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Unformatted text preview: 50 ASHRAE Journal ashrae.org January 2007 Figure 1: Typical phosphoric-acid fuel cell. 5 e – e – Hydrogen Flow Field Anode Current Collector Anode Backing MEA Hydrogen Outlet Cathode Backing Electrons Protons Cathode Current Collector Water & Air Air (Oxygen) Flow Field W hen used in distributed generation (DG) applica- tions, fuel cells have the potential to save energy and reduce emissions, and their inherent fuel-flexibility also could help address energy shortage issues through energy diversity. 1,2 In addition, fuel cells have the potential to be quieter, more reliable, and have lower maintenance costs than most technologies used for DG. This is the third in a series of articles on fuel cells for DG applications. It addresses phosphoric-acid fuel cells (PAFCs). Earlier articles addressed polymer elec- trolyte membrane (PEM) fuel cells 3 and solid-oxide fuel cells. 4 Characteristics and Status PAFCs use phosphoric acid as the electrolyte, contained within a ceramic matrix such as silicon carbide ( Figure 1 ). PAFCs can operate at temperatures up to 220°C (430°F), 5 and consequently, are less sensitive to carbon monoxide poisoning compared to PEM fuel cells. This simplifies fuel processing, i.e., the conversion of hydrocarbon fuels such as natural gas to hydrogen-rich fuel, although sulfur still must be removed from the fuel. The operating temperature range is low enough to allow use of moderately priced high-temperature materials for packaging and the balance of plant....
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- Winter '10
- Electricity distribution, Cogeneration, Fuel cell, fuel cells, ASHRAE Journal, Micro combined heat and power