Systems for generating energy from geothermal sources and methods of operating and constructing same
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Solution Overview
Problem
Geothermal energy generation systems face issues with debris and erosion in rock formations, leading to equipment damage, environmental pollution, and high maintenance costs due to the interaction of working fluids with rock surfaces and the need for frequent filter replacements or polymer coatings, which are not always effective in preventing leaks and erosion.
Innovation Solution
A pressure-tested downhole well loop system with steel-cased and cemented injection and production wells, laterals, and a multilateral connector, isolating the working fluid from rock formations and using a single heat exchange loop to minimize erosion, leakage, and maintenance, while allowing for efficient heat transfer and power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filters are provided along the flow path to prevent debris from entering machinery, then equipment damage is reduced, but maintenance cost increases due to frequent filter replacements and system complexity increases
Solution Approach 1:
The harmful working fluid is extracted from the primary cycle and separated into a secondary cycle. The secondary working fluid absorbs debris and contaminants, allowing the primary working fluid to remain clean and free from contamination, eliminating the need for filters in the primary cycle
Solution Approach 2:
A secondary working fluid acts as an intermediary between the rock formation and the primary working fluid. This intermediary fluid takes on the harmful substances and debris, protecting the primary working fluid and machinery from contamination while still enabling heat transfer
2Reliability
If a binary cycle power station is used to protect turbines from debris, then turbine damage is reduced, but heat loss increases during heat transfer between working fluids and parasitic load increases
Solution Approach 1:
The secondary working fluid serves as a mediator that directly contacts the rock formation and debris, while the primary working fluid remains isolated in a sealed loop. Heat is transferred from the rock formation through the secondary fluid to the primary fluid, protecting the turbine from debris while minimizing heat loss through direct heating of the primary working fluid
Solution Approach 2:
The system is segmented into two distinct cycles: a primary sealed cycle for power generation with clean working fluid, and a secondary open cycle for heat absorption and debris containment. This segmentation allows the turbine to be protected from debris while maintaining efficient heat transfer to the primary working fluid
3Stability of the object's composition
If flow rates are minimized to prevent erosion of rock surfaces, then rock formation integrity is maintained, but residence time underground increases
Solution Approach 1:
The harmful working fluid is extracted from the primary cycle and placed in a secondary cycle that directly contacts the rock formation. This allows the primary working fluid to flow at high rates without causing erosion, while the secondary fluid absorbs the erosive impact on rock surfaces
Solution Approach 2:
The secondary working fluid acts as an intermediary between the high-velocity primary working fluid and the rock formation. It allows high flow rates for efficient heat transfer while protecting the rock formation from erosion through its own chemical or physical properties
4Reliability
If polymer coating is applied to seal rock formations from circulating fluid, then erosion and leakage are prevented, but pressure testing becomes impossible and verification of coating integrity is difficult
Solution Approach 1:
The sealing function is extracted from the rock formation and transferred to a separate steel casing system. This allows the rock formation to remain accessible for pressure testing and inspection, while the steel casing provides the hermetic seal needed to prevent leakage and erosion
Solution Approach 2:
A steel casing acts as an intermediary barrier between the working fluid and the rock formation. This removable and testable casing provides the sealing function, allowing for pressure testing and integrity verification while the polymer coating can still be applied to the rock formation for additional protection
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 reduces the risk of erosion and leakage, minimizes maintenance costs, and enhances energy efficiency by maintaining a stable and isolated working fluid path, allowing for the use of non-conventional fluids and reducing parasitic losses, thus providing a more reliable and environmentally friendly geothermal energy generation process.
Implementation Method 1
heat transferred from the rock formation
Implementation Method 2
undergoing phase change between liquid and gas
Data Source
AI summary
The present disclosure describes a system and a method for generating energy from geothermal sources. The system includes an injection well and a production well extending underground into a rock formation, a first lateral section connected to the injection well and a second lateral section connected to the production well, the first and second lateral sections connected with a multilateral connector, defining a pressure-tested downhole well loop within the rock formation and in a heat transfer arrangement therewith. The downhole well loop cased in steel and cemented in place within the rock formation. The downhole well loop to receive working fluid capable of undergoing phase change between liquid and gas within the downhole well loop as a result of heat transferred from the rock formation. The system also includes a pump to circulate working fluid, a turbine system to convert the flow of working fluid into electricity, and a cooler.