SOCTESQA - Solid Oxide Cell and Stack Testing, Safety and Quality Assurance

Many research facilities and industrial companies worldwide are engaged in the development and the improvement of solid oxide fuel cells/stacks (SOFC) and also of solid oxide electrolysis cells/stacks (SOEC). However, the successful application of fuel and electrolysis cells/stacks in real world conditions requires reliable assessment, testing and prediction of performance and durability. Therefore the EU-project SOCTESQA will start at the beginning of May with the aim to develop uniform and industry wide test procedures and protocols for SOC cell/stack assembly. The paper presents the main objectives, the project consortium, the structure, the work packages and the workflow plan of the project. The project builds on experiences gained in the FCTESTNET, FCTESQA series of projects taking up the methodology developed there. It will address new application fields which are based on the operation of the SOFC cell/stack assembly in the fuel cell and in the electrolysis mode, e.g. stationary SOFC μ-CHP, mobile SOFC APU and SOFC/SOEC power-to-gas systems. The test procedures will include current-voltage curves, electrochemical impedance spectroscopy and long term tests both under steady state and dynamic operating conditions. The project partners are from different countries in Europe: French Alternative Energies and Atomic Energy Commission (CEA), Technical University of Denmark (DTU), Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Joint Research Centre – European Commission (JRC) from Belgium, European Institute for Energy Research (EIFER) from Germany and German Aerospace Center (DLR). All of them have long-term experience in the development, testing and harmonization of solid oxide cells/stacks. The project will have a clear structure based on an initial definition phase, the development of generic test modules, the corresponding experimental validation phases and the review of the test procedures. Several of these validation loops will result at the end of the project in final test modules, which will be confirmed by round robin tests. Moreover, the project will address safety aspects, liaise with standardization organizations and establish contact with industrial practice. This collaborative project will essentially help to accelerate the development and the market penetration of hydrogen and fuel cell (H2&FC) energy systems in Europe

Electrochemical impedance spectroscopy of SOFC and SOEC stacks

The successful development of the solid oxide fuel/electrolysis cell technology requires high quality, reliable and reproducible test results which enable the proper understanding of the corresponding electrochemical processes. Especially the different resistances, the overvoltages under electrical current and the degradation mechanisms in the stacks are not well understood. In this context, temperature and fuel gas composition gradients along the cell area and along the height of the stack play an important role under operation. Electrochemical impedance spectroscopy (EIS) is a very useful tool in order to close this knowledge gap. Therefore, the paper focuses on the improvement of the understanding of the electrochemical behavior of SOC stack repeat units with focus on electrochemical impedance spectroscopy. Both, the fuel cell (SOFC) and the electrolysis (SOEC) operation are addressed. The corresponding results have been obtained within the European funded project “SOCTESQA” (Solid oxide cell and stack testing and quality assurance). The relevant issues and parameters which influence the quality of the EIS spectra are outlined. Moreover, the results of the spectra are discussed in terms of reproducibility among different test methods. This includes the validation of the low frequency impedances with the area specific resistances of the current-voltage curves. Both operating modes (SOFC and SOEC) are compared to each other. Additionally, the high frequency impedances are validated with high current interrupt (HCI) measurements. The results obtained by fitting of the spectra with an equivalent circuit are compared with theoretical calculations

D.3.1 Test Matrix Document

The present document defines the test matrix, i.e. a list of test modules relevant for different applications. According to the project objectives the applications are SOFC (stationary and mobile), SOEC (H2- production) and combined SOFC/SOEC (electricity storage via H2). These test modules can be combined to form test programs in order to realize application-oriented testing. This test matrix has been created based on a brief review of results from the precedent project - FCTESQA dealing with cell/stack/system testing procedures for three types of fuel cells (PEMFC, SOFC and MCFC) and the on-going project STACKTEST dealing with testing procedures for PEMFC stacks. Industrial stake holders who are developing SOFC/SOEC products have been contacted to gather information regarding the required operation modes during the lifecycle of the product for each application. Feedbacks from industrial stake holders have also been integrated

D3.6 Final Document of Test Protocols

The objective of the SOCTESQA project is to develop uniform and industry wide test procedures for high temperature solid oxide cells/stacks. These test procedures shall be applicable for different applications of energy systems integrating solid oxide cells/stacks, for instance SOFC-µCHP, SOFC-APU, SOEC for H2 production (power-to-gas) and combined SOFC/SOEC for electricity storage (power-to-gas-to-power). The present document is the final compilation of 11 generic test modules developed in this project. These generic test modules can be combined to form application-specific test programs. All these test modules have been validated through extensive laboratory tests of SOC stacks by the project consortium. These individual test modules and test programs are public and can be downloaded from the project website (www.soctesqa.eu). Moreover, the guidelines and recommendations of these test modules are being transferred to standards developing organisations. In this context, based on the output of this project, an international standard (IEC 62282-8-101: Energy storage systems using fuel cell modules in reverse mode - Test procedures for solid oxide single cell and stack performance including operation in reverse mode) is currently under preparation

