In the field of hydrogen production, choosing the right electrolyzer stack is crucial. Currently, the two most popular types of stacks are the Alkaline Electrolyzer stack and the PEM Electrolyzer stack. But which one is better suited to your needs? Let’s dive deeper to help you make an informed decision.

 

1. What is an Alkaline Electrolyzer Stack?

An ALK Electrolyzer stack uses an lye solution, typically potassium hydroxide (KOH), as the electrolyte. This technology has been around for decades and is known for its reliability and cost-effectiveness. Due to its lower operational costs and longer lifespan, alkaline electrolyzer stacks are well-suited for large-scale hydrogen production.

 

2. What is a PEM Electrolyzer Stack?

A PEM Electrolyzer Stack(Proton Exchange Membrane) uses a solid polymer electrolyte. This type of stack is more compact and can operate at higher current densities, making it suitable for applications where space is limited. PEM electrolyzer stacks can better adapt to variable power inputs, making them ideal for use in conjunction with renewable energy sources such as wind and solar.

 

3. Conclusion

The choice between alkaline electrolyzer stack or PEM electrolyzer stack depends on your specific needs for hydrogen production.

ALK electrolyzer stack: suitable for low-cost, large-scale, and low water quality requirements scenarios, such as industrial by-product hydrogen and power grid peak shaving.

PEM electrolyzer stack: suitable for scenarios with high purity, fast response, and limited space, such as hydrogen refueling stations and vehicle mounted hydrogen production.

By understanding the advantages and disadvantages of each electrolyzer stack, you can optimize the hydrogen production process and achieve sustainable development goals more efficiently.

Given the current situation of PEM electrolyzer, the key to their large - scale application lies in reducing costs and optimizing performance. At present, cost reduction can be achieved by optimizing the catalyst system to reduce costs, using highly conductive support materials, and replacing them with high - performance proton exchange membranes.

I. Cost Reduction and Optimization of PEM Electrolyzer

1. Development and Application of Low - Noble - Metal Electrocatalyst 

①　Reducing Manufacturing Costs
By reducing the content of noble metals (platinum, iridium, ruthenium) and improving the efficiency of the preparation process, the manufacturing costs of PEM electrolyzer electrocatalysts can be reduced, enhancing the market competitiveness of products.

②　Improving Stability
The stability of PEM electrolyzer electrocatalyst can be improved by adding non - metallic element doping and improving the crystal structure, making them more stable and reliable during actual use.

③　Enhancing Performance
The performance of PEM electrolyzer electrocatalysts can be enhanced by adjusting the electrocatalytic activity of non - noble metals and increasing the specific surface area, reducing the activation energy barrier of the reaction and increasing the reaction rate.

2.Design and Preparation of Highly Conductive Support Materials

①　Improving Conductivity
The conductivity of PEM electrolyzer electrocatalysts can be improved by selecting appropriate support materials and increasing the contact area between the catalyst and the support material, reducing the resistance loss during the reaction.

②　Increasing Support Strength
The support strength of PEM electrolyzer electrocatalysts can be increased by enhancing the strength and toughness of the support material and improving the preparation process, preventing the catalyst from cracking or detaching during the reaction.

③　.Adjusting the Microstructure
The microstructure of PEM electrolyzer electrocatalysts can be adjusted by regulating the microstructure of the support material and changing the transport path of reactants, further optimizing the transport and reaction processes of reactants.

3.Optimization and Improvement of Proton Exchange Membrane Structure
At present, although many domestic manufacturers are researching proton exchange membranes, most industrial - grade applications and industrial projects still rely on products from the United States and other countries. Therefore, it is very important to carry out optimization, upgrading, and transformation of proton exchange membranes.

①　.Selective Permeable Membrane
Gas permeation can be reduced by introducing a selective permeable membrane. This membrane only allows the reaction gas to pass through while blocking the permeation of other gases.

②　Sandwich Structure
Gas permeation can be reduced by changing the sandwich structure. For example, a porous cushion can be introduced to divide the PEM into multiple small regions, reducing the cross - over of gas products.

4.Gas Diffusion Coefficient
Gas permeation can be reduced by lowering the gas diffusion coefficient. This can be achieved by increasing the rigidity of the polymer chain, introducing reinforcing materials, and improving the processing conditions.

Ⅱ.Optimization of Slurry Composition and Enhancement of Physical Properties

1.Optimization of Slurry Composition
Adjust the catalyst, carrier components, ionomers, and other additional materials in the slurry according to requirements to optimize its performance.

