Horizontal Bore Heat Storage for Building Heating and Cooling
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Solution Overview
Problem
Commercial HVAC systems are energy-intensive, costly, and environmentally impactful due to high electricity consumption, greenhouse gas emissions, and the use of refrigerants, while conventional geothermal systems are inefficient for heating and cooling based on ambient subterranean temperature differentials.
Innovation Solution
A system utilizing pipes installed in subterranean rock layers to extract and store thermal energy, using a heat storage medium that mimics a capacitor, allowing for efficient heating and cooling by circulating fluid through pipes to leverage the thermal capacity of rocks beneath buildings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional geothermal systems use heat pumps to leverage ambient temperature differentials, then heating and cooling can be provided, but the systems are costly and inefficient when ambient subterranean temperatures are similar to air temperatures
Solution Approach 1:
The system stores thermal energy in the subterranean rock layer during periods when thermal differentials are favorable (e.g., daytime, summer months) before they are needed. This preliminary storage action allows the system to retrieve heat or cold later when ambient temperatures make conventional geothermal systems inefficient, eliminating the need for continuous energy-intensive heat pump operation.
Solution Approach 2:
The subterranean rock layer itself serves as the heat storage medium, leveraging its high heat capacity and thermal mass to store and release thermal energy without requiring external energy input for storage. The rock naturally absorbs and releases heat based on temperature differentials, providing a self-service thermal battery that reduces reliance on active heat pumps.
2Reliability
If commercial HVAC systems operate continuously to maintain building temperature, then heating and cooling demands are met, but operational costs and environmental impact increase significantly
Solution Approach 1:
The system pre-charges or pre-discharges the subterranean thermal storage during periods of low demand or favorable thermal differentials, storing thermal energy before it is needed. This allows the HVAC system to operate intermittently rather than continuously, retrieving stored thermal energy when needed to maintain building temperature reliability while reducing overall energy consumption.
Solution Approach 2:
The system changes the operational parameters of thermal energy storage by using the subterranean rock layer's high heat capacity and thermal conductivity. By storing large amounts of thermal energy in the rock at controlled temperatures, the system can later retrieve this energy at different temperature levels, allowing flexible HVAC operation that reduces continuous electricity consumption while maintaining temperature control reliability.
3Ease of operation
If conventional HVAC systems use refrigerants and forced air systems, then heating and cooling are provided, but greenhouse gas emissions and water evaporation increase
Solution Approach 1:
The system replaces the mechanical refrigeration cycle with a thermal energy storage and retrieval system using subterranean rock. Instead of using refrigerants that may leak and cause greenhouse gas emissions, the system uses heat exchange between circulating fluid and the rock layer, eliminating harmful refrigerant emissions while maintaining effective heating and cooling delivery.
Solution Approach 2:
The system uses hydraulic circulation of fluid through pipes embedded in the subterranean rock layer to transfer thermal energy. This hydraulic approach replaces forced air systems that evaporate significant water, using closed-loop fluid circulation that minimizes water loss while effectively delivering heating and cooling to the building.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces operational costs and environmental impact by storing excess heat in warmer months for winter heating and releasing it in winter, reducing reliance on auxiliary energy sources and minimizing water evaporation.
Implementation Method 1
storing excess heat in warmer months for winter heating and releasing it in winter
Implementation Method 2
circulating fluid through pipes to leverage the thermal capacity of rocks beneath buildings
Data Source
AI summary
A system for heating and cooling buildings using geothermal heat storage includes a heat exchange system coupled to a heat storage medium including rock. The heat exchange system comprises pipes running through boreholes in the rock. The pipes of the heat exchange system are connected to pipes used within the building for heating and cooling the building. The system stores excess heat collected during the summer in the rock and discharges heat from the rock during the winter. The pipes of the heat exchange system may be arranged horizontally, and configured to run under the foundation of a building. Horizontal bores containing the pipes can be constructed using directional drilling techniques.