Hydrogen Electrolyser Stack Development: From Inception to Innovation 

In the dynamic landscape of renewable energy, the development of hydrogen electrolyser stacks has become an important element in the quest for sustainable energy solutions. These stacks, the heart of hydrogen electrolysis systems, serve as central components for producing high-purity hydrogen gas, which is integral to various industries, including transportation, industrial processes, and energy storage. In this article, we dive into the intricate world of hydrogen electrolyser stack development, aiming to provide insight for executives from engineering companies that manufacture electrolysers using stacks. 

If you are a decision maker in an engineering company looking to become a Hydrogen Stack integrator our latest guide will be a high-value asset. Download the guide here and ensure you will make informed decisions to achieve optimal efficiency. 

In the guide you will learn: 

• How to define the ideal technology. 
• What makes a good hydrogen stack? 
• Specifications of the ideal BOP configuration. 
• Electrolyser components. 
• Economic considerations. 
• Achieving optimal cost-efficiency. 
• Building your integration team. 
• Certifications & Safety. 
• A successful stack integration project: the Rockfin case study. 

The Evolution of Hydrogen Electrolyser Stacks 

The concept of hydrogen production via electrolysis dates back to the early 19th century. Sir Humphry Davy's experiments with water electrolysis in 1800 laid the foundation for understanding the principles of separating water into its constituent elements: hydrogen and oxygen. However, the development of electrolyser stacks as we know them today took time to evolve. 

Early Stacks: Simple Beginnings 

The first electrolyser stacks were rudimentary in comparison to modern iterations. They typically consisted of a series of simple electrodes immersed in an electrolyte solution within a vessel. When a direct current was applied across the electrodes, water molecules would dissociate into hydrogen and oxygen gas, with each gas evolving at opposite electrodes. These early designs had limited efficiency and scalability, making them unsuitable for large-scale hydrogen production. 

Advancements in Electrode Materials 

As the field of electrochemistry matured, so did the materials used in electrolysis stacks. The first significant breakthrough came with the discovery of efficient electrode materials. Carbon and platinum electrodes were replaced by more cost-effective and durable alternatives, such as titanium-coated electrodes and iridium oxide-based catalysts. These innovations improved the longevity and efficiency of electrolysis stacks. 

Another key milestone in Hydrogen Electrolyser Stack development was the introduction of bipolar plate technology. Bipolar plates are designed to conduct electricity between adjacent cells in a stack while simultaneously acting as gas distribution channels. This innovation significantly enhanced the structural integrity of electrolyser stacks and improved gas flow within the cells. 

Main technologies available 

Proton Exchange Membrane Electrolysers (PEM) 

The introduction of proton exchange membrane (PEM) technology in the latter half of the 20th century marked a transformative phase in stack development. PEM electrolyser stacks use a solid polymer electrolyte membrane, typically composed of a perfluoro sulfonic acid material, to separate the hydrogen and oxygen evolution reactions.  

PEM technology offers advantages, including compactness, fast start-up and efficiency. Due to its compactness, PEM electrolyser is most suitable for small-scale applications. Nonetheless, PEM systems are relatively expensive due to the need for precious metal catalysts, such as platinum and iridium, and are sensitive to impurities in the feedstock. 

Alkaline Electrolyser Stacks 

Parallel to PEM technology, alkaline electrolyser stacks also underwent significant improvements. These stacks use a potassium hydroxide (KOH) electrolyte solution, providing a cost-effective alternative to PEM technology. Advancements in electrode materials and engineering design have made alkaline electrolysis an attractive choice for large-scale hydrogen production. You can read more about the science behind Alkaline Electrolysis in our article: Unveiling the Science Behind Alkaline Electrolysis 

 As one of the earliest methods, Alkaline Electrolysis showcases robustness and reliability in hydrogen production. Utilizing cost-effective materials and an alkaline electrolyte solution, this technology offers a compelling cost advantage over other methods. Its straightforward design makes it an economically sound choice for industries seeking a reliable and proven approach to hydrogen generation. 

