Solid Oxide Fuel Cell Program Research Articles

(Invited) The SOFC Program at the DOE’s Office of Fossil Energy and Carbon Management (FECM) and National Energy Technology Laboratory (NETL)

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy (FE) and administered by the FE’s National Energy Technology Laboratory (NETL) is currently developing low-cost SOFC power generation systems. SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation. In addition, there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several projects on various aspects of high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants.

Advanced Manufacturing of Unique Solid Oxide Fuel Cell Electrode and Electrolyte Microstructures through Aerosol Deposition

Development of various additive manufacturing technologies over the years has given an opportunity for highly customizable and unique structures to be fabricated with applications towards several different industries. For ceramic manufacturing, techniques such as direct ink writing (DIW), stereolithography (SLA), and fused deposition modeling (FDM) have been utilized to construct very complex structures. These technologies have also been developed for use towards solid oxide fuel cells (SOFCs) where they have been utilized to manufacture components greater than 200 µm in thickness. Some components of the SOFC such as the electrodes, electrolyte, and barrier layer are much smaller and consist of thicknesses from 1 µm to 50 µm. Along with the reduced thickness, the electrodes of a SOFC are often comprised of a composite material where the previously mentioned technologies struggle with achieving both the required high resolution and compositional change needed to manufacture these specific components. This project’s goal is to develop an additive manufacturing technique that suits both requirements for manufacturing the electrodes, electrolyte, and barrier layer of a SOFC.The technology that has been developed to complete the manufacturing of highly customizable electrodes along with the electrolyte and barrier layer is Aerosol Deposition. The Aerosol Deposition system contains several different elements that lead to consistently tailored microstructures for the various 3-D printed parts including the use of syringe pumps, an ultrasonic atomizing nozzle from Sonaer Ultrasonics, an infrared heater, and a flexible automation system. The ultrasonic atomizing nozzle is used to convert a stream of liquid into a fine mist via mechanical vibrations. The liquid that is supplied to our ultrasonic atomizing nozzle is low solids loading solvent-based suspension containing approximately 1 - 5 vol% of solids and polymer pore formers. Suspensions are supplied to the nozzle by mechanical pressure provided from a programmable syringe pump. This technology accompanied with a flexible automation system gives the potential for highly customizable and repeatable microstructures that can aid in evaluating variables associated with the different components of the SOFC.Development of the additive manufacturing system to fabricate the anode functional layer, electrolyte, barrier layer, and cathode active and current collector layers through an automated process have been studied. For the electrodes, a microstructure that contains approximately 30% - 40% porosity is suitable to enhance the electrochemical performance of the electrode. Sintering temperatures for the electrodes typically range from 1000 °C to 1300 °C which can typically densify the microstructure and restrict the amount of porosity present. To implement porosity within the microstructure poly(methyl methacrylate) was incorporated into electrode suspensions due to their ability to diffuse out of the electrode microstructure at temperatures of ~450 °C. The electrical and mechanical properties of the separate components have been characterized accordingly utilizing electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Acknowledgements: This work was performed in support of the US Department of Energy’s Solid Oxide Fuel Cell Program. The authors would like to acknowledge the WVU Shared Research Facilities (SRF) and thank Dr. Thomas Kalapos from Leidos Research Support Team for his assistance.

(Invited) The SOFC Program at the DOE’s Office of Fossil Energy and Carbon Management (FECM) and National Energy Technology Laboratory (NETL)

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy and Carbon Management (FECM) and administered by the FECM’s National Energy Technology Laboratory (NETL) is currently developing low-cost SOFC’s and reversible SOFC systems (rSOCFs). SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation. In addition, there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several projects on various aspects of high-temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. Development of reversible SOFC systems, rSOCFs, is the new central focus of FECM. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear power plants.

Solid Oxide Cell Materials Development at Pacific Northwest National Laboratory

Pacific Northwest National Laboratory (PNNL), a U.S. Department of Energy (DOE) laboratory, has worked with government agencies and industrial collaborators to accelerate the commercialization of SOFC power systems for distributed and central power applications. This presentation will highlight work performed for the US DOE Office of Fossil Energy’s Solid Oxide Fuel Cell program. Topics to be covered include effects of contaminants and their mitigation on electrode performance; investigating volatility from cathode materials; improved cell materials; Co-free protective interconnect/BOP coatings development; capabilities of the SOFC stack test platform; and progress on industrial collaborations including seal development in electrolyzer systems fabricated using advanced manufacturing techniques such as 3D printing and rapid electromagnetic sintering.

