Geothermal energy recovery process with selective recirculation
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Solution Overview
Problem
Supercritical CO2 geothermal energy recovery systems face inefficiencies under high ambient temperature conditions, requiring energy-intensive compression and suboptimal working fluid composition.
Innovation Solution
A geothermal energy recovery system that controls the composition of the working fluid using a phase separator and controllable separator unit to optimize energy recovery efficiency by adjusting the ratio of CO2 to hydrocarbons based on ambient and process conditions, allowing for selective mixing and expansion to generate mechanical or electrical energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If supercritical CO2 is used as working fluid under high ambient temperature conditions, then geothermal energy recovery is achieved, but compression energy requirements increase significantly
Solution Approach 1:
The patent applies parameter changes by adjusting the working fluid composition based on ambient temperature conditions. When ambient temperature exceeds the CO2 critical point, the system transitions from pure supercritical CO2 to a mixture containing CO2 and a refrigerant with lower critical temperature, thereby adapting the working fluid parameters to match the operating conditions and reduce compression energy requirements.
Solution Approach 2:
The patent uses composite materials by creating a working fluid mixture combining CO2 and a refrigerant (such as ethane, propane, or isobutane). This composite working fluid leverages the properties of both components: CO2 provides high density and heat transfer efficiency, while the refrigerant component enables effective compression and phase change at higher ambient temperatures, collectively improving energy recovery efficiency while reducing compression energy demands.
2Productivity
If pure CO2 is used as working fluid, then system simplicity is maintained, but energy recovery efficiency decreases under high ambient temperature conditions
Solution Approach 1:
The patent applies dynamics by implementing a dynamic working fluid composition adjustment mechanism. The system continuously monitors ambient temperature and process conditions, then dynamically adjusts the ratio of CO2 to refrigerant in the working fluid mixture. This dynamic adaptation allows the system to maintain optimal energy recovery efficiency across varying operating conditions while managing the complexity through automated control.
Solution Approach 2:
The patent uses feedback by incorporating sensors and control systems that monitor ambient temperature, pressure, and energy recovery performance. Based on this feedback, the system automatically adjusts the working fluid composition to optimize energy recovery efficiency. The feedback loop ensures that the working fluid parameters remain aligned with current operating conditions, thereby improving productivity while managing system complexity through intelligent control.
3Temperature
If CO2 compression is performed above critical point temperature, then geothermal energy capture continues, but compression becomes energy intensive
Solution Approach 1:
The patent uses an intermediary by introducing a refrigerant component into the working fluid mixture. This intermediary substance has a lower critical temperature than CO2 and facilitates compression and phase change processes at higher ambient temperatures. The refrigerant acts as a mediator that enables effective compression without the excessive energy intensity associated with compressing pure supercritical CO2 above its critical point, thereby allowing geothermal energy capture to continue under a broader temperature range with reduced energy consumption.
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
The system enhances energy recovery efficiency by reducing compression energy requirements and maximizing CO2 sequestration, achieving improved performance across varying temperature conditions.
Implementation Method 1
a phase separator having an input port coupled to the extraction well and receiving an extracted working fluid including carbon dioxide and hydrocarbons therefrom, the phase separator operative to separate liquid and vapor portions the extracted working fluid
Implementation Method 2
the separator unit being controllably operable to separate components of the received vapor portion based on chemical composition
Implementation Method 3
an expander coupled downstream from the controllable separator unit and operable to generate mechanical or electrical energy from expansion of the modified working fluid
Implementation Method 4
a condenser coupled downstream from the expander operable to cool the expanded working fluid
Implementation Method 5
a compression device coupled downstream from the condenser operable to increase the pressure of the working fluid received from the condenser to a pressure level suited for re-injection into the reservoir
Data Source
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AI summary
A system and a method of geothermal energy recovery includes injecting carbon dioxide into a geothermal reservoir through an injection well (150), extracting a working fluid (202) including previously injected carbon dioxide and hydrocarbons entrained in a flow of the carbon dioxide within the reservoir from an extraction well (160), separating components of the heated working fluid based on chemical composition, selectively mixing the separated components according to the current conditions of the extracted working fluid to produce an output modified working fluid that having a chemical composition that is optimized for energy recovery efficiency, and expanding the modified working fluid to generate mechanical or electrical energy.