CO2 Capture in Compressed Air Energy Storage
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Solution Overview
Problem
Current CO2 capture systems from mixed gas streams, such as those from fossil fuel-fired power plants and gas turbines, are inefficient and energy-intensive, consuming significantly more energy than necessary due to high energy requirements for pressurization and heating, and lack effective integration with existing industrial processes like CAES systems.
Innovation Solution
A CAES system integrated with a CO2 capture system that utilizes pressure and temperature swings to enhance CO2 removal efficiency, coupled with heat and energy recycling throughout the system, including a heat transfer system, absorption beds, and preheating stages to optimize energy use and reduce operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CO2 capture systems are used to remove CO2 from mixed gas streams, then CO2 separation is achieved, but energy consumption increases significantly (10 to 100 times the theoretical minimum)
Solution Approach 1:
The patent combines CO2 capture with CAES system operations, merging two separate processes (CO2 separation and compressed air energy storage) into a single integrated system. The CO2 capture process is performed using the same compression and temperature swing operations already required for CAES, eliminating the need for separate energy-intensive CO2 separation equipment and operations.
Solution Approach 2:
The CAES system components serve multiple functions: the compressor performs both gas compression for energy storage and CO2 enrichment; the cooling system performs both temperature reduction for CAES and CO2 separation; the absorption bed performs both gas conditioning and CO2 capture. This multi-functionality reduces overall system energy consumption by avoiding duplicate operations.
2Measurement precision
If pressure swing absorption or temperature swing absorption is used for CO2 separation, then CO2 removal is achieved, but the process requires significant energy for pressurization and heating
Solution Approach 1:
The patent utilizes periodic compression and cooling cycles inherent to CAES operations to drive the CO2 separation process. The cyclic nature of CAES (compression during off-peak hours, expansion during peak hours) provides periodic temperature and pressure swings that enable CO2 absorption and desorption without requiring additional energy input for these swings.
Solution Approach 2:
The system exploits changes in temperature and pressure parameters during CAES operations to control CO2 absorption. During compression, temperature increases enhance CO2 absorption into the liquid solvent; during cooling and expansion, temperature decreases promote CO2 release. These parameter changes are driven by the CAES cycle itself rather than external energy input.
3Power
If CAES systems compress gas to store energy, then electrical energy is captured during off-peak periods, but the gas stream reaches high temperatures (300°C to 500°C) requiring cooling
Solution Approach 1:
The patent converts the harmful high temperature generated during gas compression into a beneficial condition for CO2 separation. The heat from compression increases the temperature to optimal levels for CO2 absorption into the liquid solvent, turning an unwanted thermal byproduct into a useful process parameter that enhances CO2 capture efficiency.
4Reliability
If the compressed gas stream is preheated through fuel combustion or heat transfer systems, then the gas can be expanded without damaging the turbine, but energy is consumed for heating
Solution Approach 1:
The system uses the heat generated during the compression phase to preheat the gas before expansion, making the system self-sufficient for its own thermal needs. The cooling system used to reduce post-compression temperature is later utilized to preheat the gas before turbine expansion, creating a closed thermal loop that eliminates or reduces the need for external fuel combustion or additional energy input for preheating.
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 integrated system significantly reduces energy consumption for CO2 capture, enabling cost-effective operation during both peak and off-peak energy consumption periods, with recycled heat and energy used to preheat the gas stream and regenerate absorbent materials, thereby increasing the efficiency and cost-effectiveness of the CO2 removal process.
Implementation Method 1
Absorption is a process that occurs when a gas or liquid solute is taken up by the volume of a solid, liquid, or gas called an absorbent
Implementation Method 2
The gas stream is usually cooled after the compression process using a heat transfer system
Implementation Method 3
The compressed gas stream can be preheated by passing it, in the opposite direction, through the heat transfer system that is used to cool the gas stream during compression
Implementation Method 4
one or more electrically activated compressors uses electricity during off-peak energy consumption periods to compress gas
Implementation Method 5
The compressed gas is then stored in a CAES reservoir, usually an underground cavern or other underground geologic formation, until it is used to produce electricity during periods of peak energy consumption. The compressed gas is converted back to electricity by expanding it through a turbine
Data Source
AI summary
A compressed air energy storage system and method of capturing CO2 during compressed air energy storage the system and method including a gas inlet pipe, at least one air compressor stage attached to the gas inlet pipe and adapted for compression of a gas, a heat transfer system to cool the gas during or after compression, the heat being recycled throughout the system, at least one absorption bed for separating CO2 from the compressed gas attached to the heat transfer system, at least one compressed gas reservoir having an inlet and an outlet, the reservoir attached at its inlet to the absorption bed, at least one preheater stage attached to the outlet of the compressed gas reservoir for heating a compressed gas after storage in the compressed gas reservoir, and at least one gas expander attached to the preheater stage and adapted for the expansion of the compressed gas.