FUEL CELLS LECTURE NO.3 FUEL CELL TECHNOLOGY
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Fuel cells produce only water and heat in their energy-generating process, they are quiet,
and they convert fuel to energy three to four times more efficiently than combustion.
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Fuel cells reduce the amount of Carbone dioxide emissions by about two-thirds.
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The intended future of fuel cells is to accomplish the following tasks:
1- Replace gas turbines in power plants,
2- Replace gasoline engines in vehicles, and
3- Replace batteries in computers and electronics.
FUEL CELL THEORY
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First demonstrated in principle by British Scientist Sir Willliam Robert Grove in 1839.
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Grove’s invention was based on idea of reverse electrolysis.
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In electrolysis, an electric current is introduced in to electrolyte.
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This flow between two electrodes causes the splitting of water.
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A fuel cell consists of two electrodes (Anode and Cathode).
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Hydrogen and Oxygen are fed into the cell.
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Catalyst at Anode causes hydrogen atoms to give up electrons leaving positively charged
protons.
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Oxygen ions at Cathode side attract the hydrogen protons.
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Protons pass through electrolyte membrane.
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Electrons are redirected to Cathode through external circuit.
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Thus producing the current (power).
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FUEL CELLS LECTURE NO.3 FUEL CELLS FOR DIRECT ENERGY CONVERSION
HISTORICAL BACKGROUND
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In 1894, Wilhelm Ostwald presented an idea of converting the chemical energy of natural
fuels directly electrochemically to electrical energy based on thermodynamics (ignored
the kinetic aspects).
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In 1933, Baur and Tolbar discovered, experimentally, the large difficulties inherent in a
direct electrochemical oxidation of a natural fuel such as coal.
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Practical cell using hydrogen as fuel was set up in the laboratory by Spiridonov in 1941.
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Oganes Davtyan has published the first monograph on the problem of fuel cells in 1947.
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In 1960, a relatively large hydrogen-oxygen fuel battery was designed by Francis Bacon
in England to produce an electric power of about 5 kW using a concentrated alkaline
electrolyte. The working temperature was 473 to 513K and the gas pressure was 2 to 4
Mpa.
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FUEL CELLS LECTURE NO.3 TYPES OF FUEL CELLS
Temp.°C
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Alkaline (AFC)
Application
70-90
Space vehicles
(reacts pure hydrogen with pure oxygen)
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Phosphoric Acid (PAFC)
150-230
Medium power plants
(phosphoric acid separates the two electrodes and accommodates a current; slow warm-up time)
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Solid Polymer (PEMFC)
70-90
Automotive application
(synthetic polymer separates the two electrodes and accommodates a current with the aid of a
catalyst)
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Molten Carbonate (MCFC)
550-650
Large power plants
(carbonate held at very high temperature separates the two electrodes to create current; slow
warm-up time)
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Solid Oxide (SOFC)
1000-1100
All sizes of power plants
(solid materials provide a matrix for electron flow; slow warm-up time)
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Direct Methanol (DMFC)
70-90
Cars and buses
(alcohol separates the two electrodes and accommodates a current)
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Regenerative (RFC)
Environment
Energy storage (wind and solar)
(closed-lope generators)
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FUEL CELLS Page 4 of 7
LECTURE NO.3 FUEL CELLS Page 5 of 7
LECTURE NO.3 FUEL CELLS LECTURE NO.3 FUEL CELL CARS
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Start to look real
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Fuel cell car - the long awaited
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Prototype vehicles have been displayed
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Clear personal transportation of the future
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Moving from laboratory vision to technical reality.
FUEL CELL APPLICATION FOR AUTOMOTIVE USE
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Proton exchange membrane (PEM) variety has emerged as the best design
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GM has obtained nearly 400 patents in PEM technology
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SOFC together with an on-board gasoline fuel processor or reformer would be suited as
auxiliary power units (APUs)
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Replacement of low efficiency alternator in automobiles
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BMW, Renault and Delphi are pursuing this approach
FUEL CELL VEHICLE CONFIGURATION
Wheels
Batteries
Fuel
Fuel
Cell
Power
conditioner
AC/DC
Drive
motor
Accessories
Wheels
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FUEL CELLS LECTURE NO.3 FUELS FOR FUEL CELL SYSTEMS
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General Motor’s and Adam Opel AG’s View (GAPC)
Long term vision :
Hydrogen
Problem
:
H2 - Storage
H2 -Infrastructure
Bridging Strategy :
conventional
Fuel Cell Systems for vehicles using
/ Pump Grade Fuels
Gasoline tank
Fuel Cell Drive System
Establishing infrastructure and storage technolo gy for
hydrogen in between co-operation of
OEM’s with mineral oil companies
GM / Exxon / Mobil / BP
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