AEM Electrolysis 

Similar to PEM, utilizes a polymer membrane, but in this case, it permits the transport of negatively charged ions. AEM technology seeks to mitigate the high cost associated with PEM systems while maintaining some of their advantages, like operational flexibility and efficiency. AEM Electrolysis can be more tolerant of impurities, but challenges remain in developing scalable, stable and durable membranes capable of conducting anions effectively. 

Solid Oxide Electrolysis 

SOEC operates at high temperatures, improving reaction kinetics and enhancing process efficiency. Additionally, the high operating temperatures allow for the utilization of waste heat from industrial processes or other sources, increasing the overall energy efficiency of hydrogen production. But the technology is still in development and struggling with reaching multi-megawatt scale. 

Key takeaways about technology 

For a highly reliable, large-scale, Hydrogen Electrolyser Stack where cost-effectiveness is paramount, Alkaline Electrolysis might be preferred. PEM Electrolysis suits applications requiring compactness, but that comes with a cost and uncertainty on long-term use. AEM Electrolysis is an evolving technology seeking to bridge the cost-efficiency gap between Alkaline and PEM systems, suitable for medium-scale applications but its track record is limited. Finally, SOEC technology's efficiency in high-temperature processes and adaptability makes it an intriguing option and could in the future unveil new opportunities as the landscape evolves. 

 
The Modern Hydrogen Electrolyser Stack 

While Proton Exchange Membrane (PEM) electrolysis has garnered considerable attention in recent years, it's worth highlighting the importance of Alkaline Electrolysis stacks, particularly for engineering companies engaged in electrolyser manufacturing. Alkaline electrolysis represents a robust and cost-effective approach to hydrogen production, and modern Alkaline Electrolyser Stacks have undergone significant advancements to meet the demands of various industrial applications. 

Modern Alkaline Hydrogen Electrolyser Stacks maintain a modular design, consisting of multiple cells with anodes, cathodes, and an electrolyte solution, typically potassium hydroxide (KOH). The modular nature of these stacks ensures flexibility, making it feasible to adjust the number of cells to match specific hydrogen production requirements, from small-scale applications to large industrial processes. 

Stargate’s Stacks can produce high-purity hydrogen gas, meeting stringent quality standards, and making them suitable for applications requiring exceptionally pure hydrogen. 

In Alkaline Electrolysis, materials are carefully selected to withstand the corrosive environment created by the KOH electrolyte. Electrodes in modern stacks are often constructed from high-quality materials such as coated titanium or stainless steel, ensuring longevity and sustained performance. Moreover, advanced catalyst materials enhance the efficiency of the hydrogen evolution reaction.  The technology has been validated by several research institutions including the Fraunhofer Institute and the University of Tartu.

That is the case of Stargate Hydrogen that a developed completely new class of electrolysers: ceramics-based alkaline Hydrogen Electrolyser Stack, that have high current densities, and high efficiencies, yet contain no precious metals. This results in significantly lower hydrogen production costs and makes the electrolysers affordable for the end-users. 

Efficiency remains a critical focus in Alkaline Electrolysis stack development. These modern stacks have been engineered to achieve higher electrical-to-hydrogen conversion efficiencies, making them more competitive with other hydrogen production methods. Alkaline Hydrogen Electrolyser Stacks offer the advantage of operating smoothly even at partial loads, ensuring a consistent supply of hydrogen, particularly in applications where power generation can fluctuate. 

To meet the demands of the digital age, Alkaline Electrolyser Stacks are now equipped with advanced monitoring and control systems. These systems enable remote monitoring of stack performance, real-time adjustments, and predictive maintenance, which ultimately reduces downtime and ensures optimal operation. 

