Green Hydrogen

Action on “Green Hydrogen” is heating up following Linde’s announcement of building a 24 MW electrolyser, to start production in second half of 2022. To be located in Germany, this will be the largest Proton Exchange Membrane (PEM) electrolyser in the world overtaking the 20 MW electrolyser recently built by Air Liquide in Canada. In contrast, the largest alkaline water electrolyser, the competing technology for Green Hydrogen, is 10 MW at Fukushima, Japan.

Green Hydrogen is the term used to denote Hydrogen produced by water electrolysis exclusively using renewable power. It is interesting to note that the capacities of electrolysers are stated in terms of power consumed and not Hydrogen produced. This is only appropriate because Hydrogen in this case acts essentially acts as a carrier of energy generated from renewable resources like hydro, solar and wind. Bulk of the Green Hydrogen will be used to power fuel cells, the competitor for batteries, to be deployed in EVs.

Linde’s announcement is also a clear indication that PEM technology is pulling away from the older alkaline water electrolysis. One of the important advantages of PEM electrolyser is that it is much more responsive to fluctuations in power, which is a typical characteristic of renewables like solar and wind. But PEM electrolysers are expensive because they require platinum.

A 3^rd technology, Anion Exchange Membrane (AEM), is rapidly emerging from the shadows. A consortium funded generously by EU is developing this technology, which claims to be cheaper because it operates in alkaline conditions and hence does not need the precious metals used by PEM. At the heart of this technology is a breakthrough development in membranes, which are reshaping and redefining many chemical processes. The developers of AEM technology are targeting to halve the cost of PEM electrolysers.