A PEM fuel cell (also called a Polymer Electrolyte Membrane fuel cell) is a device that uses hydrogen and oxygen to produce electricity through a chemical reaction. In India’s NaMo Green Rail, it acts as a small onboard power plant to generate electricity for the train’s motors. 

Key Components

The main parts are: Anode: The place where hydrogen enters, Cathode: The place where oxygen enters, Proton-conducting membrane: A special membrane that allows protons to pass through, Catalyst: A substance that helps the chemical reaction happen faster.

Working Principle

• Hydrogen Oxidation: Hydrogen enters the anode and is split into protons and electrons. The protons pass through the special membrane.
• Electricity Generation: The electrons cannot pass through the membrane, so they travel through an external wire. This movement produces electricity to power the train’s motors.
• Water Formation: At the cathode, the protons, electrons and oxygen combine to form water vapour and heat.

Key Features

• Continuous Fuel Supply: Unlike a normal battery, a PEM fuel cell can continuously produce electricity as long as hydrogen and oxygen are supplied.
• Compact and Efficient Design: It is small in size but can produce a large amount of electricity, making it useful for vehicles and other applications.
• Low Maintenance:  It has fewer moving parts than traditional engines, so it generally requires less maintenance and can be refueled with hydrogen.
• Hybrid Energy Storage: In the NaMo Green Rail, PEM fuel cells are combined with high-capacity Lithium Iron Phosphate (LFP) batteries. The fuel cell produces electricity, while the batteries store electricity and provide extra power when needed.
• High-Pressure Refuelling: Hydrogen is stored and refuelled under high pressure, at 350 bar for the train from a 500-bar green hydrogen facility.
• Safety Measures: Leak, flame and heat sensors automatically stop the hydrogen supply if danger is detected. Continuous ventilation prevents hydrogen gas from accumulating.

Applications

• Railway Transportation: In India’s NaMo Green Rail, PEM fuel cells are used to power a hydrogen train. Hydrogen trains can replace diesel trains on non-electrified routes, reducing emissions and supporting India’s Net Zero goals.
• Telecom Towers: During a power cut, PEM fuel cells can provide backup electricity to telecom towers. They start quickly and are cleaner than diesel generators.
• Portable Devices: They can be used to provide electricity for laptops, mobile phones, battery chargers, and drones.
• Backup Power Systems: They provide electricity during power cuts in places where a continuous power supply is important.
• Environmental Significance: The use of hydrogen fuel cells promotes green hydrogen production, hydrogen refuelling infrastructure and clean-energy technologies.