(Plenary) Update on the SOFC Program at the DOE’s National Energy Technology Laboratory

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy (FE) and administered by the FE’s National Energy Technology Laboratory (NETL) is currently developing low-cost SOFC power generation systems. SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation; there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several projects on various aspects of high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants.

Sr and Co Vapor-Phase Transport from LSCF Cathodes

Strontium transport contributes to degradation mechanisms in SOFCs, especially strontium zirconate formation at the interface of the cathode barrier layer with the YSZ electrolyte. High temperatures required for cathode sintering lead to Sr transport during cell construction. SEM analysis of SOFCs with LSCF cathodes shows Sr at the YSZ/GDC barrier layer interface, but no Sr throughout the GDC barrier layer itself, as would be expected for solid-phase transport. Vapor-phase transport was identified as a possible mechanism that would lead to these observations. A series of tests were performed to differentiate between surface diffusion and vapor-phase diffusion of species from LSCF cathode material at typical sintering temperatures (up to 1100°C). A GDC substrate was printed with LSCF and separated by an air gap from a YSZ target substrate. First a simple spacer ring was used to create the air gap, and strontium transport was observed via SEM-EDS (energy dispersive spectroscopy). Then, various geometries with long surface paths were employed to reduce the possibility of surface transport. The target substrates were analyzed via x-ray photoelectron spectroscopy (XPS) with high sensitivity for surface species. An open air gap did not show evidence of Sr or Co transport. A refined, enclosed air gap with long surface path length did show such evidence for Sr and Co, indicating an enclosed area to maintain significant vapor pressure was necessary for transport. An SOFC with LSCF in direct contact with a barrier layer would also provide such an environment for vapor-phase transport to occur. Furthermore, spatially resolved analysis showed a relatively uniform distribution of Sr and Co across the target substrate. This supports the vapor-phase mechanism as Sr and Co transported via surface diffusion would have been fixed preferentially to the outer edge of the target substrate. These results have implications for adjusting sintering conditions and barrier layer requirements to prevent the formation of undesired strontium zirconate. This work was performed for the US DOE Office of Fossil Energy’s Solid Oxide Fuel Cell program under the Cathode Task.

(Plenary) Update on the SOFC Program at the DOE’s National Energy Technology Laboratory

The Solid Oxide Fuel Cell (SOFC) Program, managed by the U.S. Department of Energy (DOE) Office of Fossil Energy (FE) and administered by the FE’s National Energy Technology Laboratory (NETL), is currently developing low-cost SOFC power generation systems. SOFC power systems have the potential to achieve greater than 60 percent efficiency. The SOFC’s operating temperature is lower than combustion-based processes and precludes NOx formation; there are near-zero emissions of CO2, criteria pollutants, and particulates. Furthermore, SOFC power systems require approximately one-third the amount of water relative to conventional combustion-based power systems. The Program includes the testing of SOFC with natural gas in distributed applications, including data centers. In addition to SOFC, there are several new projects on various aspects of high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water. The development of efficient systems for hydrogen production is very interesting, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants.

Current Status of Solid Oxide Fuel Cell Technology Research and Development at National Energy Technology Laboratory

The DOE Office of Fossil Energy Solid Oxide Fuel Cell (SOFC) Program is interested in the near-term commercialization of high-temperature SOFC and solid oxide electrolyzer cell (SOEC) technologies that are robust, reliable, and resilient. A recent report delivered to the United States Congress highlighted several development recommendations including the design of pilot-scale units, continued early stage research and development, increased industrial engagement, and the exploration of reversible operation of SOFC technology.The National Energy Technology Laboratory (NETL) SOFC research group currently addresses most of these recommendations. NETL’s in-house research efforts focus on the characterization, simulation, and mitigation of high temperature degradation of fuel cell components. The capstone of these efforts is NETL’s SOFC degradation modeling framework, which uses NETL supercomputing facilities to simulate SOFC performance degradation of thousands of possible electrode configurations experiencing multiple simultaneous degradation modes under a broad array of relevant operating conditions. The models for the different degradation modes are based upon experimental data (1) generated in-house, (2) referenced from available scientific publications, and (3) shared from collaborations with other industrial, academic, and national laboratory partners within the SOFC Program. The team then employs techniques in data analytics to select optimal electrodes to maximize the SOFC performance for given operating conditions. These modeling efforts guide electrode engineering efforts in-house and through external collaborations by identifying (1) which degradation modes contribute the most to overall performance degradation for given operating conditions and (2) which electrode features will have the greatest impact on lowering cell degradation and system costs. Additionally, the development on non-invasive in situ high temperature fiber optic sensors for temperature and gas composition measurement provides valuable data for inclusion in degradation models as well as informing technology development at the commercial scale. Finally, the wealth of experience gained in development degradation models and materials for reducing the cost of SOFC technology is being readily applied to reducing the cost of SOEC technology.NETL will report on its most recent progress in the field of SOFC and SOEC development, including degradation modeling, in situ fiber optic sensor development, electrode engineering, and relevant systems-level analyses.

