Phosphoric acid fuel cell
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Phosphoric acid fuel cells (PAFC) are a type of fuel cell that uses liquid phosphoric acid as an electrolyte. They were the first fuel cells to be commercialized. Developed in the mid-1960s and field-tested since the 1970s, they have improved significantly in stability, performance, and cost. Such characteristics have made the PAFC a good candidate for early stationary applications.[1]
Design
Electrolyte is highly concentrated or pure liquid phosphoric acid (H3PO4) saturated in a silicon carbide (SiC) matrix. Operating range is about 150 to 210 °C. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst.
Electrode reactions
Anode reaction: 2H2(g) → 4H+ + 4e‾
Cathode reaction: O2(g) + 4H+ + 4e‾ → 2H2O
Overall cell reaction: 2 H2 + O2 → 2H2O
Advantages and disadvantages
At an operating range of 150 to 200 °C, the expelled water can be converted to steam for air and water heating (combined heat and power). This potentially allows efficiency increases of up to 70%.[2] PAFCs are CO2-tolerant and can tolerate a CO concentration of about 1.5%, which broadens the choice of fuels they can use. If gasoline is used, the sulfur must be removed.[3] At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe.[4] However, they are much less sensitive to CO than proton-exchange membrane fuel cells (PEMFC) and alkaline fuel cells (AFC).
Disadvantages include rather low power density and chemically aggressive electrolyte.[clarification needed]
Applications
PAFC have been used for stationary power generators with output in the 100 kW to 400 kW range and are also finding application in large vehicles such as buses.[5]
Major manufacturers of PAFC technology include Doosan Fuel Cell America Inc.[6] (formerly ClearEdge Power & UTC Power[7]) and Fuji Electric.
India's DRDO has developed PAFC based air-independent propulsion for integration into their Kalvari-class submarines.[8][9]
See also
References
- ^ "Types of Fuel Cells".
- ^ Fuel Cells Archived November 23, 2010, at the Wayback Machine
- ^ Fuel Cells 2000 : Fuel Cell Basics : Types.
- ^ "Solid Oxide Fuel Cell" (PDF). www.netl.doe.gov. Archived from the original (PDF) on November 23, 2010.
- ^ Fuel Cell Today – Home Page.
- ^ http://www.doosanfuelcell.com/en/main.do.
- ^ ClearEdge Power – Media Room.
- ^ "Indian-built Scorpene to carry critical DRDO system". The Hindu. 3 Nov 2014. Retrieved 2015-10-22.
- ^ Anandan, S. (30 December 2010). "DRDO working on system to cut submarine vulnerability". The Hindu.
External links
- National Pollutant Inventory - Phosphoric acid fact sheet
- UTC Power Official Site
- Photo Gallery of Fuel Cells Being Used Today
- Cox Communications Installs Fuel Cells in California
- D.O.E. -PAFC
- Fuel Cell Basics
- Alternative Energy Magazine
- Supermarket Benefits From 400kW Fuel Cell
- Stationary Fuel Cells at Retail and Grocery Sites