PEM Water Electrolysis for Green Hydrogen

Splitting water with renewable electricity for zero-carbon fuel

Energy & Battery Technology Commercial Production $3 billion

Overview

Proton exchange membrane (PEM) electrolysis splits water into hydrogen and oxygen using renewable electricity and a solid polymer electrolyte membrane. This technology produces 'green hydrogen' with zero direct CO₂ emissions when powered by wind or solar energy. PEM electrolyzers offer fast response times (seconds), high current density, compact design, and the ability to operate at differential pressure. Global installed PEM electrolysis capacity is growing rapidly from under 1 GW to a projected 100+ GW by 2030.

Chemical Process

Deionized water is fed to the anode side of a PEM electrolyzer cell stack. At the anode, water is oxidized to oxygen, protons, and electrons using an IrO₂ catalyst. Protons migrate through the Nafion membrane to the cathode, where they are reduced to hydrogen gas on a Pt/C catalyst. The process operates at 50-80 degrees C and 30-80 bar, producing hydrogen at >99.999% purity without further purification.

Anode: 2H₂O → O₂ + 4H⁺ + 4e⁻ (oxygen evolution, IrO₂ catalyst)
Cathode: 4H⁺ + 4e⁻ → 2H₂ (hydrogen evolution, Pt/C catalyst)
Overall: 2H₂O → 2H₂ + O₂ (ΔG = +237 kJ/mol, E° = 1.23 V)

Raw Materials

  • Deionized water (H₂O) — Water treatment (Feedstock (only consumed input))
  • Renewable electricity — Wind, solar, hydro (Energy source (50-55 kWh/kg H₂))
  • Nafion membrane (perfluorosulfonic acid) — Chemours/Gore specialty polymers (Proton conductor and gas separator)

End Products

  • Green hydrogen (H₂) — Fuel cells, ammonia, steel, chemicals, energy storage (>99.999% purity, zero-carbon when renewable-powered)
  • Oxygen (O₂) — Medical, industrial, or vented (High-purity byproduct)
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Environmental Impact

Green hydrogen from PEM electrolysis produces zero direct CO₂ emissions. Life cycle emissions depend entirely on the electricity source. Water consumption is approximately 9 liters per kg H₂. The main environmental concern is the use of rare and expensive platinum group metals (Pt, Ir) in catalysts and perfluorinated membrane materials.

Safety Considerations

Recent Innovations

Anion exchange membrane (AEM) electrolysis eliminates the need for iridium and platinum catalysts using non-precious metal catalysts.
Solid oxide electrolysis (SOEC) at 700-850 degrees C achieves higher efficiency by utilizing waste heat.
Direct seawater electrolysis is being developed to eliminate deionization costs.

Production Scale

100000

tons/year

$3 billion

market value

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Frequently Asked Questions

What industry uses PEM Water Electrolysis for Green Hydrogen?
PEM Water Electrolysis for Green Hydrogen is used in the energy & battery technology sector at commercial production scale.
What process is involved in PEM Water Electrolysis for Green Hydrogen?
Deionized water is fed to the anode side of a PEM electrolyzer cell stack. At the anode, water is oxidized to oxygen, protons, and electrons using an IrO₂ catalyst. Protons migrate through the Nafion membrane to the cathode, where they are reduced to hydrogen gas on a Pt/C catalyst. The process oper
What is the economic significance of PEM Water Electrolysis for Green Hydrogen?
PEM Water Electrolysis for Green Hydrogen has a market value of $3 billion and annual production of 100,000 tons.
What is the environmental impact of PEM Water Electrolysis for Green Hydrogen?
Green hydrogen from PEM electrolysis produces zero direct CO₂ emissions. Life cycle emissions depend entirely on the electricity source. Water consumption is approximately 9 liters per kg H₂. The main environmental concern is the use of rare and expensive platinum group metals (Pt, Ir) in catalysts
What raw materials are used in PEM Water Electrolysis for Green Hydrogen?
The main raw materials include: Deionized water (H₂O), Renewable electricity, Nafion membrane (perfluorosulfonic acid).