solar laser energy cycle - magnesium as energy 2012

8/13/2019 Solar Laser Energy Cycle - Magnesium as Energy 2012

1/41

3he University of okyo

So l a r En e r g y C yc l e U s i n g M a g n e s i um

a n d L a s e r T e c h n o l o g ie s

2012.11.19 & 12.10

Given by

Shigeaki Uchida / Global Solar Initiative (GS+I), The University of Tokyo

also at Pegasos Electra Co. Ltd.

I n v i t e d L e c t u r e s o n

M ag n e s i um e n e r g y c y c l e d r i v e n b y s o la r

e n e r g y

E l em e n t a l t e c h n o lo g i e s c o n s t i t u t i n g t h e

c y c l e

So l a r p um p e d l a s e r

MgO r e d u c t i o n

Mg c om b u s t i o n /b a t t e r y


2/41


De f i n i t i o n o f t h e p r o b l em

So la r p o w e r (r a d ia t i o n ) i s t h e u l t i m a t e

r en e w a b le e n e r g y s o u rc e

H ow e v e r

Lo c a l ize d in t i m e a n d lo c a t i o n

M i sm a t c h i n g b e t w e e n su p p l y a nd

d em a n d N e e d m e a n s o f c o n v e n ie n t s t o r a g e

Mg i s a p r om i s i n g c a n d id a t e f o r t h e s t o r i n g

m a t e r i a l Mg


3/41


World annual energy demand: 1.21014 kWh 2000s = 32,000 km2 of Solar energy200200 km desert equivalent

Assume annual hours of sunshine3,000 hour/yearIssues to be Considered

Typical sunshine hours in Japan: Four hours Need energy storing means for the rest of 20 hours Need transportation from the Sun Belt Region Construction cost & Energy Payback Time of those infrastructure

A b u n d a n t s o la r po w e r o n t h e e a r t h

Solar Radiation

1kW m2 1 km2A thermal power stationSa h a r a d e s e r t 8 .61 06k m2Sa h a r a d e s e r t 8 .61 06k m2

Gob i d e s e r t 1 .31 06k m2Gob i d e s e r t 1 .31 06k m2


4/41


Mo r e t h a n 1 0 h o u r s o f s u n s h in e i s

e x p e c t e d i n d e se r t a r ea


5/41


En e rg y p r o d u c t i o n a n d p ow e r c o n t r o l

f r o m M g c om b u s t i o n

H2 combustion Power, Turbine

MgOHOHMg 22 ++

OHO

2

1H

222 +

+361 kJ/650+244 kJ/600

Co n t r o l l i n g R e a c t i o n S p e e d a n d Pow e r Slow Reaction no H2 combustion) Rapid Reaction with H2 combustion)

H2 (fuel cell) and reaction heat generation

kJ/mol

Easily generates steam at a few hundreds degree

A s i m i la r e n e rg y o u t p u t i s e x p e c t e d f r om Mg -A i r b a t t e r y


6/41


Ma g n e s i um a s e n e r g y s t o r a g e

A bu nd an c e o f M a g n es iu m

1 .2 x 10 1 5 t o n M g i n s e a w a t e r

Fo s s i l f ue l c o n s u m p t i o n : 7 x 1 0 9 t o n /y e a r < = T h i s i s t h ea m o u n t w e n e ed f o r t h e c y c l e

Sp e c i f ic e n e rg y (J /k g * ) c o m p a ra b le t o c o a l

2 5 M J /k g (J e t f u e l : 4 3 M J /k g , C o a l: 3 0 M J /k g )

En e r g y d en s i t y (c o m p a c t )

4 3 GJ /m 3 4 .3 GJ /m3 (H2a t 7 00 a t m )

H y d r og en s t o r ag e (e qu iv a l e n t )

8 .3 w t % 5 -1 0 w t% (H 2

t a n k f o r 35 0 a t m )

V e rs a t i l i t y in p ow e r g en e r a t i on

1 kW (2 .5 g /m i n , 2 0 X 4 0 X 0 .3m m ) ~ >MW /k g M g r a n g e (f l a k e d M g )

Re t r ie v a l c o m b u s t i o n re s id u e , s o l i d M gO (c o m p a re d t o CO 2)

Co n v e n i e n c e

B u lk M g is n on f l a m m a b le (N e e d >6 5 0

f o r i g n i t i o n ) Se l f ru n n in g re a c t i o n (Ex o t h e r m i c r e ac t i o n c o n t r o l l ed b yw a t e r f l o w )

