Evolution Overview

The parabolic trough plant technology discussion presented focuses on the development of Luz parabolic troug h collector designs and the continued use of Rankine cycle steam power plants. Although the ISCCS concept is likel y to be used for initial reintroduction of parabolic trough plants and could continue to be a popular design alternative for some time into the future, the approach used here is to look at how parabolic trough plants will need to develop if they are going to be able to compete with conventional power technologies and provide a significant contribution to th e world's energy mix in the future. To achieve these long-term objectives, trough plants will need to continue to mov e towards larger solar only Rankine cycle plants and develop efficient and cost effective thermal storage to increas e annual capacity factors.

Table 3. Solar radiation performance adjustment

Site

Annual

Relative

Relative

Location

Latitude

DNI

Solar

Solar Electric

(kWh/m2)

Resource

Output

United States

Barstow, California

35°N

2,725

1.00

1.00

Las Vegas, Nevada

36°N

2,573

0.94

0.93

Tucson, Arizona

32°N

2,562

0.94

0.92

Alamosa, Colorado

37°N

2,491

0.91

0.89

Albuquerque, New Mexico

35°N

2,443

0.90

0.87

El Paso, Texas

32°N

2,443

0.90

0.87

International

Northern Mexico

26-30°N

2,835

1.04

1.05

Wadi Rum, Jordan

30°N

2,500

0.92

0.89

Ouarzazate, Morocco

31°N

2,364

0.87

0.83

Crete

35°N

2,293

0.84

0.79

Jodhpur, India

26°N

2,200

0.81

0.75

1997 Technology: The 1997 baseline technology is assumed to be the 30 MW SEGS VI plant [17]. The SEGS VI plant is a hybrid solar/fossil plant that use s 25% fossil input to the plant on an annual basis in a natural gas-fired steam boiler. The plant uses the second generation Luz LS-2 parabolic trough collector technology. The solar field is composed o f 800 LS-2 SCAs (188,000 m2 of mirror aperture) arranged in 50 parallel fow loops with 16 SCAs per loop. Simila r to the 80 MW plants, the power block uses a reheat steam turbine and the solar field operates at the same HTF outle t temperature of 390°C (734°F). Solar steam is generated at 10 MPa and 371°C (700°F). The plant is hybridized with a natural gas fired steam boiler which generates high pressure steam at 10 MPa and 510°C (950 °F).

2000 Technology: The year 2000 plant is assumed to be the next parabolic trough plant built which is assumed to be the 80 MW SEGS X design [4]. The primary changes from the 1997 baseline technology is that this plant siz e increases to 80 MW, the LS-3 collector is used in place of the LS-2, the HCE uses an improved selective coating, and flex hoses have been replaced with ball joint assemblies. The solar field is composed of 888 LS-3 SCAs (510,120 m2 of mirror aperture) arranged in 148 parallel flow loops with 6 SCAs per loop. The plant is hybridized with a natura l gas fired HTF heater.

2005 Technology: The power plant is scaled up to 160 MW. Six hours of thermal storage is added to the plant to allow the plant to operate at up to a 40% annual capacity factor from solar input alone. No backup fossil operating capability is included. The LS-3 parabolic trough collector continues to be used, but the solar field size is scaled up to allow the plant to achieve higher annual capacity factor using 2,736 SCAs (1,491,120 m2 of mirror aperture) arranged in 456 parallel flow loops with 6 SCAs per loop.

2010 Technology: The power plant is scaled up to 320 MW and operates to an annual capacity factor of 50% from solar input. Again no fossil backup operation is included. This design incorporated the next generation of troug h

Table 4. Performance and cost indicators.

1997

2000

2005

2010

2020

2030

SEGS VI *

SEGS LS-3

SEGS LS-3

SEGS LS-4

SEGS DSG

SEGS DSG

INDICATOR

Base Case

25% Fossil T

w/Storage

w/Storage

w/Storage

w/Storage

NAME

UNITS

+/-%

+/-%

+/-%

+/-%

+/-%

+/-%

Plant Design

Plant Size

MW

30

80

161

320

320

320

Collector Type

LS-2

LS-3

LS-3

LS-4

LS-4

LS-4

Solar Field Area

m2

188,000

510,120

1,491,120

3,531,600

3,374,640

3,204,600

Thermal Storage

Hours

0

0

6

10

10

10

MWht

0

0

3,000

10,042

9,678

9,678

Performance

Capacity Factor

%

34

34

40

50

50

50

Solar Fraction (Net Elec.)

%

66

75

100

100

100

100

Direct Normal Insolation

kWh/m2-yr

2,891

2,725

2,725

2,725

2,725

2,725

Annual Solar to Elec. Eff.

