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Application of photovoltaic systems in Saudi Arabia
RenewableEnergyVol.2, No. 6, pp. 587-590,1992
096/) 1481/92 $5.(10+.00 PergamonPressLtd
Printedin GreatBritain.
A P P L I C A T I O N OF P H O T O V O L T A I C S Y S T E M S IN S A U D I A R A B I A S. A. M. SAID Mechanical Engineering Department, King Fahd University of Petroleum and Minerals. KFUPM-Box 13, Dhahran 31261, Saudi Arabia (Received 17 February 1992 ; accepted 27 February 1992)
Abstract--This paper addresses the issue of the economic competitiveness of PV-powered irrigation when compared with conventional diesel powered pumps in the Kingdom of Saudi Arabia. The cost comparison gives a breakdown cost of a solar photovoltaic module of US$ 2.5 per peak watt.
INTRODUCTION Today thousands of photovoltaic (PV) systems exist worldwide, providing power to small remote gridindependent applications. Thousands of PV standalone systems are being tested, and experience to date has shown them to be safe and dependable. Standalone systems are reliable, very low maintenance methods for producing moderate amounts of electicity in isolated u n m a n n e d sites. Results from a variety of such systems have been excellent, with virtually no failures in all type of weather. Reviewing PV stand-alone system applications demonstrate that PV systems offer a realistic, developed technology alternative for effective power supply. For many applicatio,~s of a remote nature, they are economically attractive. Most of the PV systems sold today are designed to provide power to remote, grid-independent or standalone applications, such as cathodic protection, railroad crossing signals, .water pumping, remote village power supply, navigational aides for sea and air, telecommunications, and refrigeration for critical medical supplies. Recent activities in this field range from state-of-the-art to economic viability. Post and Thomas [1] discussed the current and future applications of PV systems while G r o u m p o s and Papageorgious [2] proposed optimal sizing methods of stand-alone PV systems. Chambouleyron [3] considered several important aspects related to PV market evaluation and Saha et al. [4] proposed a simple methodology for analysing the economic viability of PV systems. There are a large n u m b e r of possible application areas both in the commercial and rural sectors. However, in Saudi Arabia, PV applications, only exist in the following areas : cathodic protection of pipelines ;
offshore oil platform; railway signalling; and street lighting. The major application area in Saudi Arabia is cathodic protection of pipelines. Another area where the use of PV has proven to be economically viable, but is not practiced in Saudi Arabia, is in powering water pumping systems. Hence, this article discusses briefly the application of PV cathodic protection and, in depth, the economic competitiveness of PVpowered irrigation systems. CATHODIC PROTECTION Photovoltaic power systems lbr corrosion control of steel bridge structures and oil industry facilities have been well documented in the literature [5--7]. Solar-powered cathodic protection systems have proved to be superior to sacrificial anode systems and conventional power supplied in several (oil and gas) prgduction application. Saudi Aramco uses PV standalone systems for cathodic protection of oil facilities, as do other oil companies protection of oil pipelines. More information can be obtained from a report on Modular Photovoltaic Power Supply for Cathodic Protection [8]. SOLAR PHOTOVOLTAIC PUMPS Solar 15hotovoltaic-powered pumps will be considered as an alternative to the conventional dieselpowered pumps. The type of pumps and energy storage used in a PV pumping system can have a big impact on overall costs, both short- and long-term. Storage is usually needed for the following reasons :
587
(1) Cloudy periods ; (2) Irrigation at night;
S. A. M. SAID
588 (3) Periodic irrigation. It may be provided in three forms : (1) Batteries ; (2) Pressure tanks (small capacity) ; (3) Large capacity storage tanks.