C an b e u s e d a s a ba t t e r y f u e l , M g -A i r b a t t e r y

T ec h n o lo gy t o b e d ev e l o pe d

En e rg y e f f ic i e n t r e d uc t i o n o f M gO

So la r d r i v en l as e r t e c h n o lo g y fo r t h e re d u c t i o n

* Oxidizer is not included


7/41


Re n ew a b le En e rg y Cy c l e w i t h

M g a n d So la r Pum p e d L a se r

MgO

Mg

Retrieve

Reuse

Fresh Water

Mg

Desalination

Plant

Mg Reduction

by Solar Laser

Mg Reduction

by Solar Laser

Mg Engine

H2 Fuel Cell

Mg Fuel Cell

Mg Engine

H2 Fuel Cell

Mg Fuel Cell

Mg resource in ocean 1800 Tril lion-tons

(=300,000 years of oil )

Laser Cutting, WeldingRefinement

(Fe, Al, Mg, Ti )

Chemical Assistant

Laser-related

Manufacture

Laser Cutting, WeldingRefinement

(Fe, Al, Mg, Ti )

Chemical Assistant

Laser-related

Manufacture

Conversion efficiency

30-40%

Reduction efficiency

40-50%


8/41


-80

-60

-40-20

0

20

40

0 1000 2000 3000 4000 5000MgO Temperature [K]

Mg, MgOMgOReductionAnalysis.xls

2Mg O 2 2MgO

2MgO 2Mg O 2

Temperature for spontaneous MgO reduction

Tokyo Inst. of Technology

ChangeofGibbsFreeEnergy

[kJ/mol]

Change of Gibbs

Free Energy of a

Reaction

G = H TSIf the change is

negative, the

reaction is

spontaneous

H: Enthalpy

T: Temperature

S: Entropy

Gibbs Free Energy for MgO Formation

Mg oxidizationtakes place

MgO reduction

takes place

=RT

GK exp

Eq u i l i b r i um c o n s t a n t


9/41


0

Exothermic

Endothermic

273K1/2273K

-601.8

E [kJ/mol]

MgO(s)

Mg(g)(4000K)+O(g)(4000K)478

152 Mg(g)(923K)

Mg(g)(4000K)191

1/2O2(g)(4000K)39

602602 + 478

Maximum Possible

Energy Efficiency 56

O(g)(4000K)288Dissociation

Heating

HeatingVaporization

Heating

MgO,Mg&H2O&H2.cvx

Maximum Energy Storage Efficiency through MgO ReductionThermo Chemical Evaluation


10/41


Pow e r B a l a n c e o f MgO V a p o r i za t i o n

MgO Heated region

Laser, Ilaser

Ilaser(105W/cm2)Ivap(105W/cm2) + Irad (2103W/cm2) + Icond(103W/cm2)

Ivap includes heat capacity 0.9 J/Kg, melting(1.9kJ/g), vaporization(8.2kJ.g), and dissociation9.2 kJ/g energies of MgO. Heat conduction measured. Vaporization rate0.05 g/sis measured Solar radiation concentration limit, 103 W/cm2

Laser intensity wil l be required to maintain MgO reduction > 100Natural Sun Power Power Conversion rather than Beam Quality

Heat Conduction, Icond

Radiation Loss, Irad

Vaporization, Ivap

Laser Irradiation

Power = 1 kW cw

Spot = 1 mm = 10.6 m


11/41


Why So l a r Pum p e d L a s e r ?

L a se r t e c h n o lo g y g iv e s s o lu t i o n s t o o ve r c om e t w o m a jo r

o b s t a c l e s i n u t i l i z i n g s o l a r l i g h t e n e r g y

A u t o -r e du c t i o n o f M gO w i t h 4 0 0 0 -K h ig h t em p e ra t u r e

Ad v a n t a g e o ve r c o n v e n t i on a l M g m e t a l lu r g y p ro c e s s e s

