meeting report
Small Fuel Cells 2007
Miami, FL USA
March 7-9, 2007
- University of Illinois at Urbana-Champaign
This was the 9th international conference in a very successful series on small fuel cells organized and coordinated by The Knowledge Foundation of Brookline, Massachusetts. Held at the Marriott Miami Hotel in Miami, Florida, Small Fuel Cells 2007 featured 27 talks during the main conference program and a half-day pre-conference workshop. Ample time was also provided for individual discussions enhanced by a well-attended company exhibit area and poster displays prepared by individual researchers.
Pre-Conference Workshop
The pre-conference workshop focused on durability. In his welcome to the workshop attendees, Dr. Serge Pan of The Knowledge Foundation stated that the organizers have felt the need to address small and portable fuel cell degradation and durability issues on the materials, the components and the systems level, as a variety of opinions still exist regarding the importance and ways to approach such issues. The workshop was opened by the chairperson, Dr. Michael Stelter of Fraunhofer IKTS in Germany.
Detlef Stolten of the Institute for Materials & Energy Process Engineering, discussed “A 2kW DMFC Development for Light Traction.” The Jülich Research Center has been persuading development of direct methanol fuel cells (DMFC) for power applications. In 2006 it demonstrated a 2kW system with a proven lifetime of more than 500 hours under dynamic operating conditions. The effort is now concentrating on production technology, degradation prevention and quality control procedures.
Yu Seung Kim of Los Alamos National Laboratory presented a paper co-authored with Bryan Pivovar on “Membrane-Electrode Interfacial Degradation in Direct Methanol Fuel Cells: Origin, Diagnosis and Solutions.” They explained how interfacial incompatibility between a polymer electrolyte membrane and the Nafion®-bonded catalyst layer can cause a significant performance loss in DMFC. The origin, diagnosis and solutions for interfacial problems were reviewed, and membrane-electrode assemblies possibly using low permeable alternative membranes were described.
Hyuk Chang of Samsung Advanced Institute of Technology (SAIT), Samsung, Korea, spoke on “Durability and Stability Issues on Mobile DMFC: Analysis & Technical Solution.” In addition to a continued effort to increase power performance of mobile DMFCs, increased attention is now being given to durability and stability issues. Examination of catalysis behavior on the atomic scale shows redeposition of decomposed anode catalyst atoms at the cathode. This phenomena is associated with an intermixture of defective nanocrystalline and amorphous structure. Improvements of the structure are under study. At the same time, a full passive fuel delivery mechanism has been designed along with a stability control system.
Professor George H. Miley of the University of Illinois Urbana-Champaign described “Water Management and MEA Issues Affecting Durability of Direct Borohydride Fuel Cells.” He concentrated on run-time issues for this unique liquid fuel cell. Water recirculation is essential to maintain the solubility of theNaBH4 fuel and the reaction product NaBO2, and avoid clogging of the MEA due to precipitation of either species. In addition, the design of the diffusion layer and the catalyst deposition technique are crucial to prevent small pore holdup or erosion over long run-times. Plasma depositions to improve catalysis deposition on the diffusion layer filters are under study.
Following the talks, a panel discussion , moderated by Emory S. De Castro of E-TEK/PEMEAS Fuel Cell Technologies, addressed “Degradation / Durability Studies and Validation for Micro- and Small Fuel Cells: ‘Should Do’ or ‘Must Do.’” The panelists were Philip Cox of PolyFuel Inc., Jerry Hallmark of Motorola Labs, George Miley of the University of Illinois, Xiaoming Ren of Acta S.p.A, and Detlef Stolten of Research Center Jülich. The gap between what has been achieved for lifetime in small fuel cells and what is needed was discussed. There was general agreement that the gap is closing, but more “field” data is essential. Some expressed the opinion that small fuel cells are closer to commercial goals for durability than are larger cells being developed for automobile use.
The use of higher precious metal (PM) loadings to improve performance/lifetime requirements was noted as an approach under study by some developers, while others are attempting to find alternate catalysts that allow lower loading to reduce cost. Both approaches offer advantages and disadvantages. While progress with catalysis durability is advancing, methods to insure PM recovery poses another aspect of the problem that deserves more attention. Ways to promote consumer recycling must be found. Anode lifetime considerations were also discussed. Improvements are expected through a combination of new materials (e.g., better alloys) and improved engineering methodology. Management of “start-stop” cycles remains a serious challenge since uncontrolled cycling can adversely affect anode lifetime. Down time in particular can promote degradation of components. The search for new anode catalysts to reduce cost and add lifetime was discussed. Some hope was expressed that emerging computational methods for catalyst design will accelerate this search. There was some debate about whether using micro-reformers to produce hydrogen and thus decrease the PM loading while maintaining the power level is offset by increased system complexity, hence higher cost.
