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Solar Thermal Technology

Edward C. Kern, Jr. with additions byJeff TesterSustainable Energy 10.391J, etc.

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Solar ThermalResource characteristics

High temperature for electric powergenerationMedium temperature for water heating and

comfort)

heating (human comfort)Heat for industrial processes

active building solar heating (human

Low temperature passive building solar

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Solar thermal using concentratorsFocusing requires direct, non-diffuse component

Storage or hybridization needed to be dispatchable

Distributed mid size capacity - parabolic troughs

1 -10 MWeDistributed smaller scale 10 kW -1 MWe dishesMedium temperature for water heating and active

building solar heating/cooling of buildings (HVAC)

Industrial process heat

Central station option -- power towers 10 100 MWe

-

Low temperature passive building solar heating

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Power tower with molten salt storage

Power Tower or Central Receiver

Cold SaltHot Salt

EPGS

288C565C

Energy collectiondecoupled from

power production

Heliostat

Conventional

Steam Generator

Courtesy of U.S. DOE.

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Power Towers

Courtesy of U.S. DOE.

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Heliostat FieldsCurrent heliostat

prices $125 to $159m -2

Reduction potentialfrom manufacturingscale-up

Innovative DesignsCompare with troughand PV

Courtesy of SunLab (Sandia National Laboratories and NREL partnership).

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Parabolic TroughsDeveloped by Luz for use in

Slowed thinking about largescale PV

Dispatchable hybrid design

storageParticipated commercially in1980s CA green powermarkets354 Megawatts installed by

still operating today

California in 1970s

with natural gas backup no

1991 at Kramer Junction, CA

Courtesy of NREL.

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Luz InternationalFailed commercially in1992 from:

Low natural gas and High maintenance cost Lack of certainty about tax

incentivesRestructured companystill in operation atKramer Junction

Along the learning curveon O+M innovations, e.g.receiver replacements andupgrades, storage,cleaning, etc.

electricity prices


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Dish technology

with Sterling cycle power generationSmall scale distributedapplicationsOf great interest to hightech industries andconsultantsMoving parts with 2-DtrackingExposed mirrorsShading and land useconsiderations


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Solar Thermal ChimneyHeated air, being lessdense, rises in tower;thermal source fromground based thermalcollector aroundperimeterConcept uses a windturbine in the towerflow to extract energyConceptual designs forIndia and Australia

Figure removed for copyright reasons.Source: New York Times.

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The Prototype Manzanares Solar

Chimney, SpainManzanares (south of

Madrid).Delivered power from July1986 to February 1989 witha peak output of 50 kW.Collector diameter of 240meters, with surface area of 46,000m 2.

Chimney was 10 meters indiameter and 195 meterstall.

Figure removed for copyright reasons.Source: New York Times.

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Not very practical or economic

Figure removed for copyright reasons.

Source: New York Times.

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Solar Heating of Buildings Active Systems

Can be captured in fixed or

tracking modes using flat

Even with storage needsbackup supplemental supply

Early history had many

In todays markets are easilysupported with subsidies inmid to high grade regions

available

Vary from ancient to hightech designs

Require integrated designsfor highest payback

plate or focusing collectors

failures robust systems now

Passive Systems

Figure removed for copyright reasons.Source: New York Times

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Solar Cooling of Buildings Active solar energy

capture used topower Rankinerefrigeration cycleLiBr absorption airconditioning for largebuilding(s)Thermal storage maybe required

Courtesy of NREL.

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Heating WaterFast growing under Carter

AdministrationPotential for 20-30%capture and use for year

round water heatingdemandsSubsidies in US led to rushto manufacture and installQuality was compromisedand when subsidies werecut off market collapsed

Lesson has been learned byPV advocatesCourtesy of NREL.

