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Solarthermische Kraftwerke zur Energieversorgung im Sonnengürtel Robert Pitz-Paal Institute of Solar Research German Aerospace Center (DLR) Chair Solar Technology Aachen University

Dokumentname > 23.11.2004

Was ist CSP?

Konventionelle Kraftwerke

2

2


Was ist CSP?

Solarthermische Kraftwerke

3

3


Pictures of the sun surface

5700 K q = σ T4≈ 60.000.000 W/m²


Solar constant Io = average energy per unit time which is radiated from the sun perpendicular to an area on the outer atmosphere of the earth. sun Sonne sun earth Erde earth 6

1,39 x 10 km

12700 km

32´

solar constant

8 Abstand : 1 AE = 1,5 x 10 distance distance

km

1,7 %

2 R 2S I0 AS 4 ⋅ π ⋅ R 2S 4 RS = = , I0 = IS ⋅ = σ ⋅ TS ⋅ ≈ 1360 W / m2 = 4870 kJ /(m2 y) 2 2 2 IS A AE 4 ⋅ π ⋅ AE AE AE


Diffuse and direct radiation


World solar energy supply

( space: 32 kWh / m2 / day )


Concentration Concentration factor C is defined as the ratio of Energy flux density E´ at the exit aperture of the concentrator to the energy flux to the Energy flux E ate the entrance aperture of the concentrator

E´ A C= = ´ E A

θ

A

A‘ θ‘

With E = dΦ / dA [W/m2], averaged over the aperture A resp. A´ Φ = Energy Flux [W] θ = half cone angle


Concentration factor C = ratio of the radiation flux density E´ after concentration to the radiation flux density E before concentration

Geometrical concentration ratio C C=

aperture area area of sunshape in focal plain

Technical concentration if absorber ≈ focal area C=

aperture area = AR absorber area AA


Conservation of Etendue in Concentrators

A ⋅ sin Θ = A′ ⋅ sin Θ′ 2

3D 2D

2

A ⋅ sin Θ = A′ ⋅ sin Θ′ A sin Θ′ A sin Θ′ = = C2 D = = 2 A′ sin Θ A′ sin Θ 2

C3 D


Maximum Concentration

0,534°

Cmax,3 D

sin 2 90° A A sin 90° 46200 = = ≈ Cmax, 2 D = = ≈ 46200 = 215 2 A′ sin 0,267° A′ sin 0,267° Dokumentname > 23.11.2004

Radiation concentration on parabolic mirrors

Parabolic mirrors have focal points

Point-focusing: paraboloid mirror

Line-focusing: parabolic troughs

Slide 12

www.dlr.de/enerMENA Dokumentname > 23.11.2004

Alternative concentrating geometries

Point-focusing: heliostat field (solar tower

Line-focusing: Fresnel mirror

plants)

Slide 13


Maximum mean concentration on paraboloid mirrors Aap … aperture area

αD

Aim … image area αD rr

a

a a

αD focal spot at

b focal spot at

concentration profil at the focal plane

source: DLR Slide 14


Maximum mean concentration on parabolic troughs Aap … aperture area

αD

Aim … image area αD rr

a

a a

αD l … trough length

focal spot at

Slide 15

b focal spot at


Maximum absorber temperature

- selective coatings and claddings may increment the absorber temperature - heat conduction and convection tend to reduce the absorber temperature - atmospheric influences reduce the solar radiation and reduce the absorber temperature highest possible absorber temperature (Second law of thermodynamics):

5780K

(= effective Sun temperature) Slide 16


Carnot Cycle

Q = ∫ TdS Q zu = TH ∆S Qab = TL ∆S W = Q zu − Qab Qzu − Qab TH − TL TL η= = = 1− Qzu TH TH

T TH W TL

17

∆S S Dokumentname > 23.11.2004

Effciency of a Carnot Cycle

18 Dokumentname > 23.11.2004

CSP F&E Strategie: hohe Konzentration + hohe Temperatur = hohe Effizienz => geringe Kosten

ηmax

ηcsp= ηth,Carnot* ηabsorber

Solar Tower C=1000 Parabolic Trough C =100

(Tabsorber =Tprocess) [K] 19


Thermal Storage vs. Electric Storage

η >95 % +2000 h 2000 h 200 h

Firm mid load capacity

η = 75%

CSP with storage and fossil hybridisation can provide all 3 components of value Thermal storage economically favorable

Trends in CSP > R. Pitz-Paal > 15.11.2011 Dokumentname > 23.11.2004

www.DLR.de • Folie 21

Relative electricity costs [%]

