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BY ALLEN DEARMOND AND LAUREN CUMMINGS
Generates electric power using a fuel and an oxidant
Unlike a battery, chemicals are not stored in the fuel cell; they must be replenished
Possible fuel sources: hydrogen, alcohols, hydrocarbons, gasoline Possible oxidants: oxygen, chlorine, chlorine dioxide Refueling of an internal combustion engine, efficient and quiet like a battery
Polymer Electrolyte Membrane (PEM) Fuel Cells
Direct Methanol Fuel Cells Alkaline Fuel Cells Phosphoric Acid Fuel Cells Molten Carbonate Fuel Cells Solid Oxide Fuel Cells Regenerative Fuel Cells
Anode (-) and Cathode (+) on each side of the fuel cell, divided by an electrolyte
Hydrogen gas is channeled through anode side; oxygen passes through cathode
Platinum catalyst oxidizes hydrogen atoms into H+ and electrons
Electrons pass along external circuit; conduct electricity before entering cathode
Electrolyte allows H+ to pass into the cathode In cathode, catalyst combines H+ , O2- and
electrons, forming H2O and heat
Anode:2H2 => 4H+ + 4e-
Cathode: O2 + 4H+ + 4e- => 2H2O
Net Reaction:2H2 + O2 => 2H2O
Exact opposite of electrolysis
Catalyst: increases rate of reaction without being consumed in the process
Platinum is main catalyst used in PEM fuel cells
Platinum is expensive and highly sensitive to poisoning
New platinum/ruthenium catalysts being researched for use in hydrogen fuel cells
Reaction requires lower temperatures and high humidity and pressure
Little-to-no pollution, doesn’t need to be recharged
2500 fuel cell systems have been installed globally
Used to power landfills and water treatment plants
50 fuel cell buses Every major automotive manufacturer has
designed a fuel cell-powered vehicle Mercedes-Benz projects 40% efficiency in
compact cars running on Hydrogen fuel cells Hydrogen Fuel Initiative (2003)
Fuel cells require specific humidity, pressure, etc.
Catalysts are pricey and sensitive to poisoning
Difficult to produce hydrogen Difficult to store optimum amounts of
Hydrogen If fuels other than hydrogen are used,
some greenhouse gasses are emitted Very few cars currently running on
hydrogen
Used to power personal electronic devices: cell phones, iPods, laptops
Enough energy to run for days, or weeks (instead of hours)
Potentially power all cars, airplanes, ships, etc. 60 million tons of carbon dioxide could be
eliminated from yearly greenhouse gas production
Development of cheaper and more reliable catalysts
Higher demand = cheaper
Economic crisis has greatly slowed technological advancements
Past predictions for 2010 seem unlikely Hydrogen cannot be the only alternative
fuel source to solve the energy crisis Many more years of research before
mass production will be possible
Hydrogen fuel cells are efficient, and clean
Also expensive, and require specific humidity, temperature, pressure
With more technological advancements, could be used in mass production for various applications
Not an instant fix for the energy crisis, but definitely a major component
Basic Elements: Fuel for the Future. Miramar High School. 3 March 2009.
<http://library.thinkquest.org/04apr/00215/energy/fuel_cells/fuel_cells.htm>
Fuel Cells. Princeton University. 3 March 2009. <http://www.princeton.edu/~chm333/2002/spring/FuelCells/>
Fuel Cells. U.S. Department of Energy. 9 March 2009. <http://www1.eere.energy.gov/
hydrogenandfuelcells/fu elcells/fc_types.html> Hydrogen.gov United States Government. 10 March
2009. <http://www.hydrogen.gov>. Nice, Karim and Jonathan Strickland. “How Fuel Cells
Work.” 18 September 2000. How Stuff Works.com. <http://www.howstuffworks.com/fuel-cell.htm 3
March 2009>.