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

Periodic Reporting for period 4 - REFLEX (Reversible solid oxide Electrolyzer and Fuel cell for optimized Local Energy miX)

Reporting period: 2022-01-01 to 2023-06-30

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.
4 technical and 2 economic objectives are set, aligned with the final target of increasing 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 and stacks optimisation and manufacturing has been performed and the objectives achieved. The activity on heat exchangers was also performed.

Objective 2: Decrease losses in electrical, gas and heat management at system level to ensure a highly efficient operational system
The work on power electronics has been completed and the best efficiency achieved in the laboratory for the DCDC converter was 96%, in line with the project objective (95%).
BoP components have been selected, purchased and integrated into Alpha prototype for validation, before implementation in REFLEX modules during RP4, where they will be tested during 2023 second semester.

Objective 3: Define dynamic and smart switching strategies in full operational environment to ensure the most relevant and efficient capacities of the system
The tests conducted on Alpha prototype during RP4 allowed to determine the operating limits of the stacks in terms of P, T and currents.
Sylfen also defined, coded and tested the logic of transitions between modes so as not to exceed the defined limits.
These algorithms are currently being ported to the REFLEX system and will be validated in the second half of 2023 and then tests will continue in 2024. During these tests, the global efficiency in all mode will be measured.
At the end of these tests, the system will be operated automatically, driven by the EMS Paséo.

Objective 4: Demonstrate the whole system up to TRL 6
Following the amendment at the end of RP3, the system is no longer installed in Envipark but in Cheylas in France. The number of modules has also been reduced from 3 to 2. The electrolysis power is 55 kW for a production of 10 Nm3/h of H2, in fuel cell mode the power will be up to 10 kW, the thermal production will be 6 kW. These values will be measured during tests in the second half of 2023. During the RP4 period, 5632h of operation were performed on the Alpha prototype and 135 full cycles from one mode to the other.

Objective 5: Provide hydrogen, electricity and heat with relevant costs for the application
Regarding the power-to-power application, the provision of H2, electricity and heat at relevant costs has to be considered as a whole, through the concept of TCO of the complete system. In WP6, during the previous period, maximum acceptable CAPEX and OPEX have been defined for rSOC technology to be competitive on TCO with battery and low temperature electrolysis and fuel cell systems.
The achievable CAPEX and expected selling price for the rSOC system depending on the size and the time horizon were defined, which enabled to calculate the life-cycle cost of energy for different scenarios that include: different countries across Europe, different kinds of buildings, different reference solution for the energy system that exists in the building to be compared to the rSOC.

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.
Several business cases in different countries have been considered to identify the most promising ones. Some use cases have been studied, in order to identify the technical and economical requirements for rSOC system to be integrated into relevant business models.
In RP4, the most promising use cases for rSOC systems for power-to-power in the building sector were identified. It enabled to identify markets and tendencies where the technology is competitive under the current assumptions, based on cost reduction curves predicted until 2030. It also highlights the potential of the technology compared to batteries and low temperature electrolysis + fuel cell, providing a commercial road-map for Sylfen to know what kind of buildings needs to be targeted in priority, i.e shopping centers and offices in Germany and Italy, avoiding buildings that are already equipped with PV panels.
Both technological, scientific, and techno-economical results were obtained.
Technological results were achieved 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 is the final outcome of the project as a demonstration in a relevant environment. Due to the late start of the REFLEX unit, intermediary results have been provided, obtained on the Alpha prototype. EFLEX results obtained in second half of year 2023, will be shared by Sylfen to the consortium and the project officer.
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. So far, the 5632h of operation on the Alpha prototype (being a module made of 4 stacks) and 135 full cycles from one mode to the other, is one of the longest tests reported in reversible mode at the scale of a multi-stacks module.
Techno-economical results also allowed to identify the most promising economic sectors for this technology, including the comparison of this technology with other power-to-power technologies.
power electronics
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rSOC stack picture
Smart Energy Hub concept
Smart Energy Hub Prototype
picture of cells