TASK 2 FINAL REPORT.pdf

7/25/2019 TASK 2 FINAL REPORT.pdf

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TECHNICAL ADVISOR FOR A CSP

PROJECT IN SOUTH AFRICA

DOC. CODE SO-DV-1006

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South Africa, North Cape Region,BOKPOORT

TECHNICAL ADVISOR FOR A

CSP PROJECT IN SOUTH AFRICA

Task 2

Owner Technical Specification Revision andPlant Configuration Study

Final Report


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DOCUMENT REVIEW

Review Date Changes

0 13/12/2010 Document Creation


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CONTENTS

1 OVERVIEW ........................................................................................................... 5

2 DNI ASSESSMENT ............................................................................................... 6

2.1 Available data ................................................................................................. 6

2.1.1 Satellite derived data analysis ............................................................... 8

2.2 Alternative sources of data .............................................................................. 9

2.2.1 Analysis of alternative sources of data ................................................ 13

2.3 Generation of PoE scenarios for annual hourly DNI data sets ....................... 14

3 PLANT CONFIGURATION DESIGN .................................................................... 16

3.1 General Design Parameters .......................................................................... 16

3.2 Power block design ....................................................................................... 17

3.2.1 Steam cycle considerations ................................................................. 17

3.2.2 Different cooling alternatives considered ............................................. 19

3.3 Solar field design .......................................................................................... 25

3.3.1 Main equipment consideration ............................................................. 25

3.3.2 Solar field configuration ....................................................................... 25

3.3.3 Solar field alternatives studied ............................................................. 26

3.4 Performance models ..................................................................................... 27

3.4.1 Solar radiation ..................................................................................... 27

3.4.2 Solar Field ........................................................................................... 28

3.4.3 Power Plant availability ....................................................................... 30


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3.5.4 Auxiliary cooling circuit's replacement ................................................. 34

3.5.5 Services water..................................................................................... 34

3.5.6 Potable water ...................................................................................... 35

3.5.7 Fire Protection System Water .............................................................. 35

4 POWER PLANT CALCULATIONS ....................................................................... 36

4.1 Power Block .................................................................................................. 36

4.1.1 Heat and mass balances ..................................................................... 36

4.1.2 Power block efficiencies ...................................................................... 36

4.1.3 Water Balances ................................................................................... 39

4.2 Comparative Solar Advisor Model / Propietary Model ................................... 39

4.3 Performance results ...................................................................................... 40

4.3.1 Option 1: LFO used only for anti-freezing and gland steam generation 41

4.3.2 Option 2: LFO firing up to 15%. ........................................................... 51

5 POWER PLANT OPTIMIZATION ........................................................................ 61

5.1 Methodology ................................................................................................. 61

5.2 Assessment CAPEX & OPEX ....................................................................... 61

5.3 LCOE ............................................................................................................ 63

5.4 Best configuration ......................................................................................... 64

5.4.1 Detailed results ................................................................................... 64

5.5 Radiation scenarios ...................................................................................... 71

ANNEX 1: WATER BALANCES .................................................................................. 77

ANNEX 2: CAPEX ...................................................................................................... 78


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1 OVERVIEW

The main objective of this report it is to show the results of the CSP power plant sizing

that, ACWA Power is developing in Bokpoort, North Cape Region in South Africa.

This report covers all topics included in Task 2 of the contract for Technical Adviser fora CSP project in South Africa, celebrated among ACWA Power and SOLIDA. Namely,

those topics can be summarized as follows:

1. Assessment of yearly DNI PoE scenarios for the plant site, located in

Bokpoort, South Africa. Yearly time series must be derived by SOLIDA based

on the available data and following their best criteria. As pointed out by ACWA

Power, it is better at this stage to play a conservative approach in this regard

and make sure that the DNI values utilized are not higher than those confirmedonce the actual year-round time series are available from the meteo station.

2. Assessment of yearly LFO usage. It is not yet clear the approach to be

followed by the South African government regarding maximum yearly

consumption of fossil fuels in CSP plants under the REFIT scheme. In addition

to that, LFO costs at the plant site are very high. For those reasons, ACWA

Power has indicated that it is necessary to evaluate two different alternatives:

Option 1: LFO usage only for anti-freezing labors and gland steamgeneration, in order to minimize LFO consumption.

Option 2:LFO usage to enhance the yearly output, using auxiliary LFO

heaters.

3. Assessment of different cooling options in plant performance.It is not yet

clear what will be the outcome of the water concession permitting for the CSP

plant in Bokpoort. All options, going from wet cooling tower to air cooledcondenser, are considered and compared in this report.

The report is structured so that the different topics are covered in chronological order,

i.e. the order in which SOLIDA has confronted each of them. The starting point is the

DNI assessment, where thorough explanations are given regarding the available data

and the PoE scenarios derived by SOLIDA After that different plant configuration


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2 DNI ASSESSMENT

2.1 Available data

SOLIDA has had access to the following sources of data concerning solar resource

evaluation at the site:

- Satellite derived data:

o NASA Data Base: Monthly values of global horizontal radiation (Ghi) and

normal direct radiation (DNI).

0

1

2

3

4

5

6

7

8

9

10

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Daily average radiation (kWh/m2)

DNI (KWh/m2) NASA Ghi(KWh/m2) NASA

The representative daily average values for each month of the typical

year are shown in section2.2 of this document. The resulting annual value of

DNI for this set of data is 2.733,21 kWh/m2.

o NREL Data Base: Monthly values of global horizontal radiation (Ghi) and

normal direct radiation (DNI).

Daily average radiation (kWh/m2)


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o HELIOCLIM3 Data Base: Monthly and hourly values of global horizontal

radiation (Ghi) and normal direct radiation (DNI).




- Hourly data from a measuring station located on the site (lat 28.738S, long

21.972E).

From May the 28thto July, the ground station located on the site was measuring

global horizontal radiation (Ghi) and diffused irradiation (Di) with two separate

(t CMP 6 t f th ith h d b d i t ll d)


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The table below shows the DNI monthly values measured at the site:

Month DNI (KWh/m2)

Jun 226,47

Jul 185,27

Aug 234,30

Sep 234,30

Oct 245,37

Nov 289,47

2.1.1 Satellite derived data analysis

Performing a simple analysis of the available data during the measured period it seems

obvious that the different sources of available data correlate rather differently with the

actually measured data.

0,00

50,00

100,00

150,00

200,00

250,00

300,00

350,00

Jun Jul Aug Sep Oct Nov

Monthly radiation (kWh/m2)

DNI (KWh/ 2) NREL DNI (KWh/ 2) NASA


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6,23

6,71

7,56 7,7

7,42

9,11

6,686,89

7,49 7,43

7,72

8,38

4,20

5,10

5,90

6,38

6,76

7,10

7,55

5,98

7,567,81 7,92

9,65

4

5

6

7

8

9

10

Jun Jul Aug Sep Oct Nov

DNI average daily values (kWh/m2)

DNI (KWh/m2) NREL

DNI (KWh/m2) NASA

DNI (KWh/m2) HC3DNI (KWh/m2) MEASURED

As it is show in the previous graphics, the measured data trend is very similar to

NASA/NREL data. At first sight, it my be concluded that if the current trend continues

for the rest of the year, the expected values of annual DNI may well be above 2800

kWh/m2.

