Portable Devices: Fuel Cells doc

Portable Devices: Fuel Cells A Kundu, Queen’s RMC Fuel Cell Research Centre, Kingston, ON, Canada JH Jang, Samsung Electro-Mechanics, Gyunngi-Do, Republic of Korea & 2009 Elsevier B.V. All rights reserved. Introduction The rapid growth of the portable electronics market includes ‘power-hungry’ accessories in a smaller system, which has led to the search for an alternative and ad- vanced power source due to the limited energy density of conventional lithium-ion batteries. Table 1 lists the power demand of the different portable applications. Fuel cells promise to provide a more reliable and longer operational time than batteries. As the energy is stored as a reservoir rather than as an integral part of the power source, fuel cells have advantages over batteries. Micro fuel cell products compete with power systems that utilize both direct and indirect energy conversion methods. Direct conversion may involve fuels such as methanol, ethanol, formic acid, ethylene glycol, and so- dium borohydride that are converted into electrons through a direct fuel cell system. Indirect methods re- quire the conversion of methanol, ethanol, or sodium borohydride into hydrogen. The direct supply of pure hydrogen is relatively difficult in electronic equipment applications due to storage problems (i.e., the lack of an efficient hydrogen storage material). There is also con- cern in terms of safety while carrying pure hydrogen in electrical equipment. The setup of a cost-effective, ap- propriate infrastructure for distribution of hydrogen canisters is another major challenge for which most hurdles are unlikely to be overcome in the foreseeable future. In the direct alcohol fuel cell system, the main studies center on methanol (direct methanol fuel cell (DMFC)) although ethanol-fueled systems have drawn interest in recent years. Direct mathanol fuel cell has the drawback of a high fuel crossover rate and a low rate of fuel oxidation. The micro fuel cell market can be divided into three device categories: portable electronics, military portable, and healthcare segments. In the portable electronics category, this includes handsets, personal digital assis- tants (PDAs), mobile phones, portable audio/video de- vices, digital imaging devices, and notebook computers. Micro fuel cell technologies face competition from advanced energy storage devices such as secondary (chargeable) batteries, for example, lithium-ion batteries and nickel-based batteries. However, micro fuel cells, once commercialized, hold the promise for providing more backup ‘green power’ at lower cost than competing battery technologies. It is most unlikely that micro fuel cells will compete with the primary battery. In order to compete with the primary battery, the cost component would not justify the use of micro fuel cells. Theoretically, competition with batteries from fuel cells impacts all sources of secondary batteries; however, practically it is only the high-cost, premium batteries (lithium-ion and lithium-polymer) that fuel cells really compete with. Those products that can realistically use Ni–Cd or Ni–MH are not likely to support the cost premium required for fuel cells, at least not initially. The added functions and features for more entertainment and sophisticated communications on modern handsets such as third-generation (3G) mobile phones, digital multimedia broadcasting phones, and iPhone s use up available power very quickly. Therefore, users are going to be faced with recharging their phones more often. In this case, micro fuel cells have the po- tential to improve the user’s situation. In addition, the price of 3G handsets is high enough to absorb the higher cost of embedded fuel cells. Micro fuel cells will have to compete with the rechargeable battery not only in terms of cost but also in terms of the run time, lifetime, and output power level. Apart from mobile phones, another potential market for micro fuel cells is in notebook computers. The potentially longer run time of a micro fuel cell may be competitive with conventional batteries for the notebook computer. In addition to individual portable consumer electronic products, the other po- tential market for micro fuel cells is as battery chargers. As the battery chargers are not integrated with the de- vices, these are much simpler to develop and market. There is great opportunity for micro fuel cells in the military market where there is an aggressive requirement Table 1 The power demand of the different portable applications Items Power required (W) Cellular phone 1 Personal digital assistant (PDA) 1 Notebook personal computer 20–30 Flashlights and toys 1–10 Tablet personal computer 10 Playstation portable (PSP) 2 Digital multimedia broadcast-receiving (DMB) phone 3 iPhone 2 Robot 10–15 Digital camera 1 39 . micro fuel cells have the po- tential to improve the user’s situation. In addition, the price of 3G handsets is high enough to absorb the higher cost of embedded fuel cells. Micro fuel cells. the drawback of a high fuel crossover rate and a low rate of fuel oxidation. The micro fuel cell market can be divided into three device categories: portable electronics, military portable, and healthcare. Portable Devices: Fuel Cells A Kundu, Queen’s RMC Fuel Cell Research Centre, Kingston, ON, Canada JH Jang, Samsung Electro-Mechanics,