%

10.7

12.9

13.8

14.6

15.3

16.1

Natural Gas (HHV)

GJ

350,000

785,000

0

0

0

0

Annual Energy Production

GWh/yr

89.4

238.3

564.1

1,401.6

1,401.6

1,401.6

Development Assumptions

Plants Built Per Year

2

2

2

3

3

3

Plants at a Single Site

5

5

5

5

5

5

Competitive Bidding Adj.

1.0

1.0

0.9

0.9

0.9

0.9

O&M Cost Adjustment

1.0

0.9

0.85

0.7

0.6

0.6

Operations and Maintenance Cost

Labor

$/kW-yr

32

25

21

25

14

25

11

25

11

25

Materials

31

25

31

25

29

25

23

25

23

25

Total O&M Costs

107

63

52

43

34

34

1. The columns for "+/- %" refer to the uncertainty associated with a given estimate.

2. The construction period is assumed to be 1 year.

3. Totals may be slightly off due to rounding.

* SEGS VI Capital cost of $99.3M in 1989$ is adjusted to $119.2M in 1997$. Limited breakdown of costs by subsystem is available. Performance and O&M costs based on actua l data.

t By comparison, an ISCCS plant built in 2000 with an 80 MW solar increment would have a solar capital cost of $2,400/kW, annual O&M cost of $48/kW, and an annual net solar-to -electric efficiency of 13.5%[1].

i To convert to peak values, the effect of thermal storage must be removed. A first-order estimate can be obtained by dividing installed costs by the solar multiple (i.e., SM={pea k collected solar thermal power}+ {power block thermal power}).

Table 4. Performance and cost indicators.(cont.)

1997

2000

2005

2010

2020

2030

SEGS VI *

SEGS LS-3

SEGS LS-3

SEGS LS-4

SEGS DSG

SEGS DSG

INDICATOR

Base Case

25% Fossil T

w/Storage

w/Storage

w/Storage

w/Storage

NAME

UNITS

+/-%

+/-%

+/-%

+/-%

+/-%

Capital Cost

Structures/Improvements

$/kW

54

79

15

66

15

62

15

60

15

58

15

Collector System

3,048

1,138

25

1,293

25

1,327

25

1,275

25

1,158

25

Thermal Storage System

0

0

392

+50/-25

528

+50/-25

508

+50/-25

508

+50/-25

Steam Gen or HX System

109

15

90

15

81

15

80

15

79

15

Aux Heater/Boiler

120

164

15

0

15

0

15

0

15

0

15

Electric Power Generation

476

15

347

15

282

15

282

15

282

15

Balance of Plant

750

202

15

147

15

120

15

120

15

120

15

Subtotal (A)

3,972

2,168

2,336

2,400

2,326

2,205

Engr, Proj./Const. Manag.

A * 0.08

174

187

192

186

176

Subtotal (B)

3,972

2,342

2,523

2,592

2,512

2,382

Project/Process Conting

B * 0.15

351

378

389

377

357

Total Plant Cost

3,972

2,693

2,901

2,981

2,889

2,739

Land @ $4,942/ha

11

15

18

17

17

$/kWpeakJ

$/m2

3,972 3,972 634

2,704 2,704 424

2,916 1,700 315

2,999 1,400 272

2,907 1,350 276

2,756 1,300 275

Operations and Maintenance Cost

Labor

$/kW-yr

32

25

21

25

14

25

11

25

11

25

Materials

31

25

31

25

29

25

23

25

23

25

Total O&M Costs

107

63

52

43

34

34

1. The columns for "+/- %" refer to the uncertainty associated with a given estimate.

2. The construction period is assumed to be 1 year.

3. Totals may be slightly off due to rounding.

* SEGS VI Capital cost of $99.3M in 1989$ is adjusted to $119.2M in 1997$. Limited breakdown of costs by subsystem is available. Performance and O&M costs based on actua l data.

t By comparison, an ISCCS plant built in 2000 with an 80 MW solar increment would have a solar capital cost of $2,400/kW, annual O&M cost of $48/kW, and an annual net solar-to -electric efficiency of 13.5%[1].

i To convert to peak values, the effect of thermal storage must be removed. A first-order estimate can be obtained by dividing installed costs by the solar multiple (i.e., SM={pea k collected solar thermal power}+ {power block thermal power}).

collector, possibly something like the Luz LS-4 advanced trough collector (over 3,500,000 m2 of mirror aperture). The solar field continues to use a heat transfer fluid but the collector is assumed to have a fixed tilt of 8°.

2020 - 2030 Technology: Power plant size is assumed to remain at 320 MW with 50% annual capacity factor. Thi s design assumes the technology will incorporate direct steam generation (DSG) into the collector in the solar field (over 3,200,000 m2 of mirror aperture).

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