meeting report
Small Fuel Cells for Portable Power Applications 4th International Symposium
Washington, DC
April 21-23, 2002
- AER Energy Resources, Inc.
Smyrna, GA
THIS SYMPOSIUM was organized and sponsored by The Knowledge Foundation, Brookline, Massachusetts (www.knowledgefoundation.com) and was held at the Wyndham Hotel in Washington, DC. A pre-conference workshop on April 21 dealt with three topics; "Portable Fuel Cell Markets and Market Projections" was delivered by Atakan Ozbek of Allied Business Intelligence; "Capital Availability for Power Technology Firms" was presented by R. Douglas Moffat of SunTrust Robinson Humphrey; Robert Lifton of Medis Technologies spoke on the business issues in commercializing his company's fuel cell product in his presentation, "Direct Liquid Methanol/Ethanol Fuel Cells for Portable Electronic Devices – The Race to Commercialization."
The symposium attracted about 250 people. About a dozen exhibitors were in an area outside the conference room where presentations were given. A networking lunch was held on Monday.
The following is a synopsis of papers presented in the main conference and compiled in the Proceedings booklet from The Knowledge Foundation.
Micro Fuel Cells at the Crossroads
Manhattan Scientific/Energy Related Devices's approach to fuel cell design is to use lightweight flexible plastic sheets as substrate material with non-bipolar stacking and no moving parts for air or fuel delivery. The fuel cell is looked at as a three-dimensional current-collecting problem, recognizing that different architectures have different advantages and limitations. This approach results in an uncomplicated design with the trade-off of relatively low power density, so the expectation is that the fuel cell is used in conjunction with a rechargeable battery for typical consumer products. Examples of this are illustrated in its Power HolsterTM, Piggyback, and Portable Charger MicroFuel CellTM, which are various product concepts for powering cellphones. The business proposition is that the entire fuel cell can be made for $5 and that a fuel ampoule of 35Ahr can be made for $0.10 (based on methanol costs of $0.60/gal). The cost issue for the fuel cell is explored in two fundamental material equations for the bulk conductor and the electrolyte. Status of the fuel cells is that it can deliver 400Wh/kg at room temperature at 1-5mw/cm2. Major technical issues that must be solved: improving catalyst effectiveness, water management, reducing reactant crossover, and maintaining performance over changes in ambient humidity, temperature, and pressure.
Robert G. Hockaday, chief fuel cell scientist, Manhattan Scientifics Inc./Energy Related Devices Inc., Los Alamos, New Mexico. Phone: (505) 662-0660, email: Energyrd@aol.com.
Small Fuel Cells for Portable Power Applications
MTI Micro is developing a fuel cell to meet the needs of a cellphone device for 2004. In support of this objective, MTI has several component development programs. Among them: a joint development agreement with DuPont for membrane electrode assemblies (MEAs), a miniature piezoelectric pump project, and a miniature DC-DC converter program. The case is made for using neat methanol (MeOH) by examining the steep decline in energy density as a function of MeOH concentration. The example used is a 1W, 30Wh fuel cell system with a balance of plant of 5cc operating at an efficiency of 30%. In this case, 100% MeOH gives 860Wh/l, whereas at 33% MeOH, energy density drops to 400Wh/l. For power density, MTI has demonstrated 60mW/cm2. Technical issues that need to be solved: achieving high overall energy conversion, lowering balance of plant power requirements, miniaturizing the system, and achieving a cost-competitive design.
Shimshon Gottesfeld, Ph.D., vice president of R&D and CTO, MTI MicroFuel Cells, Albany, New York, www.mechtech.com.
DMFC Pack of 3.6V-2000mW and Its Application to Mobile Electronics
Samsung makes the case for fuel cells by extrapolating that 4G phones in 2007 will have a talk time of 15 minutes with today's standard 500mAhr battery. Its analysis shows that fuel cells can be competitive with Li-ion batteries in energy density at capacities of 1500mAh and higher provided concentrations of 10M MeOH or better are achieved. DMFCs can be more cost-effective than Li-ion at capacities above 2000mAh if they reach 100mw/cm2 or better. Present status of the Samsung 2000mW fuel cell system at a nominal 3.6V and 570mA with 20cc of fuel storage is 4.8Wh at 210Wh/l and 187Wh/kg. The technical requirements that need to be met to make their fuel cells a consumer product are:
! MEAs with 3x the power density, near 0% crossover with 10M MeOH
! cost-effective solutions to managing water, carbon dioxide and heat.
Hyuk Chang, Ph.D., principal researcher, Samsung Advanced Research Institute of Technology, Suwon, Korea. Phone: 82 (31) 280-8153; email: hchang@sait .samsung.co.kr.
