Dual-Conduit Gas Cavern Storage for Fast Grid Balancing
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Solution Overview
Problem
The increasing volatility and decentralization of renewable energy sources, such as wind turbines, pose challenges for electricity grid stability, leading to unnecessary downregulation and waste of renewable energy.
Innovation Solution
A system utilizing a gas generator to produce hydrogen from the electricity grid, which is stored in an underground cavern via a dual-directional conduit system allowing simultaneous filling and withdrawal, enabling rapid and dynamic response to energy demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single connection pipe is used for gas storage in a cavern, then the device complexity is reduced, but the dynamic response speed and ability to simultaneously fill and withdraw gas is limited
Solution Approach 1:
The single connection pipe is segmented into multiple independent conduits (filling conduit and withdrawal conduit) that can operate simultaneously. This segmentation allows gas to be filled into and withdrawn from the cavern at the same time, significantly improving the dynamic response speed and energy storage/release capability without requiring complex switching mechanisms.
Solution Approach 2:
The dual-directional conduit system provides multi-functionality by enabling the cavern to simultaneously serve as both a storage facility and a release facility. The filling conduit and withdrawal conduit are designed to operate independently and concurrently, allowing the system to perform multiple functions (storage, release, simultaneous storage and release) through a unified cavern structure.
2Reliability
If wind turbines are downregulated to maintain grid stability, then the stability of the power grid is improved, but renewable energy is wasted
Solution Approach 1:
The system performs preliminary action by storing excess renewable energy in the form of gas (hydrogen or natural gas) in the cavern when generation is high and grid stability is not compromised. This pre-stored energy can be quickly released when needed, eliminating the need to downregulate wind turbines and preventing renewable energy waste while maintaining grid stability.
Solution Approach 2:
The cavern-based gas storage system acts as an intermediary between renewable energy generation and grid consumption. It decouples the fluctuating renewable energy supply from the stable grid demand by storing excess energy and releasing it when needed, thereby eliminating the need for wind turbine downregulation and preventing energy waste.
3Speed
If battery storage means are used, then the response time is improved, but the energy storage capacity is limited
Solution Approach 1:
The system combines the advantages of both battery storage and large-scale storage by nesting a fast-response gas generation system (electrolyzer or methanation plant) within the cavern storage infrastructure. The gas generator provides rapid response capability similar to batteries, while the cavern provides large-scale energy storage capacity, creating a hybrid system that achieves both fast response and high capacity.
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 enhances grid stability by minimizing downregulation of renewable energy sources, allowing for rapid energy storage and release, and providing both primary and secondary control power to the grid.
Implementation Method 1
hydrogen is generated from surplus electrical power, and the hydrogen is stored in a cavern
Implementation Method 2
The gas (in particular hydrogen) is stored in such a cavern via a connection pipe under a high pressure of typically 40 to 200 bar
Data Source
AI summary
A system for stabilizing an electricity grid using an energy store is provided. The energy store comprises a gas generator fed by the electricity grid to generate fuel and a cavern comprising a supply line. To store energy, generated fuel is introduced into the cavern via the supply line and, to withdraw energy, is removed from the cavern. The supply line is dual-directional, comprising a filling line and a removal line. It is thus possible to feed fuel into the cavern and to provide negative operating reserve relative to the electricity grid. It is also possible to simultaneously remove fuel from the cavern using the removal line for one of the use units, to generate methane using a methanation plant or for return flow. The system does not involve inconvenient switching processes in the lines thus allowing the operating reserve to be provided rapidly.