Portable fuel cells types

The dynamic behavior of fuel cells is of importance to insure the stable operation of the fuel cells under various operating conditions. Among a few different fuel cell types, the direct methanol fuel cell (DMFC) has been known to have advantages especially for portable... 

Direct methanol fuel cell technology is relatively new compared to that of fuel cells powered by pure hydrogen, and research and development are roughly 34 years behind that of other fuel cell types. Nonetheless, the DMFC appears to be the most promising as a battery replacement for portable applications such cellular phones and laptop computers, and a number of manufacturers are already introducing commercial versions of these applications. 

HFC R D work across the spectrum of fuel cell types and auxiliary components. Focus on PEM and large-scale MCFC and SOFC, and on micro DMFCs for portable applications. 

Table 3.3.1 also indicates suitable power ranges of the various fuel cell types and some of their typical applications. PEMFCs are clearly the most versatile class with strong focus on portable and automotive applications. High-temperature fuel cells are more often employed for stationary power generation. 

Micro fuel cells are primarily designed for portability. Their size is dictated by the size of the device they power. Consumer products such as laptop PCs, portable electronic video games, video cameras, PDAs, and cellular telephones are several examples of portable electronics where a micro fuel cell could be used to power the device. These fuel cells have been designed on primarily two fuel cell types, DMFC and PEMFC. These fuel cell types provide high power density based on their small size and are suitable for powering small devices. A need for high efficiency, combined with a need for lightweight and small size makes these fuel cell types ideal. 

DMFCs are usually regarded as the fuel cell type that is closest to commercial viability, despite having a relatively high cost of entry into the market. The most fitting application for DMFCs is the commercial market of portable electronics, such as mobile phones and laptop computers [7]. 

Next to the multitude of material combinations allowing various fuel cell types to be designed and built, the variety of mobile (transport), statiOTiaiy, and portable applications provokes a multitude of different cell, stack, and systems designs, guided by the implications of the different fuel cell technologies (see below). 

Linden, D. and T. B. Reddy. 2002. Handbook of Batteries, 3rd ed. New York McGraw-Hill. This comprehensive volume eovers dozens of battery types. Separate sections cover batteries used in eleetrie vehicles, as well as portable fuel cells that may be a competitive alternative to battery systems. 

This Standard applies to ac- and dc-type portable fuel cell power systems, with a rated output voltage not exceeding 600 V, for commercial, industrial, and residenhal indoor and outdoor use in non-hazardous locahons, in accordance with the Rules of the National Electric Code, ANSl/NFPA 70. 

The electrocatalytic oxidation of methanol has been widely investigated for exploitation in the so-called direct methanol fuel cell (DMFC). The most likely type of DMFC to be commercialized in the near future seems to be the polymer electrolyte membrane DMFC using proton exchange membrane, a special form of low-temperature fuel cell based on PEM technology. In this cell, methanol (a liquid fuel available at low cost, easily handled, stored, and transported) is dissolved in an acid electrolyte and burned directly by air to carbon dioxide. The prominence of the DMFCs with respect to safety, simple device fabrication, and low cost has rendered them promising candidates for applications ranging from portable power sources to secondary cells for prospective electric vehicles. Notwithstanding, DMFCs were... 

The DMFC is the most attractive type of fuel cell as a powerplant for electric vehicles and as a portable power source, because methanol is a liquid fuel with values for the specific energy and energy density being about equal to half those for liquid hydrocarbon fuels (gasoline and diesel fuel). 

Research on SOFCs started in 1990 for CHP applications and in 1992, PEM activities started to focus on CHP, traction and portable applications. Both types of systems are being actively pursued along with early demonstrations. Additionally, the use of fuel cells and bio-gas or biohydrogen is being evaluated. 

In view of the abundance of natural gas resources found since the 1980s, and natural gas being a considerably cleaner fuel than petroleum or coal for the fuel processors, the main goals of the major worldwide fuel cell programs are to develop fuel cell power plants and portable power sources using natural gas or natural gas-derived fuel cells. A chart of all types of fuel cells, using natural gas as a fuel, is presented in Scheme 9.2 the applications being considered for the different types of fuel... 

Power requirements of portable hydrogen equipment such as cameras, mobile phones or laptop computers currently covered by batteries, typically of lithium ion type, could with a small fuel cell and some 10-20 g of directly or indirectly stored hydrogen prolong operational time by a factor of 5-10. A discussion of such options using direct methanol fuel cells is made in section 4.6. 

In the past two decades, fuel cells and in particular imi-exchange membranes have become a top priority topic in material research. Fuel cells are seen as promising alternative energy conversion systems replacing the combustion-based techniques. Among the various types of fuel cells, the low-temperature fuel cells like the polymer electrolyte membrane fuel cell (PEMFQ, DMFC, or alkaline fuel cell (AFC) are the most flexible ones concerning range of appUcations e.g. portable, automotive, and stationary. 

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