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Reversible solid oxide Electrolyzer and Fuel cell for optimized Local Energy miX

Periodic Reporting for period 2 - REFLEX (Reversible solid oxide Electrolyzer and Fuel cell for optimized Local Energy miX)

Reporting period: 2019-07-01 to 2020-12-31

The REFLEX project aims at developing an innovative renewable energies storage solution, so-called “Smart Energy Hub”, 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.
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
Cells performance targets are achieved. The rSOC switching has been shown to decrease degradation rate as compared to pure SOE operation, and the degradation target was reached with G2 cell in the severe conditions of operation considered. The test in more moderate conditions let to lower degradations, and therefore it was recommended to operate the stacks in these milder conditions.
G2 cells have been integrated in stacks, and their performance and durability recorded in rSOC mode.
196 cm² active area cells have been integrated in stack. Similar performances as standard stack were recorded, validating both the cells and the stack design for this size increase.
Large power modulations have been validated at stack level in three modes: SOEC, SOFC in H2 and SOFC in CH4, with ranges 58-100%, 23-100% and 13-100% respectively.
G2-cell based Stacks for the demonstration modules has started with a batch 0 of 4 stacks for factory validation at Sylfen. The two first batches of REFLEX stacks are ready. The third batch is ongoing, the delivery will be completed in M38. Stack performances are very close with low scattering.
Modelling tasks have continued to support the understanding and optimisation of the stack thermal management, to optimise the system design and to defined the best operation strategy. Heat exchangers allowing the best performances and ease of piloting have been purchased. A solution to valorise the internal heat produced by the exothermic electro chemical reaction has also been defined to allow complete valorization by the building where the system is installed.

Objective 2: Decrease losses in electrical, gas and heat management at system level to ensure a highly efficient operational system
Power electronics systems and electrochemical storage were manufactured and validated. The DC/DC solution has been built and tested in both SOFC and SOEC. The best efficiency achieved in the laboratory for the DCDC converter was 96% exceeding the project target. Finally, AC/DC power converter and the associated control systems has been tested with the DC/DC devices and the BESS.
In WP4, BoP components have been selected and purchased. Supported by modelling tasks which highlighted the maximum heat losses acceptable, the hotbox has been manufactured. It is currently validated at Sylfen premices, and its integration with the rest of the other BoP components is ongoing.

Objective 3: Define dynamic and smart switching strategies in full operational environment to ensure the most relevant and efficient capacities of the system
The setpoints of the system defined in period 1 have been confirmed/refined following stack tests performed in WP2. The effective achievement of the targeted efficiency will be checked in period 3 as planned.
The inversion strategy to switch from one mode to the other has been validated on cells and stacks. It will be applied on the system when ready.
The battery storage system has been manufactured and lab validation terminated. Its hybridation with the rSOC system has been defined. As part of WP4, the control and command tuning software is currently in the coding phase, and its integration with instrumentation is ongoing. The validation of the operating strategy in-field is part of period 3 as planned.

Objective 4: Demonstrate the whole system up to TRL 6
The design of the Smart Energy Hub defined in WP4 aims at reaching the above-mentioned powers and hydrogen production values. All components of the system have been designed and sized for those goals. The factory acceptance test is planned in M41, and the in-field demonstration are part of period 3 as planned.

Objective 5: Provide hydrogen, electricity and heat with relevant costs for the application
In WP6, total cost of ownership has to be considered, and the maximum acceptable CAPEX and OPEX have been defined for rSOC technology to be competitive with battery and low temperature electrolysis and fuel cell systems.

Objective 6: Design a relevant business model for the whole value chain in order to ensure a viable and profitable exploitation of the technology and its integration into existing markets.
In WP6 several business cases in different countries have been considered to identify the most promising.
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).
at components scale, performance targets have been met, with valules above state of the art.
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.
power electronics
rSOC stack picture
Smart Energy Hub concept
Smart Energy Hub Prototype
picture of cells