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Space & Water Heating Barriers

No subsidies to defray initial cost fromrestructuring of electric companies (onlyUS source of renewable energysubsidies)Little infrastructure to provide service

Overcoming bad reputation from the1980s

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Passive SolarSouthern openingsThermal mass fordiurnal stabilization

accept winter and rejectsummer direct radiationHard to characterizeand promote since allsouth facing glass ispassive solar

Window technolgy to

Courtesy of U.S. National Park Service.

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Central station electric power Wide areas of high temperature collectioninvolving tracking devices

Must have high direct normal resource andlots of land, access to transmission lines Thermodynamic cycle efficiency at end of

power efficiency Thermal storage enables dispatchability

Solar thermal summary -- part 1

process upper limit of 35 to 40% heat to

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Solar thermal summary--Distributed electric power generation

Requires direct normal resource, tracking and concentratingissues

dishes

Heat to power conversion still limits performance to 30 to40% efficiencySolar thermal heating

Passive and active system opportunities

less for spaceheating and cooling Market growth provides better service infrastructure and

more robust technology

part 2

Potential for smaller scale installation using troughs and

Wide applicability for domestic water heating,

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Value of Thermal StorageStorage benefits

1) Lowers LEC2) Increases market

valueDispatch to meetpeak loads

operation throughcloudsCapacity factors>70% possible

Solar salt

mid-night

noon mid-night

Sunlight

Output

Power

Energy in Storage

noonnight

Power

mid-night

noon

solar-only

plant

mid-

Output

Energy in Storage

midnight

SunlightSunlight

base-load

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Tower Technology ProjectionsSolar

OneSolar Two

Solar TresUSA

Solar 50

Solar 100

Solar 200

Solar 220

Design Details Units 1988 1999 2004 2006 2008 2012 2018Plant output, net MWe 10 10 13.7 50 100 200 220

# Plants built (A) Volume 1 1 1 5 22 6 1

# Plants built (B) Min Volume 1 1 1 1 1 1 1

Heliostat size m 2 39 39/95 95 95 148 148 148

Heliostat type Std Std Std Std Std Std Adv

Storage Duration hours N/A 3 16 16 13 13 13

Rankine Cycle

Pressure Bar 125 125 180 180 180 180 300

Live steam Temp C 510 510 540 540 540 540 640

Reheat #1 Temp C 540 540 540 540 640

4/26/2005Reheat #2 Temp

Number of staff

C

32 33 30 38 47

540

6624

640

67

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Tower Installed Cost

0100

I n s t a

l l e d C o s

t ( $ / k W

o r

$ / k W p e a

k )

$/kWWater/

$/ le

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Solar One "New"Solar Two

Solar TresUSA

Solar 50 Solar Solar 200 Solar 220

$/kWpeak

Aerospace GradeDemo Scale

Steam

Commercial

Receiver sizeHelio size &volume

Lg. Salt StorageEfficiency

EPGS sizeReceiver size

$/kW eak = kW / Solar Multi

Switch to salt HTFDemo scaleCosts assuming new,"commercial" plant isbuilt

EPGS effic.Helio designadvances

L li d El i i

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ower Levelized Electricity

Cost (LEC)

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

Two

L E C ( $ / k W

h )

( )

Solar One "New" Solar Solar TresUSA

Solar 50 Solar 100 Solar 200 Solar 220

FCR=14%FCR=8%

ExpensivePrototypeDemo Plants

'Commercial' Plants

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L E C ( $ / k W h )

(B)

(B)

Commercial Plant LEC

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0.200

Solar Tres Solar 50 Solar 100 Solar 200 Solar 220

FCR=14%FCR=8%Min Deploy

Min DeployFinancial

Terms

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Heliostat Cost

Current heliostat prices Numerous studies byindustry, labs

A.D. Little 2001 studyestimated price at $128/m 2installed (not including $5-

10/m 2 for controls) Spanish company publicoffered heliostats for sale

at $120/m 2 $145/m 2 used for SolarTres USA

Cost Reduction

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0426s05sol Therm