Closed-Loop Geothermal Power System to Reduce Pumping Energy Loss
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Solution Overview
Problem
Geothermal power production is limited by the difficulty in creating a sufficient flow of hot water through rock structures, requiring energy-intensive pumping and resulting in a parasitic penalty on overall power output, making it uneconomic compared to other forms of power generation.
Innovation Solution
A closed-loop system using supercritical heat transfer fluids that are indirectly heated via conduction, convection, and advection within a geothermally-heated formation, with an interwell run connecting injection and production wells to facilitate heat transfer and reduce the need for mechanical pumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is forced through small cracks in fractured rock to maximize heat transfer surface area, then heat transfer efficiency is improved, but energy consumption for pumping increases significantly
Solution Approach 1:
The patent replaces the conventional mechanical pumping system with a naturally circulating two-phase fluid system. The working fluid circulates through the geothermal formation without mechanical pumps, using phase change (evaporation and condensation) and density differences to drive flow, thereby eliminating the parasitic energy consumption associated with high-pressure pumping while maintaining effective heat transfer.
Solution Approach 2:
The patent utilizes phase transitions of the working fluid (liquid to vapor in the geothermal formation, then vapor to liquid in the surface condenser) to transfer heat and drive circulation. The phase change occurs naturally due to temperature and pressure differences, providing a pump-free mechanism for fluid circulation and heat extraction from the geothermal formation.
2Productivity
If large pumps are used to force water through injection well and hot rock formation, then sufficient heat transfer is achieved, but parasitic penalty on overall power output increases
Solution Approach 1:
The patent eliminates mechanical pumping systems by using a two-phase fluid circulation system driven by natural convection and phase change. The working fluid is injected into the geothermal formation, absorbs heat and vaporizes, then the vapor rises to the surface where it condenses and returns to the formation, creating a continuous cycle without mechanical pumps, thereby eliminating parasitic energy losses.
Solution Approach 2:
The geothermal system serves itself by using the heat extracted from the formation to vaporize the working fluid, which then naturally rises and condenses, creating a self-sustaining circulation cycle. The system uses its own thermal energy to drive the circulation process, eliminating the need for external energy input for pumping.
3Temperature
If small diameter tubing is used for good heat transfer in closed-loop systems, then heat exchange efficiency is improved, but pressure drop increases requiring high pressure pumping
Solution Approach 1:
The patent extracts the working fluid from a closed-loop tubing system and allows it to directly contact and vaporize within the geothermal formation. By removing the tubing constraint and allowing open circulation with phase change, the system achieves effective heat transfer without the pressure drop penalties associated with small-diameter closed-loop tubing.
Solution Approach 2:
The patent uses phase transition (vaporization and condensation) to overcome the limitations of small-diameter tubing. The working fluid vaporizes in the formation and condenses at the surface, utilizing density differences and pressure changes to drive circulation without requiring high-pressure pumping through restricted tubing passages.
4Temperature
If many small tubes are used to compensate for small tubing diameter, then heat transfer surface area is increased, but drilling costs increase
Solution Approach 1:
The patent extracts the heat transfer process from a complex multi-tube system and simplifies it to a single wellbore circulation system. The working fluid circulates through one injection well and one production well, with heat transfer occurring through phase change rather than through multiple small-diameter tubes, thereby reducing drilling and installation costs.
Solution Approach 2:
The patent merges multiple heat transfer functions into a single circulation loop. Instead of using many small tubes to achieve sufficient heat transfer surface area, the system uses a single-phase-to-vapor transition in one wellbore, combining heat absorption, vaporization, and fluid circulation into an integrated process that requires minimal well infrastructure.
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 geothermal power production efficiency by utilizing supercritical fluids like carbon dioxide, which can circulate with minimal mechanical pumping, reducing energy losses and increasing the utility of geothermal resources, making geothermal power more economically viable.
Implementation Method 1
indirectly heated via conduction, convection, and advection within a geothermally-heated formation
Implementation Method 2
indirectly heated via conduction, convection, and advection within a geothermally-heated formation
Implementation Method 3
indirectly heated via conduction, convection, and advection within a geothermally-heated formation
Implementation Method 4
A closed-loop system using supercritical heat transfer fluids that are indirectly heated via conduction, convection, and advection within a geothermally-heated formation
Data Source
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AI summary
A process for producing power including injecting a first heat transfer fluid through an injection well to a geothermally-heated formation that contains a second heat transfer fluid. The first heat transfer fluid may then be heated via indirect heat exchange in an interwell run fluidly connected to the injection well and disposed within the geothermally-heated formation. The heated first heat transfer fluid may then be recovered through a production well fluidly connected to the interwell run. Thermal energy contained in the recovered heated first heat transfer fluid may then be converted in a power production unit fluidly connected to the injection well and the production well. The interwell run, in some embodiments, may include multiple heat exchange tubes disposed within a perforated casing or drill pipe.