Development and validation of innovative approaches, catalysts, electrolytes and components for electrolysis technologies based on low-quality water

Expected Outcome

The European Union has a set of policies aimed at preventing water scarcity, putting a special emphasis on reusing treated water. This approach is recognised in Regulation (EU) 2020/741[1], which promotes reclaimed water as an alternative source to reduce the pressure on conventional resources. In addition, the newly adopted Wastewater Directive (EU) 2024/3019[2] raises the bar for effluent quality and treatment efficiency and introduces the requirement for quaternary treatment[3] in large wastewater treatment plants (WWTPs) by 2045. As higher standards for reclaimed water are required by law and the need for energy-efficient technologies and renewable energy integrations increases, the water sector appears as an ideal partner to develop innovative solutions that valorise regenerated water, while increasing the efficiency and sustainability of wastewater systems.

Hydrogen production by water electrolysis can handle both objectives. This technology can evolve to utilise lower-quality water streams and/or take advantage of the relatively high-quality effluents resulting from water treatments. This positions water electrolysis as a strategic production pathway in a scalable and sustainable hydrogen value chain based on diverse water sources. Utilising reclaimed water in electrolysis processes not only reduces freshwater demand but also promotes circularity. However, an important effort is still needed to implement robust water electrolysis technologies that can handle the complexity of different water qualities even in the best scenarios. Therefore, a comprehensive understanding of how the low-grade water impurities interact with water electrolysis technologies, and to which grade lower requirements treatments could be sufficient in each application, is still missing.

Project results are expected to contribute to the following expected outcomes:

• Contributing to keeping European leadership for hydrogen production including innovative embedded approaches for electrolysis of low-quality water feed taking advantage of the relatively high-quality effluents resulting from advanced wastewater treatment processes (viz. tertiary/quaternary treatments²);
• Development of impurity-tolerant and durable electrocatalysts, membranes and components, supporting EU strategy towards minimising the use of CRM and/or PFAS, making it circular by design;
• Identifying pre-treatment process steps to minimise organic fouling and scaling at the electrolysis unit;
• Understanding electrolysis cell performance, degradation and failure mechanisms during operation with low-quality water feed while minimising pre-treatment steps;
• Contribute to the EU harmonisation protocols for water electrolysis developing procedures for low-quality water feed.

Project results are expected to contribute to the overall objectives and KPIs of the Clean Hydrogen JU SRIA, notably to increase current density & efficiency, reduce costs, and to decrease degradation & use of CRMs. As low-quality water electrolysis is considered, for which no KPIs are available in the SRIA, specific KPIs, to be met simultaneously, are defined below, that can be accessible to any water or steam electrolysis technologies:

• Electricity consumption @ nominal capacity (kWh/kg H2):
• LT water electrolysis: ≤ 55
• HT water electrolysis: ≤ 39 (Heat demand @ nominal capacity: ≤ 10 kWh/kg H2)
• Current density (A/cm2): ≥ 1.0
• Degradation at nominal load (%/1000 h): ≤ 1
• CRM as catalyst (mg/W): PGM ≤ 0.25
• Hydrogen purity should be at least > 99.9%

Proposals are encouraged to propose additional KPIs to quantify the achievement of the innovative approach.

Scope

Proposals should aim to realise a breakthrough water electrolysis technology that can produce hydrogen from low-quality water, i.e. beyond tap water[4] and from various sources (excluding saline and seawater) operating at low energy consumption levels. The project should demonstrate a stable electrolyser cell unit incorporating innovative solutions at the material, component, cell architecture level, and alternative half-cell reactions to overcome the challenges in the electrolysis of low-quality water. In line with EU sustainability and CRM strategies and the Clean Hydrogen JU SRIA KPIs for the selected water electrolysis technology, the prototype cell should also minimise the use of PFAS and/or CRM. The target is to validate the innovative technology at TRL 4, assessing its potential for circularity, sustainability, and economic viability.

The innovative electrolyte chemistry technology should overcome the limitations of low-quality water electrolysis addressing, amongst others, the stabilisation of pH, suspended solids, inorganic, organic and biological contaminants, material corrosion, low activity, selectivity, and durability of electrocatalysts. Special attention needs to be paid to in-depth experimental, computational, and theoretical insights into the mechanistic pathways of the degradation processes by understanding the impact of water impurities on performance and durability and the potential mitigation strategies. The project should propose innovative approaches, electrodes structures and compositions, membrane/ionomer when needed, and electrochemical reactor cells to reach effective high-performing and contaminant-resistant low-quality water electrolysis materials.

