Designing Efficient Hydrogen Fuel Cell Systems

Image Source: Waewsiri/stock.adobe.com; generated with AI

By Traci Browne for Mouser Electronics

Published May 9, 2025

Hydrogen, the most abundant element in the universe, represents a virtually unlimited energy resource. As sustainability concerns drive innovation in energy technology across many sectors, hydrogen fuel cells are emerging as promising power-generation devices with zero direct emissions.

These electrochemical systems are already powering hydrogen fuel cell electric vehicles (FCEVs) and providing backup power for data centers and hospitals.^[1],[2],[3] Future applications include decarbonizing maritime shipping and aviation as well as integrating with renewable energy systems to stabilize electric grids.^[4],[5]

For electrical design engineers, hydrogen power systems present unique challenges distinct from those of conventional power sources. This article examines hydrogen’s energy cycle, extraction methods, and sustainability implications. It will also explore the principles of proton exchange membrane fuel cells, focusing on the specialized power electronics required to transform their electrical output into usable power for various applications.

Modern Hydrogen Production Technologies

We are surrounded by hydrogen, so how do we capture it and turn it into fuel? Several methods are being used today, from the tried and true to the more innovative. The following are four primary methods of hydrogen production:

• Steam methane reforming (SMR): Natural gas is mixed with high-temperature steam and a nickel catalyst to produce hydrogen and CO₂. This process is efficient and low-cost, but it relies on fossil fuels and emits significant amounts of CO₂.
• Electrolysis: An electric current splits water into hydrogen and oxygen. When powered by renewables, this process produces high-purity hydrogen with zero direct emissions. However, the process is currently expensive.
• Photoelectrochemical water splitting: Specialized semiconductors absorb sunlight and split water. This method is in the research and pilot stages.
• Biological production: Microorganisms produce hydrogen through biological processes. This process could integrate with waste treatment, but it requires controlled environments and is not yet scalable.

While these hydrogen production methods show promise, electrolysis is particularly relevant for electrical engineers because it represents a critical intersection where electrical expertise directly enables green energy transformation. Skills in integrating power systems with renewables, electrolyzer design optimization, and developing advanced membrane technologies and electrocatalysts are essential to making hydrogen a viable cornerstone of our clean energy future.

Advanced Electrolysis Systems for Hydrogen Generation

At its core, electrolysis is a deceptively simple process that has existed for centuries. However, today’s systems have transformed the basic concept into sophisticated technology.

Modern electrolysis systems come in three primary methods, each with its own pros and cons.

• Alkaline systems are cost-effective for large-scale projects but less efficient and slow to respond to power fluctuations.
• Proton exchange membrane (PEM) systems provide higher efficiency and rapid response to power fluctuations, making them ideal for renewable energy integration. Yet, they are more expensive due to precious metal catalysts.
• Solid oxide electrolysis has the highest efficiency and fuel flexibility of the methods, with the potential for synthetic fuel production, but it remains in development.

Currently, PEM systems are the most promising, and research continues to drive costs down and efficiency up. According to the Hydrogen Council, electrolyzer costs fell by approximately 60 percent between 2010 and 2020, and will continue to drop through 2030.^[6]

Having explored how PEM technology splits water to produce hydrogen through electrolysis, we can now examine how the same fundamental principles work in reverse within PEM fuel cells to generate electricity.

Inside PEM Fuel Cell Operation

PEM fuel cells represent a unique convergence of electrochemistry, materials science, and electrical engineering. These electrochemical devices convert hydrogen and oxygen into electricity, heat, and water. PEM fuel cells consist of four main components: anode, cathode, proton exchange membrane, and catalyst layers.^[7]

Engineers often describe the structure as a sandwich. Figure 1 shows this essential arrangement.

Figure 1: PEM fuel cell. (Source: Gregory/stock.adobe.com)

The operating principle is as follows:

1. Pressurized hydrogen gas enters the fuel cell on the anode side and contacts the platinum catalyst.
2. The hydrogen molecule splits into protons and electrons.
3. Protons pass through the membrane, while electrons travel through an external circuit, creating an electric current.
4. Oxygen molecules at the cathode undergo a reduction reaction by gaining electrons that traveled through the external circuit.
5. These oxygen atoms combine with the protons and electrons to form water.

Ideally, this process occurs in a cell stack, which manufacturers then integrate into a complete system with fuel, water, air management, and coolant control hardware and software.

Understanding these principles is essential for electrical engineers working on power systems when designing applications such as backup power solutions, microgrids, and clean energy systems. Key challenges include optimizing efficiency, managing water production, and reducing costs related to the platinum catalyst.

While understanding the electrochemical principles of PEM fuel cells is necessary, their practical implementation requires sophisticated power electronics to convert the cell’s electrical output into usable power.

Critical Electronics in Fuel Cell Applications

Power electronics convert low-voltage, high-current output into usable power while addressing challenges such as transient response dynamics and unidirectional current flow.

