Elevated Reservoir Hydrostatic Pressure for CAES
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Solution Overview
Problem
Current compressed gas energy storage systems face challenges in achieving high hydrostatic pressure at the lower end of a shaft without the need for deep shafts, which are costly and time-consuming to construct, and often require additional infrastructure like pumps to enhance pressure, reducing efficiency.
Innovation Solution
A hydrostatically compensated compressed air energy storage system is designed with a compensation liquid reservoir positioned above the upper end of the shaft, creating a higher total hydrostatic pressure at the lower end through a combination of the shaft depth and reservoir elevation, eliminating the need for pumps and reducing construction costs by utilizing existing shafts and infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the shaft depth is increased to achieve high hydrostatic pressure, then the hydrostatic pressure at the lower end of the shaft is improved, but the construction cost and time are worsened
Solution Approach 1:
The patent introduces a vertical dimension by positioning the liquid reservoir at an elevated height above the shaft upper end. This elevation creates additional hydrostatic pressure head without increasing the shaft depth, thereby achieving high pressure with reduced construction time and cost.
Solution Approach 2:
The reservoir is pre-positioned at an elevated location before the shaft is fully constructed. This preliminary arrangement of the reservoir at height allows the system to generate sufficient hydrostatic pressure through the combined effect of shaft depth and reservoir elevation, eliminating the need for deep shaft construction.
2Stress or pressure
If additional infrastructure like pumps is added to enhance pressure, then the hydrostatic pressure is improved, but the device complexity and energy consumption are worsened
Solution Approach 1:
The system uses the natural hydrostatic pressure generated by the elevated reservoir and shaft depth combination to maintain pressure without requiring external pumps or mechanical assistance. The reservoir at elevation automatically provides the necessary pressure head through gravity-driven hydrostatic pressure.
Solution Approach 2:
The patent replaces mechanical pressure enhancement systems (pumps) with a purely hydrostatic pressure solution based on gravitational head from the elevated reservoir. This substitution eliminates complex mechanical components while achieving the same pressure enhancement goal.
3Stress or pressure
If the reservoir is positioned at a higher elevation, then the total hydrostatic pressure is improved, but the device complexity is worsened
Solution Approach 1:
The elevated reservoir serves multiple functions: it provides hydrostatic pressure enhancement, acts as a compensation mechanism for pressure variations, and serves as the liquid source for the shaft. This multi-functionality achieves high pressure without proportionally increasing system complexity.
Solution Approach 2:
The patent merges the reservoir function with the pressure generation function by positioning the reservoir at an elevation that directly contributes to hydrostatic pressure. This integration eliminates separate pressure generation components and simplifies the overall system architecture.
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 maintains high accumulator pressures with reduced construction costs and time, while minimizing energy consumption and operational complexity by leveraging the natural hydrostatic pressure enhanced by the elevated reservoir, ensuring efficient energy storage and retrieval.
Implementation Method 1
A compensation liquid reservoir may be spaced apart from the accumulator and may be offset above the upper end wall by a reservoir elevation that is at least about 15% of the shaft depth. A compensation liquid flow path may extend between the compensation liquid reservoir and the accumulator and may include the compensation shaft and a liquid supply conduit extending between the compensation liquid reservoir and the upper end of the compensation shaft whereby a total hydrostatic pressure at the lower end of the shaft is greater than a hydrostatic pressure at a depth that is equal to the shaft depth.
Data Source
AI summary
A hydrostatically compensated compressed air energy storage system may include an accumulator disposed underground and a compressor/expander subsystem in fluid communication. A compensation shaft may extend between an upper and a lower end and define a shaft depth. An upper end wall can cover the upper end of the shaft. A compensation liquid reservoir can be offset above the upper end wall by a reservoir elevation that is at least about 15% of the shaft depth. A compensation liquid flow path may extend between the compensation liquid reservoir and the accumulator and can include the compensation shaft and a liquid supply conduit extending between the compensation liquid reservoir and the upper end of the compensation shaft whereby a total hydrostatic pressure at the lower end of the shaft is greater than a hydrostatic pressure at a depth that is equal to the shaft depth.