ali shakouri

8/14/2019 Ali Shakouri

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A. Shakouri 12/16/2009

Ali ShakouriDirector, Thermionic Energy Conv. Center

Baskin School of EngineeringUniversity of California Santa Cruz

Nanoscale optothermo electricenergy conversiondevices

Acknowledgement: ONR,DARPA DSO, AFOSR, CEA,NSF,

NASA/UCSC (ARP, BIN-RDI)National Semiconductor,

Intel, Canon, SRC-IFC

UC Santa Barbara; 16 December 2009


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RejectedEnergy 61%

Lawrence Livermore National Lab., http://eed.llnl.gov/flow

Power ~3.3TW

1.3TW



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A. Shakouri 12/16/2009US Energy Flow 1950

3

LLNL

EnergySources

EnergyConsumption

RejectedEnergy 49

Total 31.8 QuadPopulation: 161M


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Direct Conversion of Heat into ElectricityDirect Conversion of Heat into Electricity

)()()( 2

2

tyconductivithermal tyconductivielectrical Seebeck

Z

k S

Z

=

=

V~ S T

ElectricalConductor

Hot Cold

Efficiency function of thermoelectric figure-of-merit (Z)

R load = R TE internal

T V

S =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

Thot (K)

0.5EnergyConversio

nEfficiency

3

1

2

Carnot

Solar/ Rankine

Geothermal/

Organic Rankine

ZTavg =20Coal/ Rankine

Cement/ Org.Rankine

Solar/ Stirling

ZT=S 2 /

Cronin Vining


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Impact of temperature on ICperformance15 oC temperature increase:

Interconnect delay (10-15%)Crosstalk noise increase (up to 25%)

Leakage power exponential increasewith temperature

60nm50-70% of total power Potential thermal runaway

Lifetime exponential decrease withtemperature (x ) e.g.electromigration, oxide breakdown

Clock gating and multithreshold CMOSincrease on-chip thermal variation

Thermal integrity: a must for low-power-ICdigital design, EDN 15 Sept. 2005

http://masc.cse.ucsc.eduFrancisco Mesa-Martinez, Jose Renau
http://masc.cse.ucsc.edu/http://masc.cse.ucsc.edu/


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Electric

Current

Heating Cooling= ST c I

Peltier Effect (1834)Peltier Effect (1834)

Reverse of Seebeck effect (electric currentproduces cooling/heating)


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Maximum coolingtemperature

Tmax = ZT c2

Fraction of

Carnot

Efficiency

0.1

0.4

0.3

0.2

ZT1 2 3 4

Commercial TEs

Typical CFC System

Thermoelectric (Peltier) Coolers

Conventional thermoelectricshave low efficiencies (COP of 0.5-1) and low cooling power density


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Recent Advances in Thermoelectrics

Recent advances innanostructuredthermoelectric materialsled to a sudden increase in (ZT) 300K > 1

A. Majumdar, Science 303, 777 (2004)


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Best Thermoelectric MaterialsBest Thermoelectric Materials

SS 2

Free carrier concentration

ThermalConductivity

Lattice contribution

Electronic contribution

Seebeck ElectricalConductivity

Insulator Semiconductor Metal

For almost all materials, if doping is increased, electrical conductivityincreases but Seebeck coefficient is reduced. Similarly

ZT=S 2 /


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A. Shakouri 12/16/2009Microrefrigerators on a chip

Heterostructure Integrated Thermionic Coolers;A. Shakouri and John Bower, Appl. Phys. Lett. 1997

Nanoscale heat transport and microrefrigerators on achip; A. Shakouri, Proceedings of IEEE , July 2006

Featured in Nature Science Update, Physics Today, AIP April 2001

1 m

Hot Electron Cold Electron Monolithic integration on silicon Tmax ~4C at room temp. (7C at100C) Cooling power density > 500W/cm 2


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100nsec ,time ,300nm spatial.0 1C temperature

resolution

Time ( s)

J. Christofferson,Y. Ezzahri et al.SemiTherm 2009and MRS Spring2009

1 10 100 1000

ransient Thermal Imaging ofMicrorefrigerators


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Metal film is heated by laser pulse and it acts both as a heatsource and a transducer (creates acoustic waves). It cancharacterize thermal interface resistances as well as interfacequality (acoustic mismatch).

