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Posted in Toys and hobbies on 09/04/2011 12:29 pm by admin

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The Fuel Cell Battery Knowledge ( Figure 2 )

Welcome to a laptop battery specialist of the Acer Laptop Battery First post by: www.itsbattery.com

A fuel cell is an electrochemical device that combines hydrogen fuel with oxygen to produce electricity, heat and water. The fuel cell is similar to a battery in that an electrochemical reaction takes place as long as fuel is available. The hydrogen fuel is stored in a pressurized container and oxygen is taken from the air. Because of the absence of a burning process, there are no harmful emissions, and the only by-product is fresh water. The water emitted from the proton exchange membrane fuel cell (PEMFC) is so pure that visitors to Vancouver's Ballard Power Systems were served hot tea made from this clean water.

Fundamentally, a fuel cell is electrolysis in reverse, using two electrodes separated by an electrolyte. The anode (negative electrode) receives the hydrogen and the cathode (positive electrode) collects the oxygen. A catalyst at the anode separates hydrogen into positively charged hydrogen ions and electrons; the oxygen is ionized and migrates across the electrolyte to the anodic compartment, where it combines with hydrogen. A single fuel cell produces 0.6–0.8V under load. To obtain higher voltages, several cells are connected in series. Figure 1 illustrates the concept of a fuel cell.

Figure: Portable fuel cell for consumer market
The fuel cell converts hydrogen and oxygen to electricity and clean water is the only by-product. Fuel cells can be used indoors as an electricity generator.Courtesy of SFC Smart Fuel Cell AG
(2010)

Alkaline Fuel Cell (AFC)

The alkaline fuel cell has become the preferred technology for aerospace, including the space shuttle. Manufacturing and operating costs are low, especially for the stack. While the separator for the PEM costs between $800 and $1,100 per square meter, the same material for the alkaline system is almost negligible. (The separator for a lead acid battery such as Acer LCBTP03003 Battery costs $5 per square meter.) Water management is simple and does not need compressors and other peripherals. A negative is that AFC is larger in physical size than the PEM and needs pure oxygen and hydrogen as fuels. Carbon dioxide in a polluted city can poison the stack.

Solid Oxide Fuel Cell (SOFC)

Electric utilities use three types of fuel cells, which are molten carbonate, phosphoric acidand solid oxide fuel cells. Among these choices, the solid oxide (SOFC) is the least developed but has received renewed attention because of breakthroughs in cell material and stack design. Rather than operating at the very high operating temperature of 800–1,000°C (1,472–1,832°F), a new generation of ceramic material has brought the core down to a more manageable 500–600°C (932–1,112°F). This allows the use of conventional stainless steel rather than expensive ceramics for auxiliary parts.

High temperature allows direct extraction of hydrogen from natural gas through a catalytic reforming process. Carbon monoxide, a contaminant for the PEM, is a fuel for the SOFC. Being able to accept carbon-based fuels without a designated reformer and delivering high efficiency pose significant advantages for this type of fuel cell. Cogeneration by running steam generators from the heat by-product raises the SOFC to 60 percent efficiency, one of the highest among fuel cells. As a negative, high stack temperatures require exotic materials for the core that add to manufacturing costs, lower longevity and decrease reliability. With the newer SOFC systems operating at lower temperatures, however, this drawback has been reduced.

About the Author

Welcome to a laptop battery specialist of the Apple Laptop Battery First post by: www.itsbattery.com