2023-06-16 11:20:24
On the Air Liquide premises there is an electrolyser for the production of green hydrogen.
Image: Lucas Bäuml
Green hydrogen should enable the energy transition. But under the current conditions, electrolysers can hardly be operated economically. How can it be possible to increase their efficiency?
Grune hydrogen is considered one of the central pillars of the energy and climate transition. In order to achieve the global climate goals, the world needs according to an estimate by the International Energy Agency (IEA) around 34 megatons of the gas in 2030, produced by the electrolysis of water using excess wind and solar power. Last year, however, just 109 kilotons were produced. The main obstacle to electrolysis systems in the megawatt range are the high production costs, which are currently seven euros per kilogram of hydrogen. That’s about twice that of gray hydrogen, which is usually derived from fossil fuels such as natural gas or coal. The latter accounts for 98 percent of the hydrogen currently produced worldwide and is responsible for two percent of global carbon dioxide emissions.
There are currently two electrolysis technologies on the market: PEM and alkaline electrolysers. The former use a solid, semi-permeable proton exchange membrane made of the perfluorinated polymer Nafion to split the water molecules, which takes place at the anode. This is for hydrogen ions (H+), which migrate to the cathode, permeable. In alkaline electrolysers, on the other hand, it is the hydroxide ions (OH–) that traverse the aqueous, alkaline electrolyte. Both designs have their advantages and disadvantages.
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