thermoelectrics (te) at the nanometer sun-to-fiber (s2f ...€¦ · thermoelectrics (te) at the...

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Thermoelectrics (TE) at the Nanometer Sun-to-Fiber (S2F) at the Micrometer Nobuhiko “Nobby” Kobayashi Nanostructured Energy Conversion Technology and Research (NECTAR) Baskin School of Engineering, Univ. of California Santa Cruz (Santa Cruz, California) Advanced Studies Laboratories Univ. of California Santa Cruz and NASA Ames Research Center (Moffett Field, California) NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013 1

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Page 1: Thermoelectrics (TE) at the Nanometer Sun-to-Fiber (S2F ...€¦ · Thermoelectrics (TE) at the Nanometer Sun-to-Fiber (S2F) at the Micrometer ... Cooling consumes ~40%. Heat generation

Thermoelectrics (TE) at the Nanometer

Sun-to-Fiber (S2F) at the Micrometer

Nobuhiko “Nobby” Kobayashi

Nanostructured Energy Conversion Technology and Research (NECTAR) Baskin School of Engineering, Univ. of California Santa Cruz

(Santa Cruz, California)

Advanced Studies Laboratories Univ. of California Santa Cruz and NASA Ames Research Center

(Moffett Field, California)

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013 1

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2

Santa Cruz off-Campus (2300 Delaware Ave. Santa Cruz)

Introduction to Univ. of California Santa Cruz

Silicon Valley Campus (Advanced Studies Laboratories at NASA ARC)

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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TE @

the Nanometer

1x10-6m

3

200 nm

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Background and Motivation

4

Solid state heat engine

Hot Cold Heat

engine

Work

Mechanical heat engines with

efficiencies ~40% produce 90%

of the required energy.

Waste heat generated

annually is ~18TW .

Converting even 1% of the

waste heat into electricity

($0.11/kWh) could create a

$20B annuity.

http://www.instantg

oldrefining.com/

http://www.thedaily

green.com/

interestingenergyfacts.blogspot.com/

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Background and Motivation

5

Solid state cooler

Hot Cold Cooler

Work

www.zalman.com S. Borkar (Intel)

http://www.ecse.rpi.edu/frisc/the

ses/GargThesis/chapter6.html

Annual energy cost of the

U.S. data centers was $4.5B.

(61BkWh) in 2006 (EPA 2007).

Cooling consumes ~40%.

Heat generation is spatially

and temporally non-uniform.

Hot spot can be >650W/cm2.

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Background and Motivation

6

Competitors

http://en.wikipedia.org/wiki/Stirling_engine www.sunshinekelly.com

Refrigerator COP ~5.9

TE cooler COP ~0.7

Stirling engine h ~40%

TE module h ~10%

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Traditional Thermoelectrics

7

Limitations of bulk materials

ZT = S2sT

kl + ke

S: Seebeck coefficient

s: Electrical conductivity

kl : Lattice thermal conductivity

ke: Electronic thermal conductivity

T: Temperature

hmax = hc (1+ZT)0.5-1

(1+ZT)0.5+1

Maximize s: metal

Minimize kl + ke wood

S ~ ds(E)/dE, s(E) = n(E)m(E)q

S ~ dn(E)/dE dm (E)/dE

S ~ dg(E)/dE dt (E)/dE

g: Density of states

t: Scattering time

E: Energy http://britneyspears.ac/physics/dos/dos.htm

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Traditional Thermoelectrics

8

Limitations of bulk materials

http://www.its.caltech.edu/~jsnyder/thermoelectrics/

S ~ dg(E)/dE dt (E)/dE

http://britneyspears.ac/physics/dos/dos.htm

Low-dimensional semiconductor

Energy filter

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Our “Nano” approach 1: Metal-semiconductor nanocomposites

200 nm

Advanced Approaches

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Our “Nano” approach 2: Nanowire network

Flexible TE device employing

silicon nanowires Physica Status Solidi (a) 209, 171 (2012)

Nanowire network (silicon)

Advanced Approaches Hot Power Inc.

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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S2F @

the Micrometer

1x10-6m

11

5nm

5nm

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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A large amount of energy from the sun

Background and Motivation

In a single hour the sun delivers the same amount of energy as consumed by all

of humanity in a year – about 5 × 1020J.

http://www.keepbanderabeautiful.org

Sun light Light No transportation Light Light Light Heat

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

Sun light Electricity Transport Electricity Light Electricity Heat

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13

Concentrated sun light into an optical fiber

Strategy

Sun light Concentration Transportation Light Daylighting

Use as heat or

storage for later uses

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

http://en.wikipedia.org/wiki/Thermal_energy_storage

http://www.syneco.co.uk

http://kjcoop.com

greenpowerscience.com

http://www.familievink.nl

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Concentrated sun light into an optical fiber

Strategy

Himawari System

La Foret Eng (Tokyo, Japan)

Oak Ridge System

Sunlight Direct (Oak Ridge, TN)

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Concentrated sun light into an optical fiber

Goal

Optical tr

ansm

issio

n

line

Optical colle

cto

r/con

centr

ato

r

Solar light

Solar light

NA mismatch

Mode size mismatch

Refractive index mismatch

15

f 5m f 60mm

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Concentrated sun light into an optical fiber

Goal

Need thin films with 1.4 < n < 2.8 for 400-1000nm and k as small as possible

16 NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

Optical fiber

n = 1

n = 1.5

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Enabling thin film technology

Concentrated Sun Light into an Optical Fiber

17

Niobium oxide (TEM, scale bar 5nm) Zirconium oxide (Right TEM x200k)

Aluminosilicate (SEM, scale bar 3mm)

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

1mm

with without without with

without with

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Devices

Concentrated Sun Light into an Optical Fiber

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

Courtesy: David Berkstresser and Allan Lewandowski

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Ultimate application

Concentrated Sun Light into an Optical Fiber

http://inhabitat.com

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013

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Really ultimate applications

Concentrated Sun Light into an Optical Fiber

http://mcensustainableenergy.pbworks.com www.getsolar.com

www.rainbowskill.com

Eliminate working fluid Eliminate heat engine

Eliminate tower

1m2 concentrator for

solar daylighting

25m2 concentrator for

solar thermal power

generation

Demaray and Kobayashi at the NREL solar furnace

NCCAVS Joint User Group Topical Conference, San Jose, California, February 21, 2013