What do you put in a hydrogen fuel cell?
Hydrogen fuel cells run on hydrogen gas as the fuel and oxygen from the air as the oxidant, harnessing an electrochemical reaction to produce electricity, heat, and water. In practice, reliable operation also hinges on clean, high-purity inputs, proper humidity management, and safety systems.
The basic inputs for PEM hydrogen fuel cells
In proton exchange membrane (PEM) fuel cells—the type most common in vehicles and many portable/stationary applications—the cell relies on two gas streams and moisture management to function effectively. The following inputs are essential for typical PEM operation.
- Hydrogen fuel: high-purity hydrogen gas supplied from storage tanks, reformers, or on-site generation
- Oxidant: oxygen supplied by ambient air or a separate oxygen stream
- Humidity control: properly humidified hydrogen and air to keep the polymer electrolyte membrane hydrated and conductive
- Pressure and flow control: regulated pressure and precise flow rates to ensure adequate reactant delivery and prevent starvation or flooding
- Purity and contaminants control: removal of impurities such as CO, sulfur compounds, siloxanes, and particulates that can poison catalysts
- Thermal and water management: cooling and water handling to dissipate heat and maintain appropriate membrane moisture
Conclusion: For PEM fuel cells, the core inputs are hydrogen and oxidant, with careful humidity, purity, and thermal management to sustain performance and longevity.
Inputs by fuel-cell technology
Not all hydrogen fuel cells use exactly the same feedstocks. The two most common technologies differ in what they can accept as inputs and how they manage heat and reforming.
Proton exchange membrane (PEM) fuel cells
PEM cells require clean hydrogen and an oxidant (air or pure oxygen). Hydrogen is typically delivered as a compressed gas or as a reformate gas from a reformer, and the air is filtered and humidified to maintain membrane conductivity. Humidity control, purity, and precise gas handling are critical to performance and durability at the modest temperatures they operate (roughly 60–80°C).
Solid oxide fuel cells (SOFC)
SOFCs operate at much higher temperatures (compared with PEM) and can run on hydrogen-rich gas or reformed hydrocarbon fuels (such as natural gas or biogas) after preprocessing to remove sulfur and other poisons. The oxidant is still oxygen from air (or pure O2). Fuel conditioning and reforming play a larger role in inputs for SOFCs, and thermal management is a central design concern due to the high operating temperature.
Practical considerations for inputs and operation
Beyond the raw inputs, several practical factors determine how a hydrogen fuel cell is fed and managed in real systems. Gas purity, moisture, pressure, and safety controls all influence efficiency, durability, and reliability. Emerging supply chains and infrastructure for green hydrogen—generated via water electrolysis using renewable energy—are shaping how these inputs are sourced and managed in different applications.
Safety is paramount: hydrogen leaks are odorless and highly dispersive, so systems include leak detection, ventilation, and robust shutoff mechanisms. Standards bodies and manufacturers provide guidelines on acceptable purity levels, gas testing, and maintenance schedules to prevent catalyst poisoning and degradation over time.
Summary
To operate a hydrogen fuel cell, you feed it hydrogen fuel and an oxidant such as oxygen from air, along with carefully managed humidity and clean, regulated gas streams. The exact inputs depend on the cell type—PEM cells emphasize ultra-pure hydrogen and humidified air, while SOFCs can accommodate hydrogen-rich fuels and require reforming and thorough fuel conditioning. Across technologies, purity, moisture management, proper pressure/flow, and safety systems are the key factors that determine performance and longevity.
What is the biggest problem with using hydrogen in a fuel cell?
For all the many advantages of hydrogen fuel cells, there are still a few disadvantages and challenges to address:
- Hydrogen Extraction.
- Investment is Required.
- Cost of Raw Materials.
- Regulatory Issues.
- Overall Cost.
- Hydrogen Storage.
- Infrastructure.
- Highly Flammable.
How do you refuel a hydrogen fuel cell?
Hydrogen fuel cells are not recharged in the same way as batteries; instead, they are refueled with hydrogen, which is supplied to the fuel cell to produce electricity continuously. The process is similar to filling a gas tank, where a fuel-cell electric vehicle (FCEV) connects to a hydrogen station with a pump and nozzle to fill its onboard hydrogen tanks with compressed gas. The fuel cell continues to generate power as long as a supply of hydrogen and air is provided.
- Refueling process: Refueling a hydrogen fuel cell vehicle involves using a special pump at a hydrogen station to fill the vehicle's high-pressure hydrogen tanks.
- Continuous operation: Unlike a rechargeable battery, a fuel cell does not need to be recharged. It produces electricity through a continuous chemical reaction as long as it receives a fuel source, which is hydrogen.
- How it works: In the fuel cell, hydrogen is fed to one side and oxygen (from the air) to the other. A catalyst splits the hydrogen into protons and electrons. The electrons travel through an external circuit to create electricity, while the protons pass through a membrane to reunite with the electrons and oxygen to form water.
Is hydrogen fuel cheaper than gasoline?
No, hydrogen fuel is currently more expensive than gasoline on a per-unit-of-energy basis, although its cost per mile can be comparable due to the higher fuel efficiency of hydrogen vehicles. However, the high cost of hydrogen is a major barrier to adoption, with current retail prices being significantly higher than gasoline prices in most markets. Future cost reductions are predicted as production scales up, but significant challenges remain in infrastructure and production costs.
Current cost comparison
- Higher per-unit cost: A kilogram of hydrogen costs significantly more than a gallon of gasoline, which is reflected in the higher price per unit of energy.
- Comparable cost per mile: Despite the higher per-unit cost, hydrogen fuel cell vehicles (FCVs) are about 2.5 times more efficient than gasoline engines, making the cost per mile potentially similar to that of gasoline cars.
- Market challenges: The current high cost of hydrogen is due to production and infrastructure challenges, including a lack of price transparency and a lack of market competition.
Future outlook
- Predicted cost reduction: Proponents believe that as production volumes increase, the cost of hydrogen will decrease, making it more competitive with gasoline.
- Government and industry efforts: The U.S. Department of Energy and other organizations are working to reduce the cost of hydrogen fuel through initiatives like the Earthshots program.
- Potential to be competitive: With advancements in technology and increased economies of scale, it is possible that hydrogen fuel could become cost-competitive with gasoline in the future.
Key factors to consider
- Efficiency: The higher efficiency of FCVs is a key factor in making them cost-competitive with gasoline vehicles on a per-mile basis.
- Infrastructure: The limited availability of hydrogen fueling stations is a major challenge to adoption, and building out this infrastructure will be a significant undertaking.
- Production cost: The cost of producing hydrogen is currently high, but experts believe that it could decrease significantly in the coming years as production scales up.
What goes into a hydrogen fuel cell?
A fuel, such as hydrogen, is fed to the anode, and air is fed to the cathode. In a hydrogen fuel cell, a catalyst at the anode separates hydrogen molecules into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity.
