Despite advances in addressing key technical challenges and demonstrating the feasibility of rSOC systems across various operational contexts, several challenges remain in integrating rSOC systems with existing gas and electric grids. Building on these results, the scope of this topic is to validate the performance, reliability, and economic viability of MW-scale rSOC systems in real-world conditions, providing valuable insights and data to support the broader adoption of this technology to the grid, and generating data which serve as basis for comparison with battery storage of electricity, for instance.

The reversible solid oxide system (rSOC) should be designed, developed, installed, and operated to demonstrate its capability, availability, and reliability in real-world, MW-scale applications.

The costs (CAPEX) of the whole system including multiple stacks, BoP and gas handling system (purification, compression, and control), as well as the costs for the construction and commissioning phase (e.g connection to the electricity/gas grid, electricity/gas/hydrogen costs) of the reversible solid oxide system may be funded. The OPEX (electricity and gas/hydrogen costs in demonstration/business operation) will not be funded.

Key requirements include:

• A minimum system capacity of at least 1 MW in electrolysis mode to ensure that the solution is scalable and representative of real-world deployment scenarios. The system can contain multiple modules. The modules, as building blocks for the whole system, should provide at least 10 kW electrolysis power. Modules can contain several stacks to reach at least 10 kW electrolysis . This will help in addressing the knowledge gaps associated with rSOC;
• The system should be designed to be able to deliver services to the electricity infrastructure, contributing to sector coupling and overall energy system flexibility;
• The rSOC should be connected to the electricity grid. Where relevant, a hydrogen storage system should be included to enable flexible operation in both electrolysis and fuel cell modes. The setup should allow simulation of ancillary service provision and validate the system’s role in sector coupling and grid balancing of the electric grid;
• Leverage hydrogen and/or biofuels/biogas grid connection to enable electricity generation and ensure continuous system operation when it is not operated in electrolysis mode.
• Operation for over 5,000 h under dynamic conditions, including both operation modes (SOFC/SOEC and switching) and H2 purity at least 99.5%, with performance data addressing key operational characteristics such as:
  • High ramp-up speed and cycling capability.
  • Effective heat management strategies.
• Demonstrate at least 1000 h of electrolysis operation at thermoneutral voltage according to nominal temperature with or without temperature adjustment.
• The entire setup should also include the infrastructure required for injecting hydrogen into the hydrogen grid or a storage facility.
• Hydrogen produced from the rSOC should be compressed using a compressor unit to ≥5 bar output from the complete system. This will ensure hydrogen is adequately pressurised for various applications (e.g., injection into the hydrogen infrastructure or storage tanks);
• Implementation of advanced control strategies, robust system design and optimisation of the Balance of Plant (BoP) to guarantee optimal operation and integration of the system in the electric and hydrogen infrastructure (pipeline or storage). This also includes the development of advanced control for reducing cost of maintenance and operative cost, even considering the HiL/SiL approach;
• The solution should explore the potential of reversible systems as a Long Duration Energy Storage (LDES) option, providing power-to-power conversion (from electricity to hydrogen and vice versa) and enhancing the exploitation of renewable energy sources;
• The project should produce comprehensive development and monitoring guidelines for rSOC-based systems aimed at sector coupling, also including support to regulation and standards definition;
• A comprehensive techno-economic analysis (with a focus on balancing the electricity and, potentially, the hydrogen grid) should be conducted, focusing on capital and operational costs, system lifetime and performance under real operating conditions, potential revenues from market participation (e.g., ancillary services, etc.), and the overall economic viability of integrating rSOC systems into the energy value chain;
• The analysis should also include a comprehensive Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) analysis, to evaluate the environmental impacts and economic costs associated with the entire lifecycle of rSOC.

In doing so, the following KPIs should be addressed:

• Roundtrip electrical efficiency (net) of the whole system ≥50% by 2030, with target of ≥60% by 2035. The efficiency should consider the whole system, involving the BoP (e.g., steamer, compressor, H2 processing unit, inverters, etc.) and rSOC connection to the hydrogen infrastructure;
• Reversibility – The system should demonstrate fast transition capabilities, with switching mode time from one configuration to the other equal to at least 5 min by 2030, targeting ≤2 min by 2035;
• The system should ensure a warm start time of at least 10 min achievable by 2030, targeting 5 min by 2035;
• The system should achieve low electrical energy consumption in electrolysis mode (<37 kWh/kg).
• Low level of stack degradation (<0.3%/1000 h);
• Specific cost of stacks <1000 €/kWFuel Cell.

This holistic approach will help unlock the full potential of rSOC technology, contributing to a resilient, flexible, and decarbonised European energy system.

It is expected that Guarantees of origin (GOs) will be used to prove the renewable character of the hydrogen that is produced/used. In this respect consortium may seek out the issuance/purchase and subsequent cancellation of GOs from the relevant Member State issuing body and if that is not yet available the consortium may proceed with the issuance and cancellation of non-governmental certificates (e.g CertifHy).

For activities developing test protocols and procedures for the performance and durability assessment of (reversible) electrolysers proposals should foresee a collaboration mechanism 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.

Proposals are expected to demonstrate the contribution to EU competitiveness and industrial leadership of the activities to be funded including but not limited to the origin of the equipment and components as well infrastructure purchased and built during the project. These aspects will be evaluated and monitored during the project implementation.

Proposals should provide a preliminary draft on hydrogen safety planning and management at the project level.