Nested Tank Thermal Storage for Peak Electricity Demand Shifting
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Solution Overview
Problem
Conventional technologies for heating and cooling of buildings are inefficient due to high installation costs, lack of flexibility in electricity demand shifting, and significant electricity consumption, especially during peak periods, limiting their deployment and energy efficiency.
Innovation Solution
The implementation of a system comprising a thermal battery and a thermal reservoir, where the thermal battery receives thermal energy from a heat pump and provides it to a building, while the thermal reservoir recycles lost energy back to the heat pump, allowing for flexible operation modes and reduced electricity usage during peak times, with the option to incorporate phase change materials for enhanced storage capacity and temperature regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional heat pump systems are used for heating and cooling buildings, then buildings can receive thermal energy, but electricity consumption is significant especially during peak periods
Solution Approach 1:
The thermal battery stores thermal energy in advance during off-peak electricity hours when electricity consumption is lower. This preliminary energy storage allows the system to meet peak heating or cooling demands without requiring high electricity consumption during peak periods, thus reducing overall electricity usage while maintaining reliable energy supply.
Solution Approach 2:
The thermal battery acts as an intermediary between the heat pump and the building. It decouples the timing of energy production from energy consumption, allowing thermal energy to be stored and delivered when needed. This mediator enables the system to reduce peak electricity demand while ensuring continuous reliable energy supply to the building.
2Ease of manufacture
If conventional heat pump systems are deployed, then buildings can be heated or cooled, but installation cost is high
Solution Approach 1:
The system employs a nested tank configuration where an inner tank (thermal battery) is placed within an outer tank (thermal reservoir). This nested structure consolidates multiple functions into a single integrated system, reducing the number of separate components and installation requirements. The shared infrastructure of the nested tanks lowers installation costs while maintaining high energy delivery efficiency through the coupled thermal storage system.
3Adaptability or versatility
If conventional technologies are used, then buildings can receive thermal energy, but flexibility to shift electricity demands is lacking
Solution Approach 1:
The thermal battery enables preliminary energy storage during off-peak hours, providing the flexibility to shift electricity demands away from peak periods. This time-shifting capability allows the system to operate more efficiently by utilizing lower-cost, lower-demand periods for energy production and storage, while meeting peak demands from stored energy.
Solution Approach 2:
The system converts thermal energy that would otherwise be lost from the thermal battery into a beneficial resource by directing it to the thermal reservoir. This recovered thermal energy can then be used to pre-condition the thermal reservoir for future heating or cooling needs, or to support heat pump operation during off-peak periods. This approach transforms potential energy waste into a useful resource, enhancing system flexibility while reducing overall energy loss.
4Productivity
If thermal storage capacity is increased, then energy delivery efficiency improves, but system complexity increases
Solution Approach 1:
The nested tank configuration provides an elegant solution for increasing thermal storage capacity without proportionally increasing system complexity. By placing the thermal battery within the thermal reservoir, the system achieves enhanced storage capacity using a compact, integrated structure. This nested arrangement eliminates the need for separate, distributed storage components and simplifies system architecture while maintaining high energy delivery efficiency.
Solution Approach 2:
The coupled tank system performs multiple functions simultaneously: the inner tank provides active thermal storage, the outer tank serves as both a thermal reservoir and a passive storage medium, and the interface between them enables thermal energy recovery. This multi-functionality allows the system to achieve high energy delivery efficiency through various operating modes (direct heating, thermal battery discharge, heat pump with reservoir support) without requiring separate systems for each function, thereby managing complexity effectively.
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 system enables efficient delivery of heat or cold to buildings, reduces electricity consumption, particularly during peak hours, and mitigates the 'duck curve' effect by leveraging thermal energy storage and recycling, thereby improving energy efficiency and grid stability.
Implementation Method 1
an inner tank is a thermal battery, configured to receive thermal energy from a heat pump and provide thermal energy to a building or other load
Implementation Method 2
an outer tank is a thermal reservoir, positioned to receive thermal energy lost from the thermal battery, and coupled as an energy source to an input of the heat pump
Implementation Method 3
phase change materials can be incorporated for temperature regulation or for increased thermal storage capacity
Data Source
AI summary
Methods and apparatus are disclosed for high-efficiency thermal storage with a fluid-filled “battery” tank positioned within a fluid-filled “reservoir” tank. Fluid loops couple the tanks to a heat pump and a building. The heat pump can charge the battery tank or deliver thermal energy (cold or heat) to a building, using the reservoir tank or ambient air as a thermal energy source. The battery tank can discharge energy to the building jointly with the heat pump or, at periods of peak electricity usage, with the heat pump switched off. Operating modes allow significant savings in electricity usage and mitigate the “duck curve.” Low duty cycle usage of the reservoir enables efficient underground thermal storage with less digging than conventional geothermal technologies. Additional efficiency is achieved with phase change materials installed inside a tank or in a tank wall, providing temperature regulation. Control methods are disclosed.