Enhanced carbon dioxide-based geothermal energy generation systems and methods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional geothermal energy systems face limitations due to high costs, inefficiencies, and potential environmental impacts, particularly in extracting energy from low-temperature reservoirs, where water-based systems require high temperatures and large-scale hydrofracturing, leading to inefficiencies and environmental concerns.
Innovation Solution
The use of a non-water based working fluid, such as carbon dioxide (CO2), is injected into geothermal reservoirs containing methane, causing methane to come out of solution, forming a production fluid that is heated by geothermal energy, which is then used to enhance energy recovery through combustion, increasing efficiency and allowing for economically viable energy extraction from low-temperature reservoirs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water-based geothermal systems are used to extract energy from low-temperature reservoirs, then the systems can operate with simple infrastructure, but the systems require high temperatures and large-scale hydrofracturing which reduces efficiency and increases environmental impact
Solution Approach 1:
The patent changes the working fluid from water to carbon dioxide, which fundamentally alters the thermodynamic parameters and phase behavior in the reservoir. This enables efficient energy extraction from low-temperature reservoirs without requiring hydrofracturing, as CO2 can be injected in a supercritical state and undergo phase changes that enhance heat transfer and methane release at lower temperatures.
Solution Approach 2:
The system creates a composite production fluid consisting of carbon dioxide and methane extracted from the reservoir. This composite fluid leverages the properties of both components: CO2 for heat transfer and phase change, and methane for additional energy content through combustion, thereby improving overall energy extraction efficiency from low-temperature reservoirs.
2Productivity
If non-water based working fluid (CO2) is injected into reservoirs containing methane, then the efficiency of geothermal energy recovery is increased, but the system complexity increases due to methane separation and combustion processes
Solution Approach 1:
The patent combines geothermal energy extraction with methane recovery and combustion in a single integrated system. The CO2 injection process simultaneously extracts heat from the reservoir and releases dissolved methane, which is then combusted to heat the production fluid. This merging of functions improves overall energy recovery efficiency while managing system complexity through integration rather than separate processes.
Solution Approach 2:
The system uses the methane naturally present in the reservoir as a self-provided energy source to heat the production fluid. The combusted methane serves to preheat or supplement the thermal energy needed for CO2 circulation, reducing the need for external energy inputs and improving the self-sufficiency of the geothermal system.
3Temperature
If methane is combusted to heat production fluid, then the temperature of production fluid is increased improving energy recovery, but additional equipment for methane separation and combustion is required
Solution Approach 1:
The carbon dioxide serves multiple functions in the system: it acts as the working fluid for heat extraction, as the injection medium to release methane from the reservoir, and as part of the production fluid that is heated by methane combustion. This multi-functionality reduces the need for separate dedicated equipment for each process, managing complexity while achieving high production fluid temperatures.
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 method increases the efficiency of geothermal energy recovery by utilizing the chemical energy stored in methane, enabling the exploitation of previously uneconomical low-temperature reservoirs and reducing environmental impacts associated with hydrofracturing.
Implementation Method 1
The CO2 can cause the CH4 to come out of solution with the native fluid such that the CH4 forms a production fluid with the CO2
Implementation Method 2
Exposure of the mixture to the first temperatures heats the production fluid to a third temperature that is higher than the second temperature
Implementation Method 3
at least a portion of the CH4 can be separated from the production fluid and combusted to increase the overall temperature of the production fluid
Data Source
AI summary
A system comprises an injection well for accessing reservoir at a first temperature; a production well in fluid communication with the reservoir; a working-fluid supply system providing a non-water based working fluid to the injection well at a second temperature lower than the first temperature, wherein exposure of the working fluid to the first temperature heats the working fluid to a third temperature and at least a portion of the working fluid at the third temperature is produced as a production fluid; and an energy recovery system that converts energy contained in the production fluid to electricity or heat, wherein the energy recovery system includes a waste heat recovery apparatus that recovers waste heat and uses it to heat the production fluid to a fourth temperature that is higher than the third temperature, wherein the waste heat is recovered from equipment of or a process stream.