Development and Demonstration of a Decentralised Hydrogen rSOC System
Authors: Reiter Bernd , Hauth Martin , Sztrinko Peter 
Published: July 2021

The quality of life and economic prosperity of the population depends to a large extent on a secure and sustainable electricity supply. In order to ensure this for generations to come, a comprehensive integration of renewable, decentralized electrical energy sources is necessary. Such developments are already evident in the world's largest markets. Inevitably, electricity production is increasingly being distributed over larger areas and energy supply systems are tending towards decentralization. Traditional role distributions, such as centralized feed-in and load adjustment by large power plants and decentralized demand, are being replaced by decentralized feeders at all grid levels and prosumers. Security of supply can only be achieved by balancing fluctuating output and demand. Therefore, in order to achieve the EU's 2050 climate targets, in addition to flexibility on the consumer side and sector coupling strategies, increased balancing options in the form of storage systems are required. Currently available storage technologies such as pumped storage power plants, etc. can be considered as complementary solutions. In Europe, their capacities are limited by almost exhausted utilization potentials. Since the fluctuating generation profiles also contain a significant seasonal component, long-term storage solutions are essential. In order to offer appropriate long-term storage services, the additional use of gaseous energy carriers enabled by PtG (Power-to-Gas) technologies is the only alternative.

Currently, however, PtG storage technologies are still in the development and demonstration phase, so that further research is required primarily at the system but also at the component level. Another major issue is the commercial viability related to full-load operating hours and installation cost of PtG technologies, if the operation is only given when surplus electricity is available. Fuel cell technologies like reversible solid oxide cell systems (rSOC) that combine both electrolysis and electricity generation in one unit offer great potentials to address these issues.

Within the Austrian funded R&D project FIRST (Fully Integrated Reversible Solid oxide cell system) a compact, reversible, high-temperature solid oxide (rSOC) system with a rated power of 15 kWel in SOEC operation and a rated power of 5 kWel in SOFC operation is being developed and demonstrated.

In order to realize a compact and thus economically operable system, the Balance of Plant (BoP) components are being optimized for both SOEC and SOFC operation compared to two separate units. In addition, the stand alone system targets a fast switching between gas and electricity production and enables intelligent linking with electricity, gas and heat grids.

The reversible solid oxide cell (rSOC) demonstrator shall be capable to produce H2 with > 70 % efficiency, or electricity with > 50% efficiency, in a simplified system with low operating costs. Flexible operation by rapidly switching between electrolysis and fuel cell modes within minutes to enable optimal use of electricity from fluctuating energy sources such as wind and solar. Load forecasting models are applied to respond in advance to changes in demand or yield, bringing new system control strategies to bear.

The project aims to test the usability of the technology beyond test bed operation under real operating conditions as a long-term application. Therefore, the results will be relevant to industrial stakeholders as well as utilities.

Within this work the status of the FIRST project will be presented including results from the simulative investigation and optimization within a dynamic model.