An Introduction to Fuel Cells and NanotechnologyPotential & Challenges
OpenCraft Technical Seminar October 2007
bySami Mardini
2Content
Fuel Cells
Basic Principles
Advantages
History
Applications
Commercialization
Questions
Nanotechnology
Definition
Product Applications
Nanomaterials production Methods
Questions
3The Hype Cycle 1. "Technology Trigger"The "technology trigger" or breakthrough, product launch or other event that generates significant press and interest.
2. "Peak of Inflated Expectations"A frenzy of publicity typically generates over-enthusiasm and unrealistic expectations. There may be some successful applications of a technology, but there are typically more failures.
3. "Trough of Disillusionment"Technologies fail to meet expectations and quickly become unfashionable. Consequently, the press usually abandons the topic and the technology.
4. "Slope of Enlightenment"Businesses continue through the "slope of enlightenment" and experiment to understand the benefits and practical application of the technology.
5. "Plateau of Productivity"A technology reaches the "plateau of productivity" as the benefits of it become widely demonstrated and accepted. The technology becomes increasingly stable and evolves in second and third generations. The final height of the plateau varies according to whether the technology is broadly applicable or benefits only a niche market.
X Fuel CellsNanotechnology X
4Environmental Outlook
year1000 1200 1400 1600 1800 2000
a
t
m
o
s
p
h
e
r
i
c
C
O
2
[
p
p
m
]
270
280
290
300
310
320
330
340Global CO2 levels
Source: Oak Ridge National Laboratory
2004: 378 ppm
Projections:
500-700 ppm by 2020
Industrial Revolution
5Basic Fuel Cell
Fuel
e-e-
Membrane
Air
Overall: Fuel In Electricity Out
6Basic Equations
Wel = G = nF E where F is Faraday's constant (96,487 coulombs/g-mole electron), and E is the ideal potential of the cell.
G = H TS where H is the enthalpy change and S is the entropy change. The total thermal energy available is H. The available free energy is equal to the enthalpy change less the quantity TS which represents the unavailable energy resulting from the entropy change within the system.
A+BcC+D
G = cG+GGG
7How a Fuel Cell Works
H2 2H+ + 2e- O2 + 2H+ + 2e- H2OFuel
Car / Home / Laptop
C
a
t
h
o
d
e
A
n
o
d
e
e-e-
Electrolyte
H
Oxidant
By-productBy-product
Overall: H2 + O2 H2O
+
8Why Fuel Cells?
Higher EfficiencyX 40-90%*
Clean EnergyX No CO2 emissions on H2
X
9Applications
Back-upPower
PortableElectronics Automotive
DistributedGeneration
Military & Aerospace
AuxiliaryPower
Fuel Cells1 W 1 MW
10
US Electricity Flow
Energy Information Administration- 2006 Annual Energy Review
2005 Electricity Flowin Quadrillion BTU
High Efficiency FC High Efficiency FC Distributed Generation Distributed Generation reduces conversion losses reduces conversion losses and eliminates T&D lossesand eliminates T&D losses
65% lost energy due to low efficiency generation12.7% lost electricity due to transmission and distribution
11
Fuel Cell HistoryLots of Prototypes, No Mass Adoption
Sir William Grove-1st fuel cell
1839
1889
Ludwig Mond &Charles Langer- coin fuel cell
Francis T. Bacon-1st alkalinefuel cell (AFC)
1932
1955
General Electric- 1st polymer fuel cell (PEMFC) inGemini space craft
1959
WestingHouse-1st solid oxidefuel cell (SOFC)
1962 1964
Allis-Chalmers-5 kW phosphoricacid fuel cell (PAFC)
Texas Instruments- 100 W MoltenCarbonate FuelCell (MCFC)
1965
1967
Union Carbide-AFC poweredmotorcycle
1979
United Technologies- 40 kW PAFC
Ballard Systems-100 kW PEMFCtransit bus
1993
1997
1997
Daimler Benz &Honda
- PEMFC cars
Power Corporation- 250 kW MCFC
Toshiba- 1 W PEMFC
2005
12
Types of Fuel Cells
Fuel Cell Electrolyte Major Drawbacks
AFC - 1930 Alkaline (liquid) Needs pure oxygen, corrosive liquid
SOFC - 1937 Solid oxide (solid) Expensive, thermal cycling
PAFC - 1959 Phosphoric acid (liquid) Expensive, corrosive liquid
PEMFC - 1961 Polymer electrolyte membrane (liquid/solid composite)
Expensive, short lifetime
MCFC - 1957 Molten carbonate (liquid) Expensive, corrosive liquid
SAFC - 2004 Solid acid (solid) As yet to be determined
13
Solid Acid Electrolytes
Intermediate salts and acids 1Cs3PO4+ 2H3PO4 3CsH2PO4