Test Module 14: Thermal Cycling

This test module deals with thermal cycling of solid oxide cell (SOC) either as a fuel cell (SOFC) or an electrolyser (SOEC), composed of several start-up/shut-down occurring for the overall SOC lifetime. It is a general characterization method that can be used in SOC R&D and for quality assurance

Transient operation of a solid oxide electrolysis cell

International audienceIn order to investigate the transient behaviour of a solid oxide electrolysis cell, tests were carried out on a single SOEC both under steady-state and transient conditions for 600 h. Steady-state operation was performed at the reference current of -20 A, corresponding to the thermoneutral voltage (1.28 V), whereas transient tests consisted in 1800 square waves applied over 140 cumulated hours, with a current of -1 A and -20 A as well as 0 A and -20 A. Independently from the operating conditions, the measured voltage degradation rate of 5% (70 mV)/1000 h was stable for the entire experiment. Consequently, it was concluded that an SOEC can be operated under on-off conditions with no increase of the degradation rate. This result paves the way for modular operation of a high temperature electrolyser fed with intermittent electrical energy

Electrochemical characterization of SOFC and SOEC stacks

Many research facilities and industrial companies worldwide are engaged in the development and the improvement of solid oxide fuel cells/stacks (SOFC) and also of solid oxide electrolysis cells/stacks (SOEC). However, the different stacks cannot be easily compared due to non-standardized test programs. Therefore the EU-funded project “SOCTESQA” which started in May 2014 has the aim to develop uniform and industry wide test modules and programs for SOC cells/stacks. New application fields which are based on the operation of the SOC cell/stack assembly in the fuel cell (SOFC), in the electrolysis (SOEC) and in the combined SOFC/SOEC mode are addressed. This covers the wide range of power generation systems, e.g. stationary SOFC μ-CHP, mobile SOFC auxiliary power unit (APU) and SOFC/SOEC power-to-gas systems. In order to optimize the test programs, which consist of different test modules, several testing campaigns have been performed. The project partners apply the developed test procedures on identical SOC stacks. In this project 5-cell short-stacks with anode supported cells (ASC) are used, which are provided by an established stack supplier. Altogether 10 pre-normative test modules were developed: Start-up, current-voltage curve, electrochemical impedance spectroscopy, reactant utilization, reactant gas composition, temperature sensitivity, operation at constant current, operation at varying current, thermal cycling and shut-down. The presentation compares the results of the test modules of the different project partners. Important aspects are the evaluation of the results in terms of repeatability of the different testing campaigns and the reproducibility of the results among the partners. Electrochemical properties, e.g. open circuit voltage (OCV), area specific resistance (ASR), power density, fuel utilization (FU) and impedance values of both stack and repeat units (RU) are presented . Moreover, the results are discussed in context to the test input parameters. Another important issue is the reproducibility of the different test methods, e.g. jV-characteristics and EIS-spectra. Finally, important aspects for the determination of reproducible degradation rates of SOC stacks will be presented and discussed

Solid Oxide Cell and Stack Testing, Safety and Quality Assurance (SOCTESQA)

In the EU-funded project SOCTESQA partners from Europe and Singapore are working together to develop uniform and industry wide test procedures and protocols for solid oxide cells and stacks (SOC) cell/stack assembly. New application fields which are based on the operation of the SOC cell/stack assembly in the fuel cell (SOFC), in the electrolysis (SOEC) and in the combined SOFC/SOEC mode are addressed. This covers the wide field of power generation systems, e.g. stationary SOFC µ-CHP, mobile SOFC APU and SOFC/SOEC power-to-gas systems. This paper presents the results which have been achieved so far. Besides a summary of existing test procedures a so called “test matrix” was created. This document includes generic test modules, e.g. current-voltage curves, electrochemical impedance spectroscopy, thermal cycling, electrical current cycling and long-term tests both under steady-state and dynamic operating conditions. The application specific test programs are created by combining several of these test modules

Test Module 16: Shut-Down

This test module deals with the shutdown procedures needed for termination of the SOC cell/stack operation and coming back to ambient temperature. The shutdown procedure normally should be given by the manufacturer. However, if there is no shutdown procedure available, a recommendation is given in this test module