Pow e r c o n c e n t r a t i o n is a s m a n y o rd e r s o f m a g n i t u d e

l a r g e r t h a n t h e n a t u r a l s u n l ig h t

Ad v a n t a g e o v e r a h u ge h e l io s t a t f a c i l i t y

On l y la s e r c a n p r o v i d e t h e p ow e r d e n s i t y

n e e d e d f o r t h e s p o n t a n e o u s MgO r ed u c t i o n


12/41


A h u g e f a c i l i t y i s n e e d e d f o r d i r e c t s u n l ig h t

a p p l ic a t i o n t o h ig h t em p e r a t u r e

So la r p ow e r e ng in e i n Fo n t Rom e u Fr a nc e

N a t i o n a l Re n ew a b le En e rg y La b o r a t o r y , U SA

3 0 0 0 -K s o l a r f u r n ac e r eq u i r e s a 5 0 -m s o la r c o n c e n t r a t o r a r r a y


13/41


L a s e r c a n be v e r y c om p a c t

T he la se r a bo ve c a n he a t m a gn e s ia t o 40 00 K

Ra d i a n c e o r B r i g h t n e s s c h a ra c t e r i ze s t h e p o w e r d en s i t y a n dc om p a c t n e s s o f a l ig h t s o u r c e i n W /c m 2s r

L a se r v s . So la r = 1 0 1 4

: 1 07

, in W/m2

s r

4 kW o u t p u t p ow e rc a n b e d e l iv e r e df r om t h i s c om p a c tl a s e r h e a d


14/41


L i g h t B e am Qu a l i t y

~Fo c u s a b l e Pow e r De n s i t y

Co he re n t a nd I n c o h e r e n t L ig h t so u r c e

>1 kW

Beam divergence : 1 mraddiffraction limitted

Coherent Light Source;Laser Mediumsuch as optical fiber laser Incoherent light sourceThe Sun

1.4109 m

3.81026 W

ConcentratorVery tiny angle

Etendue, an opt ical invariant: The smaller, the better

(Light source size)(Solid angle of light flux)

10

-3

m

10

-3

rad = 10

-6

mrad 10

-2

m

0.05 rad ~ 10

-3

mrad


15/41


Sun

6.96108m6.96108m

L

1.501011m

AspotA

lens

Distance to the Sun (1.51011 m) Focal Length of the Sun Collector (L m)

Sun Collector

(Fresnel Lens)

Why Laser? Why not Sun?Natural Limit of Sun Light Intensity

I0Solar intensity on the ground0.1 [W/cm2] LnSun-earth distance normalized by sun diamer100

number1Ispot 10,000I0 1000 W/cm2 Two orders of magnitude less thanrequired for MgO reduction

Focused intensity, Ispot is determined by F numberalone

02

2

02

2

02

2

0 I

F

LI

DL

DL

I

LLD

D

A

IAI n

lens

sun

sun

sun

sun

lens

spot

lensspot

=

==

Laser Pumping Aperture

~Size of Laser Medium


16/41


L a s e r i s a n e s s e n t i a l t o o l fo r t h e

M g -S o l a r Ene r g y C y c l e S umm a r y

Re n ew a b le e n e rg y c y c l e n e ed s a g oo d e ne rg y s t o r i n g

m a t e r i a l

M g is a p r o m i s i n g m a t e r i a l

U se c h e m i c a l p o t e n t ia l c h a n ge b e t w e en M g an d M gO

En e rg y c h a rg in g p r o c e s s , M gO r e du c t i o n n ee d s 4 0 0 0 K

Di r e c t s o la r p o w e r c a n n o t su s t a in t h e t e m p e ra t u re

L a se r t e c h n o l o g y p r ov id e s c om p a c t a n d e f f i c i e n t s o lu t i o n


17/41

3The Universit o Tok o

So l a r En e r g y C yc l e U s i n g M a g n e s i um

a n d L a s e r T e c h n o l o g ie s

2012.11.19 & 12.10 at Tokyo University

Given by

Shigeaki Uchida / Global Solar Initiative (GS+I), The University of Tokyo

also at Pegasos Electra Co. Ltd.

T o p i c a l L ec t u r e s o n

M ag n e s i um e n e r g y c y c l e d r i v e n b y s o la r

e n e r g y

E l em e n t a l t e c h n o lo g i e s c o n s t i t u t i n g t h e

c y c l e

So l a r p um p e d l a s e r

Mg c om b u s t i o n

MgO r e d u c t i o n


18/41


So l a r Pum p e d L a s e r

Me c h a n i sm o f Co n v e r t i n g So l a r L i g h t t o

L a s e r R a d i a t i o n =

Fo u r L e v e l L a s e r M o d e l

De s i g n Pr i n c i p l e o f So l i d St a t e L a s e r =T h e rm a l A n a l y s i s


