electriv vehicle

1. Fuel Cell
By:
1. Swaraj Pashankar
2. Nikhil Patil
3. Randhir Bhosale

2. What is fuel cell?
 A cell capable of generating electricity by converting
chemical energy of the fuel directly into electrical
energy.
 In simple words it is a electrochemical device which
converts chemical energy into electric energy.

3. History of fuel cell
It was first demonstrated by a British Scientist Sir Willliam Robert
Grove in 1839.
First practical fuel cell was demonstrated by Francis T. Bacin and
J.C. frost of Cambridge university in 1959.

4. Parts of fuel cell
1. Anode
2. Cathode
3. Catalyst
4. Electrolyte

5. Anode
The anode is the negative post of the fuel cell.
It is the electrode where oxidation takes place.
It conducts the electrons that are freed from the hydrogen molecules so that they can be
used in an external circuit.
It has channels attached into it that disperse the hydrogen gas equally over the surface of
the catalyst.

6. Cathode
 The cathode is the positive post of the fuel cell.
 It has channels etched into it that distribute the oxygen to the
surface of the catalyst.
 It also conducts the electrons back from the external circuit to
the catalyst, where they can recombine with the hydrogen ions
and oxygen to form water.

7. catalyst
It is a chemical substance which increases the rate of reaction.
The catalyst is a special material that facilitates the reaction of oxygen and hydrogen.
It is usually made of platinum powder very thinly coated onto carbon paper or cloth. The
catalyst is rough and porous so that the maximum surface area of the platinum can be
exposed to the hydrogen or oxygen.

8. Electrolyte
 A substance that conducts charged ions from one
electrode to the other in a fuel cell.
 The electrolyte is also known as the proton exchange
membrane.
 This is a specially treated material that only conducts
positively charged ions.
 The membrane blocks electrons.

9. Mechanism of fuel cell
 A fuel cell consists of two electrodes - Anode and Cathode.
 Hydrogen and Oxygen are fed into the cell.
 Catalyst at Anode causes hydrogen atoms to give up electrons
leaving positively charged protons.
 Oxygen ions at Cathode side attract the hydrogen protons.

10. Mechanism of fuel cell
 Protons pass through electrolyte membrane.
 Electrons are redirected to Cathode through external circuit.
 Thus producing the electric current.

11. Mechanism of fuel cell

12. Classification
 Fuel cells can be classified based of various criteria
given below:
1. Based on temprature range in which they operate:
Temperature Range
Low 25-100 ˚C
Medium 100-500 ˚C
High 500-1000 ˚C
Very High Above 1000 ˚C

13. Continue….
2. Based on the physical state of fuel:
Gas: hydrogen, lower hydrocarbons
Liquid: alcohols, hydrazine, higher hydrocarbons
Solid: metals etc.
3. Based on the type of electrode:
Aqueous
Non-aqueous
Solid/molten.

14. H2-O2 fuel cell
Principle:
 The fuel is oxidized on the anode and
oxidant reduced on the cathode. One
species of ions are transported from one
electrode to the other through the
electrolyte to combine there with their
counterparts, while electrons travel
through the external circuit producing the
electrical current.
Fuel
Permeable
Anode
Electrolyte
Oxidant
Permeable
Cathode
Fuel Oxidant
Cations
(+ve)
Anions (-ve)

15. Working
The Fuel gas (hydrogen rich) is passed towards the anode
where the following oxidation reaction occurs:
H2 (g) = 2H+ + 2e-
The liberated electrons from hydrogen in anode side do not
migrate through electrolyte.
Therefore, they passes through the external circuit where work
is performed, then finally goes into the cathode.
On the other hand, the positive hydrogen ions (H+) migrate
across the electrolyte towards the cathode.

