Different Types of Hydrogen Electrolysers: PEM, Alkaline, and Solid Oxide Explained

 

The high need for green hydrogen as a clean energy source has aroused keen interest in the technologies that make such production possible. Hydrogen electrolysers are prominent in this process, which effectively splits water into hydrogen and oxygen with the help of electricity. The efficiency and efficacy of green hydrogen production usually rely on the kind of electrolyser utilized.

In the blog, we take an in-depth look at three hydrogen electrolyser technologies: Alkaline and Solid. We discuss their modes of operation, relative advantages, and proper site applications for each.

 

Hydrogen Electrolysers: What are they?

Hydrogen electrolysers use electricity to perform water electrolysis, separating water molecules into hydrogen and oxygen. The resulting hydrogen can then be stored, transported, and used as a clean fuel for various applications, from industrial processes to powering fuel cells.

Various electrolysers have different uses, efficiencies, operational temperatures, and energy input sources. We shall look at the three most used types.

 

Proton Exchange Membrane-PEM Electrolysers

PEM Electrolysers are compact and capable of generating high-purity hydrogen. They use a solid polymer electrolyte membrane, which conducts protons and separates hydrogen-oxygen gases.

 

How It Works:

Water is fed to the anode side of the electrolyser.

Electricity splits water into protons, electrons, and oxygen.

The protons then pass through the proton exchange membrane to the cathode, recombining with electrons to form hydrogen gas.

 

Advantages

Compact, high-efficiency design.

Their quick response to fluctuating power inputs makes them ideal for renewable energy systems such as solar and wind.

Produces high-purity hydrogen suitable for industries that demand very high standards.

 

Applications:

Hydrogen refueling stations.

Industrial applications requiring high-purity hydrogen.

Integration of power generated from intermittent renewable sources.

 

Alkaline Electrolysers

Alkaline Electrolysers represent one of the oldest and most consolidated technologies in hydrogen production. They conduct the ions between electrodes by means of a solution at a basic pH-actual, generally using potassium hydroxide (KOH) as an electrolyte.

 

How It Works:

Water is fed to the cathode, where it is reduced to hydrogen gas and hydroxide ions: OH⁻.

The hydroxide ions pass through the electrolyte to the anode, where oxygen gas is produced, and the ions are replenished.

 

Advantages

Proven technology deployed for decades across industries.

Minor capital cost compared to a number of the other variants of electrolysers.

Long operational lifetimes.

 

Applications:

Large-scale production of hydrogen for the steelmaking and ammonia industry.

Systems where cost-effectiveness is of utmost importance.

 

Solid Oxide Electrolysers (SOEC)

A solid oxide electrolyser works at temperatures, usually in the range of 700 to 1,000°C, and offers efficiency by using not just electricity but thermal energy conversion. Its electrolyte consists of thick ceramic material.

 

How it Works:

Water in steam form is fed at the input of the electrolyser.

Electricity splits the steam into hydrogen and oxygen ions.

The oxygen ions diffuse through the solid ceramic electrolyte to the anode, forming oxygen gas.

 

Advantages:

Very high efficiency because of the use of thermal energy.

It can be used in industrial processes or concentrated solar.

Suitable for use with systems generating waste heat.

 

Applications:

Industrial sectors that involve high consumption of hydrogen.

Coupling with high-temperature processes, such as power plants or chemical manufacturing.

Advanced energy systems for efficiency and sustainability.

 

Comparison of the Three Hydrogen Electrolysers

PEM Electrolysers:

Operating Temperature: 50–80°C.

Efficiency: Average to high.

Startup Time: Fast.

Input Power Flexibility: Very good for renewable sources of power.

Hydrogen Purity: High.

Capital Cost: High.

 

Alkaline Electrolysers:

Operating Temperature: Low to moderate, ranging from 60 to 90°C.

Efficiency: Medium.

Startup Time: Slow.

Input Power Flexibility: Limited to moderate.

Purity of Hydrogen: Fairly medium to quite high.

Capital Cost: Low.

 

Solid Oxide Electrolysers:

Operating Temperature: High [700–1,000°C].

Efficiency: Very high.

Startup Time: Very slow.

Input Power Flexibility: Best with stable power sources.

Hydrogen Purity: High.

Capital Cost: High.

 

Choosing the Right Hydrogen Electrolyser

The choice of electrolyser depends on the intended application, energy source, and cost considerations.

PEM electrolysers are most compatible with renewable energy and particularly fit for installations that require compactness and high purity.

Alkaline Electrolysers: This is best for large-scale, cost-effective hydrogen production for industrial use. 

SOEC: preferred in an advanced industrial setting where efficiency and integration with waste heat can't be compromised.

 

Conclusion: The key role in the green hydrogen revolution

With the increasing demand for green hydrogen, the choice of appropriate electrolyser technology will become highly crucial to guarantee production efficiency and meet specific needs. Each of these types of Hydrogen electrolysers holds certain advantages, making them fit for different applications and environments.

Understanding the subtlety of these technologies will, therefore, help industries make informed decisions about adopting solutions that best meet their energy goals and lead toward a cleaner, greener future.  Contact us now.

 

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