Proceedings of 2014 1st International Conference on Non Conventional Energy (ICONCE 2014)

Study of Economic Viability of 200 MW Solar Chimney Power Plant in Rajasthan, India

Zainab Akhtar], K.V.S. Rao2 1,2Centre for Energy and Environment

Rajasthan Technical University Kota, India

1 akhtarzainab@gmail.com, 2 kvsraoi 2@gmail.com

Abstract- This paper presents an economic viability of solar

chimney power plant for 200 MW capacity, in Rajasthan India. Estimation of quantity of different materials required and capital cost for construction of 200 MW solar chimney power plant is done. Based on capital cost, operation cost and maintenance cost, levelized electricity cost for solar chimney power plant is calculated and compared with the other power plants based on

conventional energy resources. Finally effect of interest rate, inflation rate and number of working hours of the plant on levelized electricity cost is analyzed.

Index Terms-Solar chimney power plant, Economic analysis,

Levelized electricity cost

NO MENCLA T URE

A Annual cost of the plant, t Af Operation and Maintenance Cost, t B Glass Cost, t

C Capital cost,�

Cse Specific chimney cost, t'

Ce Present equivalent value of cost, �

D Steel Cost, t

de Diameter of chimney, m

E Concrete Cost, � F Total Material Cost, t

f Inflation rate, %

G Labour Cost, �

H Transport Cost, t' He Height of chimney, m

I Total Collector Cost, � Interest rate, %

J Chimney Cost,t

K Foundation Cost, t

L Circumferential Stiffener Cost, �

M Total Chimney Cost, �

N Depreciation time, years

o Power conversion unit cost,�

P Annual power output, kWh

This paper is divided into six sections,

L Introduction

II. Economics of SCPP:

Economics of SCPP includes,

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A. Capital cost which consists of (i) Total collector cost (ii) Total chimney cost (iii) Power conversion unit cost and

B. Operation cost & maintenance cost

III. Calculation of levelized electricity cost (LEC)

IV. Comparison of LEC of SCPP with other conventional power plants

V. Factors effecting LEC

VI. Conclusions

I. IN TRO D UC TION

India's domestic power demand in 2012 was 918 billion units and is expected to reach 1,640 billion units by 2020 at 9.8% annual growth. Thus it is required to increase installed

capacity to 390 GW by 2020 [1]. Solar energy as a renewable energy source can contribute as a part of capacity addition. The most intense solar radiation in India is located in the state of Rajasthan. Rajasthan is blessed with the critical resources like (a) high level of solar radiation, (b) 325 clear sunny days per year,(c) average daily solar incidence of 6-7 kWh/m2 (annual global radiation in Rajasthan is about 2400 kWhlm2) [2] and (d) large amounts of relatively flat and undeveloped land available which is essential for solar power production.

CylirodrtcolTowrv (ChlrMcy) "'\...

�i .. . �

�7Il' Fig. I. Working diagram of solar chimney power plant

The solar chimney technology combines three familiar components, (a) a glass roof collector, (b) a chimney situated in the center of the collector, and (c) wind turbine generators [3]. The warm air expands in the collector causing an upward buoyancy force promoting the flow of air to converge near chimney center from vast collector area. Such buoyancy

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January 16 - 17, 2014, Kalyani, WB, India.

Proceedings of 2014 1st International Conference on Non Conventional Energy (ICONCE 2014)

streams produce thrust to pressure staged wind turbines situated at the base of the chimney, and this mechanical work performed by turbine is converted into electrical energy by generators [4]. Working diagram of solar chimney power plant is shown in 'Fig.1' [5].

Solar chimney power plant (SCPP) works on pure solar energy without using any fuel and cooling water, so it will be quite fruitful to establish solar chimney in less inhabited area of India which is sunny and often have limited water resources. In contrast to other solar energy devices SCPP produces power during night also.

II. ECONO MIC S O F SOLAR CHI MNEY POWER PLAN T

As per the 1. Schlaich et al. [3], solar chimneys rated at 100 MW and 200 MW are capable of generating energy at costs comparable not only to other renewable energy power plants but also to the conventional power plants. They have concluded this based on their experience and knowledge with the prototype plant at Manzanares (Spain), number of working hours of the plant is taken as 3067 hours per year. By developing this form of solar energy utilization, by setting up large, economically viable units, environmental friendly production of energy at an appropriate cost per unit is possible in India.

A. Capital Cost

The capital cost of the solar chimney plant is a function of (i) quantity of the material used, (ii) labour cost and (iii) transportation cost. Capital cost of the solar chimney plant for 200 MW is calculated for four models taken into consideration. Models I, II, III & IV are presented by 1. Schlaich 2000 [6], D. Papageorgiou (Formula based) [7], J. Schlaich 2005 et al. [3]

and Enviromission [8] respectively, are shown in 'Table 1'. These models have different combination of chimney height,

chimney diameter and collector diameter.

