Periodic Reporting for period 3 - PROMET-H2 (Cost-effective PROton Exchange MEmbrane WaTer Electrolyser for Efficient and Sustainable Power-to-H2 Technology)
Berichtszeitraum: 2023-04-01 bis 2024-03-31
The need for de-carbonization of our society is a pressing issue raising the attention at social and political levels. The production of high value chemicals and fuels such as methanol requires hydrogen derived at the moment from hydrocarbons and resulting in large emissions of CO2. Green Hydrogen produced by water electrolysis coupled to renewable sources could be the ultimate solution to this problem. Proton exchange membrane water electrolysis (PEMWE) is the most suitable technology for this process due to its compactness and flexibility. However, the dependence on precious metal catalysts and expensive components manufactured in titanium poses a serious threat for the scale up and market penetration of this technology. PROMET-H2 project aims to develop a pressurized PEMWE with the lowest capital cost ever achieved. The main objective of PROMET-H2 project is to decrease the capital cost of the PEMWE from 1000-1500 €/kW to 500-700 €/kW without compromising its performance and durability, and replacing noble metals with others that are more benign from an environmental and economic point of view. The main ambition in PROMET-H2 is to place PEMWE as the technology of choice for production of H2 for storing renewable energy and being a competitive alternative for large scale storage, by maintaining a balance between economic/costs and environmental aspects. PROMET-H2 overall ambition will be tackled by i) developing advanced materials, including CRM-free catalysts, ii) coatings for stainless steel PTL and BPP, iii) thin membranes to reduce PEMWE cost without affecting the current KPIs performance and durability and iv) by using new stack designs to obtain more efficient PEMWE being able to reduce the system and process costs. Conclusions. PROMET-H2 has developed a PEMWE stack with a reduction in the capital costs and CRM, the significantly reduced use of critical raw materials will mitigate the limitation of material availability for the large-scale deployment of water electrolysis. CCMs with low Ir loading based on Ir on ATO have been developed achieving project target 2 Acm-² at 1.9 V with 0.2 mgIrcm-² with 1000h stable operation. Stainless steel as base material for manufacturing PTL has successfully developed. The reduction in use of CRMs is further strengthened by developing versatile and environmentally friendly recycling procedures using hydrometallurgical process, recovery rates (100% Pt, 60% Ir). In addition to the materials development, PROMET-H2 has developed a tool for testing locally the homogeneity in the current density distributions and temperatures at stack level.
Highly efficient and durable membrane electrode assemblies have been developed by integrating novel electrocatalysts with low CRM materials and will impact the next generation of components for PEM electrolysers. The tested CRM-free electrodes showed promising performances but unfortunately far away from the CRM-based catalysts. Thus, PROMET-H2 has decided to focus on the CRM drastic reduction route. Two promising candidates were selected for the OER: Iridium deposited on antimony tin oxide (ATO) (CENMAT) and the Ir mixed oxide (CSIC). DLR developed an MEA with 0.2 mgIrcm-2 in the anode using Ir mixed oxides (Sr2CaIrO6 perovskite), with a cell voltage of 1.81 V at nominal current density of 2 Acm-2, the performance full fill PROMET-H2 targets with a successful 1000 h long-term test at constant 2 Acm-2 demonstrated the Ir content in the MEA can be drastically reduced without compromising performance or durability. In parallel FZJ measured similar performances with 0.2 mgIrcm-2 using Ir-ATO (CENMAT). The activation at MEA level and scalability potential were the arguments for PROMET-H2 to selected the Ir-ATO for producing the MEAS at stack level. Chemours continued with the development of novel membranes (80 µm thickness) showed remarkably lowered H2 cross-over (ca. 0.2% H2 in O2) and was able to fulfill PROMET-H2 target of < 2% H2 in O2 at 0.5 Acm-2. But some stability studies and internal Chemours decision excluded the membrane to be assembled for PROMET-H2 stacks. MONOLITHOS developed and patented a low cost and simple recycling process, that allows the reuse of the catalysts, which is necessary for environmental and economic reasons. The hydrometallurgical leaching process for PGMs recovery developed by MONOLITHOS is proposed for CRMs recovery from End-of-Life PEMWE MEAs with efficiency higher than 99% for Pt content and 60% for Ir. Stainless steel (SS) based PTL coated with (Ti) and (Nb/Ti) coatings were advanced. A SS based PTLs with modified MPLs structures were developed in order to work with Low Ir loadings (0.2 mgIrcm-2) at low clapping pressure. A very thin Pt layer (µm) was needed. All the novel materials were integrated within Propuls novel stack concept based in Hydraulic cell compression. DLR has developed a tool to measure current densities and temperature distributions for the Propuls novel Hydraulic stack. Reports about techno-economic analysis (TEA) and life cycle assessment (LCA) were issued. The development in the PROMET-H2 project will reach industrial levels. The CAPEX of the PROMET-H2 stack was reduced by 21% compared to the CAPEX of the reference stack, with SoA materials. The project has reached most of the of key performance indicators in terms of performance, cost and durability. Business plans for commercialization and exploitation strategies have been developed and aligned with the market requirements. Promet-H2 has produced to date 12 publications in high impact factor journals and the results for the project have been presented internationally in 33 conferences and several workshops.
PROMET-H2 has developed products beyond the state of the art. Catalysts developed within PROMET-H2, were tested at MEA level. CENMAT scaled up highly active Ir supported on ATO keeping high quality. Low Ir loaded MEAS, PTLs and BPPs SS based are the core in the novel stack developed by Propuls, bringing high performances and low cost together to the novel concept of hydraulic stack compression. Propuls hydraulic stack will be brought from laboratory scale to semi industrial scale at TRL5. The hydrometallurgical process is a breakthrough step and an integral part of materials circularity to enable the effective recycling of PGMs and nafion from MEAs and its reuse in new hydrogen devices. The key value proposition lies in the sustainable processing, avoiding the use of state-of-art energy intensive and emission generating processes (e.g. pyrometallurgy). PROMET-H2 has developed novel materials for PEMWE with enhanced performance and durability that has the potential to reduce costs and CRM content, improving sustainability and secure a competitive advantage for the EU in the growing field of energy storage. The SME partners in the project are ambitious to commercialize the project results strengthening the European competitiveness in hydrogen technology