Safety Features 

Safety is a paramount consideration in the design of Hydrogen Electrolyser Stack. Multiple safety features are integrated into the stack design to prevent and mitigate potential hazards, ensuring that the production process remains secure and reliable. Additionally, modern stacks are designed to withstand a wide range of operating conditions, including variations in temperature and humidity, adding an extra layer of safety to the system. You can read more about safety features on our article: Hydrogen Safety: Addressing Concerns and Best Practices 

Integration with Renewable Energy Sources 

As the trend towards renewable energy integration continues, modern Alkaline Electrolyser Stacks have been developed with an eye towards compatibility with various renewable power sources. This integration aligns with the broader goal of sustainable hydrogen production by utilizing surplus renewable energy to drive the electrolysis process. 

Key Considerations for Alkaline Hydrogen Electrolyser Stack Development 

For decision-makers in engineering companies considering Alkaline Electrolyser Stacks for hydrogen production, it's important to keep the following factors in mind: 

• Application Suitability: Alkaline Electrolysis stacks are particularly well-suited for applications where cost-effectiveness, steady performance, and safety are essential. Understanding the specific requirements of the intended application is crucial in selecting the appropriate stack technology. 

• Scalability: Alkaline Electrolyser Stacks can be readily scaled to meet varying hydrogen production demands. Evaluating the scalability options offered by stack manufacturers is vital for accommodating diverse customer needs. 

• Regulatory Compliance: Meeting safety and environmental regulations is a non-negotiable aspect of hydrogen production. Engineering companies must ensure that the Hydrogen Electrolyser Stack adheres to industry standards and safety requirements. 

• Integration with Renewable Energy: Leveraging surplus renewable energy sources for hydrogen production is a sustainable practice. Careful consideration of how Alkaline Electrolyser Stacks can interface with renewable power systems is crucial for reducing the carbon footprint of the hydrogen production process. 

• Maintenance and Support: Access to reliable maintenance and support services is essential for the long-term performance of Alkaline Electrolyser Stacks. Choosing a manufacturer that offers comprehensive service and support can be a strategic decision for engineering companies. 

What Makes a Good Hydrogen Electrolyser Stack? 

Understanding the nuances of a superior hydrogen stack is crucial in establishing an efficient and reliable hydrogen production system. This efficiency is expressed through the electrical-to-chemical energy conversion ratio. 

• Durability: A longlasting stack is paramount for commercial applications. A good stack must exhibit stable performance over long lifetime ensuring a predictable and reliable rate of hydrogen production. 
   
• Robustness Is a key factor, considering the demanding conditions hydrogen stacks face, the ability to withstand these conditions over a wide window of operation over an extended period of time without significant degradation is essential in a quality stack. 
   

• Flexibility Is a crucial feature for industries with fluctuating hydrogen demands. An ideal Hydrogen Electrolyser Stack should offer scalability to meet changing production needs without requiring excessive modifications. 
   
• Safety: It is of utmost importance in any hydrogen production process. A reliable stack should incorporate safety features, including robust seals to prevent gas leaks or potential hazards. 
   
• A low-maintenance: It is highly desirable, reducing downtime and operational costs.  
  An effective stack design should minimize the need for frequent servicing and part replacements. 

Main Takeaways 

The evolution of hydrogen electrolyser stack development has been a remarkable journey, from the simple electrodes of the past to the highly efficient and versatile stacks of today. If you are a decision maker in an engineering company focused on electrolyser manufacturing, understanding the science and engineering behind these stacks is essential to making informed decisions about product selection and integration. 

The modern hydrogen electrolyser stack is a testament to scientific innovation and engineering excellence. These stacks play a crucial role in the production of high-purity hydrogen, contributing to the growth of hydrogen-based technologies across diverse industries. With a focus on efficiency, safety, and integration with renewable energy sources, these stacks are set to drive the future of sustainable hydrogen production. 

In an ever-changing energy landscape, staying informed about the latest developments in hydrogen electrolyser stack technology is paramount. As a trusted partner in the journey towards a sustainable future, we remain committed to providing cutting-edge solutions that empower engineering companies to thrive in this exciting era of hydrogen energy. Stargate Hydrogen has vast expertise in stack development, making them the ideal partner to collaborate to achieve sustainability goals.