Development of innovative technologies for direct seawater electrolysis

Topic description

ExpectedOutcome:

Electrolytic hydrogen production and its various uses are leading to new types of energy and chemical industry systems which allow linking of sectors such as transport, as well as, hard to abate industrial sectors, electricity production and energy storage. In line with EU policies (EU Hydrogen strategy and REPowerEU Plan) a massive deployment of electrolytic systems with a scale up to multi-MW is expected. This implies maintaining performances and efficiency as well as optimising them, by reducing the use of critical raw materials, improving purification systems for the feedwater and complex balance of plant alongside the need to extend the durability against transient, dynamic or harsh conditions as well as, the overall lifetime of the system.

Some issues experienced have been, to some extent, overcome in the case of big industrial installations. Despite of that, the progress in all, and especially local, remote, and distributed, electrolytic systems can easily be fostered by leaving aside the water purification step as well as the use of low Platinum group metals (PGM)-based catalysts maintaining reasonable trade-off between cost and durability, as well as, other advanced materials and components such as membranes, ionomers, coatings, Porous Transport Layer (PTLs), bipolar plates etc.).

On the other hand, the offshore and onshore generation of ‘green’ electricity, and related prospective hydrogen manufacturing potential, yields in an interest in the direct electrolysis of sea water. All these issues are at the moment addressed separately by various planned or ongoing research and innovative projects. The novel outcome expected for this topic relies on the development of solutions addressing more than one of them.

The solutions provided should contribute to the possible future development of a technology allowing for sustainable production of green hydrogen in remote (delocalised) and/or offshore locations using seawater as a feedstock. Under the highly delocalised premise of the availability of “cheap electrons” from renewable electricity, the electrolytic production of hydrogen faces new challenges as in numerous geographic regions deprived of freshwater reservoirs, sea/ocean water is regarded as the preferred feed choice for future environment-friendly electrolytic applications.

Seawater is usually being targeted in the areas characterised with deficits of fresh water. While technically this is not the only possible source, due to its global abundance and the global scale of the required hydrogen production development of electrolytic systems, accomplishment of seawater into electrolysis can in future yield in further integration of hydrogen into local economies of various European and non-European locations especially if it does not require desalination.

The innovative technology developed should overcome limitations of direct electrolysis of seawater addressing among others the stabilisation of pH fluctuations, physical blockages from solid impurities, precipitates and microbial contamination, materials and components corrosion, low activity, selectivity, and durability (together with the relevant recycling and reuse strategies) of the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) catalysts. It should also propose innovative materials/components structures/compositions and membrane/ionomer (when applies) to reach effective high-performing and corrosion-resistant, and thus durable, seawater electrolysis systems. The proof of concept of the innovative technology should enable direct electrochemical seawater splitting as well as brine use for energy efficient hydrogen production contributing to the overall objectives of the Clean Hydrogen JU SRIA.

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

• Target applications based on renewable hydrogen production from seawater through its direct electrolysis coupled to renewable intermittent energy sources;
• Combining electrolysis with recovery/reuse of salts and compounds from seawater brine for other applications;
• Identify the maximum concentration of contaminants (inorganic, organic, as well as, biological) allowed to operate efficiently a direct seawater electrolysers;
• Techno-Economic, Environmental and Social Analysis of the proposed technology (e.g. TEA combined with LCA, LCCA, LCSA);
• Comparison of the technology proposed proving its potential advantages against conventional approach based on desalination and freshwater electrolysis based solutions;
• Proof of principle/concept of cell/stack able to work with seawater as a direct feedstock, including especially also bivalent cations and anions;
• Development of materials/components such as separators, electrodes and catalytic materials exhibiting stability in salinity conditions characteristic for seawater;, as well as, characterised by improved reuse/recyclability features targeting the fully circular industrial environment.
• Evaluate the trade-offs between the use of critical raw materials and resulting performance of the future electrochemical device of interest or the development of innovative catalysts, free of critical raw materials;
• Estimation of the correlation of the salinity, chemical composition and microbial related factors of sea water to the efficiency, degradation, etc. of the electrolyser and its materials.
• Providing the solutions for future effective direct electrolysis of sea water for various chemical compositions and salinity range of at least 3,3 to 3,9 % (characteristic to e.g. Mediterranean Sea).

