4. Contents
Basic Elements in a PEMFC
How PEM Fuel Cell Works
How PEM FC SYSTEM works
PEM FUEL CELL Applications
The Current PEM Market
Part II
5. Overview of a Fuel Cell
A fuel cell consists of two electrodes sandwiched around an
electrolyte. Oxygen passes over one electrode and hydrogen
over the other, generating electricity, water and heat.
A fuel cell system which includes a "fuel reformer"
can utilize the hydrogen from any hydrocarbon fuel -
from natural gas to methanol, and even gasoline.
6. Different Types of Fuel Cell
Description:
PAFC - uses phosphoric acid as the
electrolyte.
(MCFC) uses high-temperature compounds
of salt (like sodium or magnesium)
carbonates (chemically, CO3) as the
electrolyte.
(AFC) operates on compressed hydrogen
and oxygen. They generally use a solution
of potassium hydroxide (chemically, KOH)
in water as their electrolyte.
(SOFC) uses a hard, ceramic compound of
metal (like calcium or zirconium) oxides
(chemically, O2) as electrolyte.
PROTON
EXCHANGE
MEMBRANE
(PEM) works with a polymer electrolyte in
the form of a thin, permeable sheet.
7. History of PEM Fuel Cell
PEM technology was invented at General Electric through the
work of Thomas Grubb and Leonard Niedrach.
GE developed a small fuel cell for a program with the U.S. Navy's
Bureau of Ships (Electronics Division) and the U.S. Army Signal
Corps. The unit was fueled by hydrogen generated by mixing water
and lithium hydride.
GE developed PEM water electrolysis technology for
undersea life support, leading to the US Navy Oxygen
Generating Plant.
Los Alamos National Lab and Texas A&M University
experimented with ways to reduce the amount of platinum
required for PEM cells.
19601960
mid-1960smid-1960s
mid-1970smid-1970s
1990s1990s
1980s1980s The British Royal Navy adopted this technology in early 1980s
for their submarine fleet.
8. What is PEM Fuel Cell?
Polymer Electrolyte Membrane FC
Description
Concept
- consists of an electrolyte membrane sandwiched between an
anode (negative electrode) and a cathode (positive electrode).
PEM fuel cells work with a polymer electrolyte in the form of a thin,
permeable sheet and allow hydrogen protons to pass through but
prohibit the passage of electrons and heavier gases.
- a thin, solid, organic compound, typically the consistency of plastic
wrap and about as thick as 2 to 7 sheets of paper. This membrane
functions as an electrolyte: allows the solution to conduct electricity
9. PEM Fuel Cell Basics
Fuel cells are operationally equivalent to a battery.
For automotive applications
hydrogen is the fuel choice.
Low temperature; Polymer
Electrolyte Membrane (PEM) type
cells are the standard devices.
The reactants or fuel in a fuel cell
can be replaced unlike a standard
disposable or rechargeable battery.
1
4
2
5
3
Electrochemical energy comes
from the reaction: ½ H2 +
½ O2 → H2O.
6
Theoretically the maximum voltage
that this reaction can generate is
1.2 V. However, in practice the cell
usually generates about 0.7 V to
0.9 V and about 1 W cm-2 of power.
11. ADVANTAGES
Rapid load
following
capability
Lower cost of
fabrication
Robust
High power
density
The Proton Exchange MembraneThe Proton Exchange Membrane
(PEM)(PEM) system allows compactsystem allows compact
designs and achieves a high energydesigns and achieves a high energy
to weight ratio.to weight ratio.
Efficient
In comparison, the internal
compaction motor has an efficiency of
about 15%.
12. HIGH
Manufacturing
Cost
Heavy Auxiliary
Equipment
Needs Pure
Hydrogen
Complex Heat
and Water
Management
Start and stop conditions induce drying and wetting, which contributes
to membrane stress. If run continuously, the stationary stack is
estimated at 40,000 hours. Stack replacement is a major expense.
Disadvantages
13. -It conducts the electrons that are freed from the
hydrogen molecules so that they can be used in an
external circuit.
-It has channels etched into it that disperse the
hydrogen gas equally over the surface of the catalyst.
Basic Elements of PEMFC
Anode
-has channels etched into it that distribute the oxygen
to the surface of the catalyst.
-conducts the electrons back from the external circuit
to the catalyst, where they can recombine with the
hydrogen ions and oxygen to form water
Cathode
Anode Reaction Cathode Reaction
H2 → 2H+ + 2e- O2 + 4H+ + 4e- → 2H2O
14. Basic Elements of PEMFC
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Electrolyte
-This specially treated material, which looks something
like ordinary kitchen plastic wrap, only conducts
positively charged ions.
- The membrane blocks electrons.
Catalyst
- 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.
- The platinum-coated side of the catalyst faces the
PEM.
20. PEM Fuel Cell Applications
The first viableThe first viable
electric alternative toelectric alternative to
the internalthe internal
combustion enginecombustion engine
for vehicles, e.g.for vehicles, e.g.
cars, motorbikes,cars, motorbikes,
buses, locomotives,buses, locomotives,
forklifts, light aircraftforklifts, light aircraft
and UAVs.and UAVs.
Portable generation systems for
domestic, industrial, military and
maritime application
Small scale power packs for
remote, unattended and
military application
On boardOn board
auxiliary powerauxiliary power
units (APUs) forunits (APUs) for
land and airland and air
transportationtransportation
DecentralizedDecentralized
power generationpower generation
for industrial andfor industrial and
domesticdomestic
applicationsapplications
General battery replacement/displacement.
21. The Current PEM Market
63%
6%10%
2%Portable
Niche
Transportation
Light Duty
Devices
Large
Stationary
3%Buses
16% Small
Stationary
Total Number of PEM Units Installed Globally By Application