DC-DC boost converters are essential for stepping up the cell output voltage to levels suitable for applications such as automotive systems and residential power. These converters use advanced configurations, including interleaved designs, to enhance efficiency and manage high current levels. They often leverage wide bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) to capitalize on their higher switching frequencies and improved thermal performance, which are critical in managing operational temperature profiles and enhancing power density.

In scenarios that require AC output, such as motor drives or grid connections, engineers typically employ a two-stage conversion process of an initial boost converter stage followed by a robust inverter. The design of grid-tied systems needs sophisticated synchronization controls to adhere to interconnection standards and to ensure stability against grid disturbances.

Energy storage integration through components like batteries or supercapacitors is crucial for managing load fluctuations and enhancing overall system resilience. Advanced energy management algorithms, such as adaptive control and predictive modeling, are needed to optimize the interaction between fuel cells, storage devices, and load demands and maximize system efficiency and component lifecycle.

Introducing a hierarchical control system is necessary because fuel systems need both split-second responses at the component level and coordination of the entire system to work properly. The low-level controllers make quick decisions about power conversion and keep individual components running smoothly. Meanwhile, the high-level controller manages heat across the system, spotting problems before they become serious and ensuring all parts work together efficiently.

When designing power electronics for fuel cell systems, engineers must prioritize key performance metrics such as efficiency, thermal management, and protection against issues like reverse currents and electromagnetic interference (EMI). These advanced design considerations enable fuel cells to effectively contribute to applications ranging from portable electronics to automobiles and the grid.

Although optimized power electronics are essential components, they represent just one piece of the integration puzzle. A complete fuel cell system requires coordinated interaction between multiple subsystems.

System Integration Challenges

The true engineering challenge in designing a hydrogen fuel cell system lies in creating a harmonious system where thermal, fluid, mechanical, and electrical subsystems work together. Temperature must be maintained within a narrow 50–80°C band, with cooling systems that respond intelligently to dynamic load conditions.^[8]

Hydrogen must arrive at precise pressure, flow rate, and purity levels. Automotive systems typically store hydrogen at 700 bar, which allows more fuel to be stored in a small space. However, that pressure needs to be dropped down to just 1–2 bar at the stack for efficient operation and to prevent damage from excessive pressure.^[9] The purity levels are important because even parts-per-million levels of contaminants can degrade catalysts.

Another challenge is the balance of plant (BOP) components that make up a significant portion of the overall system cost, often exceeding 50 percent.^[10] BOP components are all the auxiliary systems beyond the fuel cell stack itself that are required to make the fuel cell stack work properly. They include essential equipment such as air compressors, humidifiers, water management systems, sensors, and controllers. Proper sizing of these components is crucial to minimize parasitic losses and ensure efficient operation.

Finally, these modern fuel cell systems employ advanced diagnostic techniques and machine learning algorithms to predict maintenance needs and optimize performance. They can predict failure modes from membrane dehydration to catalyst poisoning.

Future Developments and Opportunities

The hydrogen fuel cell landscape is rapidly evolving, with innovations addressing current limitations through advancements in materials and manufacturing techniques. Researchers are developing alternatives to reduce precious metal content, while digital technologies enhance system performance through advanced control systems and data analytics.

Economy of scale, material improvements, and design optimizations will drive cost reductions, further expanding hydrogen fuel use to areas such as data centers, telecommunications, and maritime propulsion.^{[11],[12],[13]}

Electrical engineers are pivotal in advancing this technology by developing efficient power electronics, optimizing system integration, and driving innovation in materials science and digital controls. As fuel cells expand into new applications, engineers have an incredible opportunity to shape a truly sustainable energy future.

Sources

[1]https://www.toyota.com/mirai/
[2]https://www.datacenterfrontier.com/design/article/11427183/rethinking-the-data-center-hydrogen-backup-is-latest-microsoft-moonshot
[3]https://www.power-eng.com/hydrogen/kohler-and-toyota-partner-on-hydrogen-fuel-cell-for-us-hospital/
[4]https://www.airbus.com/en/innovation/energy-transition/hydrogen
[5]https://www.energy.gov/eere/fuelcells/articles/h2iq-hour-integrating-hydrogen-tech-and-grid-enable-efficient-and-stable
[6]https://hydrogencouncil.com/wp-content/uploads/2020/01/Path-to-Hydrogen-Competitiveness_Full-Study-1.pdf
[7]https://www.fuelcellbuses.eu/wiki/fuel-cells-hydrogen-and-fuel-cells/4-components-pem-fuel-cell
[8]https://www.energy.gov/eere/fuelcells/types-fuel-cells
[9]https://www.energy.gov/eere/fuelcells/hydrogen-storage
[10]https://www.nrel.gov/docs/fy24osti/87625.pdf
[11]https://www.plugpower.com/blog/hydrogen-fuel-cells-in-data-centers-a-clean-energy-revolution/
[12]https://fuelcellsworks.com/2025/01/22/clean-energy/fallback-friday-story-powercell-group-and-partners-deploy-hydrogen-fuel-cell-backup-power-at-telia-mobile-base-station
[13]https://energy.sandia.gov/programs/sustainable-transportation/hydrogen/fuel-cells/maritime-applications/