Portable applications

There is considerable interest in the viability of fuel cells as power sources. While most FCVs rely on PEM fuel cells, portable applications are split between the PEM and direct methanol fuel cells (DMFC). Portable fuel cell applications are those under 1.5 kW and include such products as batteries for electronics and generators. 

In recent years, Japanese companies have led the way in creating fuel cells suitable for electronics. Casio is developing a methanol reformate fuel cell to use in laptop computers and digital cameras. While the fuel cell is only about the size of a typical rechargeable battery, it lasts four times longer. According to Baker (2005a), Fujitsu Laboratories (Japan) and NTT DoCoMo have developed a prototype fuel cell for mobile 

Medis Technologies of Israel, has created a disposable auxiliary power unit, the Power Pack, for use on a wide range of electronics including cell phones, PDAs, digital cameras, MP3 players, and other small electronics. The Power Pack has a significantly longer operating time than traditional batteries. For example, when used for a cell phone, the 

The US company Millennium Cell has developed a prototype fuel cell used to power an IBM ThinkPad. Currently, the prototype runs for only 3 h, but Millennium aims to increase the running time to 8 h. The company expects the fuel cell to cost approximately 150, about the same price as a standard laptop battery. NEC, a Japanese company, has multiple versions of its DMFC laptop prototype. The most current model, released in October 2005, is 20% smaller than the 2004 model and has a power output density of 70 milliwatts (mW) per square centimeter, a 40% improvement on the previous model. One 250 Cm methanol cartridge can power the laptop for 10 h. The company plans to commercialize the laptop in 2007. 

In Korea, Samsung Advanced Institute of Technology is developing butane-powered fuel cells to act as power supplies for small electronics. As of 2006, the fuel cell produces a maximum of 100 watts (W) of electricity. The 220-gram (g) liquefied butane cartridge can power a laptop for more than 20 h. Samsung plans to commercialize the butane fuel cell in 2007 and increase the maximum power output to 300 W. In a partnership with IBM, Sanyo produced a DMFC for an IBM ThinkPad laptop computer. The protot)q)e, introduced in April 2005, provides up to 8 h of power and works with a battery in a hybrid system. 

For small power applications such as laptops, camcorders, and mobile phones, the requirements of the fuel cell systems are even more specific than for vehicle apphcations. Low temperatures are necessary and, therefore, PEM fuel eells are chosen. Possibilities for fuel cell systems are the eombination of PEM with hydrogen storage by hydrides or gas eartridges or the direet methanol fuel cell. Such type of fuel cell will be employed in portable phones and ean be adjusted for other portable applications. The requirements for portable applications are mostly focused on size and weight of the system (as well as on the temperature). Other fuel cells are, therefore, not suitable for this kind of applications. Portable devices need lower power than other fuel cell applieations and, thus, DMFC systems may be well suited for this kind of applications. With further technological improvements and better storage systems, PEM fuel cells and DMFC systems will continue to eompete in this market [74,75]. 

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A PWM switching power supply that is designed with no extraordinary loss-control methods will exliibit efficiencies as seen in Table 3-3. For switching power supplies that have no problem in getting rid of the heat, such as some off-line applications, the aforementioned efficiencies may be satisfactory. For portable applications and equipment that must be small in size much better efficiencies must be sought. To improve the overall efficiency of a power supply, several techniques can be used. 

The upper limit for passive matrix OLEDs thus depends on many factors, including the reverse current of the diodes, the current delivery of the row drivers, the roll-off in OLED power efficiency, and the brightness and contrast ratio requirements of the application. The practical limit is probably less than VGA resolution (480 rows by 640 x 3 columns, where the factor of 3 reflects the RGB subpixels for color) for power-sensitive portable applications. However, such considerations are less important where a wall-plug is available and one company in Japan (Idemitsu Kosan [190]) has demonstrated full color television using passive OLED arrays. 

C. Menachem, D. Golodnitzky, E. Peled, in Batteries for Portable Applications and Electric Vehicles (Eds. C. F. Holmes, A. R. Land-grebe), The Electrochemical Society, Pennington, NJ, 1997, PV97-18, p. 95. 

Coutanceau C, Koffi RK, Leger JM, Marestin C, Mercier R, Nayoze C, Capron P. 2006. Development of materials for mini DMFC working at room temperature for portable applications. J Power Sources 160 334. 

Gamburtzev S., Velev O.A., Danin R., Srinivasan S., Appleby A.J. Performance of an improved design of metal hydride/air rechargeable cell . In Batteries for portable application and electric vehicles. C.Holmes, A.Landgrebe ed. Pennington Electroch. Soc, 1997, 726-33. 

I.V. Barsukov, T.I. Motronyuk, V.Z. Barsukov, V.I. Drozdik. Metal-Free 1.5V Rechargeable Batteries Steps of Optimization and Prospects for the Practical Application// In book Batteries for Portable Application and Electric Vehicles, C.F. Flolmes and A.R. Landgrebe eds., The Electrochemical Society, Inc., Pennington, NJ, 592-596 (1997). 

Monochrome AMPLED flat-panel displays have been made with performance parameters attractive for battery-powered portable applications. The AM backpanel was made of polysilicon material with integrated column and row drivers. Table 1.1 shows a data sheet for a 4" diagonal monochrome display with 960 x 240 pixels [173]. The resolution in horizontal direction was 300 ppi (85pm pitch size), while the resultion in vertical direction was 100 ppi (255 pm pitch size). With 100% pixels turned on at 200 cd/m2, the entire AMPLED panel (including pixel drivers) only consumed eletric power less than 500 mW (with 100% pixels on), which was... 

In addition to these smaller applications, fuel cells can be used in portable generators, such as those used to provide electricity for portable equipment. Thousands of portable fuel cell systems have been developed and operated worldwide, ranging from 1 watt to 1.5 kilowatts in power. The two primary technologies for portable applications are polymer electrolyte membrane (PEM) and direct methanol fuel cell (DMFC) designs. 

As mentioned above, fuel cells may be used for mobile, stationary and portable applications. Table 13.4 shows the currents status of fuel cells for the three respective fields of application in terms of specific investment, lifetime and system efficiency as well as target values for the future. 

Direct-methanol fuel cells (DMFCs) have attracted considerable attention for certain mobile and portable applications, because of their high specific energy density, low poison emissions, easy fuel handling, and miniaturization [129,130], However, the methanol permeation through electrolyte membranes (usually called methanol cross-over) in DMFCs still is one of the critical problems hindering the commercialization [131,132], Nafion , a... 

Catalyst performance targets for stationary and portable applications have not been as consolidated and are usually embedded into MEA performance... 

Numerous demonstrations in recent years have shown that the level of performance of present-day polymer electrolyte fuel cells can compete with current energy conversion technologies in power densities and energy efficiencies. However, for large-scale commercialization in automobile and portable applications, the merit function of fuel cell systems—namely, the ratio of power density to cost—must be improved by a factor of 10 or more. Clever engineering and empirical optimization of cells and stacks alone cannot achieve such ambitious performance and cost targets. 

Prior to this appointment. Dr. Wilkinson was the director, and then vice president of research and development at Ballard Power Systems and involved with the research, development, and application of fuel cell technology for transportation, stationary power, and portable applications. Until 2003, Dr. Wilkinson was the leading all-time fuel cell inventor by number of issued US. patents. Dr. Wilkinson s main research interest is in electrochemical power sources and processes to create clean and sustainable energy. He is an active member of the Electrochemical Society, the International Society of Electrochemistry, the Chemical Institute of Canada, and the American Chemical Society. 

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