Phosphoric acid fuel cell
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.
Electrolyte is highly concentrated or pure liquid phosphoric acid (H3PO4) saturated in a silicon carbide matrix (SiC). Operating range is about 150 to 210 °C. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst.
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%. PAFCs are CO2-tolerant and even 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. At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe. However, they are much less sensitive to CO than PEMFCs and AFCs.
Disadvantages include rather low power density and aggressive electrolyte.
- Fuel Cells Archived November 23, 2010, at the Wayback Machine
- Fuel Cells 2000 : Fuel Cell Basics : Types.
- Archived November 23, 2010, at the Wayback Machine
- Fuel Cell Today - Home Page.
- 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.
- 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