Advanced catalysts and membranes were developed in the first period of the HPEM2GAS project by CNR-ITAE and Solvay, respectively. Short-side chain (SSC) perfluorosulfonic acid (PFSA) Aquivion® membranes and ionomers were developed and scaled up for this application. Utilizing a nanosized Ir0.7Ru0.3Ox solid solution anode catalyst and a supported Pt/C cathode catalyst, in combination with the Aquivion® membrane, gave excellent electrolysis performances exceeding 3.2 A·cm-2 at 1.8 V terminal cell voltage (~80% efficiency vs. HHV at cell level) at 90 °C. A degradation rate as low as 8 μV/h after 4,000 h operation at 3 A cm-2 at 80 °C was recorded at cell level. Stack development activities at ITM produced an efficient and compact design. The novelty of the stack design developed in HPEM2GAS lies in the gas generation part of the stack being de-coupled from ancillary services with a unique single acting hydraulic cylinder providing compression to the stack. In the second period, advanced ITM 75 cells stack, equipped with 415 cm2 active area MEAs produced by IRD, was assembled and tested.
Stack and electrolyser assessment was carried out by ITM in the second phase. Hydrogen production capacity of about 80 kg/d was demonstrated for the system at 3 A cm-2. Best efficiency at system level of 72 % vs HHV H2 was achieved at 3 A cm-2, at an operating temperature of 55°C. Differential pressure operation was demonstrated for the novel stack geometry at 20-50 bar across a wide range of the load curve.
The electrolysis plant was subjected to field-tests in Emden (Germany). The proof-of-concept of power-to-gas for the injection of the produced electrolytic hydrogen into the local gas grid was demonstrated. Regarding the exploitable results, the consortium included developers of materials, components and devices for PEM electrolysers and an end-user (SWE) that is involved in the supply of renewable power, especially from wind plants. Exploitable knowledge regarded in particular: the scaling-up and optimization of PEM electrolysis components, advanced stack design, coatings and cost effective bipolar plates, innovative compact PEM electrolysis system for grid-balancing service.
Regarding the project communication and dissemination, the public website was organised to inform interested stakeholders, as well as the general public of ongoing and finalised project activities. This also occurred through flyers, newsletters and technical project publications.