In conclusion, the panel generally agreed that progress in lifetime and durability research is bringing fuel cells closer to commercialization. Still, increased “field” experience is essential. This must be combined with research to identify limiting features where significant improvements are possible. A number of questions from the audience were fielded by the panel, showing an intense interest in this topic. This very lively workshop was closed with thanks from Dr. Pan of The Knowledge Foundation.
DoE Fuel Cell and Hydrogen Program
The main conference opened with an invited overview of the Department of Energy fuel cell and hydrogen program. Tim Armstrong of the Oak Ridge National Laboratory represented the DoE in an opening address titled: “The Department of Energy Polymer Electrolyte Membrane Fuel Cell Research and Development Activities.” A major goal of the DoE program is to develop polymer electrolyte membrane (PEM) fuel cells to replace internal combustion engines in light-duty vehicles. In addition, the program supports some work on fuel cells for stationary power, portable power and auxiliary power applications as a way to gain earlier market experience, thus establishing an early fuel cell manufacturing base. DoE’s current technical focus in these areas is on developing materials and components to reduce fuel cell system cost and extend durability.
From System Design and IntegrationToward Application and Commercialization
The first session at the conference was chaired by Dr. Deltef Stelter who provided some initial background.
Andrew P. Wallace of Jadoo Power described “Challenges and Opportunities in Deploying Commercial Fuel Cell Systems.” Consumer field data detailing practical impacts of fuel cell system deployment was presented. Jadoo systems have logged over 100,000 hours with over 75,000 start and stops while operated by consumers. Critical design features used to satisfy start/stop reliability and duty cycles include catalyst selection, anode humidification, and open cathode architecture.
Dominique Kluyskens of Angstrom Power Inc. talked about “Infrastructure Options for Micro Hydrogen Systems.” Micro fuel cell systems for portable power use refueling through the use of disposable fuel cartridges. This requires the development of a wide network for cartridge distribution, user adoption of a “primary” cartridge model and consideration of disposal and recycling of cartridges. Infrastructure must be developed while behavioral and environmental hurdles must be overcome. Micro hydrogen systems offer advantages from these points of view by providing a means of incrementally deploying systems and thus leverage off of existing infrastructure. One example is the fast refueling made possible using hydrogen or hydroid kiosks. Angstrom envisions refueling in minutes compared to 45 minutes for batteries.
Ronald J. Kelley of Gecko Energy Technologies Inc. gave a paper entitled “Enabling New Product Designs for Emerging Markets with Fuel Cells.” Fuel cell systems can enable applications that are not economical with conventional battery packs. To do this, fuel cells must take advantage of the unique large charge capability and compact form factors. Opportunities include emerging markets of sensing, wireless networking, remote monitoring, and more. As an example, 31x14x3.7cm Gecko hydrogen battery weighting 2kg can replace a 26 Li D-cell package of 49x14x3.7cm, weighing 2.6kg for powering a 3W wireless sensor. The cell estimated cost is $100 vs. $260 for the battery pack.
Jerry Hallmark of Motorola Labs described “Fuel Cells for Portable Communications.” Motorola is evaluating several fuel cell technologies to possibly exploit the need for extended operation for “remote” portable communications that lack the ability to recharge batteries from the grid. Various system configurations were noted, including external power sources for the charger, hybrid fuel cell/batteries and direct fuel cell power. Some initial opportunities for early introduction of small fuel cells focus on “remote” applications such as first responder, homeland security installations, and military (e.g., soldier power). Motorola is also working on reformed methanol fuel cells using single wall carbon nanotube technology under a National Institute of Standards ATP agreement with BASF and Johnson Matthey.
Yasuhiro Goto of the Advanced Functional Materials Laboratory, Corporate R&D Center, Toshiba Corp., spoke on “Development of DMFC for Mobile Applications at Toshiba.” Flash memory, mobile phones and notebook PCs were described. The audio player with flash memory offers 35 hours play time per fuel cartridge. The phone unit has 2.5 times higher capacity than a normal lithium battery. One fuel cartridge gives ten hours computer time via a docking station. Cartridge exchange is conventionally done while the computer is running. Technical issues still remaining for commercialization include electrode and catalyst activity improvement with lower air rates, membrane barrier strategy and stack integration
Direct Methanol Fuel Cells: Components, MEAs, Fuel
The afternoon session of day one was chaired by Dr. Hyuk Chang of Samsung Advanced Institute of Technology (SAIT), Samsung, Korea.
