Project No: FWP-40552
Performer: Pacific Northwest National Laboratory
Shailesh Vora Technology Manager National Energy Technology Laboratory 626 Cochrans Mill Road P.O. Box 10940, MS 922-204 Pittsburgh, PA 15236-0940 (412) 386-7515 firstname.lastname@example.org Briggs White Project Manager National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880, MS PO3B Morgantown, WV 26507-0880 (304) 285-5437 email@example.com Jeff Stevenson Principal Investigator Pacific Northwest National Laboratory P.O. Box 999, MSK2-44 Richland, WA 99352 (509) 372-4697 firstname.lastname@example.org
DOE Share: $55,889,667.00
Performer Share: $0.00
Total Award Value: $55,889,667.00
Performer website: Pacific Northwest National Laboratory - http://www.pnl.com
This project will accelerate the development of reliable, low-cost SOFC power generation systems capable of operation on coal derived fuels by developing advanced SOFC component materials and computational tools. Interconnection components for both atmospheric and pressurized operation will be developed. Important to this work is the evaluation and development of materials and manufacturing processes for various SOFC components (electrolyte, anode, cathode, cell-to-cell interconnections, and seals) to support higher performance and robustness, less degradation, and lower cost. In addition, this project will address the effects of coal contaminants on SOFCs and how to mitigate any deleterious effects through upstream clean-up and modification of SOFC components. This project will also identify, develop, test, validate, and optimize cost-effective cell and stack components, materials, and fabrication techniques; develop advanced computational tools and capabilities for cell and stack design analysis and optimization; test cells exposed to coal contaminants and complete analysis of the results, both post-test and using thermodynamic software; and develop and evaluate new interconnect compositions appropriate for pressurized SOFCs.
Program Background and Project Benefits
The U.S. Department of Energy (DOE) is developing the next generation of efficient fossil fuel technologies capable of producing affordable electric power with near-zero emissions. The Solid Oxide Fuel Cell (SOFC) program at DOE’s National Energy Technology Laboratory (NETL) is focused on developing low-cost, highly efficient SOFC power systems that are capable of simultaneously producing electric power, from either natural gas or coal, with carbon capture capabilities. Research is directed towards the technologies that are critical to the commercialization of SOFC technology. To successfully complete the development of SOFC technology from the present state to the point of commercial readiness, the SOFC Program efforts are aligned into three Key Technologies:
(1) Anode, Cathode, and Electrolyte (AEC) Development (2) Atmospheric Pressure Systems (3) Pressurized Systems
(1) Anode, Cathode, and Electrolyte (AEC) Development (2) Atmospheric Pressure Systems (3) Pressurized Systems
The AEC Development Key Technology is R&D in nature whereas the other two, Atmospheric Pressure Systems and Pressurized Systems, are focused on the development, demonstration, and deployment of SOFC power systems.
The AEC Development Key Technology consists of projects that will lead to substantially improved power density, enhanced performance, reduced degradation rate, and more reliable and robust systems. Research is focused on the technologies critical to the commercialization of SOFC technology, such as cathode performance, gas seals, interconnects, failure analysis, coal contaminants, fuel processing, and balance-of-plant components. Research is conducted at universities, national laboratories, small businesses, and other R&D organizations.
This project focuses on developing and evaluating advanced cell and stack components and computational tools and capabilities for cell and stack design analysis and optimization. Improved cell/stack life and performance will reduce operating cost and increase efficiency, resulting in reduction in the cost of electricity and reduction of CO2 emissions from the entire platform. Specifically, this project will develop, manufacture, and evaluate advanced component materials, manufacturing processes, and computational tools.
Project Scope and Technology Readiness Level
PNNL will identify technical barriers, prioritizes technology development needs and conduct advanced research, engineering simulation and design optimization and testing with respect to the development of reliable, low-cost, solid oxide fuel cell (SOFC) power generation systems capable of operation on coal derived fuels. The FY14 effort is focused on four tasks:
Task 1: SOFC Component Development — Develop, test and optimize high-performance, reliable cell and stack component materials and fabrication techniques for low-cost, reliable SOFC stacks.
Task 2: SOFC Modeling — Develop and utilize computational techniques for the optimization of cell and stack designs that allow mitigation of performance degradation and optimization of electrical performance in modular SOFC stack and systems.
Task 3: Experimental Support of Modeling — Obtain bulk and interfacial materials properties that support the development, optimization and validation of SOFC designs through simulation and modeling.
Task 4: Management, Technology Integration and Transfer — Provide overall technical supervision and program management, facilitate technology transfer, and integrate emerging technologies and interfaces with SOFC program participants.
The Technology Readiness Level (TRL) assessment identifies the current state of readiness of the key technologies being developed under the DOE’s Clean Coal Research Program. In FY 12, this project was not assessed. The TRL assessment process and its results including definition and description of the levels may be found in the "2012 Technology Readiness Assessment-Analysis of Active Research Portfolio".
Commissioned second generation stack test fixture.
Successfully assembled and tested 3-cell stack fixture for long-term (approximately 6,000 hours) evaluation/validation of manganese-cobalt (M-C) spinel and alumina coated interconnects.
Demonstrated excellent electrical performance of M-C spinel-coated AISI 441 for over two years (20,000 hours).