Solid Oxide Fuel Cell Development at Pacific Northwest National Laboratory

Pacific Northwest National Laboratory (PNNL), a U.S. Department of Energy (DOE) laboratory, is working with government agencies and industrial collaborators to accelerate the commercialization of SOFC power systems for distributed and central power applications. This presentation will highlight recent progress in work being performed for the US DOE Office of Fossil Energy’s Solid Oxide Fuel Cell program. Topics to be covered include effects of contaminants and their mitigation on electrode performance; investigating volatility from cathode materials; improved cell materials; Co-free protective interconnect/BOP coatings development; and design, fabrication, validation of an SOFC stack test platform; and modeling tools to evaluate and optimize SOFC stack and system performance.

Progress in the U.S. Department of Energy Office of Fossil Energy’s Solid Oxide Fuel Cell Program

The U.S. Department of Energy Office of Fossil Energy (FE) National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Program is committed to developing efficient, low-cost electricity from natural gas for MWe-class distributed generation applications in the near-term. In the long-term, the Program is focused on natural gas and coal based central power generation applications with carbon capture; maintaining cell development and core technology research to increase the reliability, robustness, and durability of cell, stack, and system technology; and providing the technology base to permit cost-competitive distributed generation applications. The program is a unique balance of strategically oriented research and development activities spanning fundamental research to prototype testing. The SOFC Program collaborates and coordinates with other fuel cell programs government-wide, including ARPA-E and DOE EERE’s Hydrogen and Fuel Cell Office. The progress of these activities, along with the status of the program’s integrated systems tests and the roadmap to deploy a MWe-class natural gas-fueled distributed generation system, will be presented.

Worldwide Status of Solid Oxide Fuel Cell Technology

The solid oxide fuel cell (SOFC) technology is expanding globally and finding new market opportunities in a variety of applications. The technology has not been fully tapped and has a promising future. The amazing versatility and applicability of the solid oxide (SO) technology is astounding as solid oxide fuel cells are developed as a source of efficient, low-cost electricity from natural gas distributed power generation, as reversible SO cells, and as solid oxide electrolyzers (SOEC) which have many applications in distributed generation (DG), hydrogen production, energy storage, microgrids, telecom backup market, combined heat and power (CHP), sensors, power to chemicals and fuels, data centers, ships, vehicles, absorption chillers, drones, and others. The United States has the greatest manufacturing capability and the most megawatts (MWs) of demonstrations of any nation due to Bloom Energy, which has over 350 MW of cumulative installation. The current US Department of Energy (DOE) Office of Fossil Energy SOFC Program administered by the National Energy Technology Laboratory (NETL) includes cell development and core technology research to increase the reliability, robustness, and durability of cell, stack, and system technology. Japan leads the world in the total number of demonstrations of the SOFC with over 60,000 kilowatt (kW)-class demonstrations by Kyocera. The European efforts of Ceres, SOLIDpower, Sunfire, Elcogen, and others represent major new directions into SO electrolysis, datacenters, and power-to-fuels. In the last decade China, through Suzhou Huatsing Power, SOFCMAN and CNFC, has made significant progress in SOFC and in electrolysis, scaling to 30-kWe and 80-kWe, respectively.

(Invited) A Decade of Progress Under the U.S. Department of Energy Office of Fossil Energy’s Solid Oxide Fuel Cell Program

The U.S. Department of Energy Office of Fossil Energy (FE) National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Program is committed to developing efficient, low-cost electricity from natural gas or coal with intrinsic carbon capture capabilities for cost-competitive distributed generation and central power generation applications. Advancements in the cost, durability, reliability, energy density, specific energy, and adoption of SOFC technology over the past decade will be chronicled to provide a picture of today’s state of the art SOFC technology. A discussion of current DOE funded research will provide an introduction to the next generation of SOFC technology and illustrate what advancements are expected in the near term. The status of these strategically oriented research projects will be presented in the context of the program’s integrated systems tests and the roadmap to deploy a MWe-class natural gas-fueled distributed generation system.