Micro Fuel Cells for Portable Electronics
Motorola's DMFC system is integrated in a low-temperature, multi-layered, co-fired ceramic, which incorporates the fuel cell stack and the balance of plant. Fuel delivery and mixing as well as CO2 gas separation is through microchannels integrated in the ceramic. Discrete components have features for assembly and mounting on the ceramic base, e.g., MEA assembly, micro pumps, sensors, and control circuitry. A prototype of this integrated DMFC was made in a 166cc package including fuel; it can run for six days yielding 86 Wh/liter. The next iteration device is targeted to deliver 226mW. The power budget breaks out as 75% to the load and 25% for all other overhead. Of this 25%, 7% is for pumps for fuel delivery, 7% for DC-DC converter, and 7% for pump for water recovery. Future overall direction is to get to 1W and higher power levels typical in portable communication devices.
In addition to the DMFC system, a miniature integrated liquid methanol steam reformer is being developed to provide hydrogen. Hardware data for the reformer: thickfilm resistance heaters are imbedded in the structure body of alumina-glass and DuPont 951AT green tape, which contains the catalyst ICI (Synetix, 33-5), Cu/ZnO/Al 2O3 powder. Performance data: 25 mliter/min feed with 95% MeOH conversion, 28sccm H2, <2% CO in output gas, heat input into reactor 6.9W.
Jeanne S. Pavio, manager, DMFC Technology, Motorola Labs, Tempe, Arizona. Phone: (480) 755-5313, email: jeanne.pavio@motorola.com.
Direct Methanol Fuel Cell Systems by Smart Fuel Cell
Smart Fuel Cell's market analysis looks at the attributes of power and runtime and concludes that there is little activity in the quadrant above five hours of runtime and 5W of power. So it is designing DMFC products for this space, which would include running a mobile office (i.e. computer, printer, phone), camping/outdoor applications, and power tools. Specifications for its hybrid DMFC/rechargeable battery are nominal 25W with 80W peak, 2.5kWh, weight 9.7kg with 2.5 liter pure MeOH fuel cartridge, dimensions 46x24x16 cm.
Manfred Stefener, CEO, Smart Fuel Cell GmbH, Brunthal-Nord, Germany. Phone: 49-89607-454-60, email: stefener@smartfuelcell.de.
Performance and Marketing Comparison of Li-ion vs DMFC
This presentation benchmarks the performance criteria of Li-ion rechargeable batteries and looks at the hurdles that fuel cells must overcome to win over existing portable applications using Li-ion. Li-ion is credited with a power density 400W/l, specific power 320W/kg, energy density 200-220Wh/l, cycle life 300-500, temperature range -20 to 40C and a cost per Wh of less than $0.40. The expectation is that Li-ion energy density will top out in the next few years at about 500Wh/liter without major breakthroughs in active materials. Present stage fuel cell energy density, specific energy, and power capabilities are below Li-ion. Major technical breakthroughs are needed in catalyst and membrane performance and miniaturization of stack and balance of plant to meet Li-ion's W/liter and Wh/liter. Similarly, cost is problematic. From a consumer standpoint, questions are raised about the ease with which users would switch from "no cost" wall charging with Li-ion to purchasing fuel cartridges. In addition, there are the difficulties in resolving the safety and air travel regulation issues associated with flammable and combustible liquids.
Kurt R. Kelty, director, business development, Panasonic, Cupertino, California. Phone: (408) 861-8408, email: keltyk@research.panasonic.com.
Miniature Biofuel Cells
Dr. Adam Heller's objective is to develop a 3mW power source that would last for three days with a footprint <1mm2 and a volume <1mm3. This type of power source would be used for biosensor-transmitter packages; for example, glucose monitoring. One approach is a glucose-air fuel cell. In such a cell, glucose is oxidized at the anode to gluconolactate and oxygen is reduced to water at the cathode. State-of-the-art devices yield power densities of 64-137mW/cm2 and an operating voltage of 0.4V. Electron conducting redox polymers "wire" enzymes to the electrodes. In the "wired" glucose electrode, electrons cascade in a potential gradient from glucose through glucose oxidase to the "wire." Cathodes are laccase-coated carbon. Immediate technical challenges are operating the cell in physiological fluid (pH 7.4, 0.14M NaCl, 37C), increasing the power density, and getting the voltage above 0.6V to allow use of available silicon converters.
Adam Heller, Ph.D., research professor, University of Texas at Austin. Phone: (512) 471-8874, email: heller@
che.utexas.edu.
