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Automated mass-manufacturing and quality assurance of Solid Oxide Fuel Cell stacks

Periodic Reporting for period 2 - qSOFC (Automated mass-manufacturing and quality assurance of Solid Oxide Fuel Cell stacks)

Berichtszeitraum: 2018-08-01 bis 2020-07-31

qSOFC project combined leading European companies and research centers in fuel cell stack manufacturing value-chain with two companies specialized in production automation and quality assurance to optimize the current stack manufacturing processes for mass production. Before the project in 2016, state-of-the-art Solid Oxide Fuel Cell (SOFC) system capital expenditure (CAPEX) was 7000-8000 €/kW of which the stack is the single most expensive component. The qSOFC project focused on SOFC stack cost reduction and quality improvement by replacing manual labour in all key parts of the stack manufacturing process with automated manufacturing and quality control.

The project was based on its industrial partner products in SOFC stack-manufacturing value-chain (ElringKlinger, Elcogen AS, Elcogen Oy, Sandvik) and motivated by their interest to further ready their products into a mass-manufacturing market. Two companies specialized in production automation and quality control (Müko, HaikuTech) provided their expertise to the project. The two research centers (VTT, ENEA) supported these companies with their scientific background and validate the produced cells, interconnects and stacks.

As a high-level-result of the qSOFC project, the partners have analyzed that at 10 MW/year production volume stack manufacturing cost of 1100 eur/kW is only slightly above qSOFC target 1000 eur/kW, which will be reached at a production volume of about 15 MW/year. Furthermore, the analysis suggests that at mass production (1 GW/year) a stack cost of 500 eur/kW can be reached which gives a solid ground for further manufacturing and quality control development and scaling up production volumes. Cell quality assurance methods, such as automatic optical inspection has been developed and validated in the cell production line. Moreover, the developed methodology is further developed and commercialized by HaikuTech and it is expected that it can also be used in other fields than SOFC cell production. Interconnect manufacturing and quality assurance has been developed, including leak detection and alignment detection of interconnect parts. Traceability methods using data matrix codes (DMC) have been developed and implemented and can be applied to interconnect designs of any manufacturer.
qSOFC project has contributed to solid oxide stack development by enhancing manufacturing and quality assurance at key parts of the stack manufacturing value-chain. The specific improvements include improved cell manufacturing and automated machine vision-based inspection system for cells, better understanding of interconnect steel and coating manufacturing and related quality assurance as well as significant cost reduction and improved stack quality through development of stack assembly and conditioning processes. All of these improvements lead to an improved quality and cost-structure of components and stacks, leading to significant cost reductions. The qSOFC partners have analyzed that at 10 MW/year production volume stack manufacturing cost of 1100 eur/kW is only slightly above qSOFC final target of 1000 eur/kW, which will be reached at a production volume of about 15 MW/year. Furthermore, the analysis suggests that at mass production (1000 MW/year) a stack cost of 500 eur/kW can be reached which. This gives a solid ground for further manufacturing and quality control development and scaling up production volumes.

In terms of technical highlights, in the qSOFC project a machine vision inspection system for cell manufacturing was developed by HaikuTech. The system is able to detect six different types of defects down to ~10 µm of size. The system performs a 100% visual inspection of a cell in 10 s, including scanning and analysis. This allows cell manufacturers to increase their production quality as well as gather data of defects vs. cell performance to further understand the critical defects and allowable occurence limits of defects. HaikuTech has now commercialized the machine vision inspection system and are offering it to cell manufacturers as well as investigating possible other uses for the system outside solid oxide cell industry.

Cell manufacturing process has been optimized for high-speed manufacturing targeting initial 10 MW/year production volume. Cell manufacturing process has also been made compliant to REACH-regulations making further upscaling easier and more environmentally friendly.

Interconnect materials as well as manufacturing and quality assurance was also developed. The production of interconnect steels as well as coated steel materials at Sandvik are ready for significant mass-manufacturing volumes. The multi-stage-manufacturing of interconnect assemblies at ElringKlinger was analysed and optimized during the project to increase quality and yield.

Stack conditioning procedures were developed in the project to reduce overall stack manufacturing time as well as CAPEX needed for manufacturing and conditioning equipment. Through modifications and streamlining of stack conditioning procedure, a 75% reduction in conditioning time was achieved, leading to 60% reduction of CAPEX costs related to stack conditioning.

All of the results and improvements developed during the qSOFC project have been implemented or are in the planning stage to be implemented at the production of related companies. As the component-manufacturers such as ElringKlinger (interconnects) and Elcogen AS (cells) provide components to several fuel cell stack manufacturers, the benefits of the project will be available not only for one specific stack manufacturer but for the whole community. Some of the innovations from the qSOFC project can also be utilized in other industrial applications outside fuel cell manufacturing. For example, the machine vision inspection system can be used with relatively small modifications to inspect quality of other products such as different fired ceramics.

qSOFC project has promoted and discussed the results through several events, including Workshops in Brugge (2017) and in Naples (2019) as well as a joint video with DEMOSOFC and INNOSOFC projects (https://youtu.be/KK-sjnnEcuo). A number of presentations, posters and articles have also be written to the scientific community and to general public.

The project has led to substancial improvement of the operations of the participating companies as well as increasing business opportunities. Partially based on the results from qSOFC and INNOSOFC -projects, Elcogen has also secured a loan from the European Investment Bank for further R&D as well as building a first factory for cells and stacks. The construction of the factory is scheduled to start in Q1/2021.
In general, fuel cells contribute to cleaner future through reduction of emissions as well as through higher conversion efficiency compared to many other technologies.

The following fields in particular have been improved beyond state of the art:
-Manufacturing know-how on multi-part interconnects allowing low-cost, high-quality manufacturing.
-SOFC cell manufacturing methods to reach 50 MW/year production volumes.
-Automated machine vision inspection of cells: 100% visual inspection of defects down to 10 µm within 10 s/cell.
-SOFC stack conditioning procedures to reduce cost and capex related to scaling up production volumes.
-Advanced characterization methods of cells using distribution of relaxation time (DRT) analysis.
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