Emory S. De Castro of E-TEK Division, PEMEAS Fuel Cell Technologies, described “Advancement in DMFC Electrode/MEA Structure and Diagnostic Methods.” E-TEK continues to study MEA component integration to optimize performance. On the cathode side, one compromise involved water ejection vs. catalyst utilization. On the anode side the trade-off is between methanol accessibility and cross-over. Both PtRu anode and Pt cathode catalysts must be finely dispersed with large surface areas, while the anode’s PtRu must be well alloyed. Diagnostic methods have been developed to examine issues of: cathode flooding, the capability to manage water accumulation, and the extent of methanol penetration into the anode porous structure and cross-over. Commercial production of MEAs is now moving towards a second generation of high performance products.
Philip Cox of PolyFuel Inc. spoke on “Role of Membrane in Determining DMFC System Performance.” The integration of the membrane with the other components is a central focus at PolyFuel. Hydrocarbon membranes are being engineered to optimize the power density, fuel efficiency and fuel cell operating conditions over a range of system architectures. Membrane production is focusing on hydrocarbon polymer chemistry, roll-to-roll membrane production, catalysis application methods, quality and pilot production standards, and process control.
Shigeaki Satoh of Kurita Water Industries Ltd., Japan, described “Development of the “Solid-State Methanol Fuel for Direct Methanol Fuel Cells (DMFC).” He described the development of a novel “solid-state methanol” fuel based on a clathrate compound technology, which traps and contains methanol as a “guest” compound in a host compound. This gives major improvements in the areas of safety and portability of methanol. A liquid-free DMFC for a portable battery charger is under development based on this technology. In addition, this technology is being extended to the storage of hydrogen fuel.
Ceramic Technologies Across Different Fuel Systems
Michael Stelter of Fraunhofer IKTS delivered a talk titled “Multilayered Ceramic Micro Fuel Cell Systems and Components”. He described how multi-layer ceramics can be used to improve micro fuel cell systems. Fraunhofer IKTS, combines multi layer ceramics and thick film technology for miniaturized PEM or DMFC stacks, and also to form complete micro systems. A low sintering temperature material can be used to form small reactors or even micro stacks. The goal is to seamlessly integrate the active fluidic elements and to extend the temperature range of small SOFC components and systems. The result represents a complete 3-D integration of electronics, fluidics and electrochemistry.
Yoshihiro Kawamura of Core Technologies R&D Division, CASIO Computer Co. Ltd., Japan, presented a paper titled “A Micro Fuel Processor with Microreactor for a Small Fuel Cell System.” Over the past several years CASIO has been working on a micro fuel processor with a methanol reformer for “on-demand production” of hydrogen for a small PEMFC system. A special thermal insulation structure allows a fast heat-up time of six seconds. Adequate H2 production is achieved with low CO concentration. The next step is to develop reliable, durable operation with various portable devices.
Paul J.A. Kenis of the Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign spoke on “Ceramic Microreactors for Reforming of Hydrocarbons.” He opened with some brief comments about another of his efforts to produce membraneless fuel cells using lamina flow in micro-fluidic structures. This main presentation described the structure, integration, and characterization of Ru on silicon carbide monoliths inside alumina microreactors. These reactors reform hydrocarbons such as propane at high fuel conversion and high hydrogen selectivity at temperatures above 800°C. The temperature is selected to avoid coking/deactivation of the catalyst supports. Over 99% ammonia conversion has been obtained at T>700°C, giving 54sccm H2. Results from propane at T>950°C show 18sccm H2 at 99.9% conversion. Future directions include integration of WGS and PROX reactors.
Poster Presentations
At the end of day one, a dedicated poster discussion time was included. During the meeting, 16 posters with published abstracts were displayed including Biofuel Cells, Nick Akers of Akermin Inc.; Fluor-free Membranes, O. Ballabio of Pirelli Labs, Italy; Separated Semi-Permeable Membranes, Robert Bening of Kraton Polymers; Carbon Supported Platinum Catalyst, Young-Hun Cho of Seoul National University in Korea; Micro Fuel Cell Stickers, Anders Lundblad of The Royal Institute of Technology in Stockholm, Swede Direct Borohydride Fuel Cells, George H. Miley of the University of Illinois; and Miniaturized SOFC, Ji-Won Son of KIST of Korea.
Hydride and Borohydride Technologies
The first morning session in day two was chaired by Professor George H. Miley of the University of Illinois at Urbana-Champaign. He noted that this was the first time in the conference series that a full session was devoted to this topic.