Micro Biofuel Cell R&D at Sandia National Laboratories
In general, biofuel cells are fuel cells that derive power from fuels harvested from living organisms. The opportunity for biofuel cells is as autonomous, long-lived, environmentally friendly power sources used for prosthetics, implants, in-situ sensors, sensors powered by flora or fauna, and life signal transponders for rescue. Biofuel cells can be divided into four categories: enzymatic, precious metal-carbohydrate, microbial, and photo. Enzymatic can provide 164mW/cm2 at 0.4V. Potential fuels are glucose, fructose, sucrose, lactose, and alcohol. The main advantage is that electrodes don't need to be compartmentalized because enzymes at the anode and cathode can immobilize them. Issues are electron transfer limitations, lifetime, limited substrates, partial oxidation, non-invasive biofuel harvesting and integration of biocomponents. Precious metal carbohydrate fuel cells have issues with fouling, crossover, and incomplete fuel oxidation. Microbial fuel cells can deliver 1mW to 10mW. Issues are with rate limitations and nutrient supply for organisms.
Douglas A. Loy, Ph.D., distinguished member of technical staff, Sandia National Laboratories, Albuquerque, New Mexico. Phone: (505) 844-4445., email: daloy@sandia.gov.
The Design and Performance of Electrocatalysts Produced by Spray-Based Routes for Fuel Cell and Battery Applications
Membrane electrode assemblies (MEAs) are a significant contributor (~50%, according to an A.D. Little study) to the cost of a fuel cell. Platinum catalyst material in the anode and cathode represents a major material cost. Superior MicroPowder spray processing method yields low Pt loading on carbon blacks with excellent performance characteristics. The process has few steps and can be easily scaled for market needs. The platform can also be used for non-precious metals and metal oxides.
Mark Hampden Smith, director and vice president, Superior MicroPowders, Albuquerque, New Mexico. Phone: (505) 342-1492, email: mhs@smp1.com.
Portable Fuel Cells Suitable for Powering Remote Analytical Equipment
Enable has portable PEM fuel cells from <1W to 1 kW. The 12W fuel cell is 2.75" in diameter x 8" long, 1.4 lbs., and nominal current of 1 amp. The discharge is flat until H2 is consumed. Metal hydride canisters provide hydrogen. The system has no moving parts, and controls consist of an on/off switch and purge valve. Target applications are for remote data gathering, analysis and communication; for example, water monitoring.
Mark Daugherty, Ph.D., vice president and general manager, DCH - Enable Fuel Cell, Middleton, WI. Phone: (608) 831-6775, email:
mdaugherty@enablefuelcell.com.
Micro-Fabricated Thin-Film Fuel Cells
for Portable Power Requirements
Micro machining and novel thin film deposition techniques are presented as alternative processes to create fuel cell systems. A micro-machined substrate platform is first prepared by growing a thin layer of silicon nitride. Standard photolithographic techniques are used to etch windows 5mm in width and gas diffusion micro pore channels. Vapor deposition processes utilizing two patterning methods – photolithography and hard masks – form the electrodes within the anode-electrolyte-cathode layer. Sputtering deposits a fine-grained columnar structure (e.g. nickel for the anode, silver for the cathode). Pores 3-5mm with 3mm spacing are formed in the layer via a photo-resist mask to create gas flow passages to the electrolyte. For the hard mask method, the electrode metal can be directly deposited with an inherent porosity by adjusting gas pressure and heating the substrate, yielding morphology of a metallic sponge that provides electrical conductivity and enables diffusion of reactant species. Micro fabricated PEM and SOFC yielded current and power outputs typical of bulk designs.
Jeffrey D. Morse, Ph.D., staff scientist, Lawrence Livermore National Laboratories, Livermore, California. Phone: (925) 423-4864, email: morse3@llnl.gov.
PEM Stack Manufacturing and Reliability
State-of-the-art biopharmaceutical filtration manufacturing technology is used to reduce 10 to 300W PEM fuel cell stack cost to 10-20% of current competitive levels and improve reliability by using "self-adjusting" seals, an integral manifold, low cost molds, and easily built assemblies.
Paul Osenar, Ph.D., chief technology officer, Protnex Technology Corp., Marlborough, Massachusetts. Phone: (508) 490-9960, email:
paul.osenar@protonex.com.
Fuel Processor Development for
Small Power Supplies
A fuel processing system has several functional components: a vaporizer for the fuel and water, a primary and secondary conversion reactor, and CO cleanup module. Fuel/Air is fed through a vaporizer and combustor. The micro hydrocarbon reformer being developed is for nominal 15W fuel cells that measure 3.4"x 0.75"x 0.22" and weigh 50g. Novel monolith catalysts using "foam" metal supports of stainless, nickel alloys with <200mm pore diameters, low pressure drops, and high catalyst activity allow steam reforming of methanol at temperatures of 340C with CO concentration ~1 volume % and H2 yield close to theoretical maximum. Fuel cells incorporating the reformers have been fabricated for 14-day missions and weigh 6.1kg with 6.1 liters of fuel/water. Testing demonstrates 720Wh/kg. This compares to a Li-ion battery, which would weigh 22kg and yield 200Wh/kg. The systems are intended for soldier portable power. Sub watt reformers are also being developed for 10-500mW power generation.
