Hydrogen Fuel Cells and their Components

Hydrogen Fuel Cell Overview

  • Definition: A hydrogen fuel cell converts hydrogen and an oxidant into electricity and heat.

Key Components of a Proton Exchange Membrane Fuel Cell

  • Anode: Receives hydrogen; a platinum catalyst splits hydrogen into protons and electrons.
  • Cathode: Receives oxidant; combines protons, electrons, and oxygen to produce water.
  • Polymer Electrolyte Membrane (PEM): Allows only protons to pass to the cathode; blocks electrons.
  • Membrane Electrode Assembly (MEA): Comprises membrane, catalyst layers, and gas diffusion layers (GDLs).

Functionality of Fuel Cells

  • Electricity Generation: Electrons travel through an external circuit, creating electrical current.
  • Heat Production: Generates heat as a by-product during the reaction.
  • Continuous Operation: Operates as long as fuel is supplied; does not require recharging.

Parts of a PEM Fuel Cell

  • Catalyst Layers: Nanoparticles of platinum that facilitate reactions at both electrodes.
  • Gas Diffusion Layers (GDL): Enhance reactant transport and manage water production.
  • Bipolar Plates: Connect MEAs in series; provide structural support and gas flow channels.
  • Gaskets: Ensure gas-tight seals between MEAs and plates to prevent leaks.

Fuel Cell Types

  1. Proton Exchange Membrane (PEM): High power density, low temperature, ideal for vehicles.
  2. Phosphoric Acid: Commercially developed, efficiency >40%.
  3. Molten Carbonate: High fuel-to-electricity efficiency, coal-compatible.
  4. Solid Oxide: 60% efficiency, suited for large applications.
  5. Alkaline: 70% efficiency, costly for transport.
  6. Direct Methanol: 40% efficiency, low operating temperature.
  7. Regenerative: Uses solar energy for hydrogen generation.

Efficiency Comparisons

  • Fuel cells: 40-70% efficiency.
  • Internal combustion engines: Up to 30% efficiency.

Key Takeaways

  • Hydrogen fuel cells are a clean energy source with a variety of applications, particularly in transportation.