On the other hand, Helioclim3 data looks very conservative, providing an annual DNI

value of around 2200 kWh/m2, more than 20% below the other satellite sources of data.

SOLIDA has decided to discard this set of data f as input for our analysis, since the

deviation range for Helioclim is too high and there are other sources of data which

seem to correlate much better with the measured data.

SOLIDA has already established contact with the Helioclim-3 support services (SoDa)

in order to solve this problem by sharing with them the ground-measured data, so thatthe parameters of satellite estimation can be fine-tuned against actually measured data

at the location. Our preliminary conclusion is that their algorithim may be using a Linke

turbidity factor which is too high for this location, thereby underestimating severely the

higher values of DNI which mostly occur around noon. This underestimation yields a

very conservative yearly sum of DNI If our preliminary conclusion is correct correcting


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satisfactorily with the actually measured data. Although alternative sources of data

have been produced, our recommendation is that the problem be fixed and that a

consistent, long term series of DNI data is obtained for this site. Otherwise, bankability

of this site may be compromised.

Through a combination of the NASA database and the Meteonorm tool, SOLIDA hasderived a DNI series of data which correlates reasonably with themeasured data. A

description of Meteonorm tool/database and NASA database is provided below.

METEONORM

Meteonorm is a comprehensive climatological database for solar energy applications. It

has a broad base of meteorological stations through which provides hourly radiation

data.

The generation of hourly values is based on the model of Aguiar and Collares-Pereira(1992) (TAGmodel: Time dependent, Autoregressive, Gaussian model). This modelconsists of two parts: the first part calculates an average daily profile; the second partsimulates the intermittent hourly variations by superimposing an autoregressiveprocedure of the first order (AR(1)-procedure) (Box etal., 1994).

In the used version, Meteonorm 6.1, satellite data is used for radiation interpolation in

remote areas. Where no radiation measurement is nearer than 300 km satellite

information is used. If the nearest site is more than 50 km away, a mixture of ground

and satellite information is used.

For the selected site, Bokpoort, Meteonorm provides hourly values radiation through

the interpolation between three weather stations near the power plant and satellite

information.

Therefore Meteonorm used sources for obtaining radiation data on the selected site are

the following:

- Upington, situated 77 km from the site (In that station temperature data has

been measured from 1961 to 2005 and radiation data from 1961 to 1970)

- Kimberley situated 273 km from the site. (In that station temperature data has

been measured from 1961 to 2005 and radiation data from 1961 to 1970)


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Meteonorm does not provide maximum and minimum values, which prevent the

generation of the PoE15 and the PoE85 scenarios.

NASA

NASA, through its' Science Mission Directorate, has long supported satellite systems

and research providing data important to the study of climate and climate processes.These data include long-term estimates of meteorological quantities and surface solar

energy fluxes. Release 6.0 extends the temporal coverage of the solar and

meteorological data from 10 years to more than 22 years (e.g. July 1983 through June

2005).

The radiation data provided by the NASA belongs to a period of 22 years, with the

following values:

- Monthly averaged global insolation incident on a horizontal surface

(kWh/m2/day).

- Minimum and Maximum difference from monthly averaged global insolation (%).

- Monthly averaged diffuse radiation incident on a horizontal surface

(kWh/m2/day)

- Minimum and Maximum values from monthly averaged diffuse insolation(kWh/m2/day).

- Monthly averaged Direct Normal Radiation (kWh/m2/day)

- Minimum and Maximum difference from monthly averaged Direct Normal

Radiation insolation (%).

Global radiation (kWh/m2/day)

Average Minimun MaximunJan 7,93 7,45 8,56

Feb 6,96 6,19 7,73

Mar 5,95 5,36 6,55

Apr 4,80 3,98 5,52


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Diffuse radiation (kWh/m2/day)

Average Minimun Maximun

Jan 2,00 1.68 2.19

Feb 1,91 1.57 2.17

Mar 1,59 1.33 1.80Apr 1,21 0.87 1.47

May 0,84 0.61 1.05

Jun 0,69 0.48 0.91

Jul 0,72 0.58 0.93

Aug 0,87 0.68 1.17

Sep 1,28 1.00 1.51

Oct 1,68 1.42 1.93Nov 1,93 1.51 2.23

Dec 1,99 1.62 2.32

Direct Normal radiation (kWh/m2/day)

Average Minimun Maximun

Jan 8,63 8,46 9,23

Feb 7,49 6,89 8,24

Mar 6,88 6,40 7,43

Apr 6,41 5,58 7,18

May 6,56 6,04 7,02

Jun 6,59 5,93 6,92

Jul 6,84 6,09 6,91

Aug 7,44 6,55 7,51

Sep 7,39 6,95 7,83

Oct 7,69 7,15 8,07

Nov 8,36 7,86 9,11

Dec 9,03 8,40 9,57


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2.2.1 Analysis of alternative sources of data

In order to find out which of the hourly radiation series available better represents the

actually measured data, SOLIDA has calculated the coefficient of determination (R2).

The coefficient of determination is a statistical method that explains how much of the

variability of a factor can be caused or explained by its relationship to another factor.Used in trend analysis, it is computed as a value between 0 (0 percent) and 1 (100

percent) higher the value, better the fit. Symbolized by 'R2' because it is square of

'Pearsons coefficient of correlation' symbolized by 'r', it is an important tool in

determining thedegree of linear-correlation ofvariables inregression analysis.

Coefficient of determination R2

Meteonorm data Nasa data

June 0,88 0,85

July 0,76 0,66

August 0,88 0,85

September 0,69 0,52

October 0,63 0,59

The table above shows the coefficient of determination between satellite derived data

and ground station measured data. It is important to note the following issues:

1. September seems to have been a rather irregular month as measured by themeteo station.

2. In theory, running correlations between actually measured data and averaged

data (which is what both Meteonorm and NASA provide) can never yield high

correlations as they are representing somewhat different phenomena.
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asset at this stage, due to the uncertainty of the different sources of data

and the short period for which actual measurements are available.

b. NASA data offer average daily DNI data as well as actually registered

maximum and minimum data, which are key for estimating standard

deviation of the monthly series and therefore inferring Probability ofExceedance scenarios.

2.3 Generation of PoE scenarios for annual hourly DNI data sets

As previously mentioned in this report, PoE scenarios can be derived for a sample of

data for which sample size, average, maximum and minimum values are known. In the

case of NASA data set, as shown in section 2.2, all those data are available. Theprocedure followed to derive PoE scenarios using the available data is described below

and the results are attached to this report as an annex.

The methodology is based on the assumption that DNI values follow a normal

distribution. There is a statistical relationship (Patnaik, 1946) between the mean range

for data from a normal distribution and , the standard deviation of that distribution.

This relationship depends only on the sample size, n. The mean of R is d2 , where

the value of d2 is also a function of n. An estimator of is therefore R /d2.

Where:

s: Standard deviation

R: range of maximum and minimum values

d2: Factor to calculate the standard deviation from the sample size.