16. At the cathode side the hydrogen atom reacts with oxygen gas
(from air) and electrons to form water as byproduct according to:
The reaction proceeds in two steps:
1. 0.5O2 + H2O + 2e¯ → 2OH ¯
2. H+ + OH ¯ → H2O
Overall reaction is given as:
Fuel + oxidant → product + heat
H2 + 0.5 O2 → H2O + heat
Continue…

17. Solid oxide fuel cell
 Certain solid have tendency to conduct electricity at high
temperature and can serves as electrolytes for fuel cell.
 SOFCs are unique since in those, negatively charged
oxygen ions travel from the cathode (positive side of the fuel
cell) to the anode (negative side of the fuel cell) instead of
positively charged hydrogen ions travelling from the anode to
the cathode, as is the case in all other types of fuel cells.
 Oxygen gas is fed through the cathode, where it absorbs
electrons to create oxygen ions. The oxygen ions then travel
through the electrolyte to react with hydrogen gas at the anode.
The reaction at the anode produces electricity and water as by-
products. Carbon dioxide may also be a by-product depending
on the fuel,

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 The voltage developed in a single fuel cell various from 0.7 to
1.4 volt.
 More power can be obtained by arranging the individual fuel
cell as a stack. In this case, each single cell is sandwiched with
one another by a interconnect.
 Therefore, electricity power ranging from 1 kW to 200 kW can
be obtained for domestic as well as industrial application.

20. Molten carbonate fuel cell
Molten carbonate cell promises high fuel-to-electricity efficiency
and the ability to utilize coal based fuels
It Uses an electrolyte composed of a molten carbonate salt mixture
.
It require carbon dioxide and oxygen to be delivered to the cathode
.
Operates at extremely high temperatures 1200 degrees .
Primarily targeted for use as electric utility applications.
It Have been operated on hydrogen, carbon monoxide, natural gas,
propane, landfill gas, marine diesel and simulated coal
gasification products.
Discharge emf of the cell is 0.8 volt.

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Because of the extreme high
temperatures, non-precious
metals can be used as
catalysts at the anode and
cathode which helps reduces
cost
Disadvantage is durability
The high temperature
required and the
corrosive electrolyte
accelerate breakdown
and corrosion inside the
fuel cell

22. Regenerative fuel cell
It is the fuel cell in which the fuel product is
recovered into its reactants.
It Uses solar energy to separate water into
hydrogen and oxygen.
Hydrogen and oxygen are fed into the fuel cell
generating electricity, heat and water.
The water byproduct is then recirculated back
to the solar-powered electrolyser beginning
the process again.
So the total efficiency of this cell is
summation of efficiencies of both stages.

23. Aluminium -oxygen cell
 It is being developed by the Lawrence National
laboratory, mainly for electric vehicle propulsion.
 Aluminium acts as negative electrode of the cell and
oxygen acts as the positive electrode of the cell, sodium
hydroxide is used as electrolyte.
 Before entering the cell, air is scrubbed to remove
carbon dioxide.
 Aluminium hydroxide is generated as product in this
cell.

24. Alkaline Fuel Cell
 The alkaline fuel cell (AFC), also known as
the Bacon fuel cell after its British inventor, is one of
the most developed fuel cell technologies. NASA has
used alkaline fuel cells since the mid-1960s, in Apollo-
series missions and on the Space Shuttle.
 Used in spacecraft to provide drinking water and
electricity
 Electrolyte: Aqueous solution of alkaline potassium
Hydroxide
 Output of 300w -5KW can be obtained.
 Power generation efficiency of about 70% can be
achieved by this cell.
 But it is too expensive for commercial applications .

25. Phosphoric Acid Fuel cell
 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.
 They are used in hospitals, nursing homes and for all
commercial purposes
 Electrolyte: Liquid Phosphoric acid
 Catalyst: platinum
 Electrical efficiency of 40%
 Advantages :using impure hydrogen as fuel and 85% of
the steam can be used for cogeneration

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27. Importance of hydrogen in
fuel cell
 Fuel Cells require highly purified hydrogen as a fuel.
 Researchers are developing a wide range of technologies to
produce hydrogen economically from a variety of resources in
environmentally friendly ways.
 Hydrogen is a secondary energy resource, meaning it must be
made from another fuel.
 Hydrogen can be produced from a wide variety of energy
resources including:
 Fossil fuels, such as natural gas and coal
 Nuclear energy
 Renewable resources, such as solar , water, wind and biomass .