TABLE I. DIMENSIONS OF SOLAR CHIMNEY PLANT FOR DIFFERENT MODELS

SI. Modal Chimney Chimney Collector

No. height (m) diameter (m) diameter (m) I J. Schlaich 2000 1500 175 4000 2 D. Papageorgiou 1500 150 5731 3 J. Schlaich 2005 1000 1 20 7000 4 Enviromission 1000 130 7000

(i) Total Collector cost

Collector of solar chimney power plant is made by large

single glazed circular roof of Plain transparent 4 mm thick glass (without any special treatment) placed few meters above the ground with the supporting frame of steel and concrete. Frame is constructed in such a way that there are no obstacles to the flow of air under the roof. Flat rolled narrow steel bars placed one meter apart is supported by light trusses set transversely to them provides strength against high winds and sand storms. Quantity of material required for SCPP for four different models is estimated by extrapolating data suggested by 1. Schlaich [6]. Quantity of material required for construction of collector of SCPP is estimated for different

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diameters of collector. 'Table II' shows amount of material required for different models of 200 MW capacity of SCPP.

TABLE II. QUANTITY OF MATERIAL REQUIRED FOR COLLECTOR

Model Glass Steel Concrete (Km') (Tonnes) (m3)

Modell 16.9 2 90609.53 45644.16 Model II 51.99 297070.87 1 209 2 2.49 Model III 51.99 297070.87 1 209 2 2.49 Model IV 34.81 194977. 21 84891.69

For collector Glass cost is taken as 458 �/sq.m [9], Steel and concrete cost are taken as 59.90 �/kg and 1944.38 �/m3

respectively by CPWD Delhi rates 2012 [10] without considering labour and transportation charges. Total material

cost of the collector for different models is shown in 'Table III' .

TABLE III. COST OF MATERIAL REQUIRED FOR COLLECTOR

Glass Steel Concrete Total Cost Cost Cost Material

Model (� Cr) (� Cr) (� Cr) Cost (�Cr)

(B) (D) (E) (F=B+D+E) Model I 775.17 54 2.75 8.87 13 26.80 Model II 1594.68 1167.91 16.50 2779.10 Model III 2381.49 1779.45 23.51 4184.46 Model IV 2381.49 1779.45 23.51 4184.46

T ABLE IV. TOTAL COLLECTOR COST FOR DIFFERENT MODELS OF SCPP

Total Labour Transport Total Material Cost Cost Cost Collector

Model « Cr) « Cr) « Cr) Cost (�Cr)

(F) (G) (H) (I=F+G+H) Model I 13 26.80 13 26.80 66.34 2719.95 Model II 2779.10 2779.10 138.95 5697.16 Model III 4184.46 4184.46 209. 2 2 8578.15 Model IV 4184.46 4184.46 209. 2 2 8578.15

Labour charges and Transportation charges are taken as 100 % and 5 % of total the total material cost [11]. Thus Collector cost for different models of SCPP for 200 MW capacity of SCPP is shown in 'Table IV'.

(U) Total Chimney Cost

Total chimney cost of SCPP can be calculated by adding chimney cost, foundation cost & circumferential Stiffener Cost.

Required Material for chimney is estimated on volume basis, by considering that the average chimney thickness increment is three millimeter for every one meter height of chimney [12]. Quantity of reinforced concrete (RCC) required for construction of chimney for different models is given in 'Table V'.

TABLE V. QUANTITY OF MATERIAL REQUIRED FOR CHIMNEY

Model Modell Model II Model III Model IV

Reinforced concrete (m3) 37091 25 3179250 1130400 1 2 24600

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Proceedings of 2014 1st International Conference on Non Conventional Energy (ICONCE 2014)

The chimney cost is simply determined as the volume of the chimney multiplied by the specific chimney cost [13],

J =0.003*TId H 2C c c sc

Where de is diameter, Hc is the height of the chimney and Cse is specific chimney cost that is RCC cost. RCC cost is �

5419.4 per cubic meter including labour and transportation charges [10]. Foundation Cost & Circumferential Stiffener Cost are considered as 2.05 % and 0.07 % of the chimney material cost [11]. Table VI shows chimney cost for different models of SCPP for 200 MW capacity.