Sample size (n) 2 3 4 5 6 7 8 9 10 15 20 24 25

d2 1,128 1,693 2,059 2,326 2,534 2,704 2,847 2,97 3,078 3,472 3,375 3,895 3,931


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For simplicity purposes, we have chosen the following PoEs:

p85 which corresponds to 1

p15 which corresponds to + 1

The corresponding values of daily DNI are calculated (shown in table below) and usedas input to Meteonorm software, which in turn derives the corresponding hourly series

of data. The complete p15 and p85 series of data are attached as annexes 3 and 4 to

this report.

Monthly Averaged Direct Normal Irradiation (kWh/m2

m)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

P15 274,15 220,11 222,08 205,53 211,75 205,86 219,04 238,89 229,02 246,26 261,15 289,94

P50 267,53 209,72 213,28 192,30 203,36 197,70 212,04 230,64 221,70 238,39 250,80 279,93

P85 260,91 199,33 204,48 179,07 194,97 189,54 205,04 222,39 214,38 230,52 240,45 269,92

The tables below show the correlation of the different series of data generated against

the ground station measured data.

Coefficient of determination R2

SITE SITE SITE SITE

METEONORM METEO_NASA_P15 METEONORM_NASA_P50 METEO_NASA_P85June 0.88 0.90 0.85 0.87

July 0.76 0.80 0.66 0.70

August 0.88 0.88 0.85 0.83

September 0.69 0.59 0.52 0.55


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3 PLANT CONFIGURATION DESIGN

3.1 General Design Parameters

The following parameters and concepts have been considered when designing the

layout for the CSP Solafrica project.

Minimize the occupied land area.

Avoid potential impacts in:

- Roads- Railways- Hydrological channels- Environmental protected areas

Avoid the occupation of abrupt areas of the land farm in order to minimize theearth movement.

The slope of the site is an important factor to be taken into account. Based onthis point, the solar field could be designed in one or several terraces.

Situation of the electrical infrastructure of the power plant respect to theevacuation substation. The location of the BOP and especially the maintransformer and overhead line route should be defined based on this criterion.

Situation of the water supply source (when wet or hybrid cooling system isused). The location of the raw water supply and effluent disposal system intothe BOP should be defined based on this criterion.

Availability of access roads. The situation of the main access to the power plantand solar fields should be defined based on this criterion.

Separation distances required between solar sub-fields, which are required for

laying out the heat transfer fluid pipes and the thermal expansion lyres.


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South Africa, North Cape Region,

BOKPOORT

3.2 Power block design

3.2.1 Steam cycle considerations

SOLIDA has utilized THERMOFLEX software to evaluate the steam power cycleefficiency.

THERMOFLEX is a modular program with a graphical interface that allows assembling

a model from icons representing different components. The program covers both

design and off-design simulation, modeling all types of commercial power plants.

The 55 MW SST 700 Siemens steam turbine has been used as an input to derive the

84 MW gross power output cycle that has served as the basis for the present study.

This steam turbine is a tandem-compound reheat condensing unit, with high

speed/high pressure section connected by a speed reduction gear to a single-flow-

single-casing low pressure reheat section.

The turbine has two rotors (high and low pressure) connected to each other through

the speed reduction gear and to the generator rotor with a solid bolted coupling. Therotors are supported by journal bearings and located axially by thrust bearings.

The steam is admitted to the HP turbine via an emergency stop valve and a control

valve.

SST-700 General Parameters:

a. Admission conditions HP-module

Admission pressure

Rated 105.0 bara/ 1522.9 psia

Normal 105.0 bara/ 1522.9 psia

Admission temperature


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BOKPOORT

c. Exhaust conditions, HP-module

Exhaust (back pressure) pressure

Normal 20.7 bara/ 300.2 psia

Alarm high 21.7 bara/ 314.7 psia

Trip high 22.8 bara/ 330.7 psia Exhaust temperature

Normal 214.0 C/ 417.2 F

Alarm high (max 1 h operation) 250.0 C/ 482.0 F

Automatic shutdown 360.0 C/ 680.0 F

d. Exhaust conditions, LP-module

Exhaust (condenser) pressure

Normal 0.066 bara/ 0.96 psia/ 1.9 "HgA

Alarm high 0.16 bara/ 2.3 psia/ 4.7 "HgA

Trip high 0.23 bara/ 3.3 psia/ 6.8 "HgA

Exhaust temperature at blade row L-1

Normal 57.0 C/ 134.6 F

Alarm high (max 1.0 h operation) 180.0 C/ 356.0 FAutomatic shutdown 200.0 C/ 392.0 F

Exhaust temperature at blade row L-0

Normal 34.0 C/ 93.2 F

Alarm high (max 1.0 h operation) 85.0 C/ 185.0 F

Automatic shutdown 105.0 C/ 221.0 F


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BOKPOORT

Curve 1: Rated temperature HP-turbine inlet (390C)

Curve 2: Rated pressure HP-turbine inlet (105 bara)

Curve 3: HP-turbine exhaust moisture limitation (VWO)

Curve 4: HP start-up limit (50C) superheatCurve 5: HP start-up limit low boiler pressure (35 bara)

Curve 6: Rated temperature LP-turbine inlet (390C)

Curve 7: Rated pressure LP-turbine inlet (19 bara)

Curve 8: LP-turbine exhaust moisture limitation (VWO)

Curve 9: LP start-up limit (50C) superheatCurve 10: LP low inlet temperature (200C)

3.2.2 Different cooling alternatives considered

In the course of this task, SOLIDA has considered the following cooling options based

on ACWA Power requirements: Wet Cooling Tower

Air Cooled Condenser

Hybrid Cooling Tower

Combine Wet Cooling Tower with Air Cooled Refrigerants

WET COOLING TOWER

This cooling system is based on the use of evaporative cooling tower, induced draft

and countercurrent flow.

Thi li t b d fi d h t h ti d di t t t


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BOKPOORT

The air can enter through one or more sides of the tower, it is achieved reducing the

height of air inlet.

In this type of tower, the hot water from the condenser enters the upper part of the

tower and it is sprayed on the filler material of the tower, coming into contact with the

air that rises through the tower. This causes a portion of the water evaporates and theother is driven by the air induced. The cooling capacity of the tower is directly

proportional to the surface and to the air-water contact time.

The cooled water is collected in a collect located at the base of the tower from where

this water is sent to the condenser. The control system can automatically control the

cooling water temperature by regulating the ventilation.

The basin of cooled water must have the necessary accessories to measure the

excess effluent, based on which we calculate the concentration of chemicals dosed inthe cooling system.

A water supply line arrives from the chemical dosing system of tower. The chemical

dosing system incorporates additives continuously or periodically to remove the

encrustations of dissolved salts, inhibit the corrosion and prevent the deposit formation

and the proliferation of organic matter. The losses occurring in the cooling water circuit,

due to the evaporation, the blowdown and the drag in the cooling tower are replaced

with the water through a supply line.

Therefore, the cooling tower has two different parts: the cooling zone and the basin

water.


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BOKPOORT

Allow great flexibility in its operation and it can work at more or less capacity

depending on the specific requirements of the plant

The wet cooling towers are able to work with low condensate temperatures

achieving higher cycle efficiency than other cooling technologies.

