Transcript hydrogen fuel cells - Department of Chemistry | Oregon State

BY ALLEN DEARMOND AND LAUREN CUMMINGS
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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
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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
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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
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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)
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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
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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
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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
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Basic Elements: Fuel for the Future. Miramar High School.
3 March 2009. <http://library.thinkquest.org/04apr/00
215/energy/fuel_cells/fuel_cells.htm>
Fuel Cells. Princeton University. 3 March 2009.
<http://www.princeton.edu/~ch
m333/2002/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>.