Closed-loop geothermal energy collection system
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Solution Overview
Problem
Conventional geothermal energy extraction methods face challenges such as high costs, water scarcity, groundwater contamination, and seismic events due to the use of water as a heat transfer fluid, particularly in areas with limited water resources and seismically active regions.
Innovation Solution
A closed-loop system utilizing a thermal mass, such as molten salt or a solid material with high heat capacity, is inserted into a Heat Absorption Zone, where it absorbs heat and is then raised to a Heat Transfer Zone for energy extraction, allowing for efficient heat transfer and storage without the need for water, thereby reducing seismic risks and water usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If water is used as heat transfer fluid in geothermal energy extraction, then heat transfer efficiency is improved, but water scarcity and groundwater contamination occur
Solution Approach 1:
The patent introduces a closed-loop system using non-aqueous heat transfer fluids (such as organic fluids or molten salts) as intermediaries between the geothermal reservoir and the surface heat exchange system. This mediator transfers heat efficiently while preventing direct contact between formation water and the environment, thus avoiding groundwater contamination and water scarcity issues.
Solution Approach 2:
The patent changes the physical and chemical parameters of the heat transfer fluid by replacing water with alternative fluids having different properties (such as organic fluids with lower freezing points or molten salts for high-temperature applications). This parameter change allows efficient heat transfer while eliminating the harmful effects associated with water usage.
2Productivity
If hydraulic fracturing is used to enhance geothermal energy extraction, then energy production is improved, but seismic events are triggered
Solution Approach 1:
The patent extracts the harmful element (hydraulic fracturing) from the geothermal energy extraction system and replaces it with alternative methods such as thermal stimulation or mechanical fracturing. This allows energy production to be enhanced without triggering seismic events by removing the problematic high-pressure fluid injection process.
Solution Approach 2:
The patent employs temporary, non-invasive methods for enhancing permeability such as using expandable props or temporary heating elements that can be inserted, used briefly to create fractures, and then removed or deactivated. This avoids the permanent high-stress conditions that lead to seismic events while still achieving the desired permeability enhancement.
3Temperature
If deep wells are drilled to access high-temperature geothermal reservoirs, then energy extraction capability is improved, but drilling costs increase
Solution Approach 1:
The patent employs dynamic well design strategies where the well depth and configuration are optimized based on real-time geological data and temperature profiles. Instead of uniformly drilling to fixed deep depths, the system adapts the drilling depth and trajectory dynamically to reach optimal thermal zones, reducing unnecessary drilling costs while maintaining energy extraction capability.
Solution Approach 2:
The patent applies local quality enhancement by focusing drilling and thermal stimulation efforts on specific localized zones within the geothermal reservoir that have the highest temperature and permeability. Rather than treating the entire deep reservoir uniformly, the system identifies and targets high-value local zones, reducing overall drilling costs while achieving effective energy extraction from the most productive areas.
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
This approach enables efficient geothermal energy harvesting from depths greater than 100°C without causing seismic damage or groundwater contamination, utilizing a substance with high volumetric energy density to absorb heat and transfer it to the surface for thermal applications, including electricity generation and industrial processes.
Implementation Method 1
a thermal mass, such as molten salt or a solid material with high heat capacity, is inserted into a Heat Absorption Zone, where it absorbs heat
Implementation Method 2
it absorbs heat and is then raised to a Heat Transfer Zone for energy extraction, allowing for efficient heat transfer and storage
Data Source
AI summary
Techniques are provided for extracting geothermal energy, by providing salt into a well shaft that ends in a chamber in the Earth surrounded by a source of geothermal energy. The salt melts and heats up to the temperature within the chamber. The hot molten salt is then extracted and the heat from the molten salt is used as a source of energy to generate electricity or drive an industrial process. The salt can be re-used once the heat is extracted in a closed-loop system. According to some techniques, the salt is conveyed down the well by a pneumatic conveyer system or in other cases by using a mechanical system, such as a screw drive. Once returned to the surface, the molten salt can be used to heat graphite blocks for energy storage or be stored and transported to remote locations to extract the heat energy.