It is the cheapest cooling technology solution.

And the main disadvantages are:

The main disadvantage of this system is that it needs a high water make-up

consumption derived from the evaporation and drift losses.

It is necessary to use chemicals and biocides for the water treatment, which

increase the operation cost.

The power consumption of the system is higher than the other cooling

technologies evaluated, due to cooling water pumps and fan motors.

AIR COOLED CONDENSER

The operation of the air cooled condenser is based on the cooling of the steam by the

basic principle of convection cooling, using the airflow as a refrigerant. It is based onthe exchange of heat between the atmospheric air and steam from the exhaust turbine.

The steam is passed through a heat exchanger composed of finned tube bundles that

increase the contact surface of the steam. It grouped into modules and mounted on a

steel support structure. The tubes bundles of the heat exchanger seem to be a house

roof. In the lower part the fans are positioned so that the air transversely flows through

the heat exchanger. The fluid is cooling with the metal contact of the air cooled

condenser, which in turn it is cooled by the airflow generate by the fans.This type of air cooled condenser uses a condensation process in two stages First, the

steam is guided from the steam turbine to the air cooled condenser where it enters in

parallel flow to the tube panels in the top part. The steam is partially condensed in the

flow parallel modules, the remaining steam is guided through the down heads in


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BOKPOORT

Air coo led condens er (Source:GEA)

The main advantages are:

It is only used air as a refrigerant, no water consumption for cooling. It can be

applied in situations where the water availability is limited.

Can be applied in situations where the plume formation is not acceptable.

The power consumption is lower than the consumption of wet cooling towers,

because the system does not employ cooling water pumps.

The main disadvantages are:

The initial capital cost is higher.

Large heat transfer surfaces are necessary. Therefore the space requirementfor installation is high.

If winter temperatures are too low it can cause freezing problems in the

process.


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BOKPOORT

It is a combination of a wet and dry cooling tower or, in other words, of an evaporative

and a convection process. The hybrid cooling tower can be operated either as a pure

wet cooling tower or as a combined wet/dry cooling tower, depending on the ambient

temperature. The heated cooling water first passes through a dry section of the cooling

tower, where part of the heat load is removed by an air current, which is often induced

by a fan. After passing the dry section, water is further cooled in the wet section of thetower, which functions similarly to an open recirculating tower. The heated air from the

dry section is mixed with the steam from the wet section in the upper part of the tower,

thus lowering the relative humidity before the air current leaves the cooling tower,

which completely reduces plume formation above the tower.

Hybr id Coo l ing Tow er (Source: Eurelectr ic)

The main advantages are:

Less water consumption than wet cooling tower technology

Plume abatement


The investment cost is higher than wet cooling tower solutions


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BOKPOORT

The combination of a wet cooling system and a dry cooling system in parallel

allows keeping the power plant working in case no water is available.


Large heat transfer surfaces are required. Therefore the space requirement for

installation within the power block is high (around 10.000 m2for a plant of thismagnitude).

More complexity in the power plant control when working in air refrigerant

mode. This is due to the variation of condensing pressure.

More complexity in the cooling system control based on the redundancy of

cooling equipment.

More complexity in the cooling piping lay-out.

The following table shows a comparison of the three possible options of cooling

Wet Cooling

TowerHybrid Cooling Tower

Air Cooling

Condenser

Site Near the water Near the water No restriction

Operation Easy More Difficult Easy

Maintenance Low High Low

Water treatment Yes Yes No

Plume Yes No (reduced) Never

Noise Yes YesSound attenuation

equipment


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BOKPOORT

3.3 Solar field design

3.3.1 Main equipment consideration

A field of distributed parabolic trough collectors collects direct radiation from the sun

and transfers it to a HTF circulating through heat collecting elements located in thefocal line of the parabolic collector.

The solar system is built up from solar collector assemblies (SCAs), each one

consisting of a row of individual trough collectors driven by a single train. The mirrored

parabolic troughs concentrate direct radiation onto the heat collection element (HCE),

which is a steel pipe with a special selective coating surrounded by an evacuated

annulus to enhance performance.

3.3.2 Solar field configuration

SOLIDA proposes two main alternatives for this solar field configuration. A four (4)

subfields configuration and a three (3) subfields configuration.

The following pictures show the solar field expansion options for ach alternative.


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BOKPOORT

mainly based on the HTF piping system sizing. In the four sub-fields configuration the

piping system must be previously prepared for the final configuration.

3.3.3 Solar field alternatives studied

SOLIDA has determined different solar field sizes that could be set at the site.

Due to the clients premises, we have analyzed only the possibility of a power plant

without thermal storage.

The different solar field configurations studied are the following:

Row-to-row spacing: 17 m

- Solar field size: 96 loops

- Number of subfields: 3

- Sub-field 1: 32 loops












Sub field 3: 44 loops


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3.4 Performance models

SOLIDA has performed its calculations using its proprietary performance model. In

order to give higher reassurance to ACWA Power, the same calculations have been

derived using SAM


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MONTH Ghi(kWh/m2) Dh(kWh/m2) DNI (kW/m2)

Jan 244,76 61,75 266,43

Feb 193,85 53,09 205,49

Mar 183,63 49,10 208,80

Apr 143,93 35,99 194,04

May 124,19 26,03 189,32

Jun 108,01 20,16 184,43

Jul 119,74 22,32 197,13

Aug 148,81 26,03 226,55

Sep 172,80 38,16 222,42

Oct 209,79 52,08 233,66

Nov 228,91 56,87 249,04

Dec 253,66 61,01 276,82

2.132,06 502,58 2.654,12

A representation of the estimated radiation data monthly distribution can be seen in the

graphic below:

50

100

150

200

250

300

kWh

/m2

Ghi(kWh/m2)

Dh(kWh/m2)

DNI (kW/m2)


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For efficiency calculations the incidence angle modifier expression, given in the final

report of the European project 'Eurotrough - II', has been used.

3.4.2.2 Parabolic reflectors

The mission of these mirrors is to reflect the incident radiation, projecting and

concentrating it on the absorber. Therefore their properties are very important in the

solar radiation collection:

Reflective aperture area: 817,5 m2

Mirror cleanliness factor: 97% (taking into account the periodic cleaning cycles)

Mirror reflectivity: 92,5%

It is considered a nominal value of the intercept factor, which decreases with

wind speed.

o IAM = 1(a * IA + b*IA^2)/cosIA

o IAM, ET II, factor a: 0,000278005

o IAM, ETII, factor b: 0,000042806

3.4.2.3 Absorbers

Absorbers are one of the main elements of the collector. These elements have

important repercussion in the high collection efficiency of solar radiation.

Number of absorbers per collector: 36

Collecting surface: 0,89 m2/absorber

Nominal absorptivity of the selecting coating: 95% Glass transmisivity: 96%

Estimation of losses derived of the connections between absorbers.

For emissivity losses calculations, it is used a mean temperature difference


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3.4.2.6 Efficiency of the collector loops

It is calculated as the ratio between the net absorbed thermal power in the loop and the

incident radiation.

The following graphic shows the loop efficiency variation as a function of the solar

radiation incidence angle.

