Modular Electrolyzer Elements for Low Stray Current Operation
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Solution Overview
Problem
Industrial multimegawatt water electrolyzer systems face challenges with low operating voltage and current efficiency due to stray electric currents, leading to increased investment costs, resistive losses, and poor power quality, which are exacerbated by the need for thyristor-based converters and high electric current.
Innovation Solution
A modular electrolyzer system design with galvanically separated electrolyzer elements, each comprising its own electrolyte circulation and gas separation systems, allowing for series connection without stray currents, enabling higher operating voltage and current efficiency, and facilitating the use of modern transistor-based power converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of electrolysis cells connected in series is increased to raise operating voltage, then power distribution losses are reduced, but stray electric currents increase causing decreased current efficiency
Solution Approach 1:
The electrolyzer system is divided into multiple independent electrolyzer elements, each with its own electrolyte circulation system. This segmentation prevents stray electric currents from affecting the entire system while allowing series connection of cells within each element, thus reducing power distribution losses without sacrificing current efficiency.
Solution Approach 2:
Electrically insulating materials are introduced as intermediaries in the electrolyte circulation channels and connections between electrolyzer elements. These intermediaries block the path of stray electric currents while maintaining electrolyte flow, enabling high-voltage series connections without current efficiency penalties.
2Power
If thyristor-based converters are used to handle high electric current at low voltage, then power conversion is achieved, but power quality deteriorates and additional energy losses occur
Solution Approach 1:
The system changes the operating parameters by enabling higher voltage operation through series connection of cells in electrolyzer elements. This parameter change allows the use of transistor-based converters instead of thyristor-based converters, improving power quality and reducing energy losses while maintaining the required power conversion capability.
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 design achieves higher current efficiency and operational flexibility, reduces stray electric currents, and lowers investment costs by allowing for the use of modern, low-cost power converters, while maintaining energy efficiency and facilitating system maintenance and automation.
Implementation Method 1
An electrochemical process where material interacts with electrodes can be for example an electrolysis process such as e.g. water electrolysis where electrical energy is converted into chemical energy carried by hydrogen gas H2
Implementation Method 2
The ionic conductivity needed for electrolysis is caused by hydroxide ions OH- which can penetrate the porous diaphragm
Implementation Method 3
The extra heat can be removed from the electrolyte by a heat exchanger to keep operating temperature within a suitable range
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
An electrolyzer system comprises electrolyzer elements (101) each comprising an electrolyzer stack (104) constituted by electrolysis cells. Furthermore, each electrolyzer element comprises a water inlet (106), a hydrogen separator tank (107) having a hydrogen outlet (108), an oxygen separator tank (109) having an oxygen outlet (110), and a channel system (111) for conducting electrolyte from the hydrogen separator tank and from the oxygen separator tank to the electrolyzer stack. The electrolyzer stacks of the electrolyzer elements are electrically connected to each other so that direct voltage of the electrolyzer system is a sum of direct voltages of the electrolyzer stacks of two or more of the electrolyzer elements. The water inlets, the hydrogen outlets, and the oxygen outlets of different ones of the electrolyzer elements are galvanically separated from each other. This enables the direct voltage of the electrolyzer system to have a desired value with low stray electric currents.