Parabolic Trough, Linear Fresnel, Power Tower A Technology Comparison Robert Pitz-Paal
Thermal Storage vs. Electric Storage
CSP with storage and fossil hybridisation can provide all 3 components of value Thermal storage economically favorable
2000 h
+2000 h
η >95 %
η
200 h
Cost of electricity for CSP system with and without storage
Electricity generation cost as function of solar multiple and storage size
solar multiple (sm)
storage 12 h rated power
no storage
0.1
Eur
o/kW
h
0.15
Cooling tower91.8%
Steam cycle6.1%
Mirror washing2.0%
Potable water0.1%
How does CSP react under desert conditions?
Water consumption
Washing (no recycling yet) 75 l / MWh (low soil.) 30 l /m² year (mirror surface) 0,5 l/m² per wasching cycle Rainfall Cairo = 25 l/m²year
Reflector Soiling • Cleaning of CSP collectors on
a weekly basis, • Soiling depends strongly on
site (and seasonal) conditions. Variations can be in the order of a factor 2-3
• 5% average soiling leads to revenue losses of 3-6 $/m²year (depending on electricity price)
• Cleaning need 20 – 40 l/m² year
Reflector Degradation?
Glass mirrors have proven high robustness over >25 years in operation
DLR has established accelerated aging methods for specific reflector types
Dry cooling
Recycling
4
Land use (m²/MWh/a)
6-8
4-6
8-12
www.DLR.de • Chart 5
(Tabsorber =Tprocess) [K]
ηηm
ax
Flat Plate Collector
Parabolic Trough
Solar Tower
Parabolic Dish
ηmax= ηth,Carnot* ηabsorber
Efficiency Potential of CSP Systems
www.DLR.de • Chart 6
Market Situation
Ground Requirements
www.DLR.de • Chart 7
Power Block steam cycle
turbine, condenser 30-280 MW
Heat Transfer & Buffer 2-10 hours
capacity
Solar Field parabolic trough
collector field 200’000 - 2’200’000 m2
Parabolic Trough Plant Scheme
www.solarpaces.org
www.DLR.de • Chart 8
Line Concentrators –how do they work?
www.DLR.de • Chart 9
Line Concentrating Collectors
1-dimensional curvature of reflector short focal distance mirror bending required receiver length equals collector length absorber typically a tube heat flux rates 0.01 – 0.1 MW/m² absorber temperature limited to 400-600°C absorber insulation required (glass) parallel rows, only horizontal installation economical heat transfer fluids: synthetic oil, water/steam, molten salt, (CO2) hydraulic and thermodynamic design to operating conditions heat storage possible net solar-to-electric peak efficiency 20-28% process heat applications performance modeling is state of the art
www.DLR.de • Chart 10
Linear Fresnel Collector – Working Scheme
receiver
mirror rows
absorber tube
secondary concentrator insulation
glass window
www.DLR.de • Chart 11
Linear Fresnel Collector - Properties
off-axis, astigmatism gaps to reduce shading/blocking flat glass, light weight less standardized than troughs max theoretical concentration and optical efficiency lower than troughs collector width up to 20 m focal length up to 30 m fix receiver distance between rows 30-40% capture 55-65% of DNI two-axis incidence angle impact low performance on sun rise/set, high at noon low wind forces (low height) first commercial plants (Novatec, Areva, )
www.DLR.de • Chart 12
What is the difference between Parabolic Trough and Linear Fresnel?
56%
26%
4% 2%
12%
64%
9%
43%
15%
3% 2%5%
64%
9%
0%
10%
20%
30%
40%
50%
60%
70%
opt. V
erlus
teW
ärmev
erlus
teAnfa
hrverl
uste
unter
es D
umpin
gob
eres D
umpin
g
Powerb
lock
Eigenb
edarf
Verluste LFKVerluste Eurotrough
www.DLR.de • Chart 13
Why higher optical losses?
www.DLR.de • Chart 14
Why more dumping losses?
Parabolic Trough Collector
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
local time
ener
gy in
kW
h
0
100
200
300
400
500
600
700
800
900
DN
I in
W/m
²
15. Junmax. power dumping
min. power dumping
used power
DNI
Linear Fresnel Collector
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
local time
ener
gy in
kW
h
0
100
200
300
400
500
600
700
800
900
DN
I in
W/m
²
15. Junmax. power dumpingmin. power dumpingused powerDNI
www.DLR.de • Chart 15
www.DLR.de • Chart 16
www.DLR.de • Chart 17
LCOE of Parabolic Trough (Algeria 2400kWh/m²a)
www.DLR.de • Chart 18
Storage
Concept of Tower Technology
www.DLR.de • Chart 19
Solar Tower
www.DLR.de • Chart 20
Solar Tower – Steam, Molten Salt Ivanpah-CA 3x123 MW Brightsource Tonopah-NV 110 MW SolarReserve Lancaster-CA 5 / 46 MW eSolar
www.DLR.de • Chart 21
Heliostats
www.DLR.de • Chart 22
Receiver Concepts
www.DLR.de • Chart 23
Solar Tower, molten salt – Gemasolar 20 MW Torresol Spain
Storage TankCold Salt
Storage TankHot Salt
ConventionalEPGS
Steam Generator
o C565290 o C
www.DLR.de • Chart 24
Ivenpah Solarturm Projekt 25
Example Reference Plant Molten-Salt Tower 100 MW Algeria
www.DLR.de • Chart 26
Transmitter
Receiver
Atmospheric Extinction between Heliostat and Receiver
LIDAR
Scattermeter
www.DLR.de • Chart 27
Aerosol Concentration close to ground surface
www.DLR.de • Chart 28
Modularity & Scalability
Slide 29 / Solar Tower
Conclusions
Trough Tower and Fresnel Systems have very different characteristics and require complex design tools for their layout
All three technologies have a realistic market potential and can further reduce costs
www.DLR.de • Chart 30
DLR - Institute of Solar Research www.dlr.de/sf www.dlr.de/tt
GIZ Renewable Energy Week > CSP Overview > Dr. Eckhard Luepfert, DLR Institute of Solar Research, Berlin 09/2012 www.DLR.de • Chart 31
Solar Tower Jülich – Solair/HitRec – Air as Heat Transfer Fluid 1.5 MW DLR / KA München
Heliostats
Receiver
Steam Generator
Storage
Hot Air 730º
Cold Air 110º Super
heated
Steam
~
www.DLR.de • Chart 32