Fuel cells are devices that generate electricity through chemical reactions, primarily using hydrogen and oxygen. They consist of components including an anode, cathode, electrolyte, and catalyst, with various types such as alkaline and proton exchange membrane fuel cells, each having distinct efficiencies and applications. While fuel cells offer advantages like being a clean energy source and high reliability, they also face challenges like high costs and safety concerns.

1. FUEL CELLS

2. PRESENTED BY:
MAIRA PERVAIZ
SIDRA JAMEEL
QURAT-UL-AIN
ANEEQA ZUBAIR

3. WHAT IS A FUEL CELL?
 A device that generates electricity by a
chemical reaction
 Uses Oxygen or another oxidizing agent
 Another fuel, generally Hydrogen.
 Electrochemical process

4. HISTORY
 The first fuel cell was constructed in 1839 by British physicist and lawyer Sir
William Robert Groove.
 For many years little was done to develop fuel cells for commercial purposes.
 Recent advances in technology and electrochemistry have made the
scientists successful to introduce the fuel cell which are more efficient, than
thermal source of electrical energy.

5. COMPONENTS:
 An anode
 A Cathode
 An Electrolyte
 A Catalyst
 Fuel
 Oxidant

6. ANODE:
 Negative post of the fuel cell.
 Conducts the electrons that are freed from the hydrogen molecules so
that they can be used in an external circuit.
 Etched channels disperse hydrogen gas over the surface of catalyst.

7. CATHODE:
 Positive post of the fuel cell
 Etched channels distribute oxygen to the surface of the catalyst.
 Conducts electrons back from the external circuit to the catalyst
 Recombine with the hydrogen ions and oxygen to form water.

8. ELECTROLYTE:
 Proton exchange membrane.
 Specially treated material, only conducts positively charged
ions.
 Membrane blocks electrons.

9. CATALYST:
 Special material that facilitates reaction of oxygen and
hydrogen
 Usually platinum powder very thinly coated onto carbon
paper or cloth.
 Rough & porous maximizes surface area exposed to
hydrogen or oxygen
 The platinum-coated side of the catalyst faces the PEM.

10. WORKING:
 Pressurized hydrogen gas (H2) enters cell on anode side.
 Gas is forced through catalyst by pressure.
 When H2 molecule comes contacts platinum catalyst, it splits into two H+ ions and two
electrons (e-).
 Electrons are conducted through the anode
 On the cathode side, oxygen gas (O2) is forced through the catalyst
 Forms two oxygen atoms, each with a strong negative charge.
 Negative charge attracts the two H+ ions through the membrane,
 Combine with an oxygen atom and two electrons from the external circuit to form a water
molecule (H2O).

11. REACTIONS:
 Anode side (an oxidation reaction)
 2H2 => 4H++ 4e-
 Cathode side (a reduction reaction):
 O2 + 4H+ + 4e- => 2H2O
 Net reaction (the "redox" reaction):
 2H2 + O2 => 2H2O

12. TYPES:
 Alkaline fuel cells
 Solid oxide fuel cells
 Phosphoric Acid Fuel Cell
 Proton Exchange Membrane Fuel
Cells
 Molten Carbonate fuel cells

13. ALKALINE FUEL CELLS:
 Operates on compressed hydrogen and oxygen.
 Efficiency is about 70 percent, and operating
temperature is 50 to 100 degrees C.
 Used in Apollo spacecraft to provide both
electricity and drinking water.
 They require pure hydrogen fuel, however, and
have platinum electrode catalysts.

14. SOLID OXIDE FUEL CELLS:
 Uses a hard, ceramic compound of metal
oxides as electrolyte
 Efficiency is about 60 percent
 Operating temperatures are about 1,000
degrees C, so no reformer is required for
extracting hydrogen from fuel
 Utility applications

15. PHOSPHORIC ACID FUEL CELL:
 Uses phosphoric acid as the
electrolyte
 Efficiency ranges from 40 to 80
percent
 Typically used for stationary power
generation

16. PROTON EXCHANGE MEMBRANE FUEL CELLS:
 Work with a polymer electrolyte in
the form of a thin, permeable sheet
 Efficiency is about 40 to 50 percent
 Suitable for homes and cars

17. MOLTEN CARBONATE FUEL CELL:
 Uses high-temperature compounds of salt
carbonates as electrolyte
 Efficiency ranges from 60 to 80 percent, and
operating temperature is about 650 degrees
C
 Developed for natural gas and coal-based
power plants to generate power for industry
and military use

18. EFFICIENCY:
 The ability of a cell to convert chemical
energy of a fuel-oxidation reaction into
electrical energy is expressed in terms of
efficiency of the cell (Ԑ). It is defined as
Ԑ=∆F∆H × 100

19. EFFICIENCY OF H2– O2 FUEL CELL:
∆F° = -273.2 kJmole-ˡ
∆H° = -258.9 kJmole-ˡ
Ԑ = ∆F/∆H
= -273.2×100/-258.9
=83%

20. ADVANTAGES:
 Clean Energy Source
 High Efficiency
 Noise Reduction
 More reliable
 Flexible technology

21. DISADVANTAGES:
 Expensive
 Catalyst cost (usually platinum)
 Durability
 Safety Hazards associated with
Hydrogen
 Hydrogen is not readily available

22. APPLICATIONS:
 Stationary
 Transportation
 Consumer Electronics
 Providing power for base stations or cell sites
 Food preservation
 Small heating appliances
 Notebook computers
 Hybrid vehicles