Improved components and tools to increase the safety of electrolysers

Expected Outcome:

Hydrogen production via water electrolysis is a cornerstone technology for achieving Europe’s climate neutrality goals and supporting the decarbonisation of industry, transport, and the energy sector. As the deployment of electrolyser systems scales up, so do concerns around their safety, durability, and long-term operational reliability. In particular, incidents related to hydrogen and oxygen mixing within cells, stacks and tanks – caused by membrane degradation, structural failures, or inadequate monitoring – pose risks not only to the systems themselves but also to their regulatory acceptance and public perception. These challenges are exacerbated during critical operating phases, such as system start-up, shutdown, and dynamic load transitions driven by fluctuating renewable electricity inputs.

This topic addresses these challenges by focusing on the development and validation of improved components and integrated tools to enhance the safety of low-temperature water electrolysers. Proposals on this topic should cover conventional low temperature electrolyser as well as emerging architectures. It should be open to diverse approaches, provided they address the core issue of increasing system safety while maintaining or improving electrochemical performance and enabling scalable, regulation-ready designs. To address these challenges holistically, proposals should also cover structural and mechanical aspects, including numerical modelling of degradation and failure mechanisms (e.g. finite element (FE) modelling), and provide design recommendations for electrolyser components to enhance operational integrity and intrinsic safety.

Project results are expected to contribute to enhancing the safety, reliability, and regulatory readiness of electrolysers by addressing critical degradation mechanisms and system design flaws that may lead to H₂/O₂ mixing and other hazardous failures.

The projects are expected to contribute to the following outcomes:

• Contribute to the safe operation of large-scale low-temperature electrolyser systems through innovative system designs and control strategies;
• Reduce gas crossover rates during dynamic operation mode compared to the current state-of-the-art, thereby enhancing intrinsic system safety, operational reliability, and mitigating critical safety risks;
• Deploy advanced, real-time detection systems for early identification of membrane or electrode degradation, enabling timely and preventive safety interventions;
• Increase electrolyser lifetime through predictive maintenance enabled by validated degradation models and integrated monitoring tools;
• Improve cell and stack designs to achieve superior gas separation performance, while minimising or eliminating the use of per- and polyfluoroalkyl substances (PFAS) membranes and promoting low-permeability alternatives;
• Incorporate Quantitative Risk Analysis (QRA) models for key failure scenarios.
• Support EU-wide safety standards by contributing to pre-normative research and the development of harmonised testing protocols for electrolyser operation and certification.

Project results are expected to contribute to the following objectives and KPIs of the Clean Hydrogen JU SRIA:

• Reducing electrolyser CAPEX and OPEX and thus the cost per kg H₂, especially by reducing the amount of Critical Raw Materials (CRM) used;
• Zero use of PFAS in ion exchange membranes and ionomers, by implementing hydrocarbon-based or composite membranes with verified chemical/mechanical stability;
• Increasing the availability of electrolysers reducing safety shutdowns due to leaks and component failures;
• Proof of the technology with long test(s) (3,000 h) under different operative regimes (i.e., RES typical profiles);
• Business model for the scale-up and industrialisation;
• Contribution to at least one new or updated EU safety standard or testing protocol

Project results should contribute to the achievement of the KPIs for increased operation availability and safety of electrolysers:

• Gas crossover incidence rate reduced by ≥ 50% compared to current state-of-the-art (PEMEL: 0.01–0.05%); (AEMEL: 0.05–0.1%) (AEL: 0.1–0.5%) and (< 0.1% in emerging architectures)
• <2 failures per 3,000 operating hours per stack
• Operational availability increased to >95% due to predictive safety controls and to reduced leak frequencies;
• Stack degradation <0.06% per 1,000 hours under nominal operation;
• Current densities of AEL:1 A/cm² ; PEMEL: 3.0 A/cm²; AEMEL: 1.5 A/cm²;
• Prioritise materials that avoid PFAS and minimise the use of PGMs, in alignment with EU sustainability and Critical Raw Materials (CRM) strategies and the SRIA KPIs for the selected technology — targeting 0 mg W⁻¹ of CRM in AEL, Ir: 0 mg W⁻¹ and Pt: 0.12 mg W⁻¹ in AEMEL, and Ir: 0.09 mg W⁻¹ and Pt: 0.06 mg W⁻¹ in PEMEL.
• Reduce electricity consumption at nominal capacity addressing the relevant SRIA 2030 KPIs of 48 kWh/kg for each electrolyser technology;
• Development of harmonised safety diagnostics and models integrated into a TRL 5 prototype.

