1 a. shakouri 3/25/2009 overview of renewable energy sources ali shakouri baskin school of...
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A. Shakouri 3/25/2009
Overview of Renewable Energy Sources
Ali ShakouriBaskin School of Engineering
University of California Santa Cruzhttp://quantum.soe.ucsc.edu/
Philips Research Lab, Eindhoven, Netherlands; 25 March 2009
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A. Shakouri 3/25/2009
34%
8%
28%
6%
Share of WorldTotal
24%
38%
26%
23%
7%
6%
US Department of Energy; Energy Information Administration (2007)
World Marketed Energy Use by Fuel Type 1980-2030
13TW
2050: 25-30TW
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A. Shakouri 3/25/2009US Energy Consumption
DOE Energy Information Administration (2007)
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Martin Green, UNSW
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A. Shakouri 3/25/2009
PV
1980 1990 2000 2010 2020
100
80
60
40
20
0
CO
E c
en
ts/k
Wh
Cost of Renewable EnergyLevelized cents/kWh in constant $2000
Wind
1980 1990 2000 2010 2020
CO
E c
en
ts/k
Wh
40
30
20
10
0
10
8
6
4
2
0
CO
E c
en
ts/k
Wh Geothermal
1980 1990 2000 2010 2020
Source: NREL Energy Analysis OfficeThese graphs are reflections of historical cost trends NOT precise annual historical data.Updated: October 2002
Biomass
1980 1990 2000 2010 2020
15
12
9
6
3
0
CO
E c
en
ts/k
WhSolar thermal
1980 1990 2000 2010 2020
70
60
50
40
30
2010
0
CO
E c
en
ts/k
Wh
Keith Wipke, NREL
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1,000,0001,000,000
100,000100,000
10,00010,000
1,0001,000
1010
100100
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1 Billion 1 Billion TransistorsTransistors
808680868028680286
i386i386i486i486
PentiumPentium®®
KK
PentiumPentium®® II II
’’7575 ’’8080 ’’8585 ’’9090 ’’9595 ’’0000 ’’0505 ’’1010
PentiumPentium®® III IIIPentiumPentium®® 4 4
’’1515
Microprocessor Evolution
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A. Shakouri 3/25/2009
McMasters & Cummings, Journal of Aircraft, Jan-Feb 2002
Airplane Speed/Efficiency Evolution
US Energy Intensity (MJ) per available seat km
@ 160kg payload/seat
NLR-CR-2005-669;Peeters P.M., Middel J., Hoolhorst A.
Airplane Speed
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A. Shakouri 3/25/2009
Vaclav Smil,Energy at the Crossroads, 2005
Felix’s forecasts of US energy consumption in year 2000 (early 1970’s)
Coal
Oil
Natural gas
Nuclear
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A. Shakouri 3/25/2009
• Significant potential in US Great Plains, inner Mongolia and northwest China
• U.S.:Use 6% of land suitable for wind energy development; practical electrical generation potential of ≈0.5 TW
• Globally: Theoretical: 27% of earth’s land is class >3 => 50 TW Practical: 2 TW potential (4% utilization)
Off-shore potential is larger but must be close to grid to be interesting; (no installation > 20 km offshore now)
Electric Potential of Wind
Nate Lewis, Caltech
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A. Shakouri 3/25/2009Turbine Sizes
Trend toward bigger turbine sizesHelge Aagaard Madsen, DTU Riso
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http://www.eere.energy.gov/
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A. Shakouri 3/25/2009Offshore Wind Farm
Nysted, Denmark A. Shakouri 11/25/2008
EE 181 Renewable Energies in PracticeCA-Denmark Summer Program
2008
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A. Shakouri 3/25/2009Geothermal Energy Potential
• Mean terrestrial geothermal flux at earth’s surface 0.057 W/m2
• Total continental geothermal energy potential 11.6 TW• Oceanic geothermal energy potential 30 TW
• Wells “run out of steam” in 5 years• Power from a good geothermal well (pair) 5 MW• Power from typical Saudi oil well 500 MW• Needs drilling technology breakthrough (from exponential $/m to linear $/m) to become economical)
Nate Lewis, Caltech
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A. Shakouri 3/25/2009Energy from the Oceans?