28. Advantages of fuel cell
 They can be installed near the use point, thereby
reducing the transmission losses.
 They have few mechanical components, so less
attention and less maintenance is required.
 Atmospheric pollution is negligible if the primary energy
source is hydrogen.
 As fuel cells don’t make noise, they can be installed in
residential areas.
 The fuel cell takes little time to go under operation.
 Space required by fuel cell in considerably less
compared to other convenient methods.

29. Disadvantages of fuel cell
 Main disadvantage of fuel cell is its high initial cost.
 Fuel cell has low service life.
 If hydrocarbon is the energy source in fuel cell then it
emits carbon dioxide and no longer a green source.
 It is comparatively expensive.
 It is difficult to handle pure hydrogen.

30. Conversion efficiency of fuel
cell
 The electric energy generated by fuel cell depends on
the free energy rather then the heat energy of overall
cell reaction.
 The free energy of formation of 1 mole of water at
atmospheric temperature and pressure is 56.67 kcal.
 The heat energy of reaction in same conditions is 98.26
kcal.
 So the theoretical efficiency of conversion of heat
energy into electric energy is 80% in case of H2-O2 cell.
 But practically, obtained efficiency is 50-60%.
 The efficiency is somewhat lower when air is used as a
source of O2.

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 The difference between the theoretical and practical
efficiency is known as polarization.
 Sometimes it is also known as over voltage.
 The effect of polarization is to reduce the efficiency of
the cell from the theoretical maximum.
 Polarization is of three types:
1. Activation polarization
2. Resistance or ohmic polarization
3. Concentration polarization.

32. Applications of fuel cell
 Domestic use
 Central power stations
 Automotive vehicles
 Special applications.

33. How can fuel cell technology
be used ??
 Transportation
 All major automakers are working to commercialize a fuel
cell car
 Automakers and experts speculate that a fuel cell vehicle will
be commercialized by 2010
 50 fuel cell buses are currently in use in North and South
America, Europe, Asia and Australia
 Trains, planes, boats, scooters, forklifts and even bicycles are
utilizing fuel cell technology as well

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 Stationary Power Stations
 Over 2,500 fuel cell systems have been installed all over the
world in hospitals, nursing homes, hotels, office buildings,
schools and utility power plants
 Most of these systems are either connected to the electric grid to
provide supplemental power and backup assurance or as a grid-
independent generator for locations that are inaccessible by power
lines

35. Continue…
 Telecommunications
 Due to computers, the Internet and sophisticated communication
networks there is a need for an incredibly reliable power source
 Fuel Cells have been proven to be 99.999% reliable

36. Mercedes-Benz: Citaro fuel cell bus on the
streets of London. Engine supplied by Ballard.
European Fuel Cell Bus Project, which saw 30
fuel cell buses operating on the roads of Europe
over the past two years.
Toyota: The FCHV-
BUS2 is a large, low-
floor, fuel-cell hybrid
bus.
Since its exhaust is free
of NOx (nitrogen
oxides) and PM
(particulate matter), it
can help improve air
quality in urban areas.

37. Casio: World's smallest fuel cell for use in
laptop PC. The polymer electrolyte fuel can
power a typical laptop computer for eight to 16
hours.
Samsung Electronics: laptop PC fuel cell using 100cc of methanol solution, enabling
continuous usage for more than 10 hours without recharging.

38. Future Applications
Application Size (kW) Fuel cell Fuel
Power systems
for portable
electronic
devices
0.001–0.05 PEMFC
DMFC
SOFC
Hydrogen
methanol
methanol
Micro-
Combined Heat
and Power
1–10 PEMFC
SOFC
LPG
Natural gas,
LPG
Auxiliary
power units
1–10 SOFC LPG
Distributed
Combined Heat
and Power
50–250 PEMFC
MCFC
SOFC
natural gas
natural gas
natural gas
City buses 200 PEMFC hydrogen
Large power
units
1000–10,000 SOFC/GT natural gas

39. UTC Fuel Cells: 200kW of electricity and 900,000 BTUs of
usable heat. This system provides clean, reliable power at
locations including a New York City police station, a major
postal facility in Alaska, a credit-card processing system
facility in Nebraska, and a science center in Japan.
UTC Fuel Cells: 5kW
fuel cell power plants
for backup power for
telecommunications
towers, power for small
businesses, and
residential use.