The proposal should consider the following elements:

• Determine the Critical Maximum Concentration (CMC) of the identified water impurities (i.e. inorganic, biological, organic) that will allow the electrolyser cell to operate efficiently while ensuring durability and performance;
• Identify deactivation and degradation mechanisms due to contaminants;
• Investigate the role of low-grade water impurities in the degradation processes of catalysts, membranes and components considering as basis those impurities generated from the self-degradation of stack/BoP materials;
• Develop and validate suitable materials (catalysts, membranes/electrolytes, coatings) and their tolerance threshold to impurities;
• Perform experimental and modelling studies to evaluate and define optimal operating conditions to maximise hydrogen yield while minimising material degradation and system inefficiencies;
• Implement and validate innovative monitoring techniques for establishing recovery, mitigation and maintenance strategies to remove/minimise the impact of impurities over the electrolysis cell lifetime;
• Validate the KPIs of the novel water electrolysis solutions at a relevant scale (>2kW) for at least 2000 hours at relevant operating conditions associated with the selected scenario and the chosen low-quality water;
• Identify application cases (case of study) by selecting potential wastewater sources such as treated industrial and urban wastewater for hydrogen production in circular economy streams;
• Considering sector-coupling (i.e. integration of wastewater treatment with hydrogen production systems), compare and contrast the metrics (economic, social, environmental and circularity analysis) of the proposed low-quality water electrolysis technology against the conventional established water electrolysis technologies considering the operational, maintenance, and energy costs associated with water treatment and electrolysis;
• Evaluate lifecycle, circularity and techno-economic feasibility of the innovative technology, including integration of water conditioning units in comparison with conventional ultra-pure water electrolysis technologies.

Consortia are expected to build further on the findings of previous projects funded by the European Innovation Council (EIC) Pathfinder Challenge 2021 (e.g. ANEMEL[5]) and explore synergies with relevant ongoing JU projects on direct seawater electrolysis (Sea4Volt[6], HySEas[7], SWEETHY[8] and ASTERISK[9]).

For activities developing test protocols and procedures for the performance and durability assessment of water electrolysers fed with low-quality water proposals should foresee a collaboration mechanism with JRC[10] (see section 2.2.4.3 "Collaboration with JRC"), in order to support EU-wide harmonisation. Test activities should adopt the already published EU harmonised testing protocols106[11] to benchmark performance and quantify progress at programme level.

For additional elements applicable to all topics please refer to section 2.2.3.2

The JU estimates that an EU contribution of maximum EUR 3.00 million would allow these outcomes to be addressed appropriately.

Activities are expected to start at TRL 2 and achieve TRL 4 by the end of the project - see General Annex B.

Technology Readiness Level - Technology readiness level expected from completed projects

Activities are expected to start at TRL 2 and achieve TRL 4 by the end of the project - see General Annex B.

[1] Regulation (EU) 2020/741 of the European Parliament and of the Council of 25 May 2020 on minimum requirements for water reuse.

[2] Directive (EU) 2024/3019 of the European Parliament and of the Council of 27 November 2024 concerning urban wastewater treatment.

[3] Quaternary treatment is the fourth stage in wastewater treatment, which specifically targets micropollutants that are often not fully removed by conventional treatment methods.

[4] Tsotridis, G. and Pilenga, A., EU harmonized protocols for testing of low temperature water electrolysis, Publications Office, 2021, https://data.europa.eu/doi/10.2760/58880

[5] https://cordis.europa.eu/project/id/101071111

[6] https://cordis.europa.eu/project/id/101192235

[7] https://cordis.europa.eu/project/id/101192418

[8] https://cordis.europa.eu/project/id/101192342

[9] https://cordis.europa.eu/project/id/101192454

[10] https://www.clean-hydrogen.europa.eu/knowledge-management/collaboration-jrc-0_en

[11] https://www.clean-hydrogen.europa.eu/knowledge-management/collaboration-jrc-0/clean-hydrogen-ju-jrc-deliverables_en