Power cells

Electrical power, produced as current, is drawn from fuel cell against a constant cell voltage. The electrical power produced by the cell is given as the product of the cell voltage and the total current drawn from the cell through the external circuit and expressed as 

Another form of fuel cell power is given as power density 

A higher current output form the cell to the electrical circuit requires a higher reactant gas consumption rate, and theoretically this should result in an increased cell power output. However, as the fuel consumption rate and current output increases, the cell output voltage drops from the maximum reversible voltage due to a number of irreversibility factors associated with the electrochemical reactions and transport processes. 

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An electrodialysis cell has the following dimensions (110 cm X 60 cm x 0.04 cm (thickness), and is used to treat water with a throughput velocity of 10 cm/sec. The product concentration is 0.0092 eq/Liter. The cell current efficiency is 0.892. Resistance across the cell is 0.205 ohm. The influent concentration is 125 mg/Liter of NaCl. Calculate the following (a) cell current, (b) cell power output, (c) the cell voltage, and (d) the energy consumption per equivalent of product transferred. 

Summary ol Hybrid Vehicle Fuel Economy Results on the FUDS and Highway Driving Cycles using Various Engines and a Fuel Cell (1) mpg diesel fuel for diesel engine and mpg gasoline equivalent for fuel cell powered vehicles... 

Although the principle of fuel cells has been known since 1838, practical applications arc fairly recent. The first applications were in the space program, where fuel cells powered the Gemini and Apollo spacecraft. In the 1960s and 1970s, fuel cells... 

In the longer term, more exotic technologies, such as fuel cells powered by hydrogen, may be feasible. These technologies are fai from being economically feasible, but rapid progress is being made. However, as conventional vehicles become cleaner, the relative emissions-reduction benefits from alternative fuels declines. 

Williams, M. Vanderborgh, N. and Appleby, J. (1997). Progress Towards a Performance Code for Fuel Cell Power Systems. ASME Joint Power Generation Conference 32 423-427. 

Perhaps the ultimate combined appliances, which are currently under development, will he microturbines or fuel cell power generators used as small-scale co-generation systems. These would supply not only electricity, but space and water heating as well. 

Fuel cells have attracted considerable interest because of their potential for efficient conversion of the energy (AG) from a chemical reaction to electrical energy (AE). This efficiency is achieved by directly converting chemical energy to electricity. Conventional systems burn fuel in an engine and convert the resulting mechanical output to electrical power. Potential applications include stationary multi-megawatt power plants, battery replacements for personal electronics, and even fuel-cell-powered unmanned autonomous vehicles (UAVs). 

Self-Test 16.2B Calculate E° for a cell powered by the reaction of mercury metal and nitric acid to form mercury(I) and NO. 

S. Chalk, FY 2000 Progress Report for Fuel Cell Power Systems, Energy Efficiency and Renewable Energy Office of Transportation Technologies, U.S. Department of Energy, Oct. 2000, p. 163. 

W. He and Kas Hemmes, Operating characteristics of a reformer for molten carbonate fuel-cell power-generation systems. Fuel Processing Technology, 67 (2000) 61. 

Fhosphoric acid does not have all the properties of an ideal fuel cell electrolyte. Because it is chemically stable, relatively nonvolatile at temperatures above 200 C, and rejects carbon dioxide, it is useful in electric utility fuel cell power plants that use fuel cell waste heat to raise steam for reforming natural gas and liquid fuels. Although phosphoric acid is the only common acid combining the above properties, it does exhibit a deleterious effect on air electrode kinetics when compared with other electrolytes ( ) including such materials as sulfuric and perchloric acids, whose chemical instability at T > 120 C render them unsuitable for utility fuel cell use. In the second part of this paper, we will review progress towards the development of new acid electrolytes for fuel cells. 

The fuel eell is a nineteenth eentuiy invention in the twentieth eentury it heeame the heart of an eleetroehemical power plant and power souree, whieh is now in a stage of advaneed technology development. Its first and only applieation since the early 1960s, has been as an auxiliary power souree for spaee flights by the National Aeronautics and Space Administration (NASA). During the past decade, development for terrestrial (eivihan and defense) applieations has led to its commercialization and research on utilization in a variety of applications. Programs in the United States, Japan, Europe, and some other eoimtries are focused on the development of fuel cell power plant/power sources for (1) base-load,... 

The enthusiasm for developing DMFCs (the fuel cell researcher s dream) evolved in the 1960s, which was really the boom period for R D activities on all types of fuel cell technologies, mainly because of NASA s vital need for fuel cell power plants for space vehicles. As early as the 1960s it was recognized that the major challenges in developing DMFCs... 

The second example describes distributed, mobile and portable power-generation systems for proton-exchange membrane (PEM) fuel cells [106]. A main application is fuel processing units for fuel cell-powered automobiles it is hoped that such processing units may be achieved with a volume of less than 8 1. 

Hussain, M.M., I. Dincer and X. Li, A preliminary life cycle assessment of PEM fuel cell powered automobiles. Appl. Thermal Eng., 27,2294-2299, 2007. 

Joensen, F. and Rostrup-Nielsen, R., Conversion of hydrocarbons and alcohols for fuel cells, /. Power Sources, 105, 195,2002. 

Callahan, M., Hydrocarbon fuel conditioner for a 1.5 kW fuel cell power plant, Proc. 26th Power Sources Symp., Red Bank, NJ, 181,1974. 

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