1. SOLAR THERMAL POWER!
GEEN 4830 – ECEN 5007!
6. Parabolic trough technology!
Manuel A. Silva Pérez
!
silva@esi.us.es !

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GEEN 4830 – ECEN 5007
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3. Solar Thermal Power Plant.
Basic configuration
Beam irradiance
Concentrator
Concentrated irradiance
Electricity
Receiver
Thermal energy
Thermal Storage
Power
Fossil fuel conversion
Boiler
Biomass
system
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4. PT power plant configuration
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5. The collector
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6. Collector
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7. Main Concentrating Technologies

8. Types of collectors
Process heat STP plant
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GEEN 4830 – ECEN 5007
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9. Main elements of the collector
 Reflector (mirror)
 Receiver tube
 Structure
 Tracking system
 Connecting elements
 Control system
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GEEN 4830 – ECEN 5007
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10. The reflector
Thin glass mirror (0.8
mm) Thick glass mirror (3 -5 mm)
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GEEN 4830 – ECEN 5007
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11. Alternative reflector materials: Reflectech
mirror film
 Specular Reflectance 94% At
25 mrad, 660 nm
 Solar-Weighted Hemispherical
Reflectance 94%
 Durability: approx. 10 yrs.
 Thickness: 0.1 mm
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GEEN 4830 – ECEN 5007
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12. Alternative reflector materials:
Alanod Miro-SUN
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13. Structure
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14. Structure
Bending
resistance
Torsional
resistance
Torque
Tube
design
LS3
Design
Torque
Box
Design
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GEEN 4830 – ECEN 5007
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15. The receiver tube
Glass pin for evacuation of gases
and steel tubes
Vacuum between glass
Glass – metal welding
Selective coated steel tube
'Getter‘ for vacuum maintenance
Expansion bellow
Glass envelope
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GEEN 4830 – ECEN 5007
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16. Receiver tubes
Schott PTR-70 Solel UVAC-2 and UVAC-3
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17. Heat transfer fluid
 Thermal oils
 Caloria (SEGS I and II, <300ºC)
 Therminol VP-1 (<400 ºC)
 Syltherm (Dow Chemical, >400ºC)
 Water / Steam
 >400 ºC
 DISS Project
 Molten salts
 ENEA facility
 Gases
 PSA Research Facility
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18. Tracking mechanisms
Electrical motor -
gearbox Hydraulic
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19. Connecting collectors
Flex hoses Rotating joints
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20. Control elements
Shadowband sensor
Controller
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21. Cleaning the mirrors
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22. Solar field configuration (I)
1 SCA 150 m
12 SCE
1 Drive Pylon
10 Middle Pylon
1 End Pylon
1 Shared Pylon (shared with next SCA)
150 m
Shared Pylon
SCE
150 m
Middle Pylon
Drive Pylon
End Pylon
Hot
Oil
Cold
Oil
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GEEN 4830 – ECEN 5007
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23. Solar field configuration (2)
Loop of
6 SCA’s
1248 m
SEGS Power Block
80 MW Rankine Cycle Headers
Cross Over
Pipes
1379 m
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GEEN 4830 – ECEN 5007
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24. Solar field configuration (3)
 Thermal losses
 Thermal losses
 unbalanced ΔP
 Higher cost
 Higher consumption
 ΔP balanced
 Lower consumption
A) Direct return
B) Inverse return
h
h
h
h
 Shorter pipelines
 Better access to collectors
 unbalanced ΔP
C) Central
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GEEN 4830 – ECEN 5007
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25. Solar field orientation
Z Z
Sol
O
S
C
Y
N
O
C
N
Y
Sol
S
X
X
S
S
E
E
a) E-W tracking
b) N-S tracking
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GEEN 4830 – ECEN 5007
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26. Basic parameters
Aperture, A
Parabolic Acceptance angle, θ
Angulo aceptancia θ
de
Reflector Rayorays
Sun solar
Absorber tube
Aperture angle , φ
Angulo aperturaφ
de
External receiver diameter , D
Diámetro
D
C =.A /Π.D
b) Concentration ratio, C
b) Acceptance angle, θ
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GEEN 4830 – ECEN 5007
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27. Energy balance. Optical losses
Beam irradiance
interception factor,
γ,
Glass envelope
(Transmissivity = τ)
Selective-coated steel tube
(Absortivity = α)
Parabolic mirror
(Reflectivity = ρ)
ηo,peak = γ·τ·α·ρ
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GEEN 4830 – ECEN 5007
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28. Geometrical losses
Sun
L = concentrator length
ϕ = incidence angle
Sol
F = focal length
Side view
Absorber tube
Reflecting surface
ϕ
ϕ
Shaded
F
area
Plant view
ED
L
Sun
Af = W x ED = W x F x tan(ϕ)
a) Shading losses
b) Loss of effective collector length
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GEEN 4830 – ECEN 5007
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29. Loss of effective collector length
ED
W
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30. Thermal losses
Absorber tube
Qabs,cond/conv. Qamb,rad
Qamb,conv
Qabs,rad.
Qv,abs.
[W/m2abs ºC] Glass envelope
UL)col = UL)abs / C
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31. Energy balance (solar to thermal)
eff
eff
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32. Typical operation curve
(clear day, no thermal storage)
Solar Efficiencies Measured at
SEGS VI
on July 1997 by KJC Operating
70 Company
% 1200
60 Direct Normal
% Radiation
1000
Direct Normal Radiatiom [W/m²]
50
%
Thermal 800
-
40 Solar
Efficiency
% Field
Efficiency
600
30
%
[%]
20 400
%
10
Solar to
Electric 200
%
Efficiency
0 (gross)
% 0
05:00 07:00 09:00 11:00 13:00 15:00 17:00 19:00 21:00
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33. Dispatchability of STP Plants
 Integration of RES on the grid:
 Dispatchability is a key factor.
 STP Plants have the potential to be dispatchable by:
 Including a Thermal Storage System (TES)
 Hybridization with fossil or renewable fuels.
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34. Andasol-type plants
(thermal storage and auxiliary boiler)
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35. Dispatchable STP Plant
 Continuous and stable operation is guaranteed by TES
and / or hybridization
50
40
MW
30
20
10
0
0 2 4 6 8 10 12 14 16 18 20 22 24
Hours
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36. TES
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37. Hybridization options
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38. SEGS 30 MW
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39. Costs
 Difficult to evaluate
 Confidentiality of contracts
 Volatility of prices
 Only 2 – 3 providers of key elements
 O&M experience restricted to US (SEGS Plants)
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40. Costs CCP – Spain. 8h TES
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41. Costs – Spain. No TES
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42. O&M Costs – Spain (8h TES)
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43. PT Technology today, pros & cons.
 Pros:
 Mature technology;
 Comercially proven, over 500 MW installed capacity;
 Extensive operational record: 9 plants operating for 15+
years
 Easier to finance
 Cons:
 Few manufacturers of key elements (recievers, mirrors…) ->
limited competence
 Limited maximum temperature -> limited efficiency
 Costly, hazardous HTF
 Limited TES options
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GEEN 4830 – ECEN 5007
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44. More…
 http://www.nrel.gov/csp/troughnet/
 Sargent & Lundy Assessment of CSP
http://www.nrel.gov/csp/troughnet/pdfs/34440.pdf
 Look for movies at youtube, e.g:
 http://www.youtube.com/watch?
v=ysDXwvNGHeM&feature=related
 http://www.youtube.com/watch?v=3OLjooHY1VA
 http://www.youtube.com/watch?
v=mDWSW8BAM3U&feature=related
 And more…
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