Economic Analysis

For the economic analysis an emerging market for solar tower plants is assumed with concentrator costs of 132 €/m2 for a 120 m2 glass-metal heliostat. The receiver costs are 16 k€/m2, 33 k€/m2 and 37.5 k€/m2 for the low, medium and high temperature receiver.

The investment costs for the conventional part (power block incl. BOP) are 560 €/kW for the Mercury system and 510 €/kW for the PGT10 Combined Cycle system.

For the detailed cost calculations a 2nd generation plant is considered. The engineering cost for gas turbine solarisation are shared between 10 similar plants, and the plant is operated remotely in a ‘virtual park’ of 4 similar plants with a high degree of automation. For the calculation of levelized electricity costs (LEC) a debt rate of 75% at 4.2% interest rate is assumed. Other financial parameters are: common equity rate of 25% at 14% rate of return, 2.5% inflation rate, 12 years debt payback time, 20 years plant lifetime.

The results of the LEC calculations for the stand-alone option can be found in [9]. The total LEC range from about 6.3 €cent/kWh to 20 €cent/kWh depending on power level, capacity factor and solar share. The solar incremental LEC are calculated as the additional costs compared to the generation at a market price of 4 €cent/kWh divided by the incremental solar generated electricity. They range from about 12.8 €cent/kWh to 41.4 €cent/kWh for the 2nd generation plants in daytime operation (Table 2).. For the largest system a total LEC of 8.6 €cent/kWh at a solar share above 50% is calculated.

power system

Mercury-50 800°C

PGT10 800°C

PGT10 1000°C

ISO rating

[MW]

4.2

16.1

16.1

annual DNI

[kWh/m2]

2791

2791

2791

receiver therm. power at DP

[MW]

3.5

18.5

28.59

solar fraction at DP

38.3%

57.8%

87.8%

total refl. area

[m2]

7038

37615

62733

receiver aperture

[m2]

12

55

82

optical tower height

[m]

50

100

130

capacity factor

54.0%

54.0%

54.0%

net. electric energy

[MWh]

17170

66294

62738

solar incremental electricity

[MWh]

3060

20511

32914

incremental solar share

17.8%

30.9%

52.5%

incremental CO2 avoidance

[t/a]

1680

9537

15304

incr. solar to electric efficiency

15.6%

19.5%

18.8%

total investment costs

[T€]

6302

20421

26023

thereof solar equipment

33.8%

37.2%

47.1%

spec. investment costs

[€/kWe]

1801

1438

1859

fixed O&M costs

[T€/a]

725

1572

1887

thereof personal expenses

33.5%

47.2%

49.7%

fuel costs

[€/MWh LHV]

13.43

13.43

13.43

levelised electricity cost (LEC)

[€/kWh]

0.1066

0.0764

0.0860

CO2 avoidance cost

[€/kg]

0.6804

0.2531

0.1884

solar incremental LEC

[€/kWh]

0.4135

0.1577

0.1276

Table 2: Summary of performance calculation and cost analysis for daytime operation

Relating the solar LEC to the annual amount of CO2 that can be avoided3 when operating the hybrid plant instead of the pure fossil reference plant, the CO2-avoidance costs can be calculated for each individual plant. For the higher power level a value well below 200 €/ton CO2 can be reached.

a CO2 production from natural gas of 200 kg/MWh LHV is assumed.

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