[ recycling ]
Fig . 2 . Cost breakdown in percentage for a PEM fuel cell ( single-stack components ) in mass production ( 10,000 units per year )
are the state-of-the-art electrocatalysts . Depending on the exact type of PEM system , customer demands , and scalability of the production process , the PGM component typically contributes 30 – 60 % of the total membrane electrode assembly ( MEA ) cost ( Figure 2 ). 4
Based on the power generation from one gram of PGMs ( U . S . DOE 2017 record ) of 8.75 kW / g , around 289 tons of PGMs are required to meet the total annual electricity demand . 5 This accounts for nearly half of the total global annual PGM consumption . Such demand is unrealistic to keep up with the expansion of the renewable energy market , increasing electricity demand , depletion of mineral reserves and rising market price of the elements , UNLESS contribution from a secondary resource – recycling – is considered .
Rich PGM content ( mainly platinum , ruthenium and iridium ) in MEA of PEMFCs
& ECs presents a high-quality , highconcentration PGM resource , which is around 10 times that of autocatalyst and 1,000 times that of primary ore . 6 Moreover , large-scale deployment of PEMFCs & ECs will accelerate in the coming years .
Current PGM recycling technology
State-of-the-art technology for autocatalyst recycling involves a pyrometallurgical process ( Figure 3 ) operating at temperatures over 1,500 ° C , followed by a series of refinery steps . 7 After nearly 50 years of operation , the route is well established and efficient . However , the technology is used by very few specialized industrial cooperations . Moreover , huge energy consumption , large initial investment , high requirement for operation and maintenance , long processing / queuing period , and health and environmental risks due to off-gas are major concerns and strong motivations for improvements or alternative technologies .
Hydrogen Tech World | Issue 7 | December 2022 29