(Invited) Electrode Engineering of Solid-Oxide Electrochemical Cells at National Energy Technology Laboratory

The National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Team performs fundamental SOFC technology evaluation, enhances existing SOFC technology, and develops advanced SOFC concepts in support of the U.S. Department of Energy SOFC Program. Program targets include a reduction in performance degradation to 0.2% per 1000 hours and a system cost of $900 per kilowatt. Research and development is essential to meet these targets. Research efforts are broadly focused on an investigation of cell and stack degradation, electrode engineering, grid integration challenges, and system analysis. The research approach is targeted to specifically address SOFC program technology development goals, especially regarding reducing stack costs, increasing cell efficiency, and increasing cell reliability and robustness. The goal of these efforts is to transfer technology that facilitates commercial acceptance of SOFC technology. This is accomplished through close collaboration with SOFC commercial developers, national laboratories, and academic institutions. NETL system-level analysis has shown that a critical consideration for reducing the cost of SOFC technology is the enhancement of electrode performance and longevity through materials and microstructure engineering. Within this scope is the special consideration of cell production costs and operating temperature. Specifically, at NETL, nano-electrocatalyst infiltrations have been a successful operation by scaling up the patented technology to a commercially-relevant scale, partnering with industrial manufacturers. The effort has continued to the construction of a scaffold microstructure that is optimized for surface modification and the development of gel-derived high surface area electrodes. Electrode materials selection has been made through a computational approach that uses electronic structure and energetics in conjunction with thermodynamics and statistical physics, identifying multicomponent oxides with high oxygen reduction reaction activity and stability. Highly reliable electrical conductivity relaxation analysis confirmed the predicted electrode materials’ superior surface exchange property when compared to the state-of-the-art lanthanum strontium cobalt ferrite. The developed electrode engineering techniques have been applied for reversible solid-oxide cell operation as well as single mode solid-oxide cells to stabilize electrodes while maintaining improved performance and longevity.

Overview of U.S. Department of Energy Office of Fossil Energy’s Solid Oxide Fuel Cell Program for FY2019

The U.S. Department of Energy Office of Fossil Energy (FE) National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Program is currently developing efficient, low-cost electricity from natural gas distributed generation applications in FY2019. The current program includes cell development and core technology research to increase the reliability, robustness, and durability of cell, stack, and system technology; and providing the technology base to permit cost-competitive distributed generation applications. The program is a unique balance of strategically oriented research and development activities spanning fundamental research to prototype testing. The SOFC Program collaborates and coordinates with other fuel cell programs government-wide, including ARPA-E and DOE EERE’s Hydrogen and Fuel Cell Office. The accomplishments of these activities, along with the status of the program’s integrated systems tests will be presented.

Overview of U.S. Department of Energy Office of Fossil Energy’s Solid Oxide Fuel Cell Program

The primary mission of the U.S. Department of Energy’s Office of Fossil Energy (FE) is to ensure the nation can continue to rely on its indigenous fossil fuel resources for clean, secure, and affordable energy. A component of that effort is the Solid Oxide Fuel Cell (SOFC) Program, administered by FE’s National Energy Technology Laboratory (NETL). The SOFC Program is committed to: developing efficient, low-cost electricity from natural gas or coal with intrinsic carbon capture capabilities for distributed generation and central power generation applications; maintaining cell development and core technology research to increase the reliability, robustness, and durability of cell, stack, and system technology; and providing the technology base to permit cost-competitive distributed generation applications. The program recently initiated two focused efforts: addressing cell and system reliability and an Innovative Concepts initiative.Based on feedback from several program participants, chromium contamination of cathode was identified as a major contributor to performance degradation and reduced system reliability. NETL has launched an initiative to address the issue of chromium contamination. The SOFC Program portfolio presently has 13 projects addressing this critical issue.The SOFC Program is also funding an Innovative Concepts initiative that supports the research, development, and demonstration (RD&D) of SOFC technology that has the potential to surpass current anode supported planar SOFC technology in terms of cost and reliability. Program participants are developing novel cell and stack architectures and/or material sets. This next-generation SOFC technology development in the near-term includes nominally 5-10 kWe-scale stack tests using cells envisioned in the developer’s future commercial systems. The status of these strategically oriented research programs, along with the status of the program’s integrated systems tests and the roadmap to deploy a MWe-class natural gas-fueled distributed generation system, will be presented.