Tides
Currents Thermal Differences
Ken Pedrotti, UCSC
Waves
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Global: Top Down
• Requires Large Areas Because Inefficient (0.3%)
• 3 TW requires ≈ 600 million hectares = 6x1012 m2
• 20 TW requires ≈ 4x1013 m2
• Total land area of earth: 1.3x1014 m2
• Hence requires 4/13 = 31% of total land area
Biomass Energy Potential
Nate Lewis, Caltech
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Amount of land needed for 20 TW at 1% efficiency:
9% of land
Chris Somerville, UC Berkeley
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Farrell et al. (Science 311, 2006)
Corn Ethanol Greenhouse Gas Emission
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Steve Koonin, BP
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Dan Kammen, Berkeley
Biofuels
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Bioenergy and Sustainable Development, Ambuj D. Sagar, Sivan KarthaAnnual Review of Environment and Resources, Vol. 32: 131-167 (November 2007)
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• Theoretical: 1.2x105 TW solar energy potential
• Practical: ≈ 600 TW solar energy potential
• Onshore electricity generation potential of ≈60 TW (10%
conversion efficiency):
• Photosynthesis: 90 TW
• Generating 12 TW (1998 Global Primary Power) requires
0.1% of Globe = 5x1011 m2 (i.e., 5.5% of U.S.A.)
Solar Energy Potential
Nate Lewis, Caltech
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A. Shakouri 3/25/2009World Insolation
12 TW
6.0-6.9
4.0-4.9
2.0-2.9
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BoyleRenewable
Energy Sources
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Chris Somerville, UC Berkeley
A. Shakouri 11/25/2008
From: Basic Research Needs for Solar Energy Utilization, DOE 2005
Potential of Carbon Free Energy Sources
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Vaclav SmilEnergy at the
Crossroads
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Specific Energy (Wh/kg)
Spe
cific
Pow
er (
W/k
g)
Combustion Engine
Energy Storage Options
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RejectedEnergy 61%
Lawrence Livermore National Lab., http://eed.llnl.gov/flow
Power ~3.3TW
1.3TW
A. Shakouri 11/25/2008
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Biomass
Petroleum
Coal
Waste Energy
India’s Energy Consumption 2005
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A. Shakouri 3/25/2009Direct Conversion of Heat into ElectricityDirect Conversion of Heat into Electricity
)(
)()( 2
2
tyconductivithermal
tyconductivielectricalSeebeckZ
k
SZ
V~ S T
Electrical Conductor
Hot Cold
Efficiency function of thermoelectric figure-of-merit (Z)
Rload = RTE internal
T
VS
Seebeck coefficient(1821)
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Power Generation Efficiencies of Different Technologies
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
400 600 800 1000 1200
ZTm=0.5ZTm=1ZTm=2ZTm=3Carnot limit
Op
tima
l effi
cie
ncy
Thot
(K)
0.5
En
erg
y C
on
ve
rsio
n E
ffic
ien
cy
3
1
2
Carnot
Solar/ Rankine
Geothermal/ Organic Rankine
ZTavg=20Coal/ Rankine
Cement/ Org. Rankine
Solar/ Stirling
C. Vining 2008
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Radioisotope Thermoelectric Generators
(Voyager, Galileo, Cassini, …)
• 55 kg, 300 We, ‘only’ 7 % conversion efficiency
• But > 1,000,000,000,000 device hours without a single failure
B-doped Si0.78Ge0.22
P-doped Si0.78Ge0.22
B-doped Si0.63Ge0.36
P-doped Si0.63Ge0.36
Hot Shoe (Mo-Si)
Cold Shoe
n-type legp-type leg
SiGe unicoupleCronin Vining, ZT Services
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Which Materials To Choose for TE Modules?Which Materials To Choose for TE Modules?
