Thermopile Energy Harvesting for Borehole Sensor Power
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Solution Overview
Problem
Current subsurface well bore sensors have limited battery life, ranging from ten to forty hours, and lack a reliable long-term power source for continuous monitoring of CO2 movement and wellbore health, necessitating a more efficient energy harvesting solution.
Innovation Solution
A system utilizing thermopiles and thermoelectric generators (TEGs) to harness thermal energy from temperature gradients within subsurface boreholes, generating electrical power for sensors and monitoring environmental parameters like CO2 plume movement and fluid displacement, with the option of thermal pulses to enhance power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If battery-powered sensors are used in subsurface boreholes, then the sensors can operate independently, but the battery life is limited to ten to forty hours
Solution Approach 1:
The sensor system generates its own power through thermopiles that convert temperature gradients in the borehole environment into electrical energy. This self-powering mechanism eliminates the need for external battery replacement and enables continuous long-term operation of the sensor network
Solution Approach 2:
The patent replaces the chemical energy storage system (batteries) with a thermoelectric energy conversion system. Thermopiles convert thermal energy from the natural temperature gradient in the borehole directly into electrical energy, substituting mechanical/chemical power sources with a thermal conversion mechanism
2Adaptability or versatility
If the borehole sensor system is expanded to include multiple sensors and monitoring capabilities, then the monitoring coverage improves, but the power requirements increase
Solution Approach 1:
The borehole is divided into multiple monitoring zones with distributed sensors at different depths. Each sensor or sensor group is equipped with its own thermopile power source, allowing independent power generation and consumption management for each segment, thereby supporting expanded monitoring coverage without proportionally increasing total power requirements
Solution Approach 2:
The system utilizes changes in thermal conductivity parameters of the surrounding formation to generate variable power output from thermopiles. As CO2 injection alters the thermal properties of the formation, the temperature gradient and thus the power generation from thermopiles dynamically adjusts to match the varying monitoring demands
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
Provides a reliable, long-term power source for wireless sensor networks, enabling real-time monitoring of CO2 plumes and wellbore health, with scalable power output and the ability to distinguish between local and regional thermal conductivity changes, supporting enhanced geothermal and oil recovery operations.
Implementation Method 1
The power source generates an electrical power in response to a temperature gradient between a surface of the casing and a surface of the tubular pipe
Implementation Method 2
The thermopile further senses heat flux in response to changes in the thermal conductivity of a formation surrounding the borehole
Data Source
AI summary
A system and method for powering a borehole sensor with thermal energy is disclosed. The system includes a tubular pipe inserted into a subsurface borehole. A borehole casing is coaxially disposed with the tubular pipe. An annular space between the casing and the tubular pipe has a power source placed in the borehole to power a sensor in response to a temperature gradient between a surface of the casing and a surface of the tubular pipe. The method includes attaching thermopiles on the borehole casing or tubing; placing the thermopile in the annulus between the casing and the tubing; inducing a thermal gradient across the thermopile; generating an electrical energy in response to the temperature gradient; powering the sensor from the generated energy; and monitoring vertical expansion of a CO2 plume.