fuel cells and its types
TRANSCRIPT
Shroff S.R. Rotary Institue of Chemical Technology (SRICT)
• Name- RAJ PAREKH• Branch- MECHANICAL,SEM-1 • Enrollment no-140990119029• Topic- Introduction to fuel cells
What is a Fuel Cell ?· Fuel and air react when they come into contact through a porous membrane (electrolyte) which
separates them.· This reaction results in a transfer of electrons and ions across the
electrolyte from the anode to the cathode. · If an external load is attached to this arrangement, a complete circuit is
formed and a voltage is generated from the
flow of electrical current.
The voltage generated by a single cell is typically rather small (< 1 volt), so manycells are connected in series to create a useful voltage.
A Fuel Cell Converts Chemical Energy to Electrical Energy
Fuel
Hydrogen
Air or Oxygen
Load
Anode CathodeElectrolyte
e-
Catalyst Catalyst
H+
Gas Diffusion Layer
Gas Diffusion Layer
Some History…..
Fuel cell principle first discoveredby William Grove in 1839.
Grove used four large cells, eachcontaining hydrogen and oxygen,to produce electric power which wasthen used to split the water in thesmaller upper cell.
Composition of Fuel CellAnodeCathodeElectrolyte Catalyst
• About 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.
• About 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. • About Electrolyte
− Proton exchange membrane.− Specially treated material, only conducts positively
charged ions.− Membrane blocks electrons.
• About Catalyst − Special material that facilitates reaction of oxygen and
hydrogen− Rough & porous maximizes surface area exposed to
hydrogen or oxygen
Working of Fuel Cells• 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.
• At the cathode side the hydrogen atom reacts with oxygen gas (from air) and electrons to form water as byproduct according to:
• The overall cell reaction is
H2 + 1/2 O2 +2e - H2O + Heat
fuel + oxidant product + Heat
Working of Fuel Cell
Electrical power production by fuel cell
Rotating shaft connected to generator for electricity production
Fuel CellType Electrolyte Anode Gas Cathode Gas Temperature Efficiency
Proton Exchange Membrane(PEM) solid polymer membrane hydrogen pure or atmospheric oxygen 75°C
(180°F) 35–60%
Alkaline(AFC) potassium hydroxide hydrogen pure
oxygenbelow80°C 50–70%
Direct Methanol(DMFC) solid polymer membrane methanol solution in water atmospheric
oxygen75°C
(180°F) 35–40%
Phosphoric Acid(PAFC) Phosphoric Acid hydrogen atmospheric
oxygen210°C
(400°F) 35–50%
Molten Carbonate(MCFC)
Alkali-Carbonates
hydrogen,methane
atmosphericoxygen
650°C(1200°F) 40–55%
Solid Oxide(SOFC) Ceramic Oxide hydrogen,
methaneatmospheric
oxygen800–1000°C
(1500–1800°F) 45–60%
Advantages/Disadvantages of Fuel Cells
• Advantages− Water is the only discharge (pure H2)
• Disadvantages− CO2 discharged with methanol reform− Little more efficient than alternatives− Technology currently expensive
• Many design issues still in progress− Hydrogen often created using “dirty”
energy (e.g., coal)− Pure hydrogen is difficult to handle
• Refilling stations, storage tanks, …
Each type of fuel cell is particularly suited to certain applications:
• PEM: most versatile, used for portable power, transportation, and stationary power
• DMFC: used for portable power• SOFC: primarily used for stationary power, in
development for transportation (e.g. semi trucks)
• MCFC: power plants • AFC: power and water production for space
vehicles (e.g. Apollo and Space Shuttle spacecrafts), in development for more general use
• PAFC: stationary power, power plants
Galvanic cell (battery)Hydrogen fuel cell
· Open system· Anode and cathode are gases in contact with a platinum catalyst.·Reactants are externally supplied, no recharging required.
· Closed system· Anode and cathode are metals.· Reactants are internally consumed, need periodic recharging.
Fuel Cell Vs. Battery
Basic operating principles of both are very similar, but there are severalintrinsic differences.
Fuel Cells in Use: Stationary Systems
Fuel Cells in Use: Stationary Systems
Fuel cell system for submarine
Fuel Cells in Use: Transportation Systems
XCELLSiS fuel cell bus prototypes
Buses are most commerciallyadvanced applications of fuelcells to date.
Are currently being used by many American and Europeancities.
Fuel Cells in Use: Transportation Systems
Many of the major car companies are developing fuel cell car prototypeswhich should come to market during the next decade. The cars use eitherpure hydrogen or methanol with an on board reformer.
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)
SOLAR FUEL CELLS ?
THANK YOU