SS2
Free carrier concentration
Thermal Conductivity
Lattice contribution
Electronic contribution
Seebeck Electrical Conductivity
Insulator Semiconductor Metal
For almost all materials, if doping is increased, electrical conductivity increases but Seebeck coefficient is reduced. Similarly ↔
ZT= S2/
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A. Shakouri 3/25/2009Microrefrigerators on a chip
Featured in Nature Science Update, Physics Today, AIP April 2001
• Monolithic integration on silicon• Tmax~4C at room temp. (7C at 100C)
UCSC, UCSB, HRL Labs
Relative Temp. (C)
50m1 µm
Hot Electron
Cold Electron
Nanoscale heat transport and microrefrigerators on a chip; A. Shakouri, Proceedings of IEEE, July 2006
J. Christofferson
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Hot Electron Filters in Hot Electron Filters in Metal/Semiconductor NanocompositesMetal/Semiconductor Nanocomposites
Assume: lattice=1W/mK, mobility ~10 cm2/Vs
Even with only modestly low lattice thermal conductivity and electron mobility of typical metals, ZT > 5 is theoretically possible
Fermi energy eV (↔ free electron concentration)
Planar Barrier
Metal/Semiconductor Nanostructure
• Need lattice-compatible composites with appropriate barrier heights
D. Vashaee, A. Shakouri;
Physical Review Letters, 2004
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ErAs Semi-metal Nanoparticles imbedded in InGaAs Semiconductor Matrix
ErAs dots are lattice-matched and incorporate without any visible defects in InGaAs despite different crystal structures (Cubic vs. Zinc-blende)
In,GaAs
Er
1nm
• “Random” ErAs particles ~ 2-3 nm
• Size is invariant to growth conditions
J. Zide et al. UCSB/UCSC
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Beating the Alloy Limit in Thermal Conductivity Beating the Alloy Limit in Thermal Conductivity ErAs:InErAs:In0.530.53GaGa0.470.47AsAs
Phonon scattering by ErAs nanoparticles 3-fold reduction in thermal conductivity beyond the alloy limit
InGaAs
0.3% ErAs:InGaAs
3% ErAs:InGaAs
6% ErAs:InGaAs
Nanoparticle
W. Kim et al. UCB/UCSB/UCSC
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A. Shakouri 3/25/2009Module Power generation results
140 m/140 m AlN
400 elements (10-20 microns ErAs:InGaAlAs thin films, 120x120m2)
G. Zeng, J. Bowers, et al. (UCSB, UCSC) Appl. Physics Letters 2006
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140
10 m module
20 m module
Ou
tpu
t P
ow
er (
W/c
m2)
T (K)
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A. Shakouri 3/25/2009Summary
• Significant amount of energy produced in the world is wasted in the form of heat (61% is US)
• Thermoelectric effects can be engineered via nanomaterials – Modify the average energy of moving electrons– Selective scattering of phonons w.r.t electrons
• Micro refrigerators on a chip (silicon based)• Localized cooling, Cooling power density > 500 W/cm2
• Metal semiconductor nanocomposites for direct conversion of heat into electricity
• Potential to reach 20-30% conversion efficiencies
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A. Shakouri 3/25/2009 A. Shakouri 11/25/2008
Nate Lewis, Caltech
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A. Shakouri 3/25/2009Plan B for EnergySeptember 2006; Scientific American; W. Wayt Gibbs
• WAVES AND TIDES (Reality factor 5)
• HIGH-ALTITUDE WIND (Reality factor 4)
• NANOTECH SOLAR CELLS (Reality factor 4)
• DESIGNER MICROBES (Reality factor 4)
• NUCLEAR FUSION (Reality factor 3)
• SPACE-BASED SOLAR (Reality factor 3)
• A GLOBAL SUPERGRID (Reality factor 2)
• SCI-FI SOLUTIONS (Reality factor 1)
– Cold Fusion and Bubble Fusion– Matter-Antimatter Reactors
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A. Shakouri 3/25/2009Can Renewables Save the World?
• Fossil fuels have excellent energy characteristics. • Wind/ geothermal are among the cheapest of
renewables. There is potential for significant growth but they can not solve our energy problem.
• Solar energy has the potential to provide all our energy needs.– Currently expensive; it is intermittent.
• Currently no clear options for large scale energy storage
• Biomass has the potential to provide part of transportation energy needs – Cellulosic biofuels and algaes are interesting but they
have not demonstrated large scale/long term potential. One has to consider the full ecosystem impact (water, food, etc.).
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John Bowers, UCSB
World Average
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Can Renewables Save the World?
• If our goal is to have a planet where everybody has a level of life similar to developed countries, energy need is enormous and it is not clear if we can do this by working on the supply side alone.
• Energy efficiency is important but it is not enough.• We need to consider changes in lifestyle, city
planning and social structure (transportation, lodging, grid).
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S. Koonin, Chief Scientist BPnrg.caltech.edu
Oil Resources
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Source: Hansen, Clim. Change, 68, 269, 2005.
400,000 years of greenhouse-gas & temperature history based on bubbles trapped in Antarctic ice
Last time CO2 >300 ppm was 25 million years ago.
John P. Holdren, 2006
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EE80J Renewable Energy SourcesSpring 2009, Also Summer 2009• Energy, power and thermodynamics• Home energy audit• Power plants, nuclear power• Solar energy • Wind energy, hydropower, geothermal • Biomass, hydrogen, fuel cells • Economics, Environmental and
Societal Impacts
CA/Denmark summer school (UCSC, UC Davis, UC Merced, Techn. Univ. Denmark, Roskilde) –Extensive field trips
EE181J Renewable Energies in Practice (July-August 2009)
UCSC Courses
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