Surface Fuel Cell Borehole Combustor Layout for Geothermal Heating
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Solution Overview
Problem
Existing subterranean heater systems using fuel cells in boreholes face issues with long-term efficiency due to potential fuel cell failures and the inability to repair or repurpose them, as they are not retrievable and operate in harsh conditions deep within the geological formation.
Innovation Solution
A geothermic heater system with a fuel cell stack assembly located at the surface, where anode and cathode exhausts are combusted by combustors disposed within the borehole to produce heated exhaust, which heats the geological formation, allowing for easier maintenance and repurposing of the fuel cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel cells are disposed in a bore hole within the geological formation, then the heating function is achieved, but the fuel cells cannot be retrieved or repurposed after operation due to the depth and harsh conditions
Solution Approach 1:
The system is divided into two functional segments: fuel cells located at the surface level and combustors located in the bore hole. This segmentation allows the fuel cells to remain accessible for maintenance and repurposing while the combustors perform the heating function in the formation. The surface location enables easy retrieval and replacement without requiring complex retrieval operations from deep bore holes.
Solution Approach 2:
A heat transfer medium (fluid circulation system) acts as an intermediary between the surface-located fuel cells and the subsurface geological formation. The fuel cells heat the fluid, which then circulates to transfer thermal energy to the formation. This intermediary approach allows the fuel cells to operate in favorable surface conditions while still achieving subsurface heating objectives.
2Productivity
If fuel cells operate for extended periods (several years) to liberate all oil from the formation, then complete resource extraction is achieved, but fuel cell failures reduce thermal output and efficiency
Solution Approach 1:
The system incorporates redundant heating capability through combustors that can compensate for fuel cell degradation or failure over extended operational periods. This beforehand cushioning ensures that even as fuel cells age and their thermal output decreases, the combustors can maintain the required heating levels to complete oil liberation, thus preserving reliability throughout the extended operational lifespan.
Solution Approach 2:
The system is designed to allow fuel cells to be recovered and replaced at the surface after extended operation. Rather than leaving failed fuel cells in the bore hole, they can be retrieved, replaced, or repurposed. This discarding and recovering approach maintains system reliability by replacing degraded components while completing the oil liberation process.
3Ease of operation
If fuel cells are placed in the bore hole, then heating is achieved, but repair or replacement is not possible due to inaccessibility
Solution Approach 1:
The system separates maintenance-critical components (fuel cells) from the heating execution components (combustors). Fuel cells are positioned at the surface where they are easily accessible for repair and replacement, while combustors remain in the bore hole to perform heating. This segmentation resolves the contradiction by placing the component requiring frequent maintenance in an accessible location while maintaining the heating function in the subsurface environment.
Solution Approach 2:
The combustor system acts as an intermediary that can compensate for fuel cell maintenance needs. While fuel cells are serviced at the surface, the combustors continue or resume heating operations, ensuring uninterrupted thermal output. This intermediary arrangement allows maintenance activities without compromising the heating capability of the overall system.
4Temperature
If combustors are disposed within the bore hole, then direct heating of the formation is achieved, but the fuel cell exhaust must be transported to the subsurface location
Solution Approach 1:
The system employs pneumatic or hydraulic transport mechanisms to convey fuel cell exhaust gases from the surface to the combustors in the bore hole. This allows efficient utilization of the exhaust as fuel for the combustors, maintaining high formation heating efficiency while managing the complexity of exhaust transport through established gas handling 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 configuration enhances the operational efficiency and longevity of the heating process by minimizing the impact of fuel cell failures and enabling easier maintenance and repurposing of the fuel cells, while maintaining robustness and efficiency in heating the geological formation.
Implementation Method 1
a plurality of fuel cells which convert chemical energy from a fuel into electricity through a chemical reaction with an oxidizing agent
Implementation Method 2
a combustor for combusting a mixture comprising at least one of the anode exhaust and the cathode exhaust to produce a heated combustor exhaust
Implementation Method 3
the combustor discharges the heated combustor exhaust, thereby heating the geological formation
Data Source
AI summary
A geothermic heater system for heating a geological formation includes a fuel cell stack assembly disposed at the surface of the geological formation and includes a plurality of fuel cells which convert chemical energy from a fuel into electricity through a chemical reaction with an oxidizing agent, thereby producing an anode exhaust and a cathode exhaust. The geothermic fuel cell system also includes a combustor disposed within a bore hole of the geological formation. The combustor combusts a mixture at least one of the anode exhaust and the cathode exhaust to produce a heated combustor exhaust. The combustor discharges the heated combustor exhaust to heat the geological formation.