Phosphoric acid fuel cell
{{Short description|Type of fuel cell}}
Image:Proton Exchange Fuel Cell Diagram.svg
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.{{Cite web|url=http://energy.gov/eere/fuelcells/types-fuel-cells#phosphoric.|title = Types of Fuel Cells}}
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%.{{Cite web |title=Fuel Cells |url=http://energycenter.org/index.php/technical-assistance/renewables/fuel-cells |url-status=dead |archiveurl=https://web.archive.org/web/20101123204231/http://energycenter.org/index.php/technical-assistance/renewables/fuel-cells |archivedate=Nov 23, 2010 |website=Center for Sustainable Energy}} 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.[http://www.fuelcells.org/basics/types.html Fuel Cells 2000 : Fuel Cell Basics : Types] {{Webarchive|url=https://web.archive.org/web/20081127051636/http://www.fuelcells.org/basics/types.html |date=2008-11-27 }}. At lower temperatures phosphoric acid is a poor ionic conductor, and CO poisoning of the platinum electro-catalyst in the anode becomes severe.{{cite web |url=http://www.netl.doe.gov/technologies/coalpower/fuelcells/seca/pubs/fchandbook7.pdf |title= Solid Oxide Fuel Cell|website=www.netl.doe.gov |archive-url=https://web.archive.org/web/20101123023857/http://www.netl.doe.gov/technologies/coalpower/fuelcells/seca/pubs/fchandbook7.pdf |archive-date=November 23, 2010}} 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.{{clarify|date=January 2012}}
Applications
File:PureCell System 400 CEP.jpg
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.[http://www.fuelcelltoday.com/about-fuel-cells/technologies/pafc Fuel Cell Today – Home Page].
Major manufacturers of PAFC technology include Doosan Fuel Cell America Inc.{{cite web | url=http://www.doosanfuelcell.com/en/main.do | title=Doosan Fuelcell America }} (formerly ClearEdge Power & UTC Power[http://www.clearedgepower.com/news/clearedge-power-completes-acquisition-utc-power ClearEdge Power – Media Room].) and Fuji Electric.
India's DRDO has developed PAFC based air-independent propulsion for integration into their {{Sclass|Kalvari|submarine|||2015}}s.{{cite news | url=http://www.thehindu.com/news/national/indianbuilt-scorpene-to-carry-critical-drdo-system/article6558305.ece| title=Indian-built Scorpene to carry critical DRDO system | work=The Hindu | date=3 Nov 2014 | accessdate=2015-10-22}}{{cite news | url=http://www.thehindu.com/news/national/article1016372.ece | title=DRDO working on system to cut submarine vulnerability | date= 30 December 2010 | first=S. | last=Anandan | newspaper=The Hindu}}
See also
References
{{Reflist}}
External links
- [https://web.archive.org/web/20090710182002/http://www.npi.gov.au/database/substance-info/profiles/71.html National Pollutant Inventory - Phosphoric acid fact sheet]
- [https://web.archive.org/web/20080828192711/http://www.utcpower.com/ UTC Power Official Site]
- [http://www.smartplanet.com/photos/off-the-grid-10-fuel-cell-deployments-photos/6266998?tag=thumbnail-view-selector;get-photo-roto Photo Gallery of Fuel Cells Being Used Today]
- [http://fuelcellsworks.com/news/2011/02/07/cox-communications-partners-with-utc-power-to-install-fuel-cells-in-california/ Cox Communications Installs Fuel Cells in California] {{Webarchive|url=https://web.archive.org/web/20111203074606/http://fuelcellsworks.com/news/2011/02/07/cox-communications-partners-with-utc-power-to-install-fuel-cells-in-california/ |date=2011-12-03 }}
- [http://www.fossil.energy.gov/programs/powersystems/fuelcells/fuelscells_phosacid.html D.O.E. -PAFC]
- [https://web.archive.org/web/20110923152407/http://www.fctec.com/fctec_types_pafc.asp Fuel Cell Basics]
- [http://www.earthtoys.com/emagazine.php?issue_number=06.04.01&article=fuelcells Alternative Energy Magazine] {{Webarchive|url=https://web.archive.org/web/20110917054335/http://www.earthtoys.com/emagazine.php?issue_number=06.04.01&article=fuelcells |date=2011-09-17 }}
- [http://www.environmentalleader.com/2010/08/31/supermarket-installs-400-kw-fuel-cell/ Supermarket Benefits From 400kW Fuel Cell]
- [http://www.fuelcells.org/info/charts/Grocery-Retail.pdf Stationary Fuel Cells at Retail and Grocery Sites]
{{Fuel cells}}