The elevated storage tank is the simplest and most economical form, especially in a system that does not require batteries for well-pumping. In most parts of Saudi Arabia, there will be no need for batteries because of the sunshine duration of at least 10 hours per day. Five types of pumps are used with PV power systems: centrifugal, submersible, jet, rotary-vane and pump jacks [9]. For deep-well systems the basic types of pump needed are jets, submersibles and pump jacks while for shallow-water systems, including springs, ponds, rivers and shallow wells, centrifugal and rotaryvane pumps are used. Considering a water requirement of 1.0 m3/min that needs to be pumped out of a deep well of 100 m total vertical head, the average amount brake power required will depend on the prime mover used to pump the water. Ifa conventional diesel powered unit is used as a prime mover, a 66 kW engine (with engine efficiency of 33% and pump efficiency of 75%) would be needed. However, if an electric motor (with power drawn from a photovoltaic array) is used as a prime mover, a 24 kW motor would be required (with motor efficiency of 90% and pump efficiency of 75%). A number of methods used to select the right size of the PV array have been reported [10-13]. Saha et al. have developed a simplified method for PV array sizing as follows [4]:
P,,v I [ L H + LHdxlO0] =
CRBE
J
(1)
For a system without battery storage, equation (1) becomes
the array size in peak watts, Pp,, that will meet the two main requirements for water consumption in Saudi Arabia. The monthly average daily horizontal total insolation, for 12 months at three different regions in Saudi Arabia is shown in Table 1, as are the values of XM and X for each location. For the present calculation, the values ofr/~ and qM have been taken as 6% and 8%, respectively, under typical conditions. The calculations show that for an average value of X of 4.42 Wh/day per peak watt, a load rating L of 24 000 watts and 5.5 hours of operation per day, the desired PV array size (Ppv) is 30 000 in peak watts. ECONOMIC ANALYSIS Recent economic analysis [14] has shown that many PV power systems without on-site storage are economically viable. Post and Thomas have reported the results of economic analysis for five remote standalone applications [1]. A number of methods for carrying out such an analysis are reported in the literature [4, 13, 15, 16]. For the present study, the annual amortized operating expense (AAOE) for any power generation system, used by Saha et aL [4] will be used. AAOE can be expressed as :
(5) For solar PV systems : C' =
C, + C >
(6)
Since storage is not required for this application (water pumping), the AAOE for the battery will be zero. The AAOE for the electronics associated with both systems (PV and conventional) will not be taken into account compared to the AAOE of the main system.
LH Pc, = X "
(2)
The value of X can be estimated from the relationship of 1
12
x = 12 y x , , M=
(3)
I
with
Lq u 3
Equations (2), (3) and (4) will be used to compute
COST COMPARISON In this study, solar PV powered pumps are considered as an alternative to conventional diesel powered pumps. Many factors are involved in making such a comparison, but this study will limit itself to those considered in eq. (5). Using this equation we will calculate the costs of a PV array per peak watt (C i) at which the solar power system (SPS) equals the costs of a diesel powered system. The results of this analysis give a breakdown cost ofa PV module C~ of US$ 2.5 per peak watt. For the computations, we have taken R = 15%, D = 15 years
Application of photovoltaic systems in Saudi Arabia
589
Table l. Monthly global insolation at horizontal surface (1~+)in kWh/m 2 day and equivalent peak hour (X~¢)of PV systems at three different regions in Saudi Arabia Central Area Month
1,~
X~
January February March April May June July August September October November December
4.0 4.8 5.3 5.8 6.3 6.6 6.8 6.6 6.0 5.2 4.3 3.5
3.0 3.6 4.0 4.4 4.7 5.0 5. I 5.(1 4.5 3.9 3.2 2.6
Eastern Area X
4.08
1~
Xv
3.7 4.6 5.8 6.9 7.4 8.1 7.7 7.6 6.7 5.6 4.4 3.9
2.8 3.5 4.4 5.2 5.6 6.1 5.8 5.7 5.0 4.2 3.3 2.9
for the SPS and 5 years for the conventional system. The annual operating amortized expenses o f the SPS and the conventional system are 3641.7+6.5C~ and US$ 20 000, respectively.
CONCLUSIONS Given today's technology and prices many experts in this field believe that one o f the potential applications for PV p u m p s is in remote areas where electricity is not supplied from central stations. However, before solar p u m p s becomes acceptable, they need to provide adequate quantities o f p u m p e d water, have a long lifetime, require minimal skilled labor, involve low maintenance costs and be economically competitive with more conventional units. The cost c o m p a r i s o n gives a breakeven cost o f a solar photovoltaic module o f US$ 2.5 pear peak watt. Acknowledqemenl The author would like to acknowledge the support provided by the Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals for conducting this study. NOMENCLATURE BE watt-hour efficiency of the battery C capital and installation cost (" capital installation cost per kilowatt of power generation ('~ cost of PV array per kWp ('~ cost of array mounting structure per kWp CR charge recovery period of the battery d number of days of storage D straight line depreciation F annual cost of fuel per kilowatt of power generation H hours of operation per day
South-Western Area X
4.54
1A~
)(+~
4.7 5.4 6.0 5.0 7.0 7.3 7.5 7.3 6.7 5.9 5.1 4.4
3.5 4. l 4.5 5. I 5.3 5.5 5.6 5.5 5.0 4.4 3.8 3.3
X
4.63
lu
average insolation on a horizontal surface of the location in kWh m 2 day L load rating in watts P power output of the system in kilowatts Pp~ array size in peak watts R rate of interest S service cost/year S' operation and maintenance expenditure per year per kilowatt of power generation X an annual average equivalent peak hours per day q~ module efficiency /I~ overall efficiency of the system.
