Fuel Cells
What Are Fuel Cells?
•	Powered by Hydrogen
•	2 electrodes, electrolyte
•	Fuel Reformer
Types of Fuel Cells
•	Proton Exchange Membrane (PEM)‏
•	Phosphoric Acid Fuel Cells (PAFCs)‏
•	Alkaline Fuel Cells (AFCs)‏
•	Solid Oxide Fuel Cells (SOFCs)‏
•	Molten Carbonate Fuel Cells (MCFCs)‏
Proton Exchange Membrane
•	Low temperature
•	Platinum catalyst
•	50W-150kW power range
•	Used by NASA on Gemini and Apollo

PEM Pros and Cons
Advantages
•	Low weight and volume
•	Low temperature
•	Up to 50% electrical efficiency 
Disadvantages
•	Catalyst cost
•	CO poisoning

Phosphoric Acid Fuel Cells
•	Use Phosphoric Acid electrolyte
•	150-200ºC
•	1.5% max CO level
•	PAFC golf cart (1970's)‏
•	50kW bus in 1999
•	Powers buildings in Times Square
Alkaline Fuel Cells
•	KOH solution electrolyte
•	150º-200ºC
•	Pure Hydrogen needed
•	12kW power
•	Francis T. Bacon (1904-1992)‏
•	Used mostly in space and underwater
Solid Oxide Fuel Cells
•	High Temperature: 800-1000°C
•	Solid ceramic electrolyte
•	45-55% electric efficiency
•	1962 Westinghouse: zirconium, CaO
•	Waste used for space heating
•	DOE mini turbine 2000
Molten Carbonate Fuel Cells
•	600-700°C
•	Molten salt carbonate electrolyte
•	75-250kW
•	50-60% efficiency
•	Nickel catalyst
•	50's: Broers & J. A.A. Ketelarr
•	10000 hour operation in 90's
Questions
•	What are the five major fuel cell types?
•	What did NASA use for the Apollo and Gemini missions?
•	 What is the operating temperatures for SOFCs?
•	 What precious metal is used as a catalyst in most fuel cells?
•	 What is one problem faced with AFCs?
More Questions
•	 What was one of the first devices to use PAFCs?
•	 Which fuel cells are the most efficient 
•	 How long did a MCFC stack run in the 1990's?
•	What is the average power range of PEMs?
•	 What makes up a generic fuel cell?
Bibliography
Curtin, Sandra. “Different types of Fuel Cells.”    				Earthtoys. 2006. fuelcells.org. 8 Jan 2009.< http://www.earthtoys.com/emagazine.php?issue_number=06.04.01&article=fuelcells>
“PEM Fuel Cells” Smithsonian. 2004. Smithsonian Institution. 11 Jan 2009. <http://americanhistory.si.edu/fuelcells/pem/pemmain.htm>
“Phosphoric Acid Fuel Cells.” Smithsonian. 2004. Smithsonian Institution. 11 Jan 2009.<http://americanhistory.si.edu/fuelcells/phos/pafcmain.htm>
“Alkali Fuel Cells.” Smithsonian. 2001. Smithsonian Institution. 11 Jan 2009.<http://americanhistory.si.edu/fuelcells/alk/alkmain.htm>
“Solid oxide Fuel Cells.” Smithsonian. 2004. Smithsonian Institution. 11 Jan 2009.<http://americanhistory.si.edu/fuelcells/so/sofcmain.htm>
“Molten Carbonate Fuel Cells.” Smithsonian. 2001. Smithsonian Institution. 11 Jan 2009.<http://americanhistory.si.edu/fuelcells/mc/mcfc.htm>