Scope:

The focus of this topic is on advancing and validating novel components and control solutions aimed at improving the operational safety of low-temperature electrolyser systems. This topic is open to a broad range of low-temperature electrolysis technologies, including conventional configurations such as Alkaline Electrolysers (AEL), Proton Exchange Membrane Electrolysers (PEMEL), and Anion Exchange Membrane Electrolysers (AEMEL), as well as emerging designs such as membrane-less electrolysers and decoupled electrolyser systems.

Proposals are expected to develop and integrate innovative materials, cell, and stack and balance-of-plant configurations, including connections, intelligent monitoring/control tools that can detect, and reduce or eliminate the risk of hazardous gas crossover, and inherently safer solutions that prevent hydrogen leaks and build-up of critical concentrations in the module. This includes but is not limited to: next-generation membrane materials with reduced gas crossover, hydrogen permeability, and improved mechanical integrity; novel electrode structures that enhance gas separation; architectures that reduce the potential leak points and physically or operationally decoupled hydrogen and oxygen evolution; novel stack and balance-of plant components integrating efficient H-O recombination catalysts. Novel and advanced optical and spectroscopic techniques for real-time, on-line monitoring of hydrogen purity can be proposed as an integral part of the system’s monitoring and control architecture. These tools can significantly reduce the risk of in-situ cell breakdown while simultaneously supporting an increased number of safe start-up/ shutdown cycles. In parallel, failed components should undergo advanced experimental analysis to identify underlying damage mechanisms and material degradation states. These insights will feed into a dedicated numerical tool—coupling finite element modelling, degradation kinetics, and operational data—to simulate, predict, and optimise component performance under varying conditions. This model should support both real-time decision-making and early-stage design improvements to enhance durability and intrinsic safety. Complementary sensing technologies—such as electrochemical and thermal conductivity sensors—may also be integrated to ensure data redundancy and robust fault validation. Sensor data streams should feed into AI/ML-based models for early anomaly detection, predictive maintenance, and optimised system response strategies.

In parallel with materials, components and hardware development, the topic also encourages the advancement of smart sensing and control solutions to ensure safe operation in real-time. These may include AI- or machine learning-based systems, ideally embedded within a digital twin framework that integrates real-time sensor data with numerical models. Such models can simulate and predict system behaviour under varying conditions, enabling early detection of faults such as membrane failure, electrode delamination, or abnormal thermal and pressure events. Spectroscopy-based diagnostics may further enhance this architecture by providing high-resolution insights into critical degradation processes. Long-term degradation modelling should be combined with embedded diagnostics to support predictive maintenance, reduce unplanned downtime, and extend operational lifetimes. Emphasis should be placed on the performance of these tools under challenging dynamic conditions—including intermittent renewable energy supply—to replicate real-world operating environments (TRL5).

Proposal should validate the proposed solutions. Testing should be carried out at the component, cell, and stack level under relevant conditions (e.g. pressure, temperature, power cycling), with clear metrics for safety, performance, durability, and regulatory compliance. The safety improvements provided by the proposed solutions should be evaluated for their beneficial effects on risk management procedures. Targeted prototype scale and cell size should be appropriate for the considered technology and future scale-up.

