9. Main elements of the collector
Reflector (mirror)
Receiver tube
Structure
Tracking system
Connecting elements
Control system
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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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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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GEEN 4830 – ECEN 5007
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18. Tracking mechanisms
Electrical motor -
gearbox Hydraulic
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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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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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29. Loss of effective collector length
ED
W
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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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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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