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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - REFLEX (Reversible solid oxide Electrolyzer and Fuel cell for optimized Local Energy miX)

Teaser

Summary

The REFLEX project aims at developing an innovative renewable energies storage solution, so-called â€œSmart Energy Hubâ€, based on reversible Solid Oxide Cell (rSOC) technology, that is to say able to operate either in SOEC (solid oxide electrolysis) mode or in SOFC (solid oxide fuel cell) mode in order to either store excess electricity to produce hydrogen, or when energy needs exceed local production, to produce electricity (and heat) again, from hydrogen or any other fuel locally available. To be more effective, the rSOC system is completed with an electrochemical storage solution allowing fast response to the electrical energy needs. The REFLEX project will demonstrate, in-field, the high power-to-power (P2P) round-trip efficiency of this technology (as compared to other H2 based solutions) and its flexibility and durability in dynamic operation (power transient and switch between electrolysis and fuel cell mode).
The challenging issue of achieving concomitantly high efficiency, high flexibility in operation and cost optimum will be duly addressed as a result of improvements of rSOC components and system, and of the definition of advanced operation strategies.

Work performed

Four technical and two economic objectives are set, all of them being aligned with the final target of increasing the efficiency and flexibility and of decreasing the cost of the rSOC technology.

Objective 1: Improve system components in order to ensure a highly efficient reversibility of the system in functional environment
Works have been performed to optimize cells for reversible operation, in terms of microstructure, thicknesses of constituting layers, interfaces, in order to achieve high power densities and long durability in flexible mode. 13 different options have been considered. A G2 cell reaching the project objectives in terms of performance (-1.2 A/cmÂ² at 1.3V in SOEC mode, 0.6 A/cmÂ² at 0.8V in SOFC mode at 700Â°C, for a fuel utilization of 85%) has been selected. An enlarged cell of 160x160 mmÂ² has been developed and a first batch delivered for integration into stacks.
Works have been conducted to optimise the stack design focused on (i) integrate a thinner cell, (ii) improve fluidic, to minimize pressure drop especially in air chamber, (iii) optimize sealing mechanical resistance to internal pressure. The modified design allowed to integrate successfully thinner cells, decrease the pressure drop on air side by a factor of 2, and to increase the tolerance of sealing to higher pressure. In parallel, the stack design has been modified to integrate the large cells.
Modelling tasks performed support the understanding and optimisation of the stack behaviour in terms of thermal management. Heat exchangers allowing the best performances and ease of piloting have been selected.

Objective 2: Decrease losses in electrical, gas and heat management at system level to ensure a highly efficient operational system
Power electronics systems and the electrochemical storage were specified and designed. Moreover, simulations and analysis were carried out for the validation of the control strategies for both modes: SOFC and SOEC. On the other hand, one of the DC/DC has been built and several tests are being performed in order to validate both modes SOFC and SOEC at their maximum power capabilities. The rest of DC/DC power converters will be built and test during the next months. Finally, AC/DC power converter and the associated control systems has been manufactured and test will be carried out together with the DC/DC devices over a wide range of operating conditions with the aim to ensure minimum loss of efficiency from the nominal rated point.
BoP components have been selected. Supported by modelling tasks which highlighted the maximum heat losses acceptable in both modes, the hotbox and the operating conditions to maximise fuel utilisation, performances and efficiency have been defined.

Objective 3: Define dynamic and smart switching strategies in full operational environment to ensure the most relevant and efficient capacities of the system
The search of optimised operation strategies have been performed with modelling tasks. The setpoints of the system have been defined, with 3 power levels (Pmin, Paverage, Pmax) for three modes (SOEC, SOFC in H2, SOFC in natural gas). The experimental activities will be performed in period 2 as planned after installation of the system to evaluate the effective efficiency. A first inversion strategy to switch from one mode to the other has been defined, and tested first on cells and stacks. It will be applied on the system when ready.
The battery storage system has been defined, designed and manufactured and lab validation is ongoing. Its hybridation with the rSOC system has been defined. The control and command (C&C) specification is ongoing. The adaptation of the software strategy to the field test configuration and the validation of this strategy in-field is part of period 2 as planned.

Objective 4: Demonstrate the whole system up to TRL 6
The in-field demonstration are part of period 2 as planned.

Objective 5: Provide hydrogen, electricity and heat with relevant costs for the appl

Final results

Both technological, scientific, and techno-economical results are expected.
Technological results are awaited at both individual components scale (improvement of cells, stacks, power electronics for flexible rSOC operation), and system scale (design of an optimised Smart Energy Hub based on rSOC components hybridized with batteries, with the associated automation and control tools and strategy). The final in-field demonstration phase of the Smart Energy Hub will be the final outcome of the project as a demonstration in a relevant environment.
Scientific results concern the improvement of the knowledge and understanding of the link between microstructures, performance and durability for cells, between design and performance for stacks, the knowledge of the behaviour of the power electronics for flexible rSOC operation, the impact of the system design and operation strategy on the overall efficiency, and finally the development of a modelling tool for rSOC system. It is also expected with the project to extend the know-how in testing and operating rSOC cells, stacks and systems, in rSOC modelling and to have a huge amount of experimental data as well as simulation data.
Techno-economical results are expected in terms of evaluation of the CAPEX and LCOE (levelized cost of energy) of Smart Energy Hub and of uscaled concept up to 1 MWe, and in terms of identification of the most promising economic sectors for this technology. It is also expected to get information about the comparison of this technology as compared to other power-to-power technologies.