Time (ps)

R(normalized)

Thin Film ThermalCharacterization

Thermal decay =>

KSi/SiGe(30%) =8.1W/mKKSi/SiGe(60%) =2.8W/mK

Acoustic echoes

Y. Ezzahri et al. Appl.Phys. Letters 2005


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p(t) p0

t0

p0 H(t)

If the thermal RC network is composed of N pairs of RC port, the unit-stepresponse, a(t) , can be expressed as:

( )( ) ( )

/

0 1

1 ii

N t

Thi

T t a t R e

== =

Temperature

Rise(K)

Time (sec)

Steady state

Szekely et al. 1988,Micred Corp.

hermal Step Function Excitation


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The unit-step response, a(t) , can be expressed as:

Logarithmic time scale

with

Time constant spectrum

1 2 3

R ( ) ( )/01

1 ii

N t

Thi

T t R e =

= R( ) ( ) ( )( )( )0 1 exp / expT t R t d

=

( )log =

( ) ( ) ( ) ( )( )( )0

1 exp expT z

a z R z d

= = ( )log z t =

Szekely et al. 1988

etwork Identificat ion byDeconvolution


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R thi C thi

Cauer network

R th1 R th2 R thi

C thiC th2C th1

R th1 R thn

C thn

R th2

C th1 C th2

Foster network

-oster Cauer Network Transformation


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30nm Al on top of 80nm superlattice (10W/mK) on Silicon substrate

Layer Inputproperty

NID

R th (K/W) 25.5 22.3Cth (J/K) 4.2x10 -11 5x10 -11

Rk=1e-8

3e-9Rk=0 Km 2/W

5e-9

7e-9

Y. Ezzahri and A. Shakouri, Rev. Sci. Instrument, 80 , 074903 (2009).

pplication of NID to Transient.hermoreflect


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A. A. Joshi and A. Majumdar; J. Appl. Phys. 74, p. 31 (1993)See also: G. Chen; Phys. Rev. Lett. 86, 2297 (2001)

i ffusive or Bal l is t ic Propagation ofHeat

Temperature (normalized)Tempera

Distance (norm.)

= /C

L=0.1 m

Diamond

Fourier

Hyperbolic Heat(Cattaneo)

Boltzmann (EquationPhonon Radiative Transfer)

Fourier

Hyperbolic

Boltzmann

Fourier

Hyperbolic

Boltzmann

=0.

1

=1


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N 2: The Greens function of the total energy density propagation K(t,x) in a solid material when there is delta-function excitation P(t)

q total relaxation time of energy carriers (funct. of wavevector q)DQ heat diffusion constantDC charge diffusion constant

coupling factor betweencharge and energy density

Z*

high frequency limit of figure of merit

*

*1 Z T

Z T =

+

( ) ( )( )

( )

( ) ( )

2 2

22

2 2 4

,,

1Q q C

q Q q C Q C

K q i q N q M P

D qM i i D q

i iD q i iD q D D q

= =

= + = + + +

B. S. Shastry, Rep, Prog, Phys72 , 016501, (2009)

:hastry s formalism energy densitypropagation

P(t)

K(t,x)


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Oscillations in the total energy density at the top free surface of the metal:due to Bragg reflection of ballistically accelerated electrons at the boundaries

of the Brillouin Zone. Energetic analog of conventional Bloch Oscillations of electrons.

2 3 (1 ) F

a fs

v = Damped oscillation of period

independent of F

and temperature

Diffusivecontribution toenergy transport(heat propagation)

Ballisticcontribution toenergy transport

a : lattice constant.v F : Fermi velocity.

