Fuel Cells—Portable Energy

General Motors has also been experimenting with H2/02 fuel cells to power an Opel Zafira minivan in which the H2 is supplied directly, stored either in ultrahigh-pressure tanks or at a very low temperature as a liquid. For liquid H2 storage GM has developed a double-walled, vacuum-insulated steel tank that holds about 10 lb of H2(l) at —435°F, good for about a 250-mile range. Alternatively, the H2 can be stored as a gas in two carbon-fiber-reinforced, 10,000-psi tanks that hold a total 

The Hy-wire, a concept car from General Motors that employs a hydrogen-based fuel cell. 

In late 2003, a Federal Express delivery van will be equipped with a GM H2/O2 fuel cell using liquid H2 as the fuel. This van will be tested for a year in Tokyo, Japan. Also, Toyota has delivered fuelcell-powered SUVs to the Universities of California at Irvine and Davis. These vehicles are powered by H2 stored as a high-pressure gas. 

To replace batteries, fuel cells must be demonstrated to be economically feasible, safe, and dependable. Today, rapid progress is being made to overcome the current problems. A recent estimate indicates that by late in this decade annual sales of the little power plants may reach 200 million units per year. It appears that after years of hype about the virtues of fuel cells, we are finally going to realize their potential.  

Fuel cells are finding use as permanent power sources. A power plant built in New York City contains stacks of hydrogen-oxygen fuel cells, which can be rapidly put on-line in response to fluctuating power demands. The hydrogen gas is obtained by decomposing the methane in natural gas. A plant of this type has also been constructed in Tokyo. 

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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). 

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... 

One of the applications for hydrogen is for Polymer Electrolyte Membrane (PEM) fuel cells. As mentioned earlier, one application is a hydrogen fuelled hybrid fuel cell / ultra-capacitor transit bus program where significant energy efficiencies can be demonstrated. Another commercial application is for fuel cell powered forklifts and other such fleet applications that requires mobile electrical power with the additional environmental benefits this system provides. Other commercial applications being developed by Canadian industry is for remote back-up power such as the telecommunications industry and for portable fuel cell systems. 

Canadian interests span into hydrogen production, delivery and utilization, primarily in fuel cell applications in transportation, stationary and portable systems. Furthermore, codes and standards for hydrogen systems are an important area of activity. The range of future electrical requirements for early adopters, such as the military, is very wide with numerous applications for various electrically powered systems. The introduction of hydrogen as an energy carrier into the commercial and military sector offer similar and sometimes unique challenges in all the areas discussed. 

The overarching drivers for the development of hydrogen technologies are climate change and reductions in oil consumption with additional benefits in emissions reductions. The use of hydrogen in fuel cell vehicles can reduce oil use and carbon plus other emissions in the transportation sector, while hydrogen can enable clean, reliable energy for stationary and portable power applications. 

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. 

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. 

Fuel cells are electrochemical devices that convert the chemical energy of the fuels directly into electrical energy, and are considered to be the key technology for power generation in stationary, automotive, portable and even microscale systems. Among all kinds of fuel cells, direct methanol fuel cells have really exhibited the potential to replace current portable power sources and micropower sources in the market (Yao et al., 2006). 

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