Methanol fuel cells powered

Figure 3.41. Structure of carbon paper (left) and carbon cloth (right) used for gas diffusion layers in PEM fuel cells. A coating of 20% (by weight) fluorinated ethylene propylene has been applied. (From C. Lim and C-Y. Wang (2004). Effects of hydro-phobic polymer content in GDL on power performance of a PEM fuel cell. Electro chimica Acta 49, 4149-4156 G. Lu and C-Y. Wang (2004). Electrochemical and flow characterization of a direct methanol fuel cell.. Power Sources 134, 33-40. Used with permission from Elsevier.)...

Lu, G., Wang, C-Y. (2004). Electrochemical and flow characterization of a direct methanol fuel cell. /. Power Sources 134,33-40. 

The Polymer Electrolyte and Direct Methanol Fuel Cells Power Output and Energy-conversion Efficiency... 

T. Hejze, B. R. Gollas, R. K. Sauerbrey, M. Schmied, F. Hofer,. O. Besenhard, Preparation of Pd-coated polymer electrolyte membranes and their application in direct methanol fuel cells,/. Power Sources 2005, 340, 21-27. 

Xie C, Bostaph J, Pavio J (2004) Development of a 2W direct methanol fuel cell power source. J Power Sources 136 55-65... 

Yamaha (2007) Challenges to commercialization of direct methanol fuel cell-powered motorbikes. Presented at the 3rd International Hydrogen and... 

Soldier hybrid direct methanol fuel cell power source 25 W 0.68 kg TRL 4/6... 

Yang, C.-C., Lue, S.J., and Shi, J.-Y. (2011) A novel organic/inorganic polymer membrane based on poly(vinyl alcohol)/ poly(2-acrylamido-2-methyl-l-propanesulfonic acid/3-glycidyloxypropyl trimethoxysilane polymer electrolyte membrane for direct methanol fuel cells. /. Power Sources, 196, 4458-4467. 

Fuel cells can run on fuels other than hydrogen. In the direct methanol fuel cell (DMFC), a dilute methanol solution ( 3%) is fed directly into the anode, and a multistep process causes the liberation of protons and electrons together with conversion to water and carbon dioxide. Because no fuel processor is required, the system is conceptually vei"y attractive. However, the multistep process is understandably less rapid than the simpler hydrogen reaction, and this causes the direct methanol fuel cell stack to produce less power and to need more catalyst. 

Interestingly, the PEMFC may also operate directly on methanol. Naturally, the problems associated with high coverage of various intermediates will be present, as mentioned above, as well as additional problems such as loss of methanol over the membrane. Nevertheless, it is possible to operate a methanol fuel cell with a voltage around 0.4 V and a reasonable current, to power small mobile devices such as portable computers and cell phones and make them independent of connection to the conventional power net. For more details on fuel cells we refer the reader to L. Carr-ette, K.A. Friedrich and U. Stimming, Fuel Cells 1(1) (2001) 5-39. 

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... 

Lasch K, Hayn G, Jdrissen L, Garche J, Besenhardt O (2002) Mixed conducting catalyst support materials for the direct methanol fuel cell. J Power Sources 105 305-310... 

Caillard A, Coutanceau C, Brault P, Mathias J, Leger JM. 2006. Structure of Pt/C and PtRu/C catalytic layers prepared by plasma sputtering and electric performance in direct methanol fuel cells (DMFC). J Power Sources 162 66-73. 

Liu H, Songa C, Zhang L, Zhang J, Wang H, Wilkinson DP. 2006. A review of anode catalysis in the direct methanol fuel cell. J Power Sources 155 95-110. 

Chapter one is an overview of the energy evolution. It introduces the technology and emission issues, safety, and alternative fuels such as natural gas, hydrogen gas, methanol, ethanol and fuel cell power. 

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. 

Fuels cells are of interest both from energetic and environmental considerations. When methanol is fed directly to an anode, as in Direct Methanol Fuel Cells , electric power is generated, making the devices suitable for small and lightweight uses [53], Alternative fuels such as polyhydric alcohols like ethylene glycol and glycerol are much less volatile and toxic, on the one hand, and electrochemically oxidizable on the other [54]. Therefore, the electrochemical oxidation of various polyhydric alcohols has been investigated in acidic as well as in alkaline conditions. 

Fuel cells o fer important advantages as a power source, such as the potential for high efficiency, clean exhaust gases and quiet operation. In addition, the direct methanol fuel cell offers special benefits as a power source for transportation, such as potential high energy density, no need for a fuel reformer and a quick response. These advantages, however, have not been fully realized yet. One of the problems is the poor performance of the fiiel electrode. Even platimun, which seems the most active single element for methanol oxidation in add media, loses its electrocatalytic activity rapidly by the accumulation of adsorbed partially oxidized products. 

Therefore, methanol is the top candidate because of its low price, less toxicity, high energy density and easy handling. Although direct methanol fuel cells may need an auxiliary system to treat unoxidized or partially oxidized fuel in the exhaust gas, direct methanol fuel cells are still a very attractive system as a portable power source. 

X. M. Ren, R Zelenay, S. Thomas, J. Davey, and S. Gottesfeld, Recent advances in direct methanol fuel cells at Los Alamos National Laboratory, J. Power Sources 86, 111-116 (2000). 

Fuels that are most directly suited to the fuel cell are the most difficult and costly to produce and distribute. Gasoline and methanol are the leading candidates to power fuel cell engines. Both the gasoline and methanol fuel cell vehicles should be more fully developed prior to making a commercial decision on fuel choice. 

Hauer, K.H., Friedmann, D.J., Moore, R.M., Ramaswamy, S., Eggert, A., and Badranarayanan, P. March 6-9, 2000. Dynamic Response of an Indirect-Methanol Fuel Cell Vehicle. Fuel Cell Power for Transportation 2000. Society of Automotive Engineers World Congress, Detroit, Michigan. 

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