TABLE VI. TOTAL CHIMNEY COST FOR DIFFERENT MODELS OF SCPP

Chimney Foundation Stiffener Total Cost Cost Cost Chimney

Model (�Cr) (f Cr) (f Cr) Cost (fCr)

(J) (K) (L) (M=J+K+L) Model I 2010.1 2 41. 20 1.40 2052.73 Model 11 17 2 2.96 35.3 2 1. 20 1759.48 Model III 61 2.60 1 2.55 .4 2 6 25.59 Model IV 663.65 1360 .46 677.7 2

(iii) Power Conversion Unit Cost

Power conversion unit cost includes cost of Turbine, Generator Flow duct & Structure to support these machines. It is taken as 4 % of the collector and chimney cost [11].

Based on these parameters Capital cost of 200 MW solar chimney plant for different models is calculated which is shown in 'Table VII'.

TABLE VII. CAPITAL COST OF SOLAR CHIMNEY POWER PLANT FOR 200 MW CAPACITY FOR DIFFERENT MODELS

Model Total Total Power

Capital cost Collector Cost Chimney Cost conversion

(�Cr ) (�Cr) unit cost (� Cr)

(� Cr) (C=I+M+O)

(I) (M) (0) Model I 2719.95 205 2.73 190.90 4963.59 Model 11 5697.16 1759.48 298.26 7754.9 2 Model III 8578.15 6 25.59 368.14 9571.89 Model IV 8578.15 677.7 2 370.23 96 26.11

Power conversion unit cost

Fig. 2. Percentage of cost of different part of SCPP

'Figure 2' shows various components of capital cost of SCPP for model I. Graph shows the collector & chimney cost

have major portion of capital cost. 'Figure 3' depicts calculated values of table.7.

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11000

10000

!ilJOO � Q. (<)00 � v 0000

2000

-lolallollrctor IclalthrmllPY PIJWPf Capdillmsl

Cmt 1ft<.) UN: (!til [OOY.r.I1IOO �rl co;!

• SchlilKh lOOO .P.!p.1teorgiOlJ .Sdllatd!lt'(r., 1&l'tiromi55ion

Fig. 3. Comparison of different components of capital cost for all the four models

B. Operation Cost & Maintenance Cost

Operation Cost of the plant is very less because SCPP works on pure solar energy without using fuel so plant runs at free of cost. The whole of the structure of SCPP is rigid except turbine and generator hence less maintenance is required, which reduces the maintenance cost. O&M Cost is considered 0.12 % of the Capital Cost [11].

III. LEVEL/ZE D ELEC TRICI TY COST (LEC)

Levelized electricity cost is the constant unit cost (per kWh) of a payment stream that has the same present value as the total cost of building and operating a generating plant over its life [14].

Based on the cost model above levelized electricity cost

(LEC) of SCPP is calculated. The present equivalent value of cost is given by,

Where i is interest rate, f is inflation rate, Af is cash flow at

the end of first year (O&M cost) & N is depreciation time. The lifetime O&M cost is added to the capital cost to determine the total present value of cost over the lifetime of the SCPP [11]. An equivalent annual cost over the lifetime of the plant can be calculated as,

A = (C + C) [ i(1 + it 1 (2)

e (1 +it -1 Where, C is the capital cost

electricity cost is calculated by,

LEC=l � J of the plant. Levelized

(3)

Where P is the annual power output in kWh.

LEC for four models of 200 MW capacity of solar chimney plant is calculated by using 'equation 3', at 8 % interest rate, 6 % inflation rate and 80 years depreciation time by considering 3000 working hours per year [3]. 'Table VIII' shows LEC for different models based on above calculations. Comparison of LEC for different models is shown in 'Fig.4'.

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Proceedings of 2014 1st International Conference on Non Conventional Energy (ICONCE 2014)

T ABLE VIII. LEVELIZED ELECTRICITY COST FOR SCPP

Model Capital O&M Present Annual Annual Cost Cost value of Cost Power LEC

(�Cr) (� Cr) O&M (�Cr) Output (�/kWh)

Cost (GWh) (t Cr)

(�) (C) (A,) (Co) (A) (P)

I 4963.59 5.95 23105 41645 600 6.94 II 7754.9 2 9.30 360.99 650.65 600 10.84 III 9571.89 1148 445.57 803.09 600 13.38 IV 96 26.11 115 5 448.09 807.64 600 1346

16 14 12

? � 10 '" .... 8 � � 6

4 2 0

J. Schlaich 2000 C. Papageorgiou J. Schlaich 2005 Erwirornissioll

Fig. 4. Comparison of LEC for different models

IV. CO MPARI SON O F LEC O F SCPP WI TH O THER CONVENTIONAL POWER PLAN T S

For 200 MW power plant, lowest calculated LEC is 6.94�/kWh for model I suggested by J. Schlaich, LEC of solar chimney power plant can be compared with the different type of power plants. 'Table IX' shows the LEC of 4 different conventional power plants working in Rajasthan [\5].

