Adiabatic CAES Heat Storage for Efficiency
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Solution Overview
Problem
Compressed air energy storage (CAES) systems face inefficiencies due to the limited reuse of heat of compression, leading to additional energy input for heating during expansion, which increases operating costs and reduces overall efficiency to around 50%.
Innovation Solution
The implementation of an Adiabatic CAES system that stores the heat of compression in a heat storage system, allowing cold air to be fed to a high-pressure compressor during charging and heating the air in the heat storage before expansion in a low-pressure turbine during discharge, utilizing a solid regenerator or tube-in-concrete heat storage units, and integrating a dehumidifier to manage moisture and prevent frost buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the heat of compression is dissipated in conventional CAES systems, then the system structure is simpler, but the roundtrip efficiency is limited to around 50%
Solution Approach 1:
The patent extracts and separates the heat management function from the compression/expansion process by introducing a dedicated heat storage system. The heat of compression is extracted and stored in a separate thermal energy storage unit, while the compressed air is cooled and stored independently. This separation allows the heat to be recovered later without complicating the main compression-expansion pathway.
Solution Approach 2:
The patent introduces a heat storage system as an intermediary between the compression process and the expansion process. This intermediary stores the thermal energy from compression and releases it during expansion, enabling efficient heat recovery without direct thermal coupling between the compressor and turbine. The heat storage acts as a buffer that decouples the timing and temperature requirements of heat release and compression.
2Reliability
If additional energy input is used for heating air during expansion, then the turbine can operate within material limits, but operating costs increase
Solution Approach 1:
The patent converts the previously wasted heat of compression into a beneficial resource for turbine operation. By storing the heat generated during compression and releasing it during expansion, the system provides the necessary thermal energy for turbine operation without requiring additional external energy input. This transforms a harmful energy loss into a useful resource that maintains turbine reliability.
Solution Approach 2:
The system serves itself by using the heat generated during compression to meet the heating requirements during expansion. The heat storage system automatically captures and releases thermal energy based on the operational cycle, eliminating the need for external heating sources and reducing operating costs while maintaining turbine reliability.
3Loss of energy
If the heat storage undergoes large temperature differences, then the efficiency is improved, but the engineering challenges and costs increase
Solution Approach 1:
The patent segments the heat storage system into multiple temperature zones or stages, each handling a specific temperature range. This segmentation allows the use of different materials and designs optimized for specific temperature conditions, reducing the engineering challenges associated with wide temperature differences while maintaining high efficiency heat transfer.
Solution Approach 2:
The patent employs parameter changes in the heat storage system, such as using phase change materials or adjusting thermal conductivity parameters, to optimize heat storage and retrieval across different temperature ranges. By dynamically adjusting thermal parameters, the system achieves efficient heat management without requiring overly complex manufacturing solutions.
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 approach enhances the roundtrip efficiency of the energy storage system to potentially 70%, reduces capital expenditure, and minimizes energy losses by effectively utilizing the heat storage across the largest temperature difference, thereby improving the economic viability of the CAES system.
Implementation Method 1
the heat storage undergoes the largest temperature difference in the system and is used most effectively
Implementation Method 2
Adiabatic (A-) CAES has been conceptualized according to embodiments of the invention, where the heat of compression is stored in a heat storage
Implementation Method 3
During compression the air is preferably cooled, and during expansion it is usually heated to permit operation within material limits
Implementation Method 4
during expansion it is usually heated to permit operation within material limits and achieve a desired performance
Data Source
AI summary
A system for air compression, storage and expansion may include a low-pressure and a high-pressure compressor, a motor, a heat storage, an air storage volume, a high-pressure and a low-pressure turbine, and a generator. The system may further include a first air path connecting sequentially the low-pressure compressor, the heat storage, the high-pressure compressor, and the air storage volume. The system may further include a second air path connecting sequentially the air storage volume, the high-pressure turbine, the heat storage, and the low-pressure turbine.