SIBANYE-Stillwater said new technology for hydrogen electroysis had been developed potentially reducing reliance on the scarce platinum group metal (PGM) iridium in favour of its more plentiful sister metal, ruthenium.
The technology – a ruthenium-based catalyst for Proton Exchange Membrane (PEM) water electrolysis – was developed by Heraeus, a German company that refines PGM concentrate as well as recycling PGMs. Heraeus and Sibanye-Stillwater first teamed in August last year to co-fund over three years technology that, if successful, would be mutually commercialised.
Hydrogen-powered fuel cells use a chemical process in which energy is created by splitting water into hydrogen and oxygen. To split the hydrogen atom, however, requires an electrolyser and energy itself. For green hydrogen to happen, this energy has to be renewable power.
According to the Hydrogen Council — a group of about 150 companies across the hydrogen value chain — green hydrogen capacity of some 175 gigawatts (GW) is expected by 2030. Of this, 40% is expected to be produced using PEM electrolysis which would consume the major portion of 300,000 ounces in annual iridium production.
a technology dependent on iridium, an element in extremely limited supply. With only about nine metric tons of iridium mined annually and widespread utilization in various industries, supply bottlenecks are imminent – unless solutions are implemented that reduce the amount of iridium used in the PEM application.
At this rate, a huge scarcity premium would be placed on iridium, making its adoption expensive for original equipment manufacturers and ultimately unsustainable.
Currently, approximately 400 kilograms (14,109 oz) of iridium is required to build one GW of capacity. A reduction to less than 100kg (3,527 oz) per GW is necessary to avoid supply bottlenecks. The ruthenium-based catalyst can enable an 85% saving on iridium compared to an iridium oxide catalyst, alleviating the potential supply concerns. Primary production of ruthenium is 3.5 times that of iridium, said the group.
“As the largest producer of primary iridium globally, we firmly believe that sustainable demand of these metals, with supply in mind, is beneficial for the entire industry,” said Neal Froneman, CEO of Sibanye-Stillwater.
“The commendable progress achieved by Heraeus in their work to date is encouraging, and we highly value our partnership in this endeavor,” he said.
