March 4, 2024
How Can Alkaline Electrolyzer Get Out of the Rat Race?
Alkaline electrolyzers have a relatively simple structure and high technological maturity. Many manufacturers have launched alkaline electrolyzers to pace with the increasing demand for green hydrogen. However, their electrolyzers tend to be similar in structures and performances, irrigating a more fierce competition. So how can alkaline electrolyzers get out of the rat race?
Alkaline Electrolyzer Technical Status
Alkaline electrolyzers continue to evolve internationally
Overseas alkaline electrolyzers have a relatively longer development history. The 1000 Nm3/h electrolyzers have already appeared as early as the last century and have gone through many technological iterations in electrodes and separators. Among them, the alkaline hydrogen production electrolyzers of Nel, ThyssenKrupp, and other eletrolyser manufacturers are the most representative.
Nel has been engaged in the research and development and production of hydrogen production electrolyzers since the 1920s. The separators it uses have evolved from asbestos materials to today’s polymer composite materials. In terms of electrodes, they have developed new non-precious metal activation technology.
Nel’s current A-series alkaline electrolytic cells use a composite diaphragm with a thickness of less than 500 μm and a surface resistance of about 250 mΩ/cm2; the cathode uses a Raney Ni-based multi-element coating catalyst (NiMo alloy, etc.), and the anode uses activated nickel, which is effective Reduce overpotential.
ThyssenKrupp’s electrolyzer comes from its mature chlor-alkali electrolyzer process. It adopts zero-gap technology. The distance between the electrode and the diaphragm is almost zero, reducing the solution resistance.
Thyssenkrupp adopts low-voltage operating conditions and a square tank structure to optimize the electrolyte flow field, promote bubble circulation, and reduce bubble resistance. Moreover, the unit cells of ThyssenKrupp’s electrolyzer are independent of each other, which is conducive to later disassembly and maintenance. Combined with the optimization of electrodes and membranes, the electrolysis efficiency of ThyssenKrupp’s alkaline electrolyzer has been increased to more than 80%.
Domestic alkaline hydrogen production electrolyzers face the dilemma of homogeneity
Although there are many alkaline electrolyzer products in China, judging from the published information, there are fewer differences in their structure and performance. The homogenization of domestic electrolyzers can be summarized in three aspects.
Firstly, the current alkali electrolyzers mainly focused on high hydrogen production, and the technical route is to increase the electrode area and the number of cells. This kind of “stacking solution” has achieved a rapid breakthrough in hydrogen production through the 1000 Nm3/h alkaline electrolyzers. However, the 1000Nm3/h electrolyzer can be longer than 6 meters and heavier than 40 tons.
Using this solution to increase hydrogen production will lead to many problems such as high transportation and maintenance costs, poor electrolyte sealing, and intensified reverse current corrosion.
Secondly, alkaline electrolyzers are made of similar materials with similar structures. A vast majority of domestic electrolyzers are tie-rod cylindrical electrolyzers. The bipolar plates have a circular structure, the electrode base is a nickel mesh, the catalyst is a nickel-based alloy, and the separator is a polyphenylene sulfide (PPS) membrane.
At present, the components of existing alkaline electrolyzers in China are almost all industrial products with mature technology under the traditional industrial system, and there are not too many innovations and technical barriers. Under this situation, it will be easier for participants to find suppliers and achieve assembly and expansion of production capacity. While the cost of the industry chain decreases, products will also face severe homogeneous competition.
Thirdly, the performance of alkaline electrolyzers tends to be homogeneous. There is no obvious difference in current density, DC power consumption, electrolysis efficiency, etc. The homogeneity of components of alkaline electrolyzers results in homogenization of performance.
According to the current published data, the DC power consumption of most high-quality alkaline electrolyzers is around 4.3 kWh/Nm3H2, the hydrogen production efficiency is around 75%, and the minimum working load range is above 20%, and all of them are medium and high pressure operation above 10 bar.
Get Rid of Rat Race from Multiple Dimensions
Auxiliary management systems, electrolyzer structures, and core materials may be the next direction for alkaline electrolyzer breakthroughs.
The auxiliary management system is directly related to the dynamic control capability of the electrolyzer, and is an important guarantee for the adaptability of wind and solar power fluctuations and safe production. An efficient hydrogen production auxiliary management system will be a breakthrough point in the future.
The structure of the electrolytic cell is related to many aspects such as the level of space utilization and flow field distribution. It is an important direction for reducing the volume and resistance of the alkaline electrolyzers.
The diaphragm is an important part that causes the internal resistance and additional energy loss of the electrolyzer, and the impact is greater under high current density. Reducing the diaphragm resistance is the direction that must be overcome to increase the current density of the alkaline bath.
Optimizing electrode materials makes the greatest contribution to achieving rapid breakthroughs in alkaline electrolyzers.
On one hand, electrode materials determine the performance of alkaline electrolyzers. Large electrode overpotential and poor kinetic performance are the main reasons for the low current density, high DC power consumption, and low electrolysis efficiency of domestic alkaline electrolyzers. Even the slow response, small load range, and excessive volume of alkaline electrolyzers are also related to this.
On the other hand, the current optimization space for electrode materials is huge and feasible. Most domestic electrolyzers use relatively cheap nickel-based materials with extremely high hydrogen evolution overpotential (around 200 mV@100A/m2), while scientific research institutes and catalyst-specialized companies have accumulated decades of technology experience in hydrogen production electrode materials. A large number of higher performance (overpotential below 100 mV) and lower cost materials have not yet been applied.
To sum it up, the rapid development of the hydrogen energy industry has put forward higher requirements for electrolyzer products. It’s feasible to break the deadlock by optimizing the design of the structure and materials of alkaline hydrogen production electrolyzers. In the future, alkaline hydrogen production electrolyzers are about to enter a new round of technology and market competition.
Check out the status of hydrogen production rlectrolyzers in China and overseas markets to get more information.