0,0%

10,0%

20,0%

30,0%

40,0%

50,0%

60,0%

70,0%

0 10 20 30 40 50 60 70

1050 kWh/m2

900 kWh/m2

750 kWh/m2

600 kWh/m2

450 kWh/m2

300 kWh/m2

3.4.3 Power Plant availability

It has been set at 98% of the percentage time when the power plant is available for

normal operation.

This parameter takes into account the scheduled stops for maintenance labors and

those forced shutdown due to unavoidable reasons.

3.4.4 Configuration of power block

The production model require the introduction of the power cycle parameters that allow

perform the conversion between the thermal energy collected in the solar field and the

electric energy produced in the generator terminals.

As it was described in previous sections, the model has taken as reference the SST-


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1. Freezing prevention (anti freezing): These heaters can supply heat to the HTF

system to prevent HTF freezing.

2. Gland steam: a small boiler can be used to supply supplemental steam. It can

be avoided; some CSP plants in Spain have managed to skip it. Also some of

the SEGS plants do not have it. However for guarantee reasons vis a vis the

turbine manufacturer and hence due to bankability issues, it seems necessary

to consider this boiler.

Option 2: LFO firing up to 15%.

CSP power plants can operate in three modes:

Solar only mode: in this mode the HTF collect the thermal energy necessary in

the steam generator flowing only through the solar field.

Hybrid model (solar and fuel): The auxiliary fuel-fired HTF heater acts, in

parallel to the solar field, as and additional source to heat the HTF. This mode

is useful for reducing start-up time in the morning, as a booster in the event of

inclement meteorological conditions and for extending solar operating time in

evening hours.

Fuel only mode: in this case the auxiliary fuel fired HTF heater is the only

source of energy to produce turbine inlet steam. The HTF flow by-passes thesolar field entirely and circulates between the HTF heater and the steam

generator. This mode allows the production of electricity independently from

solar insolation or during solar field shutdowns.

This kind of plant has specific needs of conventional fuel due to the following reasons:

1. Enhancement of yearly output: during periods of low solar insolation and in the

evenings when electrical generation is planned, the supplemental fossil-fired

HTF heater can be operated to provide energy to produce turbine steam (solar

and fuel mode). The supplemental fossil-fired HTF heater can also be operated

alone to provide energy to produce turbine steam (fuel only mode).

2. Freezing prevention (anti freezing): These heaters can supply heat to the HTF


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Firing strategy: Top up solar field plus stand-alone firing if necessary to reach

15% limit.

The type of conventional fuel source considered is LFO. Light Fuel Oil (LFO) is a crude

oil distillated. It is light in color and has on average a specific gravity in the range of

0.82 to 0.86. LFO is usually composed mostly of carbon (86% wt.), hydrogen (13%

wt.) and sulphur (0.1 to 0.2% wt.). It also contains trace amounts of ash and sediments.

Density 0.85 - 0.86 kg/litre

Kinematic Viscosity 1 - 3 cSt

Boiling Point 340-400 C

Calorific value 44 MJ/kg typical

Ashes 0.05 %wt maximum

3.4.6 Energy losses

Energy losses that are been taken into account are described below:

Daytime and nighttime losses of the HTF piping system. These include thermal

losses of the steam generator system, HTF pipes and the expansion and

overflow tanks.

Heat losses in collector loops: the model calculates these losses as the

difference between the theoretical maximum power that could be absorbed in

the collector loops and the power actually absorbed due to the efficiency.

- The model considers the selective coating emissivity variation as a

function of the temperature.

Shading: the model is able to calculate the quantity of energy that the solar field

is unable to collect due to the projected shadows on the adjacent collectors.


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A CSP power plant presents the self-supply power of a conventional

thermoelectric power plant, namely, pumping of condensate, feedwater pumps,

cooling water pumping, fans etc.

3.5 Water Consumption Model

The water balance of the plant has been carried out for an optimized plant without

thermal storage.

In order to carry out the study of the needs of raw water and the volume of the

generated discharge in the Solafrica Solar Thermoelectric Power Plant, the calculation

has been structured in two phases:

Phase I: Study of the water flows consumed and the discharges generated by

the different configurations of the power plant in nominal operating conditions.

Phase II: Definition of the power plant consumptions and discharge total

volumes.

The main water consumptions for the proper functioning of Solar Thermoelectric Power

Plant are as follows:

3.5.1 Cooling system water necessities

Three possible cooling system alternatives have been considered for the power plant:

Wet cooling towers.

Air cooling condenser.

Hybrid cooling towers.

A simulation of water consumption has been made for each different cooling system,

using Thermoflex softwarebalances and SOLIDAs proprietary model.

3.5.1.1 Wet cooling towers


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Considering a cooling system for the power plant with hybrid cooling tower, the

operation of the towers has been modeled taking into account the functioning of the

power block, the expected environmental conditions (conditions of the evaporation

process and drift losses that happen inside the towers) and the system blowdowns.

3.5.1.3 Air cooled condenserIn order to simulate the cooling with air cooled condensers, the functioning of the power

block and the expected environmental conditions (conditions of dry cooling process)

have been considered.

3.5.2 Washing mirrors water

The water used for periodic cleaning of the solar fields mirrors, it is water from the

demineralization system of the power plant. In order to carry out the calculations of

flows and volumes consumed annually in performing this task, the following

considerations have been taken into account:

3 times a month (1 time per week) a low-pressure washing will be carried out

- Amount of water needed: 2,80 l/m2.

- Frequency: three weeks a month.

1 time per month, a high-pressure washing will be carried out

- Volume of water required: 2,24 l/m2.

- Frequency: one week per month.

3.5.3 Blowdowns water replacement

The continuous blowdowns and venting that are conducted in different points of thewater-steam circuit, imply the need to replace the circuit with the same amounts of

water in the condenser.

The water consumption results for the water-steam system, have been obtained from

the simulation made with the software "Thermoflex" and a proprietary model.

DOC CODE


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Therefore, based on the estimated annual operating hours of the plant, it is obtained

the total volume of services water consumed.

3.5.6 Potable water

Based on other power plants with the same staff (40 people) and considering an

average consumption of 300 liters per person and day, the annual consumption ofpotable water in the power plant is estimated.

3.5.7 Fire Protection System Water

The flow required for the fire protection system of the power plant, is considered to be

intermittent, so that for the total water consumption of the power plant, it will be

considered a first filling of the system.

DOC CODE SO DV 1006


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4 POWER PLANT CALCULATIONS

4.1 Power Block

4.1.1 Heat and mass balances

The analyzed power plant is based on a conventional Rankine steam cycle with reheat,but with solar energy as the heat source to generate the steam to drive the turbine.

All the heat balances are for a steam cycle with two-casing reheat turbine and six

turbine extractions leading to two high pressure feedwater heaters, three low pressure

feedwater heaters and a deaerator.