Overview of U.S. Department of Energy Office of Fossil Energy’s Solid Oxide Fuel Cell Program

The U.S. Department of Energy Office of Fossil Energy (FE) National Energy Technology Laboratory (NETL) Solid Oxide Fuel Cell (SOFC) Program is committed to developing efficient, low-cost electricity from natural gas or coal with intrinsic carbon capture capabilities for distributed generation and central power generation applications; maintaining cell development and core technology research to increase the reliability, robustness, and durability of cell, stack, and system technology; and providing the technology base to permit cost-competitive distributed generation applications. Recent program efforts focused on addressing cell and system reliability (finding chromium contamination of the cathode a major contributor to performance degradation and reduced system reliability) and an Innovative Concepts initiative (developing novel cell and stack architectures and/or material sets). The status of these strategically oriented research programs, along with the status of the program’s integrated systems tests and the roadmap to deploy a MWe-class natural gas-fueled distributed generation system, will be presented.

Development of Medium-Temperature Solid Oxide Fuel Cell Materials and Single Cells in Estonia

Estonian solid oxide fuel cell program started in 2001. Solid oxide fuel cell single cells based on Ni-Ce0.9Gd0.1O2-δ or Ni-Zr0.92Y0.08O2-δ supporting anodes, bi-layered Zr0.92Y0.08O2-δ | Ce0.9Gd0.1O2-δ or Zr0.9Sc0.1O2-δ | Ce0.9Gd0.1O2-δ electrolytes and micro-meso-porous La0.6Sr0.4CoO3-δ, Gd0.6Sr0.4CoO3-δ or Pr0.6Sr0.4CoO3-δ cathodes prepared from nano/microporous powders at different sintering temperatures and pore former additions in the raw cathode and anode pastes have been studied. Different physical (XRD, high-temperature XRD under electrochemical working conditions, FIB-SEM, AFM, and BET) and electrochemical (cyclic voltammetry, chronoamperometry and electrochemical impedance) methods have been applied. Influence of the anode and cathode porosity, depending on the electrode preparation methods, and also of the bi-layered electrolyte properties (chemical composition, thickness, etc.) on the power density of the single cells has been shown and discussed. During last two years the synchrotron radiation based X-ray absorption spectroscopy under electrochemical polarization, gas feeding and temperature cycling conditions has been applied for analysis of anode surface composition.

GE SECA Prototype System Development and Testing

This paper summarizes the prototype system development and testing under Solid State Energy Conversion Alliance (SECA) Solid Oxide Fuel Cell Program. There were two generations of the SECA prototype systems developed. The Gen 1 prototype system met or exceeded the SECA requirements over a 1720h test, achieving 41% peak system efficiency and 5.4 kW peak net power. The Gen 2 prototype achieved 49.6% peak efficiency and 5.6 kW peak net power over a 120h commissioning test. The Gen 2 prototype system has been delivered to National Energy Technology Laboratory (NETL) for final testing.

Solid Oxide Fuel Cell (SOFC) Development in Denmark

The SOFC technology under development at Risø National Laboratory (RISØ) and Topsoe Fuel Cell A/S (TOFC) is based on an integrated approach ranging from basic materials research on single component level over development of cell and stack manufacturing technology to system studies and modelling. The effort also comprises an extensive cell and stack testing program. Systems design, development and test is pursued by TOFC in collaboration with various partners. The standard cells are thin and robust with dimensions of 12 x 12 cm2 and cell stacks are based on internal manifolding. Production of cells is being up-scaled continuously. The durability of the standard stack design with standard cells has been tested for more than 13000 hours including nine full thermal cycles with an overall voltage degradation rate of about 1% per 1000 hours. Recently, the degradation rate has been significantly reduced by introduction of improved stack component materials. 75-cell stacks in the 1+ kW power range have been tested successfully. Stacks have been delivered in a pre-reduced state to partners and tested successfully in test systems with natural gas as fuel. The consortium of TOFC and RISØ has an extended program to develop the SOFC technology all the way to a marketable product. Stack and system modelling including cost optimisation analysis is used to develop multi kW stack modules for operation in the temperature range 700-850oC. To ensure the emergence of cost-competitive solutions, a special effort is focused on larger anode-supported cells as well as a new generation of SOFCs based on porous metal supports and new electrode and electrolyte materials. The SOFC program comprises development of next generation of cells and multi stack modules for operation at lower temperature with increased durability and mechanical robustness in order to ensure long-term competitiveness.