Organic Fluid Geothermal Storage in Permeable Geological Traps
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Solution Overview
Problem
Geothermal energy production is limited by low overall efficiency, rapid depletion of thermal deposits, and technical difficulties in implementing and maintaining geothermal systems, particularly due to rock permeability and cooling issues, which restricts the effective use of this renewable energy source.
Innovation Solution
A system that utilizes a working fluid with specific characteristics, such as Liquefied Petroleum Gas (LPG), injected into permeable geological formations to store energy by heating it with geothermal heat, allowing for efficient enthalpy increase and storage, and subsequent extraction and reuse, optimizing energy production and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional geothermal systems inject water at low temperature to heat it in deep formations, then the working fluid can be heated by geothermal flux, but the rocks are significantly cooled requiring long regeneration periods of three to five weeks
Solution Approach 1:
The invention changes the temperature parameter of the injected working fluid from conventional low temperature (room temperature) to high temperature (above 150°C). This parameter change allows the fluid to be heated more quickly by geothermal flux, reducing the rock regeneration period from three to five weeks to a much shorter duration, thereby resolving the contradiction between heating efficiency and rock regeneration time
Solution Approach 2:
The invention applies preliminary heating to the working fluid before injection into the geological formation. By pre-heating the fluid to high temperature, the system reduces the thermal load on the rocks and accelerates the heating process, allowing faster energy extraction without requiring long regeneration periods
2Productivity
If hydraulic fracturing is practiced to create porosity in low permeability rocks, then the heat transfer fluid can circulate and heat up, but the process is complex to implement and poses ecological risks
Solution Approach 1:
The invention targets specific local geological formations that naturally possess adequate permeability and porosity characteristics. By selecting formations with inherent suitability for fluid circulation, the system achieves effective heat transfer and energy production without requiring hydraulic fracturing, thus avoiding the ecological risks and complexity associated with fracturing operations
Solution Approach 2:
The invention extracts or removes the hydraulic fracturing step from the geothermal energy extraction process. By identifying and utilizing geological formations that naturally allow fluid circulation, the system eliminates the need for artificial fracturing, thereby reducing implementation complexity and avoiding ecological harm
3Productivity
If multiple production sub-zones are created artificially to achieve continuous energy production, then the heat transfer fluid can be circulated successively, but the system becomes complex and costly to produce
Solution Approach 1:
The invention achieves continuous energy production by utilizing a single geological formation with sufficient volume and permeability to support continuous fluid circulation and heat exchange. This approach maintains continuous useful action without requiring multiple artificially created sub-zones, thereby avoiding the complexity and cost associated with managing multiple production zones
4Length of stationary object
If geothermal energy is exploited in deep formations with low permeability, then the resource can be accessed, but the circulation speed of water in natural rocks limits flow and desired temperatures are only reached in exceptional sites
Solution Approach 1:
The invention changes the physical parameters of the working fluid by using high-temperature fluid (above 150°C) instead of conventional low-temperature water. This parameter change increases the fluid's energy content and heat transfer efficiency, enabling effective exploitation of deep geological formations regardless of their permeability characteristics, thereby overcoming the limitation of slow circulation speeds
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 enhances energy storage and production efficiency, reduces environmental impact, and allows for the valorization of abandoned oil sites, providing a sustainable and renewable energy solution with improved thermodynamic yields and reduced ecological risks.
Implementation Method 1
a permeable geothermal formation capable of heating a fluid injected into said formation
Implementation Method 2
a working fluid in liquid phase under the temperature and pressure conditions in the trap
Data Source
Figure 1
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AI summary
The invention relates to a geothermal system (100) for storing power in thermal form and for generating power which comprises a surface segment (10) in which the enthalpy (H) of an organic accumulator fluid (30) is transformed into usable power, and comprises an underground segment (20), including an injection well (22) leading into a lower portion (21b) of an underground geological trap (21) and a production well (23) in an upper portion (21a) of the trap. In addition: - the fluid at a liquefying pressure PL lower than 106 Pa at a temperature of 15°C, with lower density than water, cannot be mixed with water; - the trap (21) constitutes a storage reservoir in which permeable and porous rocks (211) make it possible to contain and debit the accumulator fluid (30) kept at a temperature close to the temperature of the rocks of the trap; - the surface segment (10), the injection well (22), the trap (21) and the production well (23) determine a closed circuit for the accumulator fluid (30) in which the accumulator fluid is contained. The invention also relates to a method (500) for storing power in thermal form and for using the stored power by thermodynamic recycling of an organic fluid.