Proton exchange membrane electrolysis
Proton exchange membrane (PEM) electrolysis is the electrolysis of water in a cell equipped with a solid polymer electrolyte (SPE) that is responsible for the conduction of protons, separation of product gases, and electrical insulation of the electrodes. The PEM electrolyzer was introduced to overcome the issues of partial load, low current density, and low pressure operation currently plaguing the alkaline electrolyzer. It involves a proton-exchange membrane.
| Proton exchange membrane electrolysis | |
|---|---|
Diagram of PEM electrolysis reactions. | |
| Typical Materials | |
| Type of Electrolysis: | PEM Electrolysis |
| Style of membrane/diaphragm | Solid polymer |
| Bipolar/separator plate material | Titanium or gold and platinum coated titanium |
| Catalyst material on the anode | Iridium |
| Catalyst material on the cathode | Platinum |
| Anode PTL material | Titanium |
| Cathode PTL material | Carbon paper/carbon fleece |
| State-of-the-art Operating Ranges | |
| Cell temperature | 50-80°C |
| Stack pressure | <30 bar |
| Current density | 0.6-10.0 A/cm2 |
| Cell voltage | 1.75-2.20 V |
| Power density | to 4.4 W/cm2 |
| Part-load range | 0-10% |
| Specific energy consumption stack | 4.2-5.6 kWh/Nm3 |
| Specific energy consumption system | 4.5-7.5 kWh/Nm3 |
| Cell voltage efficiency | 57-69% |
| System hydrogen production rate | 30 Nm3/h |
| Lifetime stack | <20,000 h |
| Acceptable degradation rate | <14 µV/h |
| System lifetime | 10-20 y |
Electrolysis of water is an important technology for the production of hydrogen to be used as an energy carrier. With fast dynamic response times, large operational ranges, and high efficiencies, water electrolysis is a promising technology for energy storage coupled with renewable energy sources. In terms of sustainability and environmental impact, PEM electrolysis is considered as a promising technique for high purity and efficient hydrogen production since it emits only oxygen as a by-product without any carbon emissions. The IEA said in 2022 that more effort was needed.