T ABLE IX. LEC OF DIFFERENT PLANT IN RAJASTHAN

Energy Installed

Name of Util itylPower Station Capacity Source

(MW) Mahi Hydel power station RRVUNL

Hydro 140 Rajasthan

Anta CCPP N TPC L TO. Rajasthan Gas &

419 liquid fuel

Ramgarh gas RRVUNL Rajasthan gas 110.5 Kota thermal power station RRVUNL

coal 1 240 Rajasthan

Average

V. F AC TOR S E F FEC TING LEC

Rate of sale of power (�/kWh)

140

3.8 2

2.85

2.50

2.65

A. Effect of different combination of interest rate and inflation rate on LEe

'Figure.5' presents LEC for first model at different combinations of interest rate & inflation rate for 80 years depreciation time.

R. Effect of interest rate on LEe

LEC calculated for model I for 200 MW at 8 % inflation rate with 80 years depreciation time is plotted with respect to different interest rates. 'Fig.6' shows the effect of interest rate on LEC. LEC is low at less interest rate and increases with

interest rate.

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C. Effect of inflation rate on LEe

'Figure.7' shows the effect of inflation rate on LEC for model I at constant interest rate of 6 %. With increase in

inflation rate LEC also increases.

:2 � "" � 1£ OJ �

� � � c 0 � £ o!I � � V>

� � .:

16 14 12 10

8

6 4 2 0

i�13%, 1�16%

i�17%, t�15%

i�16%, 1�14%

i�15%, 1�13%

i-1496, f-1296

i=13%,I=ll%

i=12%,1=10%

i=11%,f=<)%

1=10%,1=8%

;=9%,1=7%

;=8%,1=6%

5 10

LEe (RsjKWh) 15 20

Fig. 5. LEC at different interest rates & inflation rates

9 10 11 12 13 14 15 16 17

Interest rate 1%)

Fig. 6. Comparison of LEC for 200 MW power plant at different interest rates fixing 8 % inflation rate

60 50

� 20 -'

10 o

7 8 9 10 11 12 13 14 15 Inflation rate 1%1

Fig. 7. Comparison of LEC for 200 MW power plant at different inflation rates fixing 6 % interest rate

D. Effect of working hours on LEe

Solar chimney power plant is a rigid structure and is not a

machine hence break down of plant occurs rarely and plant is in working condition all the time with less maintenance hours.

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Proceedings of 2014 1st International Conference on Non Conventional Energy (ICONCE 2014)

:Iv

�- 10 � 8 v � 6

-

I I :l,,{lU .lOtiO l:"UO �uou lo:"UO �ooo -I:'IJU :'lWU

WO�lnehollrs

Fig. 8. Comparison of LEC for 200 MW plant at different working hours

Effect of total working hours of the plant on LEC for 200 MW plant of model I is shown in 'Fig.S', which shows that LEC of the plant is significantly affected by total working hours of the plant. LEC reduces as working hours of plant

increases.

VI. CONCL U SION S

1) Major component of capital cost of solar chimney power plant is cost of the collector and chimney.

2) Solar chimney power plant has levelized electricity cost of 6.94 t/kWh which is not only competitive with the other renewable energy power plants but also in future it is competitive to conventional fossil fuel power plants as the

fossil fuels are getting depleted at faster rate and thereby increasing fuel cost.

3) Fixing the inflation rate at S %, the influence of interest rate on LEC changes significantly (though not phenomenal) from about S �/kWh at 9 % interest rate to 14 �/kWh at 17

% interest rate.

4) At 6 % interest rate the influence of inflation rate on LEC is phenomenal, changing from about 6 t/kWh at 7 % inflation

rate to 50 tlkWh at 15 % inflation rate.

5) LEC increases with increase in interest rate & inflation rate and reduces with increase in working hours of the plant. Solar chimney can produce electricity at low cost with low interest rate and with low inflation rate.

6) As SCPP works on pure solar energy it requires no fuel. It produces power not only during the day but also during

night in contrast to other solar energy devices.

7) As the labour cost is 100 % of material cost, it is labour intensive for construction, thereby creating more jobs and employment to people which is suitable for populous countries like India.

S) Per MW cost (Lowest of the models) of the plant construction is about � 24.S2 cr, which is higher compared to thermal/hydel power plants but the life of SCPP is about SO years and with almost nil maintenance cost and no fuel cost to run the plant.

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AC KNOWLE DG MEN T

This work is the part of M.Tech Thesis work done at Centre for energy and environment, Rajasthan Technical University Kota, India.

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