Proton Exchange Membrane (PEM) electrolysers are a high-performance pathway for producing hydrogen through electrolysis. PEM electrolysers use a solid polymer electrolyte (proton exchange membrane) to split water into hydrogen and oxygen using electricity. The membrane allows only positively charged hydrogen ions (protons) to pass through, while blocking gases and electrons, enabling the separation of hydrogen with high purity.

What is a PEM Electrolyser?

The concept dates back decades, but modern advancements have made it more efficient. PEM electrolysers split water into hydrogen and oxygen using a solid polymer membrane, which prevents contamination from electrolytes while creating a hydrogen gas that requires minimal post-processing before use in fuel cells, chemical production, and sensitive industrial processes.

How PEM Electrolysis Works

PEM stacks run at moderate temperatures, commonly in the 50°C to 80°C range. The system feeds water into the anode side, where it splits into oxygen, protons, and electrons. The membrane conducts protons to the cathode, while electrons travel through an external circuit. At the cathode, hydrogen gas is formed as protons and electrons recombine. This configuration produces hydrogen with high purity and at pressures that reduce or eliminate the need for mechanical compression.

Catalysts:

Platinum Group Metals (typically platinum and iridium)

Advantages of PEM Electrolysers

Rapid Response and Flexibility

PEM electrolysers start and stop quickly (within seconds or minutes), making them ideal for renewable energy sources like wind and solar, where power supply fluctuations are common. You don’t need to wait for warm-up cycles or full-load conditions.

Compact and Scalable Design

PEM electrolysers are smaller and lighter compared to Alkaline and SOEC systems, making them easy to install, even in tight spaces. Stacking units allows output to scale from a few kilowatts to multi-megawatt deployments.

High Energy Efficiency

PEM electrolysers are highly efficent, allowing the system to produce more hydrogen from the same amount of electricity, thereby reducing overall energy costs.

High Purity Hydrogen Output

PEM systems produce very pure hydrogen. The purity of the initial output eliminates the need for most post-processing, which is often required for alkaline or biomass-based methods.

Challenges of PEM Technology

While PEM electrolysers have proven themselves in laboratory and commercial settings, several challenges limit their adoption in large-scale hydrogen production. Engineers and project developers should weigh these factors carefully when selecting PEM technology for new installations.

Catalyst Dependence

PEM stacks require expensive platinum group metals (PGMs), particularly platinum and iridium, to catalyze the electrochemical reactions. These metals are scarce, rare, and subject to volatile supply chains. As project sizes increase, the material cost associated with PGMs becomes a barrier to scaling production capacity.‍

Stack Costs

The thin polymer membrane in PEM systems must withstand high current densities and pressure differentials while maintaining chemical stability. This requires advanced manufacturing and strict quality control, both of which increase cost per kilowatt of installed capacity. For many industrial customers, stack cost remains the largest contributor to overall system expense.‍

Durability Under Variable Loads

Although PEM units can respond quickly to changes in power input, that flexibility places stress on the membrane and catalyst layer. Frequent cycling accelerates degradation, which shortens the stack lifetime. When using renewable-energy sources, this durability issue must be factored in as it can lead to additional replacement costs.‍

Complex Water Management

PEM systems require a precise water composition and a consistent supply. The membrane must remain hydrated for efficient proton conduction, but excess water can flood the electrodes and reduce performance. This balance requires auxiliary components and controls that add both complexity and cost.

At Power To Hydrogen (P2H2), our work begins with acknowledging the proven performance of PEM technology. But rather than stopping there, we advance beyond its constraints with a hybrid AEM electrolyser system. By blending the performance characteristics of PEM with the cost and durability benefits of alkaline systems, our approach addresses the economic and technical barriers that have historically restricted PEM growth. Learn more about our AEM electrolysers and contact us to see how we can help you with your hydrogen production needs.

PEM Electrolyser Applications

Grid and Energy Storage

Electric grids are under increasing pressure to balance supply and demand, especially as renewable sources like wind and solar fluctuate throughout the day. PEM electrolysers offer a stable solution by converting excess electricity into hydrogen, which can be stored and used later. This hydrogen storage can be injected into natural gas pipelines through power-to-gas systems, kept on-site for later conversion back into electricity using fuel cells, or deployed as a flexible energy source to help stabilize the grid when demand spikes.

Transportation Fuel Supply

As the hydrogen fueling station network expands, PEM technology enables reliable on-site production of hydrogen. Hydrogen for buses, trucks, and passenger vehicles can be generated cost-effectively, even at remote locations.

Industrial Hydrogen Use

Many industrial processes rely on hydrogen, but most of it is still produced from fossil fuels via steam methane reforming. PEM electrolysis allows industries to replace carbon-intensive supply chains with on-site hydrogen production.

Comparing PEM Electrolysis to Other Technologies

PEM vs Alkaline Electrolysis

PEM electrolysers generally perform better than alkaline electrolysers due to their higher purity hydrogen output and quicker response to power changes. Alkaline electrolysers may be cheaper upfront, but they typically require more space and have slower reaction times.

PEM vs Solid Oxide Electrolysis (SOEC)

Solid Oxide Electrolysers (SOEC) operate at very high temperatures (600°C - 1000°C). These higher operating temperatures make SOEC suitable mainly for industrial uses where heat is abundant. PEM electrolysers operate at significantly lower temperatures, typically between 50 °C and 80°C, making them safer and more straightforward for a broader range of applications.

PEM vs AEM Electrolysis

The objective of Power To Hydrogen's AEM electrolysis technology is not simply to match PEM’s performance but to deliver measurable improvements in critical engineering categories.

  • Lower Material Cost: Eliminating PGMs significantly reduces costs and positions hybrid AEM systems for easier expansion into multi-megawatt projects without resource bottlenecks.
  • Improved Safety: Power To Hydrogen's AEM electrolysers use Dilute electrolytes, which reduce risks for operators and simplify compliance with safety regulations.
  • Simplified Water Management: Hybrid membranes reduce the strict water balance requirements seen in PEM stacks, lowering system complexity.
  • Greater Durability: Extended operational lifetime under variable loads provides a more reliable solution for renewable-powered hydrogen plants.
  • Comparable Efficiency: P2H2 hybrid AEM systems maintain efficiency levels competitive with PEM units while addressing cost and lifetime challenges.

For engineers tasked with designing hydrogen production assets, these differences provide a clear case for selecting hybrid AEM over conventional PEM. Power To Hydrogen offers a system that delivers high-purity hydrogen, fast dynamic response, and pressure flexibility while reducing capital and operational burdens.

Future Outlook for Electrolysis

By 2030, analysts project the deployment of multi-gigawatt electrolysers across the globe, especially as fossil-fuel-based hydrogen production phases out. Electrolysis is poised to play a leading role in:

  • National hydrogen strategies and government policies across the world
  • Export-focused hydrogen markets
  • Decarbonizing heavy industry and mobility sectors

Cost Reduction Trends

Improvements in membrane conductivity, material durability, and system stability are driving costs down for electrolysers. Government subsidies and large-scale manufacturing are also helping close the price gap between electrolyser systems. Regional credits and hydrogen incentives can further shift project economics. The specifics of these programs change over time and by country. Our team can walk you through current programs in your region and build a path that fits your timeline.

Get Started With Power To Hydrogen Electrolysis Solutions

Looking to integrate electrolysers into your project, but aren’t sure if you need a PEM system or another type of electrolyser? Power To Hydrogen can help. Our hydrogen experts will meet with you to discuss your project needs and provide clear recommendations for the optimal system to achieve your goals. Contact us today to get started.