Parabolic Trough, Linear Fresnel, Power Tower A … · Parabolic Trough, Linear Fresnel, Power...

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


Market Situation

Ground Requirements


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


Line Concentrators –how do they work?


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


Linear Fresnel Collector – Working Scheme

receiver

mirror rows

absorber tube

secondary concentrator insulation

glass window


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, )


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


Why higher optical losses?


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


LCOE of Parabolic Trough (Algeria 2400kWh/m²a)


Storage

Concept of Tower Technology


Solar Tower


Solar Tower – Steam, Molten Salt Ivanpah-CA 3x123 MW Brightsource Tonopah-NV 110 MW SolarReserve Lancaster-CA 5 / 46 MW eSolar


Heliostats


Receiver Concepts


Solar Tower, molten salt – Gemasolar 20 MW Torresol Spain

Storage TankCold Salt

Storage TankHot Salt

ConventionalEPGS

Steam Generator

o C565290 o C


Ivenpah Solarturm Projekt 25

Example Reference Plant Molten-Salt Tower 100 MW Algeria


Transmitter

Receiver

Atmospheric Extinction between Heliostat and Receiver

LIDAR

Scattermeter


Aerosol Concentration close to ground surface


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


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

~


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