Working of Fuel Cell and its types and electrical characteristic also its efficiency

1. Fuel Cell
Presented By:
Waleed Abdullah(2019-EE-603)
Course:
Renewable Energy

2. Table of Content
• Construction
• Working
• Application
• Efficiency
• Types
• Advantages and Disadvantages

3. Introduction
• It is electrochemical device that convert energy produced from chemical reaction
into electrical energy.
• It provide DC voltage which can used to
power motor and electrical appliances
by using inverter.

4. Principle
• Fuel cell consist of electrode, electrolyte & catalyst to facilitate the
electrochemical redox reaction.
• The basic argument can be represented as.
• At Anode
2H2 4𝐻+ + 4ⅇ−
• At Cathode
• 𝑂2 + 4𝐻+
+ 4ⅇ−
→ 2𝐻20

5. Construction
• Anode: Negative post of fuel cell. Conducts the electron that are freed from
hydrogen molecule that can used in external circuit. Etched channel disperse
hydrogen gas over the surface of catalyst.
• Cathode: Positive post of fuel cell. Etched channels distribute oxygen to surface
of the catalyst. Conduct electrons back from external circuit to catalyst,
Recombine with hydrogen ion and oxygen to form water.
• Catalyst: Special material of platinum powder very thin coated onto carbon cloth
that facilitate reaction. Rough & porous maximize surface area exposed to
hydrogen or oxygen. The platinum coated side of catalyst faced the PEM.

6. Working
• A fuel cell generates electrical power by continuously converting the chemical energy of
a fuel into electrical energy by way of an electrochemical reaction. The fuel cell itself has
no moving parts, making it a quiet and reliable source of power. Fuel cells typically utilize
hydrogen as the fuel, and oxygen (usually from air) as the oxidant in the electrochemical
reaction. The reaction results in electricity, by-product water, and by-product heat.

7. Continue..
• When hydrogen gas is introduced into the system, the catalyst surface of the membrane splits hydrogen
gas molecules into protons and electrons. The protons pass through the membrane to react with oxygen
in the air (forming water). The electrons, which cannot pass through the membrane, must travel around it,
thus creating the source of DC electricity.
• Overall reaction
2𝐻2 + 𝑂2 → 2𝐻2O

8. Application
• Used as power sources in remote areas.
• Used to provide off-grid power supplies.
• Can be applicable in both hybrid and electric
vehicles.
• Waste water treatment plant and landfill.
• Cellular phone, laptop and computers.
• Telecommunication, MP3 players, etc.

9. Efficiency

10. • Fuel cell's thermodynamic efficiency
• Csv
• where n is number of electrons transferred during the reaction
• F is the faraday constant, and Ecell is cell potential.
• The electrical work is measured by the Gibbs function change, and the heating value
of the fuel is measured by the enthalpy change.

11. Types:
• Proton Exchange Membrane Fuel Cells (PEMFC)
• Direct Methanol Fuel Cells (DMFC)
• Phosphoric Acid Fuel Cells (PAFC)
• Alkaline Fuel Cells (AFC)
• Molten-Carbonate Fuel Cells (MCFC)
• Solid Oxide Fuel Cells (SOFC)

12. Proton Exchange Membrane Fuel Cells (PEMFC)
• Their efficiencies are the highest available at around 45% (HHV).
• Also called as polymer electrolyte membrane fuel cells.
• Currently operating units range in size from 30 W to 250 kW.
• The temperature range that these cells operate in is between 50oC to 80oC
Direct Methanol Fuel Cells (DMFC)
• These cells use the same polymer electrolytes as PEM cells do.
• But they offer the significant advantage of being able to utilize a liquid fuel, methanol
(CH3OH), instead of gaseous hydrogen.

13. Phosphoric Acid Fuel Cells (PAFC)
• These fuel cells involve the use of phosphoric acid as an electrolyte in order to channel
the H+
• The working temperatures of these cells lie in the range of 150oC – 200oC
• Electrons are forced to travel to the cathode via an external circuit because of the non-
conductive nature of phosphoric acid.
• Due to the acidic nature of the electrolyte, the components of these cells tend to corrode or
oxidize over time.

14. Alkaline Fuel Cells (AFC)
• This was the fuel cell which was used as the primary source of electricity in the Apollo
space program.
• In these cells, an aqueous alkaline solution is used to saturate a porous matrix, which is in
turn used to separate the electrodes.
• The operating temperatures of these cells are quite low (approximately 90oC).
• These cells are highly efficient. They also produce heat and water along with electricity.

15. Molten-Carbonate Fuel Cells (MCFC)
• The electrolyte used in these cells is lithium potassium carbonate salt. This salt becomes
liquid at high temperatures, enabling the movement of carbonate ions.
• Similar to SOFCs, these fuel cells also have a relatively high operating temperature of
650oC
• The anode and the cathode of this cell are vulnerable to corrosion due to the high
operating temperature and the presence of the carbonate electrolyte.
• These cells can be powered by carbon-based fuels such as natural gas and biogas.

16. Solid Oxide Fuel Cells (SOFC)
• These cells involve the use of a solid oxide or a ceramic electrolyte (such as yttria-
stabilized zirconia).
• These fuel cells are highly efficient and have a relatively low cost (theoretical efficiency
can even approach 85%).
• The operating temperatures of these cells are very high (lower limit of 600oC, standard
operating temperatures lie between 800 and 1000oC).
• Solid oxide fuel cells are limited to stationary applications due to their high operating
temperatures.

17.  Advantages:
• High Efficiency- when utilizing co-generation, fuel cells can attain over 80% energy
efficiency
• Good reliability- quality of power provided does not degrade over time.
• Noise- offers a much more silent and smoother alternative to conventional energy
production.
• Environmentally beneficial- greatly reduces CO2 and harmful pollutant emissions.
• Size reduction- fuel cells are significantly lighter and more compact.

18.  Disadvantages:
• Expensive to manufacture due the high cost of catalysts (platinum)
• Lack of infrastructure to support the distribution of hydrogen
• A lot of the currently available fuel cell technology is in the prototype stage and not yet
validated.
• Hydrogen is expensive to produce and not widely available