PH 0101 Unit-5 Lecture-61 Introduction A fuel cell configuration Types of fuel cell Principle, construction and working Advantage, disadvantage and application PH0101 UNIT-5 LECTURE 1

PH 0101 Unit-5 Lecture-62 Every fuel cell has two electrodes, one positive and one negative, called, respectively, the cathode and anode. The reactions that produce electricity take place at the electrodes In all types of fuel cell, hydrogen is used as fuel and can be obtained from any source of hydrocarbon. The fuel cell transform hydrogen and oxygen into electric power, emitting water as their only waste product. What is fuel cell? A Fuel cell is a electrochemical device that converts chemical energy into electrical energy 1.Introduction

PH 0101 Unit-5 Lecture-63 Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes. A single fuel cell generates a tiny amount of direct current (DC) electricity. A converter is used to produce AC current In practice, many fuel cells are usually assembled into a stack. Cell or stack, the principles are the same. In 1932, Francis Bacon developed the first successful FC. He used hydrogen, oxygen, an alkaline electrolyte, and nickel electrodes.

PH 0101 Unit-5 Lecture-64 (+) (-) AnodeCathode Electrolyte A fuel cell consists of two electrodes namely an anode and a cathode and sandwiched around an electrolyte. An electrolyte is a substance, solid or liquid, capable of conducting oving ions from one electrode to other. 2.A fuel cell configuration

PH 0101 Unit-5 Lecture-65 3.Types of fuel cells There are diffrent types of fuel cells, differentiated by the type of electrolyte separating the hydrogen from the oxygen.The types of fuel cells are: Alkaline fuel cells (AFC) Direct methanol fuel cells (DMFC) Molten carbonate fuel cell (MFFC) Phosphoric acid fuel cells (PAFC) Polymer electrolyte membrane fuel cells (PEMFC) Solid oxide fuel cells (SOFC)

PH 0101 Unit-5 Lecture-66

7 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. Electrons (e - ) Fuel Permeable Anode Electrolyte Oxidant Permeable Cathode Fuel Oxidant Cations (+ve) Anions (-ve) 4. Principle, construction and working of H2-O2 fuel cell

PH 0101 Unit-5 Lecture-68 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.

PH 0101 Unit-5 Lecture-69 At the cathode side the hydrogen atom reacts with oxygen gas (from air) and electrons to form water as byproduct according to: H 2 + 1/2 O 2 +2e - H 2 O + Heat fuel + oxidantproduct + Heat The overall cell reaction is

PH 0101 Unit-5 Lecture-610

PH 0101 Unit-5 Lecture-611 The liberated electrons from the hydrogen are responsible for the production of electricity. The water is produced by the combination of hydrogen, oxygen and liberated electrons and is sent out from the cell. The DC current produced by fuel cell is later converted into AC current using an inverter for practical application. 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.

PH 0101 Unit-5 Lecture-612 Hydrogen Oxygen Electrical power production by fuel cell Rotating shaft connected to generator for electricity production

PH 0101 Unit-5 Lecture-613 Advantages Zero Emissions: a fuel cell vehicle only emits water vapour. Therefore, no air pollution occurs. High efficiency: Fuel cells convert chemical energy directly into electricity without the combustion process. As a result, Fuel cells can achieve high efficiencies in energy conversion. High power density: A high power density allows fuel cells to be relatively compact source of electric power, beneficial in application with space constraints. 5.Advantage, disadvantage and applications

PH 0101 Unit-5 Lecture-614 Quiet operation: Fuel cells can be used in residential or built-up areas where the noise pollution can be avoided. No recharge: Fuel cell systems do not require recharging. Disadvantages It is difficult to manufacture and stores a high pure hydrogen It is very expense as compared to battery

PH 0101 Unit-5 Lecture-615 Applications 1.Portable applications They used in portable appliances and power tools They can be used in small personal vehicles They are used Consumer electronics like laptops, cell phones can be operated They can be used in Backup power

PH 0101 Unit-5 Lecture Transportation applications They can be used for transport application in the following areas, Industrial transportation Public transportation Commercial transportation (truck, tractors) Marine and Military transportation

PH 0101 Unit-5 Lecture Power distribution application Fuel cells can be used for the distribution of power in various fields such as, Homes and small businesses Commercial and industrial sites Remote, off-grid locations (telecom towers, weather stations)