Evaluated performance of coatings with reduced (or zero) cobalt content.
Optimized ultrasonic spray process for interconnect coatings. An ultrasonic spray process was evaluated and successfully developed for the application of cerium oxide-modified M-C coatings aluminization on metallic interconnects.
Conducted a microscopic study which included evaluation of interconnect coatings using composition and phase analysis. It was determined after one year that the oxide scale under the coating consisted of a continuous matrix of titanium-doped chromium oxide with dispersed grains of manganese-chromium oxide. No evidence of impending degradation was found using high-resolution transmission electron microscopy provided by Carnegie Mellon.
Completed the ASME SOFC design basis document. This living document, modeled after those published by the ASME, acts as a repository for the current best practices in the design of structurally-sound SOFC stacks. The baseline version of the design guide covers all major aspects of stack design and is supported by five appendices of technical reference material. The document will be reviewed every six months and updated on an as-needed basis to continually reflect the state-of-the-art in SOFC stack design.
Demonstrated that sodium volatility from soda lime glass and potassium volatility from potassium silicate had no discernible effect on performance of lanthanum strontium manganite/yttria-stabilized zirconia (LSM/YSZ) composite cathodes and lanthanum strontium cobalt ferite (LSCF) cathodes.
Identified new coal gas contaminant absorber materials. It was found that an absorber bed containing potassium carbonate completely captures phosphorus at temperatures of 350 degrees Celsius (ºC) and above, and completely captures arsenic at temperatures of 600 ºC and above. This represents a possible inexpensive option for removing these contaminants from coal gas.
Investigated the role of cell voltage on contaminant attack. A parametric study of cell voltage and coal contaminants phosphorus, arsenic, sulfur, selenium, and hydrogen chloride on anode degradation was completed. No changes in the cell degradation rate at different operating voltages were observed in the presence of phosphorus, arsenic, and hydrogen chloride; however, distinctly different responses to sulfur and selenium were observed at different voltages.
Transferred stack test fixture capability to NETL. Single-cell stack fixtures were delivered to and commissioned at NETL. This establishes the capability at NETL for independent parallel evaluation of materials and concepts for cells and stacks.
Devitrifying &"refractory” sealing glasses were optimized in terms of softening temperature, wetting behavior, and coefficient of thermal expansion.
Evaluated a new sealing approach incorporating a glass which is compliant at SOFC operating temperatures through single and dual atmosphere testing. Compliant seals improve mechanical robustness of SOFC stacks by reducing residual stresses during stack operation and thermal cycling. Process optimization studies were performed to control pore size and volume fraction porosity. Additions of zirconia fillers to form a glass/zirconia composite can improve dimensional stability at operating temperature. Collaborative development efforts at PNNL and ORNL involving glass only and glass/zirconia particle or fiber composites were continued.
Continued a long-term (>20,000 hours) study evaluating the effects of applying surface modifications to ferritic stainless steel interconnect materials prior to application of protective spinel coatings. Substantial improvement in scale adhesion and spallation resistance (compared to unmodified surfaces) can be achieved, particularly through surface blasting or grinding.
Provided topical report to SECA industry teams summarizing benefits of select surface modifications on scale adhesion / spallation resistance of steel-based interconnects.
Effects of humidity in air on LSM- and LSCF-based cathodes were quantified as a function of operating temperature and time.
Performed high temp XRD analyses on working LSCF cathodes as a function of operating time, voltage, and temperature. Changes in the perovskite structure and overall phase assemblage were quantified.
Developed and implemented a continuum damage-healing modeling framework to simulate the thermal-viscoelastic behavior of compliant glass seals in SOFC stacks using finite element analysis. Sensitivity studies on the seal design parameters were performed to evaluate the effects of material properties and operating conditions on seal mechanical behavior for the seal design engineering effort.
Developed a modeling framework that automatically creates reduced order models (ROMs) for SOFC stacks. The frame-work interface guides the user through the analysis procedure, samples and interrogates the multi-parameter operating space using the detailed stack model, performs regression to generate the response surfaces, and implements the response surfaces into a ROM submodel for general use within system modeling software.
Developed a user-friendly interface for the 2D SOFC-MP software to perform pre-processing and post-processing for SOFC stack evaluations. The pre-processing capability enables users to enter and modify SOFC model geometry, stack operating conditions, and simulation control parameters, while the post-processing capability helps users to visualize the solution results for various physical quantities across the stack model domain.
Benchmarked the 2D SOFC-MP modeling tool against experimental data. Model simulations for ten cases with different fuel compositions and temperature boundary conditions were successfully verified with experimental thermocouple data from a state-of-the-art stack for H2 and reforming fuel compositions.
Developed models to investigate humidity effects on cathode performance. Micro-scale modeling is used to understand competition of water with LSM activity and kinetics of possible reactions, while meso-scale modeling is used to quantify the corresponding electrochemical degradation within the electrode microstructure.
Modified the interconnect lifetime prediction methdology to be informed from interfacial indentation data of oxide scale-substrate interfaces with different surface modifications.
Completed a 24,000 hour oxidation test of several interconnect samples confirming that a shot-peening surface treatment can substantially extend interconnect lifetimes.