2.Enhancement of Physical Properties
The quality of the MEA can be improved by enhancing physical properties such as the particle diameter, rheology, and Zeta potential in the slurry.

3.Introduction of Additional Functions
The lifespan and reliability of the MEA can be improved by introducing additional functions such as antioxidants and reducing agents.

Ⅲ.Improvement and Optimization of MEA Processing Technology Measures

1.Selection of Coating Methods
Select appropriate coating methods such as electrochemical deposition, ultrasonic spraying, and transfer printing according to requirements to optimize the catalytic performance of the MEA.

2.Modification of Coating Equipment
Modify the existing coating equipment according to requirements to achieve roll - to - roll coating, etc., to meet industrial demands.

3.Monitoring of Coating Film Quality
Establish a coating film quality inspection system to monitor the quality of the coating film in real - time and implement feedback control to ensure the quality of the MEA.

1. Technical Principles  

    Define Hydrogen Production Requirements: Determine the appropriate hydrogen production technology based on the scale and purity requirements of your facility. For example, water electrolysis may be more suitable for research institutions or the electronics industry that require high-purity hydrogen in relatively small quantities, as it can produce hydrogen with a purity of over 99.99%. For large-scale industrial hydrogen use, such as in oil refining or chemical industries, steam methane reforming (SMR) may be a more economical choice if abundant fossil fuel resources are available.  

2. Capacity and Scale  

    Assess Hydrogen Demand: Accurately evaluate future hydrogen usage based on production plans and process requirements. Large chemical enterprises may require hydrogen production equipment with a daily output of thousands or even tens of thousands of cubic meters, while small hydrogen refueling stations or laboratories may only need equipment with a daily output of a few hundred or even tens of cubic meters.  

Consider Space Constraints: The footprint and height of hydrogen production equipment are also important factors. Steam methane reforming equipment typically requires a larger site, including reactors and purification systems, while water electrolysis equipment is more compact and occupies less space. If the facility has limited space, compact hydrogen production equipment, such as skid-mounted water electrolysis systems, should be considered.  

3. Purity Requirements  

   Production Process Needs: Different industrial processes have varying hydrogen purity requirements. For instance, in semiconductor manufacturing, hydrogen purity must exceed 99.999% to avoid impurities affecting chip quality, while in some ordinary chemical hydrogenation reactions, a purity of around 98% may suffice.  

Supporting Purification Equipment: If the hydrogen produced by the equipment does not meet the required purity, additional purification systems must be considered. For example, pressure swing adsorption (PSA) systems can further enhance hydrogen purity by removing impurities such as carbon dioxide, carbon monoxide, and water vapor.  

4. Cost Factors  

   Equipment Procurement Costs: The prices of hydrogen production equipment vary significantly depending on the type and scale. Generally, water electrolysis equipment, especially those using proton exchange membrane (PEM) technology, has a higher initial investment, while steam methane reforming equipment is relatively cheaper, though the price also depends on capacity and technical parameters.  

Operation and Maintenance Costs: These include energy consumption, raw material costs, and maintenance expenses. Water electrolysis has high energy consumption, with electricity being the primary operating cost, while steam methane reforming requires significant fossil fuel consumption, making raw material costs a major factor. Additionally, advanced hydrogen production equipment may require specialized technicians for maintenance, increasing operational costs.  

Lifecycle Costs: Consider the equipment's lifespan, depreciation rate, and maintenance costs to calculate the total cost over its lifecycle. Equipment with higher upfront costs but stable performance, long service life, and low maintenance costs may offer better cost-effectiveness in the long run.  

5. Safety and Reliability  

   Safety Performance: Hydrogen production involves flammable and explosive gases, making safety critical. Choose equipment with comprehensive safety features, such as overpressure protection, overtemperature protection, and hydrogen leak detection and alarm systems. Additionally, the materials and manufacturing processes of the equipment must comply with relevant safety standards to ensure safe operation.  

Reliability and Stability: The reliability of the equipment directly impacts production continuity and stability. Select suppliers with a strong reputation, mature technology, and extensive application experience. Their products are typically better designed, manufactured, and quality-controlled, reducing the risk of equipment failure and downtime.  

6.Supplier's Technical Support 

   Additionally, consider the supplier's technical support and after-sales services, including equipment installation and commissioning, operator training, maintenance services, and spare parts supply. Timely and professional technical support ensures smooth equipment operation and minimizes losses caused by equipment failures.