19/41


a s i c Com p o n e n t s o fSo l a r Pum p e d L a s e r

Solar pumped lasers use sun light to

directly pump (activate or excite)

laser media and convert it to

coherent laser radiationun

Sun lightLightcollector

Laser mediumLaser


20/41


Sun

6.96108 m6.96108 m

L

1.501011m

AspotA

lens

Distance to the Sun (1.51011 m) Focal Length of the Sun Collector (L m)

Sun Collector(Fresnel Lens)

Why Laser? Why not Sun?Natural Limit of Sun Light Intensity

I0Solar intensity on the ground0.1 [W/cm2] LnSun-earth distance normalized by sun diameter100

number1Ispot 10,000I0 1000 W/cm2 Two orders of magnitude less thanrequired for MgO reduction

Focused intensity, Ispot is determined by F numberalone

02

2

02

2

02

2

0 IF

LI

DL

DL

I

LLD

D

A

IAI n

lens

sun

sun

sun

sun

lens

spot

lensspot

=

==

Laser Pumping Aperture

~Size of Laser Medium


21/41


Ba s i c E l em e n t s o f So l a r L a se r

L a s e r Os c i l la t o r

Fr e s n e l l e n s

So l a r r a d i a t i o n

Laser


22/41


Laser Devise :Laser Devise : solar pumped lasersolar pumped laser

Cr:Cr:NdNd:YAG:YAG ~Economical and efficient~Economical and efficient

Negligible amount ofresource for lasermaterial

Water for powerconcentration andcooling

low manufacturingcost 0

0.5

1

1.5

2

400 500 600 700 800(nm)

(/cm)

Nd absorption

Cr + Nd absorption

Wave length (nm)

Absorptio

n

coefficien

t(cm-1)

Concept

Solar spectrum


23/41


Qua l i t a t i v e d e s c r i p t i o n o f l a s e r

O s c i l l a t i o n ~ Sp o n t a n e o u s & S t i m u l a t e d


24/41


Four-Energy-Level Model of Nd Ion

Most important: To form a population inversion between the upper and

lower laser level

Population inversion: status that upper level has more ions than the

lower level against the thermal equil ibrium condit ion


25/41


Upper level

Lower level

Pumping

Stimulated EmissionLaser Photon) Spontaneous EmissionPower Loss)

Nd:YAG

Fo u r L e v e l L a s e r Eq u a t i o n s

The equations deal with the number densities of

population inversion, N2 and laser photon,

2

2

2 N

NBRdt

dN

p =

=

caNBVdt

d 1

2

HR mirror Output mirror

Laser photons are generated from

stimulated emission and lost through the

output mirror

Population inversion, N2 is added the

pumping and reduced by both stimulated

and spontaneous emission

At oscillation condition, steady state is realized, i.e. d/dt = 0


26/41


Laser Power as a Function of Pumping

Power in Oscillation Condition

( )

( )

+

+

=

+

+

=

=

a

sT

photon

T

med

aT

pa

T

T

med

pca

e

out

Vf

P

f

A

chl

fRV

f

f

lRVh

L

cP

1

11

1

1

2

2

Expression for Laser Power

Solar Power(Input)

Slope

Efficiency

Threshold Photon Lifetime in Cavityc

Lec

( ) aTa f

122

++ Cavity Loss

a

Tf

2

2 Ratio of Output Coupling toMedium Loss

medefcta AlV Mode Volume=Gain lengthGain cross section

T he Ex p r es s i o n In c l u d e s

Tw o L a s e r Os c i l l a t i o n

C h a r a c t e r i s t i c s ;

S lo p e Ef f i c i e n c y

T h r e sh o l d


27/41


Axial PumpingAxial Pumping ConfigurationConfiguration

A x i a l p um p i n g c o n f i g u r a t i o n w i t h t a p e r e d l i g h t c a v i t y h a s

b e e n d e s i g n e d fo r e f f i c i e n t s o l a r p ow e r c o n c e n t r a t i o n


28/41


01020304050607080

800 1000 1200 1400 1600 1800 2000 [W]

Calculation

Experiments

Model Calculation Well ReproducesModel Calculation Well Reproduces

Experimental ResultsExperimental Results

Both Slope

Efficiency and

Threshold are wellreproduced by

theoretical model

LaserOutput[W]

Solar Input [W]


29/41


L im i t o n L a s e r M e d i a T h i c k n e s s T h e rm a l s h o c k l i m i t

