Thermal Energy Storage Coupling for Stable Solid Oxide Electrolysis
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Solution Overview
Problem
Current thermal energy storage systems face challenges in efficiently storing and delivering high-temperature heat, particularly when using variable renewable energy sources, due to issues like thermal runaway, high costs, and inefficiencies in maintaining outlet temperature, as well as limitations in charging and discharging rates and control systems that fail to account for weather and energy demand variations.
Innovation Solution
A thermal energy storage system that integrates vertically oriented thermal storage units with insulative layers and a blower for air flow, coupled with a dynamic insulation system, which uses cooler air to preheat the system and maintain temperature, and a controller to manage energy based on forecasts, enabling efficient charging and discharging of high-temperature heat for industrial applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If thermal energy storage systems use variable renewable energy sources for charging, then energy sustainability is improved, but temperature control stability deteriorates due to intermittent supply
Solution Approach 1:
The system preheats air using stored thermal energy before it enters the electrolysis cells, ensuring that temperature requirements are met even when renewable energy supply is intermittent. This preliminary heating action guarantees stable operating conditions for the electrolysis process regardless of when charging occurs.
Solution Approach 2:
Thermal energy storage acts as an intermediary between variable renewable energy sources and the electrolysis system. The storage system decouples the intermittent charging from the continuous operation requirements, buffering temperature fluctuations and providing stable heat supply to maintain electrolysis cell temperature.
2Productivity
If high-temperature heat is stored and delivered efficiently, then energy delivery performance is improved, but system cost increases
Solution Approach 1:
The system uses the hot air exiting the electrolysis cells, which still contains significant thermal energy, and directs it back through the thermal storage units for reheating. This self-service approach recovers waste heat, reducing the need for additional energy input and lowering operational costs while maintaining high energy delivery performance.
Solution Approach 2:
Instead of discarding the cooled air exiting the electrolysis cells, the system recovers its thermal energy by passing it through the thermal storage media. This recovery process extends the useful life of the thermal energy and reduces the energy required for reheating, thereby lowering system costs while maintaining productivity.
3Loss of energy
If thermal storage units are vertically oriented with insulative layers, then heat retention is improved, but device complexity increases
Solution Approach 1:
Insulative layers are applied locally at critical locations where heat loss would be most significant, such as between vertically oriented thermal storage units and at the extremities of the system. This targeted approach improves heat retention effectiveness while minimizing the overall complexity compared to complete insulation of the entire system.
Solution Approach 2:
The thermal storage system is divided into discrete vertically oriented units with insulative layers between them. This segmentation allows for modular construction and maintenance while the insulative barriers between units prevent lateral heat transfer, improving overall heat retention without requiring a monolithic complex structure.
4Productivity
If a blower system is used for air flow management, then charging and discharging rates are improved, but energy consumption increases
Solution Approach 1:
The control system monitors temperature and flow conditions to regulate blower operation, activating the blower only when thermal energy needs to be transferred between storage units or when electrolysis cells require heated air. This feedback-controlled operation maintains high charging and discharging rates while minimizing unnecessary blower operation and associated energy consumption.
Solution Approach 2:
The blower operates periodically rather than continuously, cycling on and off based on the thermal state of the system. During periods when thermal energy is being actively stored or retrieved, the blower operates at high rate to maximize charging/discharging speed. During steady-state periods, the blower remains off or operates at minimal capacity, reducing energy consumption while maintaining productivity when needed.
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 effectively stores and delivers high-temperature heat efficiently, reducing costs and extending the life of heating elements, while providing continuous and dispatchable energy despite variations in renewable energy supply, and optimizing energy use based on weather and demand forecasts.
Implementation Method 1
a plurality of thermal storage units (TSUs) configured to store thermal energy
Implementation Method 2
deliver the stored energy in the form of hot air, hot fluids in general, steam, heated CO2
Implementation Method 3
A thermal energy storage system that integrates vertically oriented thermal storage units with insulative layers
Data Source
AI summary
An energy storage system (TES) converts variable renewable electricity (VRE) to continuous heat at over 1000° C. Intermittent electrical energy heats a solid medium. Heat from the solid medium is delivered continuously on demand. Heat delivery via flowing gas establishes a thermocline which maintains high outlet temperature throughout discharge. The delivered heat which may be used for processes including power generation and cogeneration. In one application, the energy storage system provides higher-temperature heat to a solid oxide electrolysis system to maintain in an electrolysis operating temperature range during operation and nonoperation, thereby increasing the efficiency of the temperature control.