Phosphoric acid fuel cell stationary applications

Because of this extreme sensitivity, attention shifted to an acidic system, the phosphoric acid fuel cell (PAFC), for other applications. Although it is tolerant to CO, the need for liquid water to be present to facilitate proton migration adds complexity to the system. It is now a relatively mature technology, having been developed extensively for stationary power usage, and 200 kW units (designed for co-generation) are currently for sale and have demonstrated 40,000 hours of operation. An 11 MW model has also been tested. 

Phosphoric acid fuel cell (PAFC) working at 180-200 °C vfith a porous matrix of PTFE-bonded silicon carbide impregnated with phosphoric acid as electrolyte, conducting by the H cation. This medium-temperature fuel cell is now commercialized by ONSI (USA), mainly for stationary applications. 

Phosphoric acid fuel cells (PAFC) use liquid phosphoric acid as an electrolyte - the acid is contained in a Teflon-bonded silicon carbide matrix - and porous carbon electrodes containing a platinum catalyst. The PAFC is considered the "first generation" of modern fuel cells. It is one of the most mature cell types, the first to be used commercially, and features the most proven track record in terms of commercial applications with over 200 units currently in use. This type of fuel cell is typically used for stationary power generation, but some PAFCs have been used to power large vehicles such as city buses. 

Phosphoric acid fuel cell (PAFC)—Phosphoric acid electrolyte with platinum catalyst. It can use hydrocarbon fuel and is suited for stationary applications. It can generate both electricity and steam. As many as 200 units in sizes ranging from 200 kW to 1 mW are in operation. 

The section on intermediate temperature fuel cells has just one entry on each fuel cell type. With decreasing operation temperature, the Molten Carbonate Fuel Cell technology is critically discussed (Molten Carbonate Fuel Cells) before two related systems relying on the unique protrui conducting properties of phosphoric acid are described. While the well-established phosphoric acid fuel cell (PAFC) is developed for stationary applications (Phosphoric Acid Fuel Cells for Stationary Applications), polybenzimidazole (used as a matrix for phosphoric acid) fuel cells even have some potential for mobile and small applications (Polybenzimidazole Fuel Cell Technology). 

The phosphoric acid fuel cell (PAFC) was the first fuel cell to be commercialized and shares some technologies with the PEMFC, such as the porous electrodes and the platinum catalysts. The liquid phosphoric acid allows high operating temperatures, around 200 C. Fuels must be free of carbon monoxide, as with the PEMFCs. With rated power over 50 kW, PAFC systems are used for stationary applications. 

Phosphoric Acid Fuel Cells for Stationary Applications... 

There are various types of fuel cells that are under development. The most noticeable ones are polymer electrolyte membrane (PEM) fuel cells, phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). PEM fuel cells are mainly being targeted toward transportation needs due to their ability to provide high power densities at reasonable operating temperatures ( 100°C). PAFCs and MCFCs are being developed primarily for stationary applications since their power densities are lower than PEM. SOFCs are currently being developed for both stationary applications and transportation applications but high-temperature material development is needed before they become commercially viable. 

Aindow TT, Haug AT, Jayne D (2011) Platinum catalyst degradation in phosphoric acid fuel cells for stationary applications. J Power Sources 196 4506 514... 

Power capacity for current electric utilities has been purchased at a cost of about l,000/kW, with costs of about 300/kW for modern natural gas systems (Kempton and Letendre, 1997). Current PEM fuel cell system costs are of the order of 10,000 per kW for automotive systems and at least 2,500 per kW for small stationary systems (compared with costs of about 4,000 per kW for 200-kW stationary phosphoric acid fuel cell systems), but costs for vehicle applications are projected to rapidly decline to much lower levels as production expands—perhaps even as low as 50/kW in mass production (Lomax et al., 1997). 

Second, molten carbonate fuel cells have electric efficiencies of 47 to 50 percent or more, which significantly reduces their fuel costs for stationary applications compared with both phosphoric acid and pem fuel cells, whose overall efficiency when running on natural gas might not exceed 35 to 40 percent. Third, high temperatures allow relatively inexpensive nickel to be used as a catalyst rather than pricey platinum, which is required by the lower-temperature fuel cells. Fourth, these fuel cells are far more tolerant of carbon monoxide, which can poison the electrochemical reaction of pem... 

Many types of electrolytes have been used in fuel cells. Water solutions of acids, such as phosphoric, sulfuric, and trifluoroacetic acids (acidic electrolytes), and bases such as sodium hydroxide or potassium hydroxide (alkaline electrolytes), can be incorporated into efficient cells. Cells using water solutions as electrolytes have complex problems of water management and electrolyte retention under conditions of severe physical motion. These will probably not be suitable for automobile service. For stationary applications described in Chapter 6 the water based electrolytes may offer advantages. 

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