The proposal should demonstrate at the end of the project the construction and validation on a stack with the following requirements:

• PEMEL: minimum 100 kWel designed to operate at >100 bars of output pressure. The stack should exhibit a minimum operation performance of current densities > 3.0 A/cm² at <1.9 V.
• AEMEL: minimum 50 kWel designed to operate at >50 bars of output pressure. The stack should exhibit a minimum operation performance of current densities > 1.5 A/cm² at <1.85 V.
• AEL: minimum 100 kWel designed to operate at >30 bars of output pressure. The stack should exhibit a minimum operation performance of current densities > 1 A/cm² at <2 V.
• Other emerging low temperature electrolysers: minimum 5 kWel designed to operate at >30 bars of output pressure. The stack should exhibit a minimum operation performance of current densities > 1 A/cm².

Stacks should be validated for performance and safety for a minimum of 1000 h under diverse operating regimes (steady-state, dynamic load-following, frequent start/stop cycles, and off-normal transients), with results reported under harmonised EU protocols (see below).

Additional KPIs may be proposed, in particular for non-conventional architectures (e.g., decoupled designs), provided that key safety and performance KPIs are fulfilled. Wherever possible, testing should adopt or contribute to harmonised EU protocols and pre-normative research efforts. Proposals are encouraged to liaise with standardisation bodies (e.g., CEN, CENELEC, ISO) and relevant regulatory stakeholders to ensure compatibility with emerging safety frameworks and certification pathways. This alignment is critical for ensuring that innovations move beyond the laboratory and into safe, deployable commercial systems.

Projects are also expected to contribute to the definition or refinement of safety-relevant KPIs, beyond traditional efficiency and cost metrics. These may include indicators such as crossover detection sensitivity, response time of safety shut-off systems, operational uptime due to preventive maintenance, leak probabilities, or compliance with forthcoming regulatory thresholds on gas purity and leakage. KPIs should be integrated in a comprehensive safety-by-design evaluation of the proposed solutions both at component and at system level. Where possible, KPIs should align with EU safety standards and be backed by sensor-based data to support reliable validation and comparison across systems.

To address the full complexity of the safety challenge, proposals should adopt a multidisciplinary approach and involve actors across the electrolyser value chain. This may include component manufacturers (membranes, electrodes, sensors), electrolyser OEMs, digital technology providers (AI, modelling, control systems), testing laboratories, and certification or regulatory entities.

Applicants should clearly articulate the added value and innovation of their proposed approach relative to the state-of-the-art . Projects should also reference, complement and build on existing European initiatives (e.g. European Hydrogen Safety Panel) and projects (e.g., REFHYNE^[1], HYScale^[2], DELYCIOUS^[3], INSIDE^[4], , PEACE^[5], HYPRAEL^[6], ADVANCEPEM^[7] and projects funded under Topic HORIZON-JTI-CLEANH2-2023-01-01^[8]), and demonstrate how they build upon and complement the results of ongoing JU projects^[9]. Duplication of effort should be avoided, and synergies with parallel EU or national initiatives should be identified. In particular, while predictive maintenance tools have previously been explored with a focus on performance and lifetime, their integration here plays a critical role in enabling the early detection of safety-relevant failures, thereby reinforcing the complementarity between the two project scopes.

For activities developing test protocols and procedures for the performance and durability assessment of electrolysers 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 protocols^[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 3 and achieve TRL 5 by the end of the project - see General Annex B.

Technology Readiness Level - Technology readiness level expected from completed projects

[1] https://cordis.europa.eu/project/id/779579

[2] https://cordis.europa.eu/project/id/101112055

[3] https://cordis.europa.eu/project/id/101192075

[4] https://cordis.europa.eu/project/id/621237

[5] https://cordis.europa.eu/project/id/101101343

[6] https://cordis.europa.eu/project/id/101101452

[7] https://cordis.europa.eu/project/id/101101318

[8] HORIZON-JTI-CLEANH2-2023-01-01: Innovative electrolysis cells for hydrogen production

[9] https://www.clean-hydrogen.europa.eu/projects-dashboard/projects-repository_en

[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