The following balances are included in the attached file Heat&Mass_balances:

Rankine cycle with wet cooling tower analyzed at different loads: 100-90-75-50-40%

Rankine cycle with wet cooling tower analyzed at full load with different

temperatures: 35-25-15 C

Rankine cycle with air cooling condenser analyzed at different loads: 100-90-

75-50-40%

Rankine cycle with air cooling condenser analyzed at full load with differenttemperatures: 35-25-15 C

Rankine cycle with hybrid cooling tower analyzed at different loads: 100-90-75-

50%

Rankine cycle with hybrid cooling tower analyzed at full load with different

temperatures: 35-25-15 C

4.1.2 Power block efficiencies

SOLIDA has utilized THERMOFLEX software to evaluate the steam turbine efficiency.

The outputs of the steam turbine for the 84 MW gross power output have been derived

from the 55 MW SST 700 Siemens steam turbine

DOC CODE SO-DV-1006


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The following graphic shows the curve described by the data presented in the table and

the curve traced by the model to simulate the operation of the turbine. As shown the

equation that calculates the model fits perfectly with the actual operation of the turbine.

0,0%

5,0%

10,0%

15,0%

20,0%

25,0%

30,0%

35,0%

40,0%

45,0%

0 20 40 60 80 100 120 140 160

55 MW Steam Turbine Efficiency

The following graphics simulate the operation of the turbine depending on the cooling

system used.

Wet cooling system

Q (MWth) P(MWe) Efficiency (%)

79 29 36,1%

102 38 37,1%

156 60 38,5%

189 74 38,9%

211 82 39,0%



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Dry cooling system


31 8 25,2%

63 19 30,7%

113 39 34,3%164 58 35,4%

215 77 36,0%

Hybrid cooling system


31 8 25,6%

63 20 31,2%

113 39 34,9%

164 59 36,0%

215 79 36,6%

TECHNICAL ADVISOR FOR A CSPDOC. CODE SO-DV-1006


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4.1.3 Water Balances

Based on an estimation of the power plant's operation during a year, and taking into

account the criteria indicated in previous paragraphs, the water balances for the

different configurations of the power plant have been calculated. They include the

nominal flows for the different consumption currents of the power plant. In addition to

that, for each evaluated case, the total water consumption has been included.

The different water balances analyzed are shown in Annex 01 to this report.

4.2 Comparative Solar Advisor Model / Propietary Model

In order to give higher reassurance to ACWA Power, SOLIDA has performed the

calculation of the power plant energy production for Option 1 (LFO used only for anti-freezing and gland steam generation) and wet cooling tower, using the Solar Advisor

Model.

The following table shows the obtained values of both models:

Net Power Output (GWhe)_P50

Solar Field Size SAM PROPIETARY

96 114,2 123,8

120 144,9 150,7

132 156,4 160,5

144 166,2 168,7

156 174,2 175,4

168 181,4 181,4180 187,3 186,7

204 196,4 193,2



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For 168 loops solar field size, SOLIDA has evaluated monthly values:

Net Power Output (GWhe)_P50

SAM PROPIETARY

JAN 19,6 20,0

FEB 15,3 14,6

MAR 14,0 14,5

APR 13,6 13,3

MAY 11,8 11,5

JUN 9,1 9,7

JUL 10,8 11,2

AUG 16,5 15,5SEP 16,8 16,6

OCT 17,0 17,3

NOV 17,7 18,0

DEC 19,2 19,3

Both series presents a coefficient of determination (R2) of 97,63%.

4.3 Performance results

As it is described below, SOLIDA has performed its calculations using its own

proprietary performance model.




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Page 41

4.3.1 Option 1: LFO used only for anti-freezing and gland steam generation

The results are shown below:

RESULTS WET COOLING TOWER 96 120 132 144 156 168 180 204

Total Gross electricity production GWhe 146 177 188 198 207 214 221 230

Total Auxiliary consumptions GWhe 17 20 21 23 24 25 26 29

Total Net Electricity production GWhe 129 157 167 176 183 189 194 201

Maximum net power output MWe 74,6 75,1 75,1 75,1 75,0 75,0 75,0 74,9

LFO Heaters

% LFO usage, base thermal input % 0,0% 0,0% 0,0% 0,0% 0,0% 0,0% 0,0% 0,0%

Equivalent hours steam turbine h 1.737 2.103 2.243 2.360 2.462 2.549 2.626 2.738

Thermal Efficiency annual Solar Field 46,6% 44,5% 43,0% 41,4% 39,7% 38,1% 36,6% 33,6%

Solar-Electric Efficiency Annual 15,5% 15,1% 14,6% 14,1% 13,5% 13,0% 12,4% 11,4%

DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98% 98% 98% 98% 98% 98% 98% 98%

Electricity losses 2% 2% 2% 2% 2% 2% 2% 2%

Net electricity injected to the grid GWhe 124 151 160 169 175 181 187 193

Net equivalent hours of CSP plant h 1.659 2.008 2.138 2.247 2.339 2.418 2.488 2.581




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RESULTS AIR COOLING CONDENSER 96 120 132 144 156 168 180 204





LFO use





DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98% 98% 98% 98% 98% 98% 98% 98%







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Page 43

RESULTS HYBRID COOLING TOWER 96 120 132 144 156 168 180 204





LFO use





DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98% 98% 98% 98% 98% 98% 98% 98%






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4.3.1.1 Gross and net electricity production

The annual electricity output results for the different configurations evaluated are

included hereafter.



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4.3.1.2 Solar/Electrical efficiency

The solar/electrical efficiency results for the different configurations evaluated are

included hereafter.

4.3.1.3 Total water consumptions

The following results determine the water consumptions, for a production of the solar

power plant without use of LFO.

Wet cooling tower results

Th t t bl i di t th t i t t t ti f th l t f



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Total 635,567.14 737,438.92 778,291.44 813,328.87 845,745.24 875,055.94 901,570.28 944,980.02

As shown in the diagram below, the water consumption increases with increasing the

number of the solar field loops. In turn, it is observed that the most important water

consumption it is produced by the cooling system.

The following graph shows the monthly water consumption evolution of the power plant

for the different solar field sizes and a cooling system based on wet cooling tower. At

the same time, it is possible to see how the water consumption increases with the solar

field size.



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Air cooling condenser results

The next table indicates the most important and totals water consumptions of thepower plant for the different solar field sizes based on an air cooling condenser system.

Water Consumption-Air Cooling Condenser (m)

ConsumptionLoops

96 120 132 144 156 168 180 204

Power Cycle Water 16,820.16 16,820.16 16,820.16 16,820.16 16,820.16 16,339.38 17,888.64 16,820.16

Mirror Washing Water 43,636.36 54,545.45 60,000.00 65,454.55 70,909.09 76,363.64 81,818.18 92,727.27

Others 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00

Blowdown Water Treatment 37,367.66 43,960.46 47,256.86 50,553.26 53,849.66 56,855.51 61,088.19 67,035.27

Total 124,704.18 142,206.07 150,957.02 159,707.97 168,458.91 176,438.53 187,675.01 203,462.70

As shown in the diagram below the water consumption increases with increasing the





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The following graph shows the monthly water consumption evolution of the power plant

for the different solar field sizes and a cooling system based on air cooling condenser.

At the same time, it is possible to see how the water consumption increases with thesolar field size.





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Hybrid cooling tower results

The following table indicates the most important water consumptions of the power plant

for the different solar field sizes based on a hybrid cooling tower system.