Qt h[W/m3]Wa s t e h e a t

Fs h a p e Sh a p e f a c t o r 1 28 / s l abr o d

RT[W /m ] T h e rm a l sh o c k p a ra m e t e r 700 / YAG

t [m ] Me d i um d i m e n s i o n a lo n g t em p e r a t u r e g r a d ie n t

SSa f e fa c t o r 0 .10 .3

PumpPpumpWaste heatQthV

Laser radiationPlaser

Laser medium (volume V)

t

SQ

RF

tth

Tshape

M d i t h i k d d


30/41


Me d i um t h i c k n e s s de p e nd e n c e

o f L a s e r Pow e r

0

10

20

30

40

50

60

70

80

600 800 1000 1200 1400 1600 1800

Input Solar Power [W]

3 53 9

9

100

World Record of Solar Pumped Laser

Thicker media are preferable but

Also medium broke


31/41


T h e h i gh e s t p o w e r r e c o r d e d c o r r e sp o n d s t o

t h e t h e r m a l l i m i t o f t h e r o d m e d i um

80 W is close to the highest power that the 9 medium canaccommodate

St

RFQ

Tshape

th 2=

Measured medium effective (activated) volume, V

Extraction efficiency, (Model Calculation)Maximum output power would be

WVQ

I th 90

11max =

=


32/41


33/41


A n o t h e r h ig h e s t T A P h a s b e e n a c h i e ve d

3. M.Landoat alOptics Communication 2003

1.M.Weksler,at alIEEE J QE 1988

2. V.Krupkin,.at alProc.SPIE 1993

4. Our Study, Yabe LabTokyo Inst of Tech,Okamoto Opt

Laser Output[W]Collector Size[m2] TAP [W/m2]

24.4 16.66.6

60500

46

38.56606.851.47

1.550.76

6.7

Totaltal Areaea Performancerformance Laser outputaser output [W]W]Collector area [mollector area [m2]Reflects the future plant cost effectiveness

80 20.00.0.0. Our Study, Yabe LabTokyo Inst of Tech,Okamoto Opt

Set in March 07

New!

Currentperformance:

30%

absorption

Limited by

thermal load

=>More and

distributed

absorption

A t h ib i l i t


34/41


An o t h e r p o s s ib i l i t y Sl a b t y p e l a s e r m e d i a

Design laser media that absorbs pumping power

through its wide area

Principle of design

Achieve high absorption while avoiding

thermal fracture

Laser oscillation

Solar power

T h i c k n e s s a n d n um b e r o f m e d ia d e p e n d o n


35/41


T h i c k n e s s a n d n um b e r o f m e d ia d e p e n d o n

p um p in g p o w e r

Thick

Small pump power

Less media Thin

Large pump power

More media

Stacked laser media for the areal pump power absorption scheme

Thin

With reflection

More media

% f


36/41


9 0% a b s o r p t i o n f o r w h o l e la s e r m e d i a sy s t em

0.00.20.40.60.81.01.2

1.41.6

2

4

6

8

10

0.5 0.6 0.7 0.8 0.9 1Absorption

Blue: 200 W/cm 2Red : 400 W/cm 2

Thickness

Number of Media

No reflection

Thickness&Number.qpc

S i d i t h i t h 1


37/41


S i x m e d ia t h i n n e r t h a n 1 c m

0.5

1.0

1.5

2.0

2.5

2

345678910

50 100 150 200 250 300 350 400Pumping power [W]

Number

Thickness

Thickness&Numbre-Pump

Blue: without reflectionRed : with reflection

Current performance

More than 1500 Wis absorbed in thestacked media1 kW laser outputcan be expected

[W/cm2]

P t t f h l f i l t k i t


38/41


Pr o t o t y p e o f h a l f -p i p e s o l a r t r a c k i n g s y s t em

Master-Slave Sun Tracking System has been tested

Driving power 30W (to be 1% of laser output)

Master

(active tracker)Slave

Lens1Lens2

Laser1Laser2


39/41


Pr e l im i n a ry d e v i c e f o r s l a b m e d i um

Radiator

Laser medium

Window

Solarlight

Cu holder

G l f t h R& D


40/41


Go a l o f t h e R& D

Conversion efficiency

30-40%

To MgO reduction plant

Solar Laser Array

680 t M d ti /d / 2 5k 2


41/41


680-ton Mg production /day /2.5km2

solar laser energy cycle - magnesium as energy 2012

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