Thermal Energy Storage with Rankine Cycle for Firm Renewable Capacity
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Solution Overview
Problem
Renewable energy sources face challenges in providing stable frequency and voltage support, leading to curtailment and inefficiencies due to their inability to form microgrids and respond to load changes, while existing storage solutions like batteries are costly and limited in long-duration capacity.
Innovation Solution
Integration of thermal energy storage with a Rankine cycle and combustion turbines or reciprocating engines to provide firm capacity, utilizing excess renewable energy to heat storage systems and convert thermal energy back to electricity when needed, thereby maintaining frequency and voltage and minimizing fuel consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If thermal energy storage is integrated with Rankine cycle and combustion turbines, then firm capacity and long-duration energy storage are provided, but device complexity increases
Solution Approach 1:
The patent combines thermal energy storage tanks with Rankine cycle power generation equipment into an integrated system. The thermal storage tanks store heat energy that can be converted to electricity through the Rankine cycle, merging storage and generation functions into a unified system that provides both long-duration storage and firm capacity while sharing common infrastructure.
Solution Approach 2:
The thermal energy storage system serves multiple functions: it stores excess renewable energy for later use, provides firm capacity for load serving, enables microgrid operation during grid outages, and supports frequency and voltage regulation. This multi-functionality justifies the added complexity by delivering diverse value from a single integrated system.
2Productivity
If excess renewable energy is used to heat thermal storage systems, then renewable energy utilization is maximized, but energy conversion efficiency decreases
Solution Approach 1:
The system converts excess renewable energy that would otherwise be curtailed into stored thermal energy. By using the thermal storage system to capture and store surplus solar or wind energy as heat, the system transforms the problem of over-generation into a beneficial stored resource that can be converted to electricity when needed, thereby maximizing renewable utilization while managing conversion losses.
3Duration of action of stationary object
If thermal energy storage systems are used for long-duration storage, then storage duration is extended, but initial investment cost increases
Solution Approach 1:
The thermal energy storage system uses phase-change materials or high-temperature thermal storage media that can store large amounts of energy density-wise. The system serves itself by using stored thermal energy to drive the Rankine cycle power generation, eliminating the need for separate backup power sources and reducing overall system costs despite the initial investment in thermal storage infrastructure.
4Reliability
If microgrid capability is implemented with thermal storage, then reliability during grid outages is improved, but system complexity increases
Solution Approach 1:
The patent integrates thermal energy storage with power generation equipment to create a self-contained microgrid system. The thermal storage tanks are combined with Rankine cycle generators and control systems that can autonomously manage power generation and distribution, merging multiple functions into a unified microgrid architecture that maintains reliability while managing complexity through integration.
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 solution enables the maximization of variable renewable resources, reduces fuel consumption, and provides stable frequency and voltage for extended durations, addressing the limitations of current storage solutions and renewable energy variability.
Implementation Method 1
utilizing excess renewable energy to heat storage systems
Implementation Method 2
convert thermal energy back to electricity when needed
Implementation Method 3
combustion turbines or reciprocating engines to provide firm capacity
Data Source
AI summary
The invention relates generally to methods and apparatus for integration of renewable and conventional energy to enhance electric reliability and reduce fuel consumption and emissions via thermal energy storage.