Y. Ezzahri and A. Shakouri PRB, 79, 184303, (2009)

nergetic Bloch Oscillations( )hastry Osci llations


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Phonon minibands in SiGe superlattices

Y. Ezzahri et al. Physical Review B, 2007

Superlattice

Pho

Measuredphonon

spectrum

Calculation

527GHz


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A. Shakouri 12/16/2009Superlattice SiGe/Si vs. Bulk SiGe

Younes Ezzahri et al.InterPACK07, THERMES 07

Material

Thermal

Conductivity(W/mK)3 measurement

Power

factor S2

(10 -3 W/K 2m)

Figure-of-

Merit,ZTSi0.8 Ge 0.2 alloy (Microrefrigerator Tmax =4.0K)

5.9 1.6 0.08Superlattice Si/Si 0.75 Ge0.25 (3nm/12nm) (Microrefrigerator Tmax =4.2K)

6.8-8.7 2.2 0.085


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Thermal Conductivity of SiGesuperlattice vs. SiGe alloy


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A. Shakouri 12/16/2009Thin Film Microrefrigerator Optimization

Current SiGematerial

Decrease thermalconductivity

IncreaseSeebeck coef.

IncreaseSeebeck coef.

Decrease thermalconductivity

Younes Ezzahri et al. InterPACK07

10 microns thick, 50x50 m 2 monolithic microrefrigerator

with ZT~0.5 can cool a 1000W/cm2

hot spot by >15C.


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A. Shakouri 12/16/2009Silicide nanoparticles in SiGe

300K0.8% nanoparticles

Silicon

Si 0.5 Ge 0.5Ge

NiSi2

ZT (300K) ~0.5

ZT (900K) ~1.8

Natalio Mingo et al. Nano Letters 2009

Predictions:


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Monte Carlo simulation of TE energy exchange

InGaAs InGaAsP InGaAs

Heat Sink Anode

Bias

Hot SourceCathode

Cathodecontactlayer

Anodecontactlayer

Barrier (main-layer)

Mona Zebarjadi, Keivan Esfarjani,Ali Shakouri (Phys. Rev. B 2006)

LargeSeebeck

Q =- S.T c .I

electrons

SmallSeebeck

SmallSeebeck

Q = S.T h.I

A f l t /T (i


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Average energy of electrons /T (i.e.local Seebeck coefficient) vs. distance

Increasingvoltage

200

160

120

8040 mV

Mona Zebarjadi, Keivan Esfarjani, A. Shakouri Applied Physics Letter 2007

Large Seebeck Small Seebeck(contact)Small Seebeck

(contact)

Local Seebeckcoefficient( V/K)

2E23

B J)3

52

(ne

m2e

T5k e +++=

O ti i TE Effi iOptimi e TE Efficienc


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0

1

2

3

4

5

6

7

8

-1

0

1

2

3

4

5

0 2 4 6 8 10 12 14

Z T

( E b ar r i er -E f

) / k BT

Fermi Energy (eV)

Conserved

Non-conserved

Optimize TE Efficiency:Optimize TE Efficiency:(Metal/Semiconductor Nanocomposites)(Metal/Semiconductor Nanocomposites)

Assume: lattice =1W/mK, mobility ~10cm 2/Vs

Even with only modestly low lattice thermal conductivity and electron

mobility of typical metals, ZT > 5 is possible with hot electron filters

Fermi energy eV ( free electronconcentration)

Planar Barrier

Metal/Semiconductor

Nanostructure

. . ,D Vashaee and A Shakouri . . .Phys Rev Lett 92 , / ( ).106103 1 2004

Hot and coldelectrons inequilibrium

Hotelectronfilter

h i i C i C


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Ali Shakouri , Director Thermionic Energy Conversion Center

ONR (2003-), DARPA(2008-)

4nm(Zr, W)N

2nm ScN

UCSC (Bian, Kobayashi), Berkeley (Majumdar), BSST Inc. (Bell), Delaware (Zide), Harvard (Narayanamurti), MIT (Ram), Purdue (Sands), UCSB

(Bowers, Gossard)

Engineering current andheat flow usingnanostructures Goal: direct conversionof heat into electricitywith > 20-30% efficiency(ZT>2.5)

ErAs Semi metal Nanoparticles


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ErAs Semi-metal Nanoparticlesimbedded in InGaAs Semiconductor Matrix

Erbium is co-deposited at a growth rate which is a fixed fractionof the InGaAs growth rate (MBE growth, 60 microns thick films)Solubility limit is exceeded islands are formed