The Value of CSP Electricity

105

no storage, electricity costs = 100%

100 95 90 85 80 75

0

5

10

15

Storage capacity [full-load hours] * assuming specific investment costs for the storage of 10 Euro/kWh Dokumentname > 23.11.2004

CSP vs PV Simulation of supply and demand with increasing PV share Summer

Source: NREL/TP-6A20-52978, Nov. 2011


CSP vs PV Simulation of supply and demand with increasing PV share Spring Frühjahr

Source: NREL/TP-6A20-52978, Nov. 2011 Dokumentname > 23.11.2004

CSP vs PV Simulation of supply and demand with increasing PV share 20% PV

Source: NREL/TP-6A20-52978, Nov. 2011 Dokumentname > 23.11.2004

Types of Concentrating Solar Thermal Technologies

Dish-Stirling

Solar Power Tower

Parabolic Trough

Linear Fresnel Dokumentname > 23.11.2004

Parabolic Trough Collector  Advantages:  Large scale proven technology  Bankable  Disadvantages:  Up to now max. temperature of HTF limits the efficiency  Nearly flat side topography needed © DLR


Linear Fresnel Collector  Advantages:  Simple construction  High land use  Possible integration into buildings  Disadvantages:  Low efficiency  State of the art without storage © DLR Quelle: MSM Dokumentname > 23.11.2004

Solar Power Tower  Advantages:  High efficiency potential  High cost reduction potential  Usable in hilly area  Disadvantages:  Less commercial experience  Radiation attenuation by dust in the atmosphere


Dish-Stirling  Advantages:  Very high efficiency  Small units  Decentralized application  Disadvantages:  Expensive  No storage


Real data of CSP dispatchable generation (Andasol III data) Andasol 3: Facts & Figures > Owner: Marquesado Solar S.L. > Location: Aldeire/La Calahorra (Granada, Spain) > Technology: Parabolic trough incl. 7.5h molten salt storage > Capacity: 50 MWel > Size of the collector area: ~ 500,000 m² > Forecasted electricity production: ~200 GWh/a > Annual CO2 savings: 150,000 tonnes > Commissioning in autumn 2011 > Investors:

> EPC contractor: UTE Source: RWE Innogy, F. Dinter Dokumentname > 23.11.2004

Continuous generation 24 h/d 11.09.2012 – 18.09.2012 1200

100 90

Power [MW] Hot Salt tank Level [%]

70

800

60 600

50 40

400

30 20

Solar Radiation [w/m2]

1000

80

200

10 0

0

HOT SALT TANK LEVEL(%)

POWER S5 (MW)

DNI (W/m2)

Source: RWE Innogy, F. Dinter Dokumentname > 23.11.2004

Dispatchable generation 22.03.2012

Dispatchability test

30

25

Power [MW]

20

15

10

5

0

Plan-Power (MW)

Actual-Power (MW)

kWh/m2 2d DNI > 4 KWh/m

Source: RWE Innogy, F. Dinter Dokumentname > 23.11.2004

Market



Market



Market: Medium term generation to 2018


Ivanpah (Brightsource) solar tower 130 MW connected to grid, S eptember 24, 2013 (Total 390 MW)

36


Cresent Dunes (100 MW Molten Salt, 6 h Storage)

37


Challenges: Collectors

Lightweight construction

New designs

Entire collector performance measurement and STANDARDs Dokumentname > 23.11.2004

Challenges: Heat Transfer Fluids for Higher Temperature Liquid salt

Liquid metal

0

10 (m)

5 2.5

7.5

Particles


Challenges: Advanced Solar Power Cycles (Solarized Design) Top-cycles with pressurized air, liquid salt, liquid metal or particles

Molten salt in parabolic troughs SCA #4

SCA #5

Hot Salt Pumps Hot Salt Tank 500–580 °C

Header Return SCA #6

SGS Supply SH

Recirculation Pump

COP

Drainage Tank

EVA

Heat Trace ECO SCA #3

SCA #2

Cold Salt Tank 290 °C

SCA #1 Header Supply

SGS Return

Cold Salt Pumps


Conclusion

CSP is one of the possible CO2 free systems for electricity production CSP systems can be equipped with a high efficient storage system, enabling them to deliver dispatchable electric power CSP enables a higher feeding of PV and wind power to the grid The demand for cost reduction of CSP systems lead to Higher temperatures of the heat transfer fluid Higher steam parameters New heat transfer fluids like molten salt, liquid metal and particle


Thank you for your attention
