulation, and proper sizing to ensure efficient heat storage and retrieval. Factors such as the geology of the site, available land, and local climate should also be considered during the planning and implementation stages.
Overall, incorporating a seasonal heat storage system as an upgrade to geothermal systems can enhance energy efficiency, reduce reliance on fossil fuels, and provide a more sustainable and cost-effective heating solution for residential and commercial buildings.