REFERENCES
I. H. N. Post and M. G. Thomas, Photovoltaic systems for current and future applications. Solar Enewy 41, 465 (1988). 2. P. P. Groumpos and G. Papageorgious, An optimal sizing method for stand-alone photovollaic power systems. Solar Energy 38, 341 (1987). 3. I. von Chambouleyron, A third world view of the photovoltaic market. Solar Enerfly 36, 381 (1986). 4. H. Saha, P. Basu and S. B. Ray, Applications of photovoltaic systems--An economic appraisal with reference to India. Solar Energy 41,513 (1988). 5. Solar Electricity as a Power Source Ibr Cathodic Protection. Report No. FHWA-DP-34-1, US Department of Transportation, Arlington, VA (1978). 6. H. A. Braiverd, Solar cells show promise for pipeline cathodic protection. Oil Gas J. 78, 75 (1982). 7. D. Noran, Solar energy used for production. Oil Gas J. 76, 80 (1978). 8. Review of Aramco Photovoltaic Power Supply for Cathodic Protection Specifications. RI/KFUPM Report (1983). King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia. 9. W. Dankofl; Pumping water. Solar Age 2, 28 (1984). 10. D. L, Evans, A simplified method for predicting photovoltaic array output. Solar Energ3' 27, 555 ( 1981). 11. H. H. Saha, Design of a photovoltaic electric power
590
S. A. M. SAID
system for an Indian village. Solar Energy 27, 103 (1981). 12. E. E1-Rafey and M. E|-Sherbiny, Load/weather/insolation database for estimating photovoltaic array and system performance in Egypt, Solar Energy 41, 531 (1988). 13. M. Buresch, Photovoltaie Energy Systems. McGraw Hill (1983). 14. National Photovoltaic Program: Five-Year Research
Plan 1987 1991. DOE/CH 10093-7, US Department of Energy, Washington, D.C. (1987). 15. A. Takla, The development of solar energy utilization in developing countries, UNIDO Development and Transfer of Technology Series No. 5 (1978). 16. J. A. White, M. A. Agee and K. E. Case, Principles of Engineerin9 Economic Analysis, Wiley, Chichester (1977).
096/) 1481/92 $5.(10+.00 PergamonPressLtd
Printedin GreatBritain.
A P P L I C A T I O N OF P H O T O V O L T A I C S Y S T E M S IN S A U D I A R A B I A S. A. M. SAID Mechanical Engineering Department, King Fahd University of Petroleum and Minerals. KFUPM-Box 13, Dhahran 31261, Saudi Arabia (Received 17 February 1992 ; accepted 27 February 1992)
Abstract--This paper addresses the issue of the economic competitiveness of PV-powered irrigation when compared with conventional diesel powered pumps in the Kingdom of Saudi Arabia. The cost comparison gives a breakdown cost of a solar photovoltaic module of US$ 2.5 per peak watt.
INTRODUCTION Today thousands of photovoltaic (PV) systems exist worldwide, providing power to small remote gridindependent applications. Thousands of PV standalone systems are being tested, and experience to date has shown them to be safe and dependable. Standalone systems are reliable, very low maintenance methods for producing moderate amounts of electicity in isolated u n m a n n e d sites. Results from a variety of such systems have been excellent, with virtually no failures in all type of weather. Reviewing PV stand-alone system applications demonstrate that PV systems offer a realistic, developed technology alternative for effective power supply. For many applicatio,~s of a remote nature, they are economically attractive. Most of the PV systems sold today are designed to provide power to remote, grid-independent or standalone applications, such as cathodic protection, railroad crossing signals, .water pumping, remote village power supply, navigational aides for sea and air, telecommunications, and refrigeration for critical medical supplies. Recent activities in this field range from state-of-the-art to economic viability. Post and Thomas [1] discussed the current and future applications of PV systems while G r o u m p o s and Papageorgious [2] proposed optimal sizing methods of stand-alone PV systems. Chambouleyron [3] considered several important aspects related to PV market evaluation and Saha et al. [4] proposed a simple methodology for analysing the economic viability of PV systems. There are a large n u m b e r of possible application areas both in the commercial and rural sectors. However, in Saudi Arabia, PV applications, only exist in the following areas : cathodic protection of pipelines ;
offshore oil platform; railway signalling; and street lighting. The major application area in Saudi Arabia is cathodic protection of pipelines. Another area where the use of PV has proven to be economically viable, but is not practiced in Saudi Arabia, is in powering water pumping systems. Hence, this article discusses briefly the application of PV cathodic protection and, in depth, the economic competitiveness of PVpowered irrigation systems. CATHODIC PROTECTION Photovoltaic power systems lbr corrosion control of steel bridge structures and oil industry facilities have been well documented in the literature [5--7]. Solar-powered cathodic protection systems have proved to be superior to sacrificial anode systems and conventional power supplied in several (oil and gas) prgduction application. Saudi Aramco uses PV standalone systems for cathodic protection of oil facilities, as do other oil companies protection of oil pipelines. More information can be obtained from a report on Modular Photovoltaic Power Supply for Cathodic Protection [8]. SOLAR PHOTOVOLTAIC PUMPS Solar 15hotovoltaic-powered pumps will be considered as an alternative to the conventional dieselpowered pumps. The type of pumps and energy storage used in a PV pumping system can have a big impact on overall costs, both short- and long-term. Storage is usually needed for the following reasons :
587
(1) Cloudy periods ; (2) Irrigation at night;
S. A. M. SAID
588 (3) Periodic irrigation. It may be provided in three forms : (1) Batteries ; (2) Pressure tanks (small capacity) ; (3) Large capacity storage tanks.
