Pumped thermal systems with dedicated compressor/turbine pairs
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Solution Overview
Problem
Current energy storage systems face challenges in achieving high efficiency, reliability, and low capital costs for large-scale energy storage, particularly in storing electrical and thermal energy, and are often geographically or resource-limited.
Innovation Solution
The development of pumped thermal energy storage systems that utilize a closed fluid flow path with a compressor, heat storage units, and a turbine, allowing the system to operate as both a heat engine and a heat pump, with a working fluid that undergoes thermodynamic cycles to efficiently store and release energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single compressor and turbine are shared between charge and discharge modes, then device complexity is reduced, but efficiency and reliability deteriorate due to incompatible operating requirements
Solution Approach 1:
The system is segmented into dedicated charge-mode components (compressor 1, turbine 3) and discharge-mode components (compressor 2, turbine 4). Each component is optimized for its specific operational mode, eliminating the compromises required by shared components and improving overall system reliability.
Solution Approach 2:
The system merges two complete independent thermodynamic cycles (charge cycle and discharge cycle) into a single integrated system. Each cycle has its own compressor-turbine pair, allowing both modes to operate at optimal efficiency simultaneously or independently.
2Device complexity
If a single compressor and turbine are shared between charge and discharge modes, then capital costs are reduced, but roundtrip efficiency deteriorates
Solution Approach 1:
By segmenting the system into mode-specific components, each compressor and turbine is designed and operated exclusively for its optimal mode (charge or discharge), maximizing thermodynamic efficiency and minimizing energy losses during operation.
Solution Approach 2:
Each dedicated compressor-turbine pair operates at optimized pressure ratios, temperatures, and flow rates specific to its mode, allowing the system to achieve higher roundtrip efficiency through parameter optimization that would be impossible with shared components.
3Reliability
If the system uses a closed fluid flow path with dedicated compressor/turbine pairs, then efficiency and reliability improve, but device complexity increases
Solution Approach 1:
The system divides functionality into separate charge and discharge cycles with dedicated components, where each segment is simplified and optimized for its specific function, making the overall complex system manageable through modular design.
Solution Approach 2:
The closed fluid flow path and heat storage units serve multiple functions: they are used in both charge and discharge modes, and can operate independently or in combination, providing system flexibility that justifies the increased component count.
4Adaptability or versatility
If the system operates as both heat engine and heat pump with dedicated components, then versatility in energy conversion improves, but device complexity increases
Solution Approach 1:
The system provides universal energy conversion capability by implementing both heat pump mode (for energy storage) and heat engine mode (for energy generation) with dedicated components, allowing flexible adaptation to different operational requirements and energy sources.
Solution Approach 2:
The system dynamically switches between charge and discharge modes based on energy demand and availability, with each mode utilizing its optimized compressor-turbine pair, allowing the system to adapt to varying operational conditions while maintaining high efficiency.
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
These systems achieve high roundtrip efficiency and flexibility in energy storage and retrieval, capable of storing electrical and thermal energy with minimal entropy generation, and can be used in various energy conversion processes without storage, making them suitable for power generation and distribution.
Implementation Method 1
a compressor, a first heat storage unit, a turbine, and a second heat storage unit downstream of the turbine and in thermal communication with the working fluid
Implementation Method 2
The system alternately operates as both (i) a heat engine to provide mechanical work from heat and (ii) as a heat pump to use mechanical work to store heat
Implementation Method 3
Heat exchange (sensible energy transfer) between the working fluid of the system and the heat storage fluids can occur in counter-flow heat exchangers
Implementation Method 4
The system can operate as a heat engine by transferring heat from the hot side to the cold side, resulting in net mechanical work output
Implementation Method 5
The mechanical work inputs and/or outputs may be converted from/to electrical work using a motor/generator
Data Source
AI summary
In an example, a system configured to operate in a heat pump mode and heat engine mode is disclosed. The system may comprise a first working fluid path, first hot thermal storage (HTS) fluid path, and first cold thermal storage (CTS) fluid path for operation in the heat pump mode. The first working fluid path may be configured to circulate the working fluid through, in sequence, a first compressor, first hot side heat exchanger, first turbine, first cold side heat exchanger, and back to the first compressor. The system may also comprise a second working fluid path, second HTS fluid path, and second CTS fluid path for operation in the heat engine mode. The second working fluid path may be configured to circulate the working fluid through, in sequence, a second compressor, second hot side heat exchanger, second turbine, second cold side heat exchanger, and back to the second compressor.