Richard M. Mohring of Millennium Cell Inc. discussed “Chemical Hydride Technology for Portable PEM FC Applications.” Millennium Cell is developing chemical hydride-based hydrogen storage technology to power PEM fuel cells for diverse applications within the military, medical, industrial, and consumer markets. These power sources combine a sodium borohydride-based “Hydrogen on Demand®” technology with PEM fuel cells. Examples include the Protonex P2 solider power system which uses three 24-hour fuel cartridges to replace a 13 battery pack, thus reducing both weight and cost. Jadoo 100W cartridges for IFS24 radio and XRT can reduce weight by 50-60% compared to standard units. A supply system combined with a Gecko passive PEM cell in a small video camera was demonstrated at the conference.
Fumiharu Iwasaki of the R&D Division, Micro & Nano Technology Center, Seiko Instruments Inc., talked about their “High Power Passive Type PEFC Using Chemical Hydride.” He was describing a small-scale fuel cell system where the H2 fuel is generated from chemical hydrides without power consumption. The goal is a unit with a higher power output than for the previously demonstrated passive models. A five-stack, 10W system with size 200x65x53 mm provides 20Whr at 11.1 volts. A 50W system under development has demonstrated 100Whr.
Philippe Capron of DTNM/LCH, Atomic Energy Commission (CEA) of France, described “CEA Development of a DBFC (Direct Borohydride Fuel Cell).” CEA is developing the technology for novel portable fuel cells, namely Direct Borohydride Fuel Cells, which operate at room temperature. An alkaline anion-exchange membrane and composite electrodes in which non-noble metals may be used (e.g., Ag, Ni) are employed. The high theoretical electromotive potential (1.64V compared to 1.23V for PEMFC), and high theoretical yield (0.91 compared to 0.83 for PEMFC) are important advantages of the DBFC. Use of borohydride-based liquid fuel achieves a high specific energy which is very competitive with batteries for small power devices. To date, power densities of 200mW/cm2and 140m/cm2have been achieved with 2M and 5M NaBH 4 solution, respectively, during 500 hours of operation. Catalysts to suppress H2 production at the anode have been successfully developed. Work on further improvements by reducing membrane permeation is under way.
DMFC/Catalysts
Olaf Conrad of CMR Fuel Cells (UK) Ltd., presented “Compact Mixed-Reactant DMFCs: Enabling Stack Power Densities of Greater than 500W/l.” A unique mixed-reactant flow-through fuel cell stack architecture was demonstrated earlier. Now the technology has been improved to enable power densities of several hundred W/l. Materials development, MEA architecture and stack engineering were discussed. The continued development of selective catalysts like RuSex/C and RhxSy/C are key to competitive power. A three-cell bipolar stack (10cm2/ MEA) providing 0.75W (80°C) and giving an active stack power density of ~500W/l was described. Extensive CFD modeling was used to design the unique “hole-type” MEAs.
Xiaoming Ren of Acta S.p.A., described the company’s effort to achieve “Breakthroughs and Challenges in Platinum-free Portable Power.” Increasing attention is being paid to platinum-free catalysts in alkaline anionic membrane fuel cells for portable power applications. Acta offers a range of HYPERMEC™ platinum-free catalysts to address this need. Tests were reported for a variety of fuel cells, including an ethanol fueled unit giving 28mW/cm2(room T) over 800 hours of static operation. Performance at 80°C increased to 145 mW/cm2. A direct sodium borohydride/air cell achieves ~150mW/cm2(Room T) with 5% NaBH 4 solution. Methanol, ethylene and glycerol cells were also noted. Ultimate goals include 1000hr durability, Pt-free catalysts, cheap membranes and reduced (or no) external electrolyte.
Russell Marvin of MTI Micro Fuel Cells, gave a paper titled “Progress in Developing DMFC Technology to Beat Current Battery Performance.” Progress in advancing DMFCs vs. batteries is largely focused on increasing run-time. This revolves on optimization of fuel cell size, fuel tank size, packing efficiency, and fuel economy. He showed graphs of how critical trade-offs among these factors can beat the battery on run-time. Fuel economy seems to be a strong driving factor for longer run-times. Cell voltage, crossover, DC-DC converter efficiency, and parasitics lose also need to be optimized. Power vs. voltage trade-offs along with DC-DC converter challenges and topologies were discussed.
SOFCs
The afternoon session was opened by Jerry Hallmark of Motorola. He noted that the high temperature achieved in SOFCs offers advantages for select applications where thermal and heat management is possible.