The elevated storage tank is the simplest and most economical form, especially in a system that does not require batteries for well-pumping. In most parts of Saudi Arabia, there will be no need for batteries because of the sunshine duration of at least 10 hours per day. Five types of pumps are used with PV power systems: centrifugal, submersible, jet, rotary-vane and pump jacks [9]. For deep-well systems the basic types of pump needed are jets, submersibles and pump jacks while for shallow-water systems, including springs, ponds, rivers and shallow wells, centrifugal and rotaryvane pumps are used. Considering a water requirement of 1.0 m3/min that needs to be pumped out of a deep well of 100 m total vertical head, the average amount brake power required will depend on the prime mover used to pump the water. Ifa conventional diesel powered unit is used as a prime mover, a 66 kW engine (with engine efficiency of 33% and pump efficiency of 75%) would be needed. However, if an electric motor (with power drawn from a photovoltaic array) is used as a prime mover, a 24 kW motor would be required (with motor efficiency of 90% and pump efficiency of 75%). A number of methods used to select the right size of the PV array have been reported [10-13]. Saha et al. have developed a simplified method for PV array sizing as follows [4]:
P,,v I [ L H + LHdxlO0] =
CRBE
J
(1)
For a system without battery storage, equation (1) becomes
the array size in peak watts, Pp,, that will meet the two main requirements for water consumption in Saudi Arabia. The monthly average daily horizontal total insolation, for 12 months at three different regions in Saudi Arabia is shown in Table 1, as are the values of XM and X for each location. For the present calculation, the values ofr/~ and qM have been taken as 6% and 8%, respectively, under typical conditions. The calculations show that for an average value of X of 4.42 Wh/day per peak watt, a load rating L of 24 000 watts and 5.5 hours of operation per day, the desired PV array size (Ppv) is 30 000 in peak watts. ECONOMIC ANALYSIS Recent economic analysis [14] has shown that many PV power systems without on-site storage are economically viable. Post and Thomas have reported the results of economic analysis for five remote standalone applications [1]. A number of methods for carrying out such an analysis are reported in the literature [4, 13, 15, 16]. For the present study, the annual amortized operating expense (AAOE) for any power generation system, used by Saha et aL [4] will be used. AAOE can be expressed as :
(5) For solar PV systems : C' =
C, + C >
(6)
Since storage is not required for this application (water pumping), the AAOE for the battery will be zero. The AAOE for the electronics associated with both systems (PV and conventional) will not be taken into account compared to the AAOE of the main system.