RandomErAsparticles~ 2-3 nm

HAADF/STEM of ErAs Embedded


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HAADF/STEM of ErAs EmbeddedNanoparticles in In 0.53 Ga 0.47 As

,n GasEr

1nm

Growth direction

D. O. Klenov, D. C. Driscoll, A. C. Gossard, S. Stemmer, Appl.Phys. Lett. 86 , 111912 (2005)

STEM: ErAs particles have rocksalt structure

The As sublattice is continuousacross the interface

Beating the Alloy Limit in ThermalBeating the Alloy Limit in Thermal


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Temperature [K]

0 200 400 600 800

T h e r m a l

C o n

d u c t

i v i t y

[ W / m - K

]

0

3

6

InGaAs

0.3% ErAs:InGaAs

3% ErAs:InGaAs

6% ErAs:InGaAs

Beating the Alloy Limit in ThermalBeating the Alloy Limit in ThermalConductivity: Theory/ ExperimentConductivity: Theory/ Experiment

W. Kim, et al. PhysicalReview Letters 2006

Phonon scattering by ErAs nanoparticles 3-fold reduction in thermal conductivity beyond the alloy limit

a k

F r e q u e n c y

Wavevector

)(k

Atoms/AlloysNanostructures

a k

F r e q u e n c y

Wavevector

)(k

a k

F r e q u e n c y

Wavevector

)(k

Atoms/ AlloysAtoms/AlloysNanostructuresNanostructures

M bili ( h )


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Je-Hyeong Bahk, Mona Zebarjadi et al. submitted (2009)

Mobility (Theory vs. Experiment)

S b k ( h i )


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Solid lines aretheoretical prediction (no f i t t ing)

Seebeck (Theory vs. Experiment)

Scattering

mechanisms: Polar optical phononsAcoustic phononsIntervalley phononsImpurity

Alloy scatteringNano particle scattering:

(Born, Partial Wavetechnique)

100

120

140

160

180200

220

240

260

300 400 500 600 700 800 900

n-InGaAlAs (control)ErAs:InGaAlAs

(b)

S e e b e c

k C o e

f f i c i e n t

( V / K )

T (K)

. % :0 6 ErAs InGaAlAs

Control( ,2E18 Si no

)Er

Je-Hyeong Bahk, Mona Zebarjadi et al. submitted (2009)

Th l t i fi f it (ZT)


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Thermoelectric figure-of-merit (ZT)

J. Zide et al. submitted (2009)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

300 400 500 600 700 800

n-InGaAlAs (control)ErAs:InGaAlAs

Z T

T (K)

. % :0 6 ErAs InGaAlAs

Refractory (Zr W)N/ScN Metal/SemiconductorRefractory (Zr W)N/ScN Metal/SemiconductorRefractory (Zr W)N/ScN Metal/SemiconductorRefractory (Zr W)N/ScN Metal/Semiconductor


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4 nm (Zr,W)N

2 nm ScN

ZrN layers alloyed with W 2N Reduction in thermal conductivity Closer lattice match with ScN layer

/ ( , ) / HAADF STEM image of Zr W N ScN : superlattice Courtesy Joel Cagnon and

,Susanne Stemmer UCSB

Refractory (Zr,W)N/ScN Metal/Semiconductor Refractory (Zr,W)N/ScN Metal/Semiconductor Superlattices for Higher Temperature OperationSuperlattices for Higher Temperature OperationRefractory (Zr,W)N/ScN Metal/Semiconductor Refractory (Zr,W)N/ScN Metal/Semiconductor Superlattices for Higher Temperature OperationSuperlattices for Higher Temperature Operation

V. Rawat, T. Sands, J. Cagnon, S. Stemmer et al. 2008

Thermal conductivity reduction in metal/Thermal conductivity reduction in metal/


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Thermal conductivity reduction in metal/Thermal conductivity reduction in metal/semiconductor nitride superlatticessemiconductor nitride superlattices

2-fold decrease in thermal conductivity of ZrN/ScN superlattices

to


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Cross-plane electrical conductivity

0

0.5

1

1.5

2

2.5

3

250 300 350 400 450 500

ExperimentSimulation

T (K)

dEc=0.97 eV

ElectricalConductivity(

-1-cm-1)