Jerry L. Martin of Mesoscopic Devices LLC gave the first paper titled “Portable Solid Oxide Fuel Cell Systems.” Mesoscopic Devices has demonstrated several compact, portable solid oxide fuel cell generators that build on advances in lightweight, efficient balance of plant equipment and high power density stacks. SOFC generators of 75 and 250 Watts are being commercialized. Versions of these systems have been demonstrated operating on either kerosene or propane. The 250W net (280W gross) unit gives 28-30% efficiencies and 28V DC. Applications include remote sensing, leisure vehicles and boats, and portable power tools.
Mark L. Richardson of SOFCell and a consultant for Alberta Research Council (ARC) in Canada described “Tubular Micro-SOFC for Remote Power Applications.” ARC is developing a Tubular Micro Solid Oxide Fuel Cell (¼SOFC). It offers two main potential advantages: substantial increase in the electrolyte surface area per unit volume of a stack and quick start up. Since fuel cell power is directly proportional to the electrolyte surface area, a reduction of the ¼SOFC tube diameter from 22mm to 2mm increases the electrolyte surface area in a stack at least eight times. Due to its thin wall, a ¼SOFC has extremely high thermal shock resistance and low thermal mass. The characteristics are fundamental to obtaining rapid start up and turn off times in these systems.
Aaron Crumm of Adaptive Materials Inc. presented “Commercialization of Portable Solid Oxide Fuel Cell Systems.” Adaptive Materials has developed micro-tubular fell cell systems for military applications in the 20 to 50W power range. Advantages of this include the use of commercially available light hydrocarbons (ultimately going to JP8) as a fuel source. These systems operate at energy densities >1000 Whr/kg (20W), with the potential to achieve 1500Whr/kg over a ten-day mission. This exceeds current battery performance and also provides a significant weight reduction. Initial field tests identified some problems which have now been overcome to offer good durability, high system efficiency, operation in extreme environments, load following, no (or low) thermal or acoustic signatures, and sulfur tolerance.
Advances in Fuel and System Design
Erhard Ogris and Sebastian Schebesta, Alvatec Production and Sales GmbH, described an approach to “Elegant Hydrogen Generation Based on Reactive Metal Alloys.” A major challenge for hydrogen-based fuel cells is the safe storage of fuel or, alternately, on-the-spot production. Alvatec is studying ways to generate pure hydrogen by a reaction of metal alloys such as Li 3 AL 2 , CaAL 19 and Mg 2 AL 3 . Generators providing from 0.6 to 100sccm are being developed for use with fuel cells from 0.1 to 100W. One example uses the generator in combination with the 50-180mW Fraunhofer PEM Micro fuel cells. These generators produce a high steady hydrogen flow rate plus easy handling, good safety and low cost.
Anders Lundblad of myFC AB in Sweden described an “Easy-to-Replace Passive Type Fuel Cell Sticker.” The flexible “sticker” fuel cell design is adhesively attached to a support with hydrogen feed. Despite a very simple design, the “sticker” fuel cell can provide power density levels of ~300 mW/cm2. “Stickers” are suitable for mass production (i.e., inexpensive) and easy to replace. Tests indicate 600mW/cm3, less than ~€1 per W. The first application target is a mobile phone charger, followed by a phone add-on, then full integration into the phone.
The closing talk by Erik Kjeang of the Institute for Integrated Energy Systems, University of Victoria, (IESVic) described a “High-Performance Microfluidic Vanadium Fuel Cell.” This design incorporates a high-surface area porous carbon electrode. A peak power density of 70mW/cm2has been obtained at room temperature, significantly higher than previously reported for microfluidic fuel cells. In addition, low-flow rate operation demonstrates excellent fuel use. To optimize the design, various options such as use of graphite rods vs. carbon paper for diffusion layers have been examined. The microfluidic vanadium design is aimed at cost-effective and rapid fabrication. IESVic plans next to extend this to biofuel.
ABT reporter, session chair and Ilini Professor George Miley.
Millennium Cell's.Dr. Richard Mohring talks of Hydrogen on Demand.
Fumiharu Iwasaki, manager of Seiko’s R&D Division, speaks on PEFC.
Chairperson Dr. Michael Stelter of Germany opens the conference.
Presenter Dr. Philippe Capron of France’s CEA gathers his thoughts.
Two attendees take a Pepsi break in the exhibit hall.
Dr. Olaf Conrad of CMR Fuel Cells, U.K., talks of DMFCs.
Dr. Xiaoming Ren of Acta S.p.A. talks of platinum-free power.
Russ Marvin of MTI Micro Fuel Cells talks about progress in DMFC.
Dr. Jerry Martin of Mesoscopic Devices speaks of portable SOFCs.