PropertiesX Solid state proton conductivity
X Impermeable
50 100 150 200 250 3001E-8
1E-6
1E-4
0.01
1
C
o
n
d
u
c
t
i
v
i
t
y
(
1
/
c
m
)
Temperature (C)
Polymer (Nafion)
Solid Acid (CsH2PO4)
superprotonic
normal phase transition
Solid Acid Conductivity
14
Solid Acid Electrolytes
too cold
too hot
minimum conductivityfor fuel application
optimal operating
temperature
operating fuel cells at optimal temperatures
expensive catalysts
inefficientcooling
expensive materials
poor thermal cycling
low cost materials
simpler system
0 200 400 600 800 1000
1E-3
0.01
0.1
1Solid Oxide
YSZ
C
o
n
d
u
c
t
i
v
i
t
y
(
1
/
c
m
)
Temperature ( C)
Polymer (PEM)Nafion
Solid AcidCsH2PO4
15
Alternative Fuels
HydrogenX Cleanest but lowest energy density
X Issues in production, distribution and storage
X Massive new infrastructure will be needed for automotive applications
RenewablesX Biofuels: Ethanol, Biodiesel
X May be carbon neutral
Opportunity FuelsX Industrial process byproduct gases
16
0
2
4
6
8
10
Gasoline Ethanol Methanol LiquidHydrogen
CompressedHydrogen
E
n
e
r
g
y
D
e
n
s
i
t
y
(
k
W
h
/
L
)
Energy Density of Fuels
Liquid fuels have more than 7 times the energy density of compressed hydrogen fuelLiquid fuels have more than 7 times the energy density of compressed hydrogen fuel
17
Fuel Cell Adoption Curve assuming price & performance targets are met
$10
$100
$1,000
$10,000
$100,000
1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018
S
y
s
t
e
m
P
r
i
c
e
$
/
k
W
C
o
m
m
o
d
i
t
y
V
a
l
u
e
Automotive
R&D Prototype
Military
Back-up Power
APU
Residential
Industrial Commercial
Consumer Portable
Central Generation
Timeline
18
Core Product
Stack SystemCellElectrolyte
from electrolytes to stacks
19
Telecom BackUp Power
5 kWPEM
System
FuelStorage
Battery bank
Diesel Genset
+Vs.
20
Long Haul Diesel Truck APU
Class 8 trucks with sleeper cabs. APU provides power for heating/cooling eliminating overnight idling. Expect legislation to be introduced in 2010 timeframe.
Truck Idling (Argonne National Lab Study) 1,830 hours/year idling per truck (6 hours/day)
458,000 trucks travel >500 miles from base per day
838 million gallons of fuel per year for idling
140 g/hour NOx; 8,200 g/hour CO2
21
SummaryFuel Cellsand Solid Acid Fuel Cells
Efficient energy conversion devices
Mass adoption held up for over half century by high cost/low durability
Solid Acid Electrolytesfirst new fuel cell electrolyte in 40 yrs
X Excellent material properties for fuel cells
Fuel cells part of the future energy landscape
X More efficient use of standard fuels
X Enabling technology for carbon free and carbon neutral energy cycles
22
Fuel Cells
Questions ?
23
Increase PerformanceApproach: Nanoparticle Electrolyte
catalyst
catalyst
3000x 10000x
Size mismatch in current electrodes leads to small active SAnano-sized electrolyte particles dramatically increase active SASize mismatch in current electrodes leads to small active SA
nano-sized electrolyte particles dramatically increase active SA
Optimized electrode
Nanoparticle catalyst
Percolatingelectrolyte & catalystparticles
Non-ideal electrode
Large, isolated electrolyte particle
24
Active Catalytic Surface AreaA Physical Picture
True triple phase boundary
Point junctions between electrolyte and catalyst
Limited by electrolyte surface area
Pt
CsH2PO4 O2 (gas)H+
H2O (gas)
25
Active Electrolyte Surface AreaSurface area a function of particle size
10 100 1000 10000
0
20
40
60
80
100
0.4Pt:C 90 m2/g
C
s
H
2
P
O
4
S
p
e
c
i
f
i
c
S
u
r
f
a
c
e
A
r
e
a
/
m
2
g
-
1
CsH2PO4 Particle Radius / nm
Pt black 28 m2/g
currentstandard
Need to increase electrolyte surface area to increase active surface area
Typical catalyst-electrolyte surface areas greater than 20 m2/g
Solid acid surface area less than 2 m2/g (500 nm)
Need to decrease particle size by an order of magnitude!
Need to decrease particle size by an order of magnitude!
Surface Area as a Function of Particle Size
26
0 2 4 6 8 100
200
400
600
800
P
o
w
e
r
d
e
n
s
i
t
y
/
m
W
c
m
-
2
Inverse average particle size / m-1
Nano-Particle ElectrolyteSolid acid particle size effect
Dramatic performance increases due to increasing catalytic activity with decreasing electrolyte particle size.