LH Pc, = X "
(2)
The value of X can be estimated from the relationship of 1
12
x = 12 y x , , M=
(3)
I
with
Lq u 3
Equations (2), (3) and (4) will be used to compute
COST COMPARISON In this study, solar PV powered pumps are considered as an alternative to conventional diesel powered pumps. Many factors are involved in making such a comparison, but this study will limit itself to those considered in eq. (5). Using this equation we will calculate the costs of a PV array per peak watt (C i) at which the solar power system (SPS) equals the costs of a diesel powered system. The results of this analysis give a breakdown cost ofa PV module C~ of US$ 2.5 per peak watt. For the computations, we have taken R = 15%, D = 15 years
Application of photovoltaic systems in Saudi Arabia
589
Table l. Monthly global insolation at horizontal surface (1~+)in kWh/m 2 day and equivalent peak hour (X~¢)of PV systems at three different regions in Saudi Arabia Central Area Month
1,~
X~
January February March April May June July August September October November December
4.0 4.8 5.3 5.8 6.3 6.6 6.8 6.6 6.0 5.2 4.3 3.5
3.0 3.6 4.0 4.4 4.7 5.0 5. I 5.(1 4.5 3.9 3.2 2.6
Eastern Area X
4.08
1~
Xv
3.7 4.6 5.8 6.9 7.4 8.1 7.7 7.6 6.7 5.6 4.4 3.9
2.8 3.5 4.4 5.2 5.6 6.1 5.8 5.7 5.0 4.2 3.3 2.9
for the SPS and 5 years for the conventional system. The annual operating amortized expenses o f the SPS and the conventional system are 3641.7+6.5C~ and US$ 20 000, respectively.
CONCLUSIONS Given today's technology and prices many experts in this field believe that one o f the potential applications for PV p u m p s is in remote areas where electricity is not supplied from central stations. However, before solar p u m p s becomes acceptable, they need to provide adequate quantities o f p u m p e d water, have a long lifetime, require minimal skilled labor, involve low maintenance costs and be economically competitive with more conventional units. The cost c o m p a r i s o n gives a breakeven cost o f a solar photovoltaic module o f US$ 2.5 pear peak watt. Acknowledqemenl The author would like to acknowledge the support provided by the Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals for conducting this study. NOMENCLATURE BE watt-hour efficiency of the battery C capital and installation cost (" capital installation cost per kilowatt of power generation ('~ cost of PV array per kWp ('~ cost of array mounting structure per kWp CR charge recovery period of the battery d number of days of storage D straight line depreciation F annual cost of fuel per kilowatt of power generation H hours of operation per day
South-Western Area X
4.54
1A~
)(+~
4.7 5.4 6.0 5.0 7.0 7.3 7.5 7.3 6.7 5.9 5.1 4.4
3.5 4. l 4.5 5. I 5.3 5.5 5.6 5.5 5.0 4.4 3.8 3.3
X
4.63
lu
average insolation on a horizontal surface of the location in kWh m 2 day L load rating in watts P power output of the system in kilowatts Pp~ array size in peak watts R rate of interest S service cost/year S' operation and maintenance expenditure per year per kilowatt of power generation X an annual average equivalent peak hours per day q~ module efficiency /I~ overall efficiency of the system.
REFERENCES
I. H. N. Post and M. G. Thomas, Photovoltaic systems for current and future applications. Solar Enewy 41, 465 (1988). 2. P. P. Groumpos and G. Papageorgious, An optimal sizing method for stand-alone photovollaic power systems. Solar Energy 38, 341 (1987). 3. I. von Chambouleyron, A third world view of the photovoltaic market. Solar Enerfly 36, 381 (1986). 4. H. Saha, P. Basu and S. B. Ray, Applications of photovoltaic systems--An economic appraisal with reference to India. Solar Energy 41,513 (1988). 5. Solar Electricity as a Power Source Ibr Cathodic Protection. Report No. FHWA-DP-34-1, US Department of Transportation, Arlington, VA (1978). 6. H. A. Braiverd, Solar cells show promise for pipeline cathodic protection. Oil Gas J. 78, 75 (1982). 7. D. Noran, Solar energy used for production. Oil Gas J. 76, 80 (1978). 8. Review of Aramco Photovoltaic Power Supply for Cathodic Protection Specifications. RI/KFUPM Report (1983). King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia. 9. W. Dankofl; Pumping water. Solar Age 2, 28 (1984). 10. D. L, Evans, A simplified method for predicting photovoltaic array output. Solar Energ3' 27, 555 ( 1981). 11. H. H. Saha, Design of a photovoltaic electric power
590
S. A. M. SAID
system for an Indian village. Solar Energy 27, 103 (1981). 12. E. E1-Rafey and M. E|-Sherbiny, Load/weather/insolation database for estimating photovoltaic array and system performance in Egypt, Solar Energy 41, 531 (1988). 13. M. Buresch, Photovoltaie Energy Systems. McGraw Hill (1983). 14. National Photovoltaic Program: Five-Year Research
Plan 1987 1991. DOE/CH 10093-7, US Department of Energy, Washington, D.C. (1987). 15. A. Takla, The development of solar energy utilization in developing countries, UNIDO Development and Transfer of Technology Series No. 5 (1978). 16. J. A. White, M. A. Agee and K. E. Case, Principles of Engineerin9 Economic Analysis, Wiley, Chichester (1977).