Water Consumption-Hybrid Cooling Tower (m)

Consumption Loops96 120 132 144 156 168 180 204



Others 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00


Total 522,878.47 579,308.80 610,424.71 632,389.90 653,203.92 673,665.65 690,909.43 721,598.63



consumption is produced by the cooling system, decreasing slightly against the wet

cooling system.





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Page 51

4.3.2 Option 2: LFO firing up to 15%.

RESULTS WET COOLING TOWER 96 120 132 144 156 168 180 204





LFO Heaters

Hours in operation, Fuel only mode h 0 0 0 0 0 150 290 510

% Electricity production (solar and fuel mode) 15,0% 15,0% 15,0% 15,0% 15,0% 13,2% 11,7% 9,4%

% Electricity production (fuel only mode) 0,0% 0,0% 0,0% 0,0% 0,0% 1,8% 3,3% 5,6%

% Electricity production total 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0%

LFO Total Consumption GWh th 81,3 97,4 103,9 109,6 114,2 119,3 123,5 130,2




DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0%

Electricity losses 2,0% 2,0% 2,0% 2,0% 2,0% 2,0% 2,0% 2,0%






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Page 52

RESULTS AIR COOLING CONDENSER 96 120 132 144 156 168 180 204





LFO Heaters




% Electricity production total 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0%LFO Total Consumption GWh th 81,3 97,4 103,9 109,6 114,2 119,3 123,5 130,2




DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0%


Net electricity injected to the grid GWhe 136 166 177 186 194 200 205 212Net equivalent hours of CSP plant h 2.001 2.438 2.592 2.730 2.843 2.939 3.025 3.125





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Page 53

RESULTS HYBRID COOLING TOWER 96 120 132 144 156 168 180 204





LFO Heaters




% Electricity production total 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0% 15,0%

LFO Total Consumption GWh th 81,3 97,4 103,9 109,6 114,2 119,3 123,5 130,2




DNI kWh/m2 2.654 2.654 2.654 2.654 2.654 2.654 2.654 2.654

Availability 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0% 98,0%







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4.3.2.1 Gross and net electricity production

The annual electricity output results for the different configurations evaluated are

included hereafter.




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4.3.2.2 Solar/Electrical efficiency

The solar/electrical efficiency results for the different configurations evaluated are

included hereafter.

4.3.2.3 Total water consumptions

The following results determine the water consumptions, for a production of the solar

power plant with use of LFO.

Wet cooling tower results

The next table indicates the most important and totals water consumptions of the

power plant for the different solar field sizes, based on a wet cooling tower system.




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consumption is produced by the cooling system.

The following graph shows the monthly water consumption evolution of the solar power

plant for the different solar field sizes and a cooling system based on wet cooling tower.

At the same time, it is possible to see how the water consumption increases with the

solar field size.




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Air cooling condenser results

The next table indicates the most important and totals water consumptions of the

power plant for the different solar field sizes based on an air cooling condenser system.

Water Consumption-Air Cooling Condenser (m)

ConsumptionLoops

96 120 132 144 156 168 180 204



Others 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00 26,880.00


Total 126,846.94 144,348.83 153,099.78 161,850.72 170,601.67 178,581.28 188,103.57 205,605.46


number of the solar field loops. Unlike other cooling systems, this is due to the mirror

washing system consumption.




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Hybrid cooling tower results

The next table indicates the most important water consumptions of the power plant for

the different solar field sizes based on a hybrid cooling tower system.

Water Consumption-Hybrid Cooling Tower (m)

ConsumptionLoops

96 120 132 144 156 168 180 204






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The following graph shows the monthly water consumption evolution of the solar power

plant for the different solar field sizes and a cooling system based on hybrid cooling

tower. At the same time, it is possible to see how the water consumption increases withthe solar field size.




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5 POWER PLANT OPTIMIZATION

5.1 Methodology

The definition of the best solar field configuration is based on a Levelized Cost of

Electricity (LCOE) model calculation.

This LCOE requires:

CAPEX estimation for each configuration

OPEX estimation for each configuration

Tariff: (REFIT)

Basic plant parameters (% degradation, LFO costs, etc)

Financial parameters (inflation, discount rate)

5.2 Assessment CAPEX & OPEX

For each configuration of those considered in the former section, SOLIDA has

estimated CAPEX and OPEX values.

The initial spares cost is included in our CAPEX figures. Regular spares are included in

OPEX.

The main assumptions for the execution of this subtask are as follows:

1. All costs are in $ and referred to updated prices in the Spanish market

2. Earth movement has been estimated with a value of 1 m3 for each 1 m2 of

power plant area.

3. Civil works has been estimated based on a typical BOP lay-out, with building

areas of a 55 MW CSP plant in Spain.

4. Main equipment has been estimated based on a typical BOP lay-out.




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Page 62

CAPEX ($) 96 120 132 144 156 168 180 204WCT 262.597.090 289.819.781 302.958.149 317.706.272 331.257.767 344.766.511 358.446.258 386.660.374

HYB 267.777.955 295.000.646 308.139.015 322.887.138 336.438.632 349.947.376 363.627.123 391.841.239

ACC 276.188.289 303.410.980 316.549.349 331.297.472 344.848.967 358.357.711 372.037.457 400.251.574

WCT_LFO 269.359.877 296.582.568 309.720.936 324.469.060 338.020.554 351.529.298 365.209.045 393.423.161

HYB_LFO 276.494.462 303.717.153 316.855.522 331.603.645 345.155.140 358.663.884 372.343.630 400.557.747

ACC_LFO 284.904.797 312.127.488 325.265.856 340.013.979 353.565.474 367.074.218 380.753.964 408.968.081

OPEX ($) 96 120 132 144 156 168 180 204

WCT 6.861.600 7.028.482 7.111.172 7.186.483 7.256.049 7.315.205 7.380.721 7.504.157

HYB 6.772.044 6.902.294 6.977.214 7.042.093 7.118.721 7.168.257 7.212.614 7.325.898

ACC 6.453.931 6.553.487 6.610.560 6.664.893 6.721.942 6.766.676 6.811.033 6.912.425

WCT_LFO 11.105.539 12.393.864 12.917.102 13.360.726 13.773.569 14.180.816 14.522.744 15.077.329

HYB_LFO 11.015.714 12.290.205 12.800.186 13.263.047 13.625.381 14.030.204 14.370.175 15.077.329

ACC_LFO 10.757.498 11.986.584 12.492.332 12.941.206 13.303.540 13.704.194 14.041.538 14.589.202




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5.3 LCOE

The definition of the best solar field configuration is based on a Levelized Cost of

Electricity (LCOE) model calculation.

The financial assumptions are:

Inflation: 2%

Discount Rate: 10%

Other assumptions:

% degradation: 0,7 %

REFIT ($/MWh): 417,62

LCOE ($/MWh) 96 120 132 144 156 168 180 204

WCT 303,03 270,53 263,86 261,22 260,41 260,43 261,72 269,91

HYB 323,91 288,37 281,11 278,13 277,28 277,16 278,34 286,97

ACC 338,39 302,96 295,24 292,34 290,99 291,35 292,99 301,53

WCT_LFO 290,13 264,27 258,96 256,76 256,31 257,19 258,76 266,62

HYB_LFO 314,76 285,03 278,79 276,17 275,14 276,12 277,84 286,92

ACC_LFO 328,39 296,72 290,06 287,03 285,68 286,85 288,53 296,94




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5.4 Best configuration

5.4.1 Detailed results

At it is show in the previous section there are no sensible variations of LCOE for 144

loops cases to 168 loops cases. SOLIDA has determined to study the 168 loops case

in depth.

