Mechanical-chemical energy storage with absorbent reservoir
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Solution Overview
Problem
Conventional energy storage systems face inefficiencies due to heat loss during gas compression, limited round trip efficiency, and self-discharge issues, particularly in compressed air energy storage (CAES) and electrochemical batteries, which hinder the effective use of stored mechanical energy for grid stability and emergency applications.
Innovation Solution
A mechanical-chemical energy storage system that utilizes an absorbent reservoir to chemically absorb and desorb a working fluid, recycling heat generated during condensation to drive desorption, allowing for efficient energy storage and retrieval by compressing and expanding the fluid, thereby maintaining high energy density and power output without self-discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat of compression is stored in a medium (such as water) as sensible heat, then heat recovery is achieved, but energy density is reduced and self-discharge occurs
Solution Approach 1:
The patent utilizes phase transitions of the working fluid (gas to liquid during compression, liquid to gas during expansion) to store and release energy. The working fluid transitions between phases in a closed cycle, allowing energy to be stored during compression and recovered during expansion without the energy density losses associated with storing heat in separate media.
Solution Approach 2:
The working fluid acts as an intermediary that carries energy through phase transitions. Instead of storing heat in a separate medium like water, the working fluid itself undergoes phase changes to store and release energy, eliminating the need for separate heat storage media and their associated energy density penalties.
2Quantity of substance
If conventional CAES systems compress gas to high pressure, then energy storage is achieved, but heat loss reduces round trip efficiency
Solution Approach 1:
The patent converts the harmful heat of compression into a beneficial resource by using it to drive the endothermic desorption reaction of the absorbent material. The heat that would normally be lost during gas compression is now utilized to release the working fluid from the absorbent, improving overall system efficiency.
Solution Approach 2:
The patent merges the compression process with the desorption process by using the heat generated during compression to drive desorption. This integration allows the system to recover and reuse heat that would otherwise be wasted, improving round trip efficiency while maintaining energy storage capacity.
3Power
If electrochemical batteries are used for energy storage, then power delivery is improved, but performance degradation occurs during discharge
Solution Approach 1:
The patent replaces electrochemical battery systems with a mechanical-chemical energy storage system using compressors, expanders, and absorbent materials. This mechanical approach avoids the performance degradation issues inherent in electrochemical batteries during discharge, providing stable power delivery over the complete discharge cycle.
Solution Approach 2:
The patent changes the fundamental operating parameters from electrochemical reactions to mechanical compression/expansion cycles with chemical absorption/desorption. This parameter change eliminates the voltage degradation and capacity fade problems that occur in batteries during discharge, maintaining consistent power delivery.
4Loss of energy
If multiple stages are added to recover energy, then round trip efficiency increases, but capital cost increases
Solution Approach 1:
The system uses self-service heat recovery where the heat generated during compression automatically drives the desorption process, and the heat generated during absorption automatically drives the expansion process. This self-service approach improves round trip efficiency without requiring additional active components or multiple energy recovery stages.
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 achieves high round trip efficiency and energy density by recycling heat to enhance the enthalpy of the working fluid, reducing self-discharge and operational costs, and allowing for scalable and long-lasting energy storage solutions.
Implementation Method 1
an absorbent reservoir to chemically absorb and desorb a working fluid
Implementation Method 2
recycling heat generated during condensation to drive desorption
Implementation Method 3
compressing a gas to a higher enthalpy state
Implementation Method 4
the gas is expanding to a lower enthalpy state
Data Source
AI summary
This invention generally relates to mechanical-chemical energy storage. In particular, the invention relates to a mechanical-chemical energy storage system that stores energy by simultaneously compressing a gas to a higher enthalpy state and recovering the heat of compression by driving a somewhat reversible chemical reaction. The heat energy in the chemical reaction is then recovered while the gas is expanding to a lower enthalpy state.