Dramatic performance increases due to increasing catalytic activity with decreasing electrolyte particle size.
Today1000 nm
Milestone 1180 nm
Power Density as aFunction of Particle Size
27
What is Nanotechnology ?
The application of nanoscale materials and properties to
X improve performance of existing materials or products
X create useful size dependent properties
X create new products
The development of methods and processes to produce nanomaterials
Identifying the chemical and physical changes that occur at the nanoscale.
Developing new tools to measure and analyze highly miniaturized structures.
28
Just Small is Not Enough!
Dimensions have to play a critical role ( typically in the range of 1 to 100 nanometers)
Some materials when smaller than 100 nm exhibit useful and different chemical and physical properties than bulk
29
Examples of size dependent properties
Catalytic X how the material enhances chemical reactions
ElectrochemicalX how the material transfers electrons to other chemical constituents
Magnetic propertiesX how the electrons interact to induce magnetic poles
Optical properties X how the material interacts with light (e.g., its color)
Difficult to predict at what size a particular material will transition from bulk to size-dependent properties. X Threshold is different for each material and each property.
For example, nanoscale gold will have different colors throughout the nanoscalesize range, but the size-dependent catalytic properties do not dramatically change until gold features are smaller than five nanometers.
30
High Refractive Index Encapsulant for LED Lighting. Over 80% of the light emitted from blue-LED chip is lost
X Due to a large difference in the refractive index between LED bare chip (semiconductor or organic) and encapsulant
n2
n1Emission Layer
TIR
n1 > n2
LED ChipLED Chip
EncapsulantEncapsulant
31
High Index Encapsulation Solution For Brighter LED
Light extraction efficiency of LED encapsulant increases with hiLight extraction efficiency of LED encapsulant increases with higher refractive gher refractive index, which approaches the RI of LED (2.7). RI of starting polyindex, which approaches the RI of LED (2.7). RI of starting polymer is 1.5mer is 1.5
32
Medical Applications
Targeted and IntelligentDrug Delivery
X Nanoparticle drug carriers coated with nano-sensors
recognize diseased tissues
attach to them
release drug exactly where needed.
X enter damaged cells and release enzymes to auto-destruct or auto-repair
33
Nanoparticle ProductionOverview of Approaches
CompositionX Requires gaseous/liquid precursorsX Gas phase enables direct synthesisX Contamination varies with process
Particle size and distributionX Depends on quench conditionsX Depends on reactant densityX Initial result generally retained
CompositionX Reaction chemistry and precursorsX Broad range of possible synthesis routesX By products/contamination
Particle size and distributionX Large variation in particle size distributionsX Difficult to reach/retain nano-scaleX Possible post processing required
Production Methods
Gas PhaseNucleation
Solid StateSynthesis
PlasmaVaporization
Flame/Spray Pyrolysis
AerosolTechniques
Solution -Precipitation
Solution -Suspension
MechanicalMilling
Slide Courtesy of NanoGram Corporation
34
Nanoparticles Production Challenges
Size Control
Size Distribution
Purity
Throughput
Scalability
Agglomeration
Ecomomics
35
Laser-Driven Nanoparticles Synthesis
36
Nanotechnology Summary
Great Science
X Multi-disciplinary: chemistry, physics, biology, engineering
Great Potential
X Energy, Electronics, Medicine, Environment, Security,..
Significant Time and Investment Still Needed
X Create meaningful successes
X Expectations Management
37
Nanotechnology
Questions ?
An Introduction to Fuel Cells and NanotechnologyPotential & ChallengesContentThe Hype CycleEnvironmental OutlookBasic Fuel CellBasic EquationsHow a Fuel Cell WorksWhy Fuel Cells?ApplicationsUS Electricity FlowFuel Cell History Lots of Prototypes, No Mass AdoptionTypes of Fuel CellsSolid Acid ElectrolytesSolid Acid ElectrolytesAlternative FuelsEnergy Density of FuelsFuel Cell Adoption Curve assuming price & performance targets are metCore ProductTelecom BackUp PowerLong Haul Diesel Truck APUSummaryFuel CellsIncrease Performance Active Catalytic Surface AreaA Physical PictureActive Electrolyte Surface Area Surface area a function of particle sizeNano-Particle Electrolyte Solid acid particle size effectWhat is Nanotechnology ?Just Small is Not Enough!Examples of size dependent properties High Refractive Index Encapsulant for LED Lighting.High Index Encapsulation Solution For Brighter LEDMedical ApplicationsNanoparticle Production Overview of ApproachesNanoparticles Production ChallengesLaser-Driven Nanoparticles SynthesisNanotechnology SummaryNanotechnology