Photovoltaics in the Arab world

Download Photovoltaics in the Arab world

Post on 21-Jun-2016

217 views

Category:

Documents

2 download

TRANSCRIPT

  • Solar Cells, 6 (1982) 239 - 249 239

    PHOTOVOLTAICS IN THE ARAB WORLD

    M. A. KETTANI*

    Islamic Foundation for Science, Technology and Development, P.O. Box 9833, Jeddah (Saudi Arabia)

    (Received September 30, 1981)

    Summary

    There is great interest in photovoltaic conversion in the countries which make up the Arab world. Research in universities and applications in the field are both increasing at a fast pace. This paper gives an overview of all this activity and explains the reasons for this interest. More specifically it defines "economic attractiveness factors" such as "insolation factor" and "remoteness factor" that determine whether a photovoltaic application would be economical at a given geographical point.

    1. Introduction

    The area under consideration comprises the countries of the Arab League (the Arab world). It includes territories extending over 77 longitude from the Atlantic Ocean (17 W longitude) to the Indian Ocean (60 E longitude} and over 35.5 latitude from the Mediterranean coast (37.5 N latitude) to tropical Africa (2 N latitude). It covers a total surface area of 13 700 000 km 2 of which 10 200 000 km z are in Africa and 3 500 000 km 2 in Asia. The total population in 1981 was equal to 170 million people of whom 117 million were in Africa and 53 million in Asia.

    The average insolation received by the Arab world can be estimted at about 520 cal cm -2 day - i (about 250 W m -2) or a total of 3.4 X 109

    The average insolation received by the Arab world can be estimated at about 520 cal cm -2 day -1 (about 250 W m -2) or a total of 3.4 X 109 MW. In 1 year, therefore, the Arab world receives about 30 X 10 i5 kWh of solar energy or 100 Q units (1 Q = l0 is B.t.u. = 2.93 X 10 i4 kWh), more than six times the estimated oil reserves of the Earth [1]. There are indications, however, that the diffuse component of insolation can be as high as 20%; this is due mostly to dust in the air which is widely present in desert areas.

    *On leave from the University of Petroleum and Minerals, Dhahran, Saudi Arabia.

    0379-6787/82/0000-0000/$02.75 Elsevier Sequoia/Printed in The Netherlands

  • 240

    2. Photovoltaic research in Arab countries [2]

    Interest in solar energy in the Arab world started in the universities in the late 1950s and early 1960s. This interest took many forms, including basic research in photovoltaic power conversion. At present this research is carried out in only a few countries.

    In Algeria, a photovoltaics group at the Centre des Sciences et de la Technologie Nucl~aire in Algiers studies and develops CdS-Cu2S thin film photocells and experiments with photovoltaic panels.

    In Egypt, a group at the Solid State Laboratory, National Research Centre, Dokki, Cairo, works on semiconductors. The group has received scholarships from the Laboratoire de Bellevue, Solid State Physics, Centre National de la Recherche Scientifique (CNRS), and work is done mainly on CdS and CdTe. There is also interest in photovoltaic power conversion at the Physics Department, American University, Cairo, where research is carried out on silicon cells. Similar work is being done at the Mechanical Engineering Department, Al-Mansurah University.

    Commercially available solar cells are tested in the Kuwait environment at the Physics Department of Kuwait University and, in Lebanon, the CNRS has supported a small photovoltaic conversion project involving experimen- tation with silicon cells.

    The solar energy group at the Physics Department, Mohammed V University, Rabat, Morocco, established a photovoltaics laboratory in 1979.

    In Saudi Arabia, studies mainly of a theoretical nature have been carried out at the Electrical Engineering Department, University of Petroleum and Minerals, on the direct conversion of solar energy into electricity, including photovoltaic conversion. Photovoltaic units for student demonstration are also located at the Mechanical Engineering Department, University of Riyadh.

    In Sudan, the Solar Energy Department, Energy Research Institute, Khartoum, tests silicon photocells brought from the U.S.A. and incorporates them into integrators for solarimeters. Work on silicon photovoltaic cells is also carried out at the Physics Department, College of Science, University of Khartoum, mostly in cooperation with the Philips Company in the Netherlands.

    The photovoltaics group at the Ecole Nationale d'Ing~nieurs de Tunis carries out the following projects in Tunisia.

    (a) Cu-Cu20 photocells are produced by the oxidation of copper in vacuum at high temperatures; Cu20 has been obtained with an efficiency of 5%.

    (b) Si-SnO2 Schottky diodes (thin film heterojunctions) are fabricated by the deposition of SnO 2 on silicon monocrystals using the spray method. The deposition of indium oxide (In203) on silicon is also tested. Efficiencies of 7% have been obtained.

