Alkaline Electrolyser (Atmospheric)

Alkaline electrolysers operate by using an alkaline solution, typically potassium hydroxide (KOH) or sodium hydroxide (NaOH), as the electrolyte, depending on the specific design and application requirements. 

• Operating Pressure: Up to 30 bar (435 psi), with some systems operating at atmospheric pressures around.
•  Operating Temperature: Between 60°C to 90°C (140°F to 176°F).

When an electric current is applied, water molecules split into hydrogen and oxygen gases at the electrodes. Hydrogen gas is collected at the cathode, and oxygen gas is collected at the anode.

External impacts, such as impurities in the water, fluctuations in power supply, and environmental conditions, can affect the performance and durability of alkaline electrolysers. Proper filtration and stable power sources are essential. Those factors impact the so-called balance of plant, which includes all subsystems necessary for the electrolyser’s operation, such as water purification, power supply, and gas handling systems.

Impurities can also cause degradation of the electrodes, reduce the efficiency of hydrogen production, and lead to contamination of the produced hydrogen gas. They can also cause unwanted side reactions, increase maintenance costs, and reduce the overall lifespan of the electrolyser.

Polymer piping systems, such as the Polypropylene piping solution PROGEF, are highly resistant to corrosion with a good chemical degradation, which helps in maintaining the purity of the electrolyte solution. Additionally, they can ensure long-term durability and reduce the risk of impurities entering the system.

Visit our PROGEF polypropylene (PP-H) welded system page for more information about its benefits.

Apart from the PROGEF system, our SYGEF ECTFE components offer extraordinarily good corrosion and permeation resistance. Even with highly concentrated media like lies of different KOH-concentration, the system boasts high chemical resistance with maximized system service life.

Learn more about SYGEF ECTFE.

The media used in alkaline electrolysers is typically a liquid electrolyte solution. The most common electrolyte is a concentrated solution of potassium hydroxide (KOH) in water, also known as lye. The concentration of KOH in the electrolyte solution generally ranges from 25% to 35% by weight.

This concentration is chosen to provide optimal conductivity while maintaining the stability and efficiency of the electrolysis process. Higher concentrations of KOH can improve the conductivity of the solution but may also increase the corrosiveness and maintenance requirements. The chosen concentration balances these factors to achieve efficient hydrogen production and system longevity.

Selecting the right plastic for an alkaline electrolyser requires considering the chemical composition of the electrolyte, as different plastics have varying chemical resistances. Additionally, the operating temperature and pressure must be taken into account since these factors can affect the thermal and mechanical properties of the plastics. The desired lifetime of the electrolyser is also crucial, as different plastics degrade at different rates. Lastly, material cost can significantly impact the overall cost of the electrolyser. Thorough testing is essential to determine the suitability of a specific plastic for a particular application in an low pressure alkaline electrolyser.

Not every pipe material is suitable for transporting aggressive liquids and gases. The use of incorrect materials can lead to problems. With our Chemical Resistance Tool, you can now find the right materials for your project both quickly and easily.