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

• Energy consumption @ nominal load: 53 kWh_e/kg for low temperature EL and <40 kWh_e/kg + <10 kWh_th/kg for high temperature EL.
• Current density for nominal operation: ≥ 0,5 A/cm².
• Degradation: ≤ 5 %/500h.
• Operational flexibility: 20 to 100 % of nominal load.
• Minimal capacity of the electrolyser 20 gH₂/h.
• PGM electrode load: < 0.4 mg/W.

The achieved purity of hydrogen should be of at least 99%.

The expectations stemming from the aforementioned expected outcomes create a set of challenges to be overcome in order to produce electrolysers of various scale of power for distributed hydrogen production, performed without other than basic mechanical filtration or purification of seawater. In order to understand and tune reaction mechanisms describing the desired catalytic activities and the overall stability and selectivity, special attention needs to be paid to in-depth experimental, computational and theoretical insight into the mechanistic pathways and properties of the electrode-electrolyte interface under operating conditions. The major effort should, therefore, focus on one hand on the improvement of the hydrogen electrode to work in this harsh environment and on the other hand on the improvement of the selectivity towards the oxygen evolution at the anode electrode, as well as, to the durability issues stemming from both corrosion processes and catalyst (and membrane when applies) poisoning.

The project should consider the following requirements:

• Identify and develop suitable materials (catalysts, membrane when implemented, coatings, Porous Transport Layers, Bipolar Plates, sealings), as well as electrolyser design options and operating conditions relevant to the seawater composition of interest in correlation with electrolyser cell performance and selectivity.
• Experimental and model-based studies on the durability of materials, components and resulting prototype in harsh environment.
• Optimise advanced cost effective and limited CRM use electrocatalysts concerning activity, durability, and selectivity for the HER and OER with high tolerance to poisoning caused by chlorides, salts, and various contaminants (including ammonia and organic contaminants) present in seawater.
• Reduce the experimental efforts by means of the application of computer modelling tools including computational material science-based simulation approach.
• Integrate and test corrosion resistant new cost effective and available components into a prototype short stack (> 5cells) operated under dynamic mode simulating the intermittent behaviour of solar or wind power sources (RES).
• Identify the correlations between the durability of the component/system under development and its cyclic operating conditions.
• Operate the stack under representative conditions (to evaluate its performance and durability for at least 2000 h of cumulative operation and a minimum of 1500 cycles from idle to nominal operating conditions to simulate the dynamic electricity input from fluctuating renewable sources). The degradation rates should be measured during this time and reported in %/1000 h.
• Identify, define, and test a safe operating window in terms of durability based on the typical characteristics (e.g. salinities) of at least two types of sea feedwater corresponding to the prospective areas of application – relevant synthetic seawater according to the above identified geographic regions can be considered at some stages of long-term testing while final tests should consider the use of the natural water samples.
• Assess the circularity and techno-economic and environmental feasibility of the proposed technology, including the CRM cost – system durability tradeoff and evaluation of the brine as a source of extractable raw materials.

Consortia are encouraged to explore synergies with relevant ongoing projects funded by the European Innovation Council (EIC) Pathfinder Challenge 2021EIC Pathfinder Challenges 2021 (HORIZON-EIC-2021-PATHFINDERCHALLENGES-01), as relevant.

Proposals are encouraged to explore synergies with projects within the metrology research programme run under the EURAMET research programmes EMPIR and EMRP (in particular on metrology for standardised seawater pHT measurements and metrology for ocean salinity and acidity.

Activities related to test protocols and procedures for the performance and durability assessment of water electrolysers fed with low grade water should foresee a collaboration with JRC (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 to benchmark performance and quantify progress at programme level.

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

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

The JU estimates that an EU contribution of maximum EUR 4.00 million would allow these outcomes to be addressed appropriately.

The conditions related to this topic are provided in the chapter 2.2.3.2 of the Clean Hydrogen JU 2024 Annual Work Plan and in the General Annexes to the Horizon Europe Work Programme 2023–2024 which apply mutatis mutandis.

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