ScN(6 nm)/ZrN(4 nm)superlattice

Fit to I-V-T yields barrier height of 280 meV

Transport is thermionic

S(300K) meas = 0.82 mV/K

Purdue and UCSC

M.Zebarjadi, V. Rawat et al. Journal of Electronic Materials 2009

Z N/S N ZT di i


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A. Shakouri 12/16/2009ZrN/ScN system: ZT prediction

Model assumes 5 x 10 21 carriers/cm 3 in

ZrN m* (ZrN) = 1.5 m 0 m* (ScN) = 0.2 m 0 100 periods of metal(4

nm) / semiconductor(6nm)

= 1.8 W/m-K Mobility from in-plane

measurement of ScN k not conserved

Electronic BTE using energy balance formulation

.

.

.

. . . .9 .9 .

K K

9 K9 K

K K K K

Z T

dEc (eV)

ZT

Fit with experiment gives Ec of 0.97 eV and B = 0.28 eV

Ec [eV]

M.Zebarjadi, V. Rawat et al. Int. Thermoelectric Conf. 2008

W f l d l f b i i


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AlN_low pIate

200 elements of p-ErAs array

Wafer scale module fabrication

AlN_upper plate

200 elements of n-ErAs array

AlN_low plate

AlN_upper plate20 m elements

400 element generator Gehong Zeng, John Bowers (UCSB)


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A. Shakouri 12/16/2009Module Power generation results

140 m/140 m AlN

400 elements (10-20 microns ErAs:InGaAlAs thin films,120x120 m 2), array size 6x6 mm 2

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

O u t p u t

P o w e r

( W / c m

2 )

T (K)

Working with BSST on high power density moduledemonstration

Mi i R f iMi i t R f i t


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A. Shakouri 12/16/2009Miniature Refrigerator Miniature Refrigerator

EntropyDecrease

EntropyIncrease

Cathode Barrier Anode

Energy

ConductionBand

A. Shakouri, International Thermoelectric Conference Proceedings, 1998

S d L f Th d i ?S d L f Th d i ?


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Cathode Barrier Anode

Energy

ConductionBand

Second Law of Thermodynamics?Second Law of Thermodynamics?

EntropyDecrease

A. Shakouri, International Thermoelectric Conference Proceedings, 1998

I j ti C t I t ll C l d Light E ittInjection Current Internally Cooled Light Emitter


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Injection Current Internally Cooled Light Emitter Injection Current Internally Cooled Light Emitter

n p

Kevin Pipe, Rajeev Ram and Ali Shakouri, Photonic Techn. Lett., Apr. 2002

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0- 4 0 0

- 2 0 0

0

2 0 0

4 0 0

6 0 0

Joule

Contact

Conv. q Active

ICICLE q Active

Current Density (A/cm 2)

q(W/cm

2)

0 1 2 3 4-2.2

-2

-1.8

-1.6

-1.4

-1.2

-1

-0.8

GaSb/GaInAsSb.

Electrically pumpedoptical refrigeration

Optimal Internal Cooling in Diodes


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0 0.5 1 1.5 2

-40

-20

0

20

40

Temperature(K)

6 10 5

J = 8 10 5 A/cm 2

5 10 54 10 5

2 10 5

Position (micron)

Optimal Internal Cooling in Diodes

Kevin Pipe, Rajeev Ram and Ali Shakouri, PRB 2002

HgCdTe diode

holes

electrons

NPIheat cool cool

heatcool cool

S t i bl E Ch ll


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John Bowers, UCSB

World Average

Sustainable Energy Challenge

A FRAMEWORK FOR PRO-ENVIRONMENTAL


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A FRAMEWORK FOR PRO ENVIRONMENTALBEHAVIOURSDefra January 2008

The headline behaviour goals

-Install insulation; microgeneration-Increase recycling-Waste less (food)-More responsible water usage-Use car less for short trips; more efficient vehicles-Avoid unnecessary flights (short haul)-Buy energy efficient products-Eat more food that is locally in season-Adopt lower impact diet

Elizabeth Shove, Sociology Department, Lancaster University, UKhttp://www.soe.ucsc.edu/classes/ee080j/Spring09/


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A h a !