Option 1: LFO used only for anti-freezing and gland steam generation

168 L WCTDNI P gross Auxiliary P net

kWh/m2 MWhe MWhe MWhe

JAN 266,43 23.655 2.862 20.794

FEB 205,49 17.324 2.112 15.213

MAR 208,80 17.176 2.053 15.123APR 194,04 15.664 1.764 13.900

MAY 189,32 13.451 1.482 11.969

JUN 184,43 11.382 1.267 10.114

JUL 197,13 13.133 1.445 11.687

AUG 226,55 18.115 2.014 16.101

SEP 222,42 19.477 2.238 17.239

OCT 233,89 20.435 2.455 17.980

NOV 249,04 21.337 2.613 18.724

DEC 276,82 22.935 2.855 20.080

168 L ACCDNI P gross Auxiliary P net


JAN 266,43 21.751 2.857 18.894

FEB 205,49 15.930 2.114 13.816

MAR 208,80 15.794 2.041 13.753

APR 194,04 14.403 1.723 12.680




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168 L HYBDNI P gross Auxiliary P net


JAN 266,43 22.317 2.616 19.701

FEB 205,49 16.344 1.932 14.412

MAR 208,80 16.205 1.875 14.330

APR 194,04 14.778 1.601 13.176MAY 189,32 12.690 1.342 11.348

JUN 184,43 10.738 1.149 9.589

JUL 197,13 12.390 1.309 11.081

AUG 226,55 17.091 1.826 15.264

SEP 222,42 18.376 2.036 16.340

OCT 233,66 19.279 2.243 17.036

NOV 249,04 20.130 2.392 17.738

DEC 276,82 21.638 2.617 19.020




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Water Consumption-168 Loops (m)

ConsumptionsWet

CoolingTower

HybridCoolingTower

AirCooling

Condenser

Power Cycle Water 693,136.56 497,787.97 16,339.38

Mirror Washing Water 76,363.64 76,363.64 76,363.64Others 26,880.00 26,880.00 26,880.00

Blowdown Water Treatment 78,675.75 72,634.04 56,855.51

Total 875,055.94 673,665.65 176,438.53

As shown in the diagram below, the higher water consumption of the solar power plant

occurs with the wet cooling tower option. Moreover, it can also be seen that the air

cooled condenser option reduces notably the yearly water consumption.




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S h Af i N h C R i


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South Africa North Cape Region


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Option 2: LFO firing up to 15%.

168 L WCTDNI P gross Auxiliary P net


JAN 266,43 26.483 3.095 23.388

FEB 205,49 19.386 2.284 17.102

MAR 208,80 19.272 2.223 17.049

APR 194,04 18.738 2.021 16.717

MAY 189,32 16.737 1.757 14.980

JUN 184,43 16.556 1.704 14.853

JUL 197,13 17.098 1.776 15.321

AUG 226,55 21.269 2.280 18.989SEP 222,42 22.451 2.486 19.964

OCT 233,66 23.449 2.704 20.746

NOV 249,04 24.058 2.840 21.218

DEC 276,82 25.889 3.100 22.790

168 L ACC DNI P gross Auxiliary P netkWh/m2 MWhe MWhe MWhe

JAN 266,43 24.210 2.809 21.401

FEB 205,49 17.721 2.076 15.645

MAR 208,80 17.616 2.013 15.603

APR 194,04 17.132 1.813 15.319

MAY 189,32 15.300 1.569 13.731

JUN 184,43 15.136 1.516 13.620

JUL 197,13 15.632 1.583 14.049

AUG 226,55 19.446 2.040 17.405

SEP 222,42 20.522 2.235 18.287




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168 L HYBDNI P gross Auxiliary P net


JAN 266,43 24.840 2.812 22.029

FEB 205,49 18.182 2.076 16.106

MAR 208,80 18.074 2.016 16.058

APR 194,04 17.577 1.821 15.757MAY 189,32 15.698 1.578 14.120

JUN 184,43 15.530 1.526 14.004

JUL 197,13 16.038 1.593 14.446

AUG 226,55 19.952 2.052 17.900

SEP 222,42 21.056 2.245 18.810

OCT 233,66 21.992 2.452 19.540

NOV 249,04 22.566 2.582 19.984DEC 276,82 24.282 2.822 21.460




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Water Consumption-168 Loops (m)

ConsumptionsWet

CoolingTower

HybridCoolingTower

AirCooling

Condenser

Power Cycle Water 787,746.41 544,605.08 17,674.98

Mirror Washing Water 76,363.64 76,363.64 76,363.64Others 26,880.00 26,880.00 26,880.00

Blowdown Water Treatment 81,601.83 74,081.99 57,662.67

Total 972,591.87 721,930.70 178,581.28

As shown in the diagram below, the higher water consumption of the solar power plant

occurs with the wet cooling tower option. Moreover, it can also be seen that the aircooled condenser option reduces notably the yearly water consumption.




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5.5 Radiation scenarios

Option 1: LFO used only for anti-freezing and gland steam generation

RESULTS WET COOLING TOWER (168L) P15 P50 P85

Total Gross electricity production GWhe 227 214 203

Total Auxiliary consumptions GWhe 26 25 24

Total Net Electricity production GWhe 201 189 179

LFO Heaters

% LFO usage, base thermal input % 0,0% 0,0% 0,0%

Equivalent hours steam turbine h 2.708 2.549 2.417

Thermal Efficiency annual Solar Field 39,3% 38,1% 37,6%

Solar-Electric Efficiency Annual 13,4% 13,0% 12,8%

DNI kWh/m2 2.728 2.654 2.556

Availability 98% 98% 98%

Electricity losses 2% 2% 2%Net electricity injected to the grid GWhe 193 181 172

Net equivalent hours of CSP plant h 2.572 2.418 2.293




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, p g ,BOKPOORT

RESULTS AIR COOLING CONDENSER (168 L) P15 P50 P85

Total Gross electricity production GWhe 209 197 187

Total Auxiliary consumptions GWhe 26 25 24

Total Net Electricity production GWhe 183 172 163

LFO Heaters

% LFO usage, base thermal input % 0,0% 0,0% 0,0%

Equivalent hours steam turbine h 2.490 2.343 2.223

Thermal Efficiency annual Solar Field 39,3% 38,1% 37,6%

Solar-Electric Efficiency Annual 12,2% 11,8% 11,6%

DNI kWh/m2 2.728 2.654 2.556

Availability 98% 98% 98%

Electricity losses 2% 2% 2%

Net electricity injected to the grid GWhe 176 165 157

Net equivalent hours of CSP plant h 2.580 2.425 2.299


PRO

Documents

TASK 2 FINAL REPORT.pdf