Oxide thermoelectric power generationOxide thermoelectric power generation

Ryoji Funahashi Ryoji Funahashi

National Institute of Adv. Ind. Sci. & Tech. National Institute of Adv. Ind. Sci. & Tech.

2009 Thermoelectrics Applications WorkshopOct. 1, 2009 @Hotel Del Coronado, San Diego, CA

Thermalpower plant

Automobile Factory

Incinerator

Used energy Energy loss

Thermoelectricmodule

Waste heat Waste heat

Thermalpower plant

Automobile FactoryIncinerator

Used energyUsed energyEnergy lossEnergy lossWaste heat

電気エネルギー電気エネルギーElectrical energy Electrical energy Contribution to energyContribution to energy

& environmental problems & environmental problems

Dilute distributionDilute distribution

ThermoelectricThermoelectricconversionconversion

Total primary energyTotal primary energy(Several 100 mil. kl/year in Japan)(Several 100 mil. kl/year in Japan)

Waste heatWaste heat

Heat energy

Electrical energy

At high temperature in airSafety, Relief & Cheapness

OxideOxide

Bi2

Te3

Pb-Te alloyCoSb3

Zn3

Sb4

Si-Ge alloy

Conventional TE materialsConventional TE materials

Toxic elementRare elementMeltingOxidation

Limitation onpublic application

Problems in TE generationProblems in TE generation

PresentConducting materials

heating element ・transparent

filmInsulating materials

transistor・insulator

Ionic conductorsMagnetic materialsSensing materials CatalysisSuperconductors

Classical, AdvancedClassical, Advanced& Human friendly& Human friendly

Ancient timesEarthenwareClay imagePigments

Middle agesCeramic wareBrickGlass

Oxide materialOxide material

Oxide TE materialOxide TE material

http://ohtaki.cube.kyushu-u.ac.jp/Ohtaki_Lab/index.html

NaCoO4

ZnO

100

10-1

10-2

10-3

ZT30

0K

1018 1019 1020 1021

ne

(cm-3)

SL oxide TE filmSL oxide TE film

S. Yeo et al,APL 89, 233120(2006)

ZnO, Mn2

O3

, Ga2

O3 Heating Phase separation in grainsZnGa0.3

Mn1.7

O4

（Cubic）ZnGa1.5

Mn0.5

O4

（Tetragonal）Phase Separation in Nano-scale

Slow cooling

Phase separationPhase separation

Conductive nano-structured oxide

400 600 8002

3

4

5

6

Temperature (K)

Ther

mal

con

duct

ivity

(Wm

-1K

-1) Zn(Mn, Ga)2

O4

ZnGa0.3

Mn1.7

O4+ ZnGa1.5

Mn0.5

O4

Nano-structured

Micro-mixture

A. Kosuga, et al., Jpn. J. Appl. Phys., Vol. 48, 010201-010203 (2009).

3 K/h

50 K/h

1150℃3h

600℃

3, 50 K/h

4h

Co3

O4 + MnO2

Co-rich : Cubic

Mn-rich : TetragonalWith many twin boundaries

200 400 600 800 1000 1200

2.0

3.0

4.0

50 K/h3 K/h

(W

m-1

K-1

)

T

(K)

CoCo1.51.5

MnMn1.51.5

OO44

ZTZT

= 0.01= 0.01

20m

20m

LaNiO3

(Ni-113)CaMnO3

(Mn-113)

La, CaNi, Mn

n-type

Co Ca O

Ca3

Co4

O9

(Co-349)

p-type

400 600 800 1000 1200 Temperature (K)

ZT

Co-349 single

CeFe3.5

Co0.5

Sb12

SiGe

Zn4

Sb3

Bi0.5

Sb1.5

Te3

PbTe

1.5

1.2

0.9

0.6

0.3

0 Ni-113 polyMn-113 poly

Co-349 poly

ModulesModules

TE properties oxidesTE properties oxides

@ High temperatureMetal・・・great thermal expansionOxide・・・small thermal expansion

Mechanical strengthContact resistance

Good junctionsGood junctions

p-type oxide n-type oxide

electrode metal

ExfoliationExfoliation

Metal vs. Oxide・・・Different electronic properties

High contact resistanceHigh contact resistance

Ag paste (commercially available)Ag paste (commercially available)++

pp--type oxide powdertype oxide powder

JunctionJunction

0

5

10

15

20

25

0 1 2 3 4 5 6Current (A)

Ope

n ci

rcui

t vol

tage

(V)

0

5

10

15

20

25

30

Out

put p

ower

(W)

TH

= 690 ℃TC

= 175 ℃

1300℃10

cm

135 pairs

TE oxide moduleTE oxide module

DurabilityDurability45

min

1273K15min

45m

in

45m

in

45m

in

1273K15min

Time

Tem

pera

ture

Measure@ r. t.

Measure@ r. t.

15min 15min

Heater

Water jacket

-10

-5.0

0.0

5.0

10

15

20

0 2 4 6 8 10Cycle # n

(Rn-

R 0)/R

0×10

0 (%

)oxide total

junction

pp--legleg

-10

-5.0

0.0

5.0

10

15

20

0 2 4 6 8 10Cycle # n

(Rn-

R 0)/R

0×10

0 (%

)

oxide

total

junction

nn--legleg

Space : 1.2 mmDevice area/Total area : 49 %2008. 7

0.0

1.0

2.0

3.0

4.0

2008July

2008September

2008November

Pow

er d

ensi

ty (k

W/m

2 )

Heater :1273 KWater : 298 K

space

Space between devices：Dead space

0.8 mm62 %

0.5 mm83 %

Power densityPower density

TE conversionTE conversion

1273 1173 873 673 473Temperature (K)

Steam turbine

Turbine・・・Expensiv200kW200kWSelfSelf--conclusionconclusion

IncineratorIncinerator

ApplicationApplication

SteamWater heater

Module

Water

Steam

Lead

Topping heat recoveryTopping heat recovery

New concept of TE power generation New concept of TE power generation

OxidesOxidesHigh Temperature Use

Topping Recovery of Waste Heat Topping Recovery of Waste Heat

Establish New Concept for Conversion Systems Establish New Concept for Conversion Systems

ThermoelectricThermoelectricsystem system

EnergeticEnergeticoriginorigin

Conversion systemConversion systemEngine

Heat exchangerFuel cell

etc.

ToppingTopping

ThermoelectricThermoelectricsystem system

EnergeticEnergeticoriginorigin

Conversion systemConversion systemEngine

Heat exchangerFuel cell

etc.

BottomingBottoming

Oxide TE Oxide TE ConclusionConclusion

Strong pointsStrong points

-High durability against high temperature and oxidation

-No secure elements

-No toxic elements

-Mass production

-Light weight

-Small thermal expansion

Reliable, Safe, and Cheap systemReliable, Safe, and Cheap system

Weak points Weak points

-Low ZT

-High ZTmax

temperature

-Brittle

New materialNew material

http://staff.aist.go.jp/funahashihttp://staff.aist.go.jp/funahashi--rr/english/Index.htm/english/Index.htm

Thank you very muchThank you very much