Practicalconsciousness

Awareness and choice

Informs a lot of discussion about how to engender sustainabilityConsiders habits in isolationOften implausible in terms of daily routines e.g. comfort, cleanliness

Elizabeth Shove, Spring 2009http://www.soe.ucsc.edu/classes/ee080j/Spring09/


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choice, change, belief , attitude,

information, behaviour

But what if we see consumption as

consequence of ordinary practice?What is required in order to be a normalmember of society?

How does this change, and with whatconsequence for sustainability?


Comfort and indoor environments


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it is becoming normal to expect 22degrees C inside, all year round, allover the world and whatever theweather outside

Cleanliness and showeringit is becoming normal to shower once or

twice a day (in the UK, the amount of water used for showering is expected toincrease five fold between 1991-2021)

LaunderingFrom once a week to once a day or more, but with lower temperatures thanever before

Similar trends naturalisation of need

but possibly differentdynamics

and differentimplications for thefuture

Comfort, cleanliness and convenience By Elizabeth Shove, 2003

Comfort and indoor environments

Thermal comfort research


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Thermal comfort research

Defining

comfort


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Reflexive/conspicuous consumption

Routine/ordinary consumption

Where mosteffort hasfocused

Where the realchallenges lie

Individual belief, attitude, behaviour,information, persuasion

Practice, convention, routine, dynamicsof sociotechnical systems, structuring of options, standardisation, globalisation


International Summer School in


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A. Shakouri 12/16/2009Renewable Energies

CA/Denmark Program

UC Santa Cruz; UC Davis; UC MercedTech. University of Denmark; Aarhus;Copenhagen; Roskilde (2008)

CurriculumGuest Lectures by Experts (technology,policy, business, social issues)

Extensive Field trips; student projects

Renewable Energy Microgrid /Sustainable


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gy gCommunity Development at NASA Ames

Ken Kay Associates,

William Berry, UniversityAssociates LLC, et al.

US-China Green Tech Conf.,Beijing, China, Nov. 2009

(UCSC, NASA, Foothill/De Anza College, etc.)

Summary


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Metal / semiconductor nanocomposites can improve

thermoelectric energy conversion Mid/long wavelength phonon scattering Hot electron energy filtering

Micro Refrigerators on a Chip Localized cooling (10 150 m, 4-7C), based on SiGe, InP, > 500

W/cm 2

Fast transient thermal imaging using thermoreflectance Resolution: ~250nm, 0.01C, 100ns

Network identification by deconvolution for transientthermal analysis; Ballistic/diffusive energy transport

Renewable energy and sustainable developmenteducation and Research

Summary

Acknowledgement


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A. Shakouri 12/16/2009Acknowledgement

Mona Zebarjadi (UCSC) - Material Research Society Gold Graduate StudentAward , Boston, MA 2007

Yan Zhang, James Christofferson, et al. (UCSC/UCSB) IEEE Transactions onComponents and Packaging Best Paper Award 2006

Je-Hyoung Park, Xi Wang, Yan Zhang (UCSC) - Student Award, AdvancedThermal Workshop International Microelect. Packaging Society , 2005-2009

Daryoosh Vashaee (UCSC), Joshua Zide (UCSB) , Xiaofeng Fan (UCSB) -Goldsmid Award (Best Graduate Student Research) , International

Alumni: Daryoosh Vashaee (Prof. Oklahoma State) , Yan Zhang(Tessera) , Rajeev Singh (Sun Power), Zhixi Bian (Adj. Prof. UCSC), James Christofferson (Res. Scientist UCSC), Kazuhiko Fukutani(Canon) , Javad Shabani (PhD student, Princeton), Younes Ezzahri (Prof.Univ. Poitier) , Mona Zebarjadi (MIT), Je-Hyoung Park (Samsung) ,Tammy Humphrey, Virginia Heriz, Travis Kemper

Postdocs/Graduate Students: Helene Michel, Xi Wang, Kerry Maize, Hiro

Onishi, Tela Favaloro, Paul Abumov, Phil Jackson, Oxana Pantchenko,Amirkoushyar Ziabari

ali shakouri

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