Difference between the AEM and PEM electrolyzers

AEM (Anion Exchange Membrane) and PEM (Proton Exchange Membrane) electrolyzers are both types of electrolysis devices that use electricity to split water into its constituent parts, hydrogen and oxygen. However, there are some key differences between these two types of electrolyzers.

Technical Difference

The main technical difference between AEM (Anion Exchange Membrane) and PEM (Proton Exchange Membrane) electrolyzers lies in the type of membrane used and the resulting electrochemical reactions that occur.

• Membrane Material: AEM electrolyzers use an anion exchange membrane that selectively allows negatively charged ions (such as hydroxide ions) to pass through, while blocking positively charged ions (such as hydrogen ions). In contrast, PEM electrolyzers use a proton exchange membrane that selectively allows only positively charged ions (protons) to pass through.

• Electrolyte: AEM electrolyzers use an alkaline electrolyte (such as potassium hydroxide), while PEM electrolyzers use an acidic electrolyte (such as sulfuric acid). The pH of the electrolyte affects the electrochemical reactions that take place at the electrodes and determines the type of catalyst needed for the reactions.

• Operating Conditions: AEM electrolyzers typically operate at a higher pH and temperature than PEM electrolyzers. The higher pH allows for faster transport of anions through the membrane, resulting in higher current densities. The higher temperature also increases the rate of the electrochemical reactions. In contrast, PEM electrolyzers operate at a lower temperature and pressure, which reduces the risk of membrane degradation and allows for more efficient use of catalysts.

• Catalysts: AEM electrolyzers can use non-precious metal catalysts, such as nickel or iron, due to the alkaline electrolyte and anion exchange membrane. PEM electrolyzers require precious metal catalysts, such as platinum, to facilitate the proton exchange reaction.

Capital Expenditure Difference

The capital expenditure (CAPEX) for AEM and PEM electrolyzers can vary depending on the specific model, size, and manufacturer. However, as a general rule, AEM electrolyzers are typically less expensive to manufacture than PEM electrolyzers, primarily due to the simpler design and use of lower-cost materials.

One of the reasons for this cost difference is that AEM electrolyzers do not require expensive platinum-based catalysts, which are commonly used in PEM electrolyzers to facilitate the proton exchange reaction. Instead, AEM electrolyzers can use less expensive catalysts or even non-precious metal catalysts, which can significantly reduce the cost of the system.

Additionally, AEM electrolyzers typically use an alkaline electrolyte, such as potassium hydroxide, which is less expensive than the acidic electrolyte used in PEM electrolyzers. This can further reduce the overall cost of the system.

Overall, the lower CAPEX of AEM electrolyzers can make them an attractive option for large-scale industrial applications, where cost-effectiveness is a primary concern. However, it's important to note that the operating and maintenance costs of the two systems can also vary, and should be taken into account when evaluating the total cost of ownership over the lifespan of the system.

Operational expenditure difference 

The operational expenditure (OPEX) for AEM (Anion Exchange Membrane) and PEM (Proton Exchange Membrane) electrolyzers can vary depending on factors such as electricity costs, maintenance requirements, and catalyst degradation.

• Electricity Costs: Both AEM and PEM electrolyzers require electricity to split water into hydrogen and oxygen. The electricity costs can vary depending on the source of electricity, the efficiency of the electrolyzer, and the size of the system.

• Maintenance Requirements: Both AEM and PEM electrolyzers require regular maintenance to ensure optimal performance and longevity. However, the specific maintenance requirements can vary depending on the type of electrolyzer. For example, PEM electrolyzers require regular replacement of the precious metal catalysts used in the system, which can be costly. In contrast, AEM electrolyzers may require more frequent membrane replacement or cleaning, which can increase maintenance costs.

• Catalyst Degradation: Over time, the catalysts used in PEM electrolyzers can degrade due to exposure to harsh operating conditions, such as high temperature and acidic electrolyte. This can result in reduced efficiency and higher maintenance costs. AEM electrolyzers, which do not require precious metal catalysts, may have lower catalyst degradation rates and lower maintenance costs as a result.

Overall, the OPEX difference between AEM and PEM electrolyzers can depend on a variety of factors and can be difficult to predict accurately. In general, AEM electrolyzers may have lower OPEX costs due to their simpler design and use of lower-cost materials. However, the specific OPEX costs will depend on the operating conditions and maintenance requirements of the specific system in question.

The choice between AEM and PEM electrolyzers will depend on the specific application and performance requirements. AEM electrolyzers may be more suitable for large-scale industrial applications, while PEM electrolyzers may be more appropriate for smaller-scale or portable applications.