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- 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. 遺看稼岳庄稼顎艶. 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俗 2OH 俗 2. H+ + OH 俗 H2O Overall reaction is given as: Fuel + oxidant product + heat H2 + 0.5 O2 H2O + heat 遺看稼岳庄稼顎艶
- 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,
- 18. 遺看稼岳庄稼顎艶 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.
- 21. 遺看稼岳庄稼顎艶 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
- 26. 遺看稼岳庄稼顎艶
- 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 dont 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.
- 31. 遺看稼岳庄稼顎艶 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
- 34. 遺看稼岳庄稼顎艶 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. 遺看稼岳庄稼顎艶 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 0.0010.05 PEMFC DMFC SOFC Hydrogen methanol methanol Micro- Combined Heat and Power 110 PEMFC SOFC LPG Natural gas, LPG Auxiliary power units 110 SOFC LPG Distributed Combined Heat and Power 50250 PEMFC MCFC SOFC natural gas natural gas natural gas City buses 200 PEMFC hydrogen Large power units 100010,000 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.