Jamelyn D. Holladay, research engineer, Battelle, Pacific Northwest National Laboratory, Richland, Washington. Phone: (509) 375-6717, email: jamelyn.holladay @pnl.gov.
Fuel Processor for Generating Pure Hydrogen for
Fuel Cells from Sulfur-Containing Fuels
Fuel cells gain a major advantage if they can use fuel sources in the existing distribution network; e.g., natural gas, gasoline, diesel, jet fuel. InnovaTek has developed micro fuel atomization and injection nozzles, micro channel heat exchangers, a patented catalyst, and a H2 purification scheme using hydrogen membrane separation. Commercial product introduction is expected in 2005. A stationary fuel processor is expected to cost $500-800/kW.
Patricia M. Irving, Ph.D., president and CEO, InnovaTek, Inc., Richland, Washington. Phone: (408) 375-1093, email: irving@tekkie.com.
Market and Technical Issues in Commercializing
Air-Breathing Alkaline Electrolyte Power Sources
For Portable Devices
Primary zinc-air cells with diffusion air managers can provide runtime two to five times that of alkaline or rechargeable batteries in handheld consumer electronic products, e.g., digital cameras, camcorders, cellphones, PDAs. The long-standing problem of zinc-air-limited field life has been overcome with diffusion air managers. The technology is mature and ready for commercialization. Two key issues in commercialization are: 1) determining an appropriate form factor for zinc-air cells that would make global scale distribution attractive and 2) establishing the technical road map for designing an air mover into electronic products. One approach to the form factor issue is to use established commercial sizes so zinc-air may be interchangeable with existing batteries; e.g., Rayovac Corp. has developed zinc-air AA cells. Moving along the technical road map, miniature fans have been developed that are quiet, low cost, and suitable for design-in to hand-held devices.
Dennis Sieminski, business development manager, AER Energy Resources, Symrna, Georgia. Phone: (770) 433-2127 ext 252, email: d_sieminski@aern.com.
High Energy Density in a 20 Watt Portable
DMFC Power Source
Ball Aerospace is following up on its 60W DMFC prototype with a 20W system. The unit will be 1.3 liters (8"x 4"x2.5") with an external 0.6 liter cartridge that will hold 1320Wh of methanol. System weight will be 1.18kg (0.7kg system + .48kg fuel). Continuous power capability 0- 20W with an ambient operating temperature range of 0-40C. In addition, a hybrid intelligent power system is being developed that will allow use of multiple energy sources by soldiers in the field. The electronic device sits between the portable electronic device and a number of potential power sources – fuel cell, battery, AC source, DC source, solar PV, or wind generator. It communicates with all attached power sources and supplies regulated power to the load from them while managing battery charging.
Timothy K. Quackenbush, Ph.D., systems engineer, Ball Aerospace, Boulder, Colorado. Phone: (303) 939-6353, email: tquackenb@ball.com.
Status of Development of Portable DMFC Stacks at
Forschungszentrum Julich
DMFCs have been a research topic at this institute for the last four years. Approximately 25 staff members are engaged in R&D. The areas include: optimized electrode and cell structures with work on catalyst and diffusion layers and membranes with low MeOH permeation, cell and stack development with work on flow field and manifold design, modeling of DMFCs (for example, oxygen, current density and temperature distribution), and development of manufacturing methods in coating and laminating of various parts of the membrane electrode assembly (MEA). This includes the gas diffusion layer (GDL), gas diffusion electrode (GDE), polymer electrolyte membrane (PEM), and catalyst-coated membrane (CCM). The institute started with a 2W, 2.1liter DMFC stack in '98; it now has a 10W, 0.2liter stack. Power density has gone from 5W/l to 120W/l.
Jurgen Mergel, head of DMFC Group, Institute for Materials and Processes in Energy Systems, Julich, Germany. Phone: 49-2461-615996, email: j.mergel@fz-juelich.de.
Monopolar DMFC Fuel Cells
The monopolar concept is to use the same metal grid for the anode of one cell and the cathode of the next cell. This establishes an efficient in-plane interconnection with no contacts. A completely self-contained, portable 12v, 15W DMFC demonstrates the flexibility of this approach. The device uses 4M MeOH. The U.S. Army Research Lab is supporting the work.
Alan Cisar, Ph.D., manager, electrochemical conversion and storage, Lynntech Inc., College Station, Texas. Phone: (979) 693-0017, email: alan.cisar@lynntech.com.
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