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While renewable energies locally installed in buildings are increasing; there is a potential or even a need to store them to promote their self-consumption. Being efficient, modular and scalable, reversible Solid Oxide Cell (rSOC) technology can play a key role. Works undertaken in the frame of the REFLEX European project are presented, starting with the optimization of each individual component, ie. cells, stacks and BoP components such as power electronics. With the support of modelling activities, the rSOC based system, made of 3 modules of 4 stacks each, coupled with a battery storage has been designed in such a way to ensure achieving maximum efficiency, while still operating the system in safe and lifetime-optimal conditions. The site where the system will be installed has been prepared. Furthermore, techno-economic simulations have been carried out to evaluate market driven requirements on system sizing and costs to be competitive with other storage solutions.

The power ramp rate capabilities of a 5 kW proton exchange membrane fuel cell (PEMFC) system are studied theoretically and experimentally for grid support service applications. The fuel supply is implemented with a fixed-geometry ejector and a discrete control solution without any anode-side pressure fluctuation suppression methods. We show that the stack power can be ramped up from 2.0 kW to 4.0 kW with adequate fuel supply and low anode pressure fluctuations within only 0.1 s. The air supply is implemented with a centrifugal blower. Air supply ramp rates are studied with a power increase executed within 1 and 0.2 s after the request, the time dictated by grid support service requirements in Finland and the UK. We show that a power ramp-up from 2.0 kW to 3.7 kW is achieved within 1 s with an initial air stoichiometry of 2.5 and within 0.2 s with an initial air stoichiometry of 7.0. We also show that the timing of the power ramp-up affects the achieved ancillary power capacity. This work demonstrates that hydrogen fueled and ejector-based PEMFC systems can provide a significant amount of power in less than 1 s and provide valuable ancillary power capacity for grid support services.

This paper presents a dynamic simulation study of the operation of a Power-to-Gas process. The process consists of three parallel 3MW alkaline electrolyzers driven by real-life national grid frequency data. These feed H2- and O2- compressor trains and storages processes followed by a methanation reactor. The process is controlled on two levels, where on the lower level stabilizing controllers are utilized to control e.g. flows and pressures by manipulation of e.g. valves and compressors. On the higher level, an operational scheduling of the electrolyzer operation is used. On this level the process can be operated as a primary grid frequency control reserve. To meet the local grid balancing needs, scheduling when to operate in frequency control could be determined beforehand from cost-efficient bidding in the local Electricity Spot and Regulation Power Markets. We assess a 24 hour period, in which the process operates to and from frequency control, from the point of view of how well the process can dampen variations. More precisely the effect of this operational scheduling on the electrolyzers, H2-storage system and CO2-methanation reactor is studied. Modelling of the process is done with a commercial, dynamic process simulator, Apros[...].

This paper addresses the operational profitability and benefits of co-production and dynamics in renewable Power-to-Fuel or Power-to-Chemical processes, when utilized to stabilize the power grid. To reach climate neutrality, the transport sector must switch to climate-neutral or climate-positive fuels or power. This can be done by a proper mix of electric vehicles where the power is based on renewable electricity, hydrogen vehicles where the hydrogen is based on side-product hydrogen or renewable power based processes, or by using in existing vehicle fleet renewable biofuels instead of fossil fuels. For hydrogen-based or hydrocarbon-based chemical industry, similar change needs are obvious. Today, renewable fuels can be produced with biomass based plants or in bio-refineries. If biomass cannot be utilized or there is a lack of some sustainable chemicals like hydrogen in the bio-process, new so called Power-to-X plants could be used to produce renewable fuels or chemicals of non-biomass origin (X refers to the end product of the plant). These processes are utilizing hydro, solar or wind power via electrolysis for production of the needed additional hydrogen fraction. Optimized day- or week-ahead planning can increase considerably the value of renewable Power-to-X plant operation. Such optimal operation can enhance commercial viability of the Power-to-X plants, and in this way introduce these climate-positive, mid-sized and distributed units into a smart grid. In this paper, we show examples on the value of such optimal dynamic operation together with the value of the dynamics of key unit processes and intermediate storages, while at the same time reaching a high share of sustainable solar and wind power in the end product.

SofcPower 2007-2012 was a Finnish SOFC systems research project aimed to develop a complete SOFC power plant demonstration. This goal was reached and during the project, the demonstration plant produced thousands of hours of power to the Finnish electric grid. The project gathered together several research institutes and companies, with the main funding being provided by the Finnish Funding Agency for Technology and Innovation TEKES. This summary compiles the main features and achievements of the five-year project.