    (c) Hydrogen is produced by photoelectrolysis using Ti-TiO 2 diodes. (d) Silicon monocrystals and possibly amorphous silicon are produced.

  • 241

    (e) Photovoltaic plants are modelled theoretically using computers to study absorption, spectral response and barriers.

    (f) AsGa photocells are fabricated by evaporation. (g) Work on CdS and CdTe and on the electroreflectance for interface

    studies is being carried out in cooperation with Nice University, France. The Laboratoire de Bellevue, CNRS, helps this group by supplying it with raw materials.

    The photovoltalcs group at the Faculty of Sciences, Tunis University, has two projects.

    (a) GaxAll-x As is studied by the Raman resonant effect in collabora- tion with the Centre of Electronic Studies, Montpellier, France.

    (b) The optical properties and transfer phenomena are investigated in non-homogeneous semiconductor components, such as semiconductors with dendritic surfaces and semiconductors with impurities (e.g. germanium in A1203) , in collaboration with Exxon Linden, New York, and the University of Sydney, New South Wales, Australia.

    Another photovoltaics group, that at the Faculty of Sciences and Technology, Sfax, is interested in Schottky heterojunctions, such as Si-A1, Si-Au, Si-SiO2-A1 and Si-SiOe-Au, produced under vacuum.

    3. Photovoltaic projects in Arab countries [2]

    Demonstration projects are in operation in many Arab countries. In Egypt, bids have been made by the Ministry of Electricity and

    Energy for photovoltaic cells and photovoltaic irrigation pumps. A profes- sor from the American University, Cairo, has studied the social impact of television using photovoltaic cells on a remote village in the Nile delta.

    The Jordanian Telecommunication Corporation, Amman, has developed a photovoltaic-powered telephone system for remote villages. Another project, sponsored in part by the Jordanian army, consists of the installation of more than 100 emergency photovoltaic-powered telephones along highways. One of the features of this project is the achievement of the construction of a low consumption transmitter-receiver suitable for the photocell power capacity. Passive cooling was provided in the pole structure in order to avoid overheating of the electronic parts.

    The government in Oman has considered the installation of photo- voltaic plants of 15 kW capacity for desalting sea water in remote villages and, in Qatar, a small demonstration photovoltaic generator was installed by Lucas Service Overseas, Gt. Britain, in 1977.

    In Saudi Arabia, the Saudi Arabian Centre of Science and Technology and the U.S. Department of Energy manage jointly the Saudi Arabian-U.S. Program for Cooperation in Solar Energy (SOLERAS) initiated in 1978. This is a 5 year programme, financed equally by the two governments to a total of U.S. $100 million. One of the most important projects being implemented under this programme is the establishment of a 350 kW

  • 242

    photovoltaic station near Riyadh. A large U.S. aerospace firm won the U.S. $30 million design and construction project. The system is made up of 160 photovoltaic concentrator arrays, each array containing 272 silicon cells. Point-focusing Fresnel lenses concentrate the Sun's rays by a factor of 33. The system will be in commission by the end of 1981. In addition, a photo- voltaics firm has built a photovoltaic-powered house for demonstration, to the north of Jeddah; desalination of water, air conditioning and lighting are all powered by the Sun.

    A general agreement for collaboration on solar energy was signed in 1977 between Electricit~ de France (EDF) and Electrico (a branch of the Ministry of Industry and Electricity, Riyadh, Saudi Arabia). This was followed in 1978 by a specific agreement worth U.S. $5 million whereby EDF supplied the ministry with one 30 kW Solar Energy Research Institute-Renault photopile unit at a cost of FF 6 million (and one 45 kW pump made by the Soci~t~ Fran~aise d'Etudes Thermiques et d'Energie Solaire).

    Small photovoltaic applications in Saudi Arabia started in the early 1960s with the installation of the first (French) photovoltaic beacon at Madinah airport. By 1980, the General Directorate of Telephones had installed more than 300 photovoltaic emergency telephones on the Saudi highways.

    In Sudan, it is proposed to use solar electricity in a solar village project in the north of the Kordofan province.

    In 1980, the Ministry of Electricity in Syria bought a 0.8 kW photo- voltaic generator from France for experimental purposes.

    In Tunisia, the Research Institute on Arid Zones, Ariana, has received a photovoltaic pump from Elf-Aquitaine, France, at a cost of U.S. $6000. If this proves to be a success, more than 20 such pumps will be ordered. In contrast, in 1972 the Ministry of Agriculture installed a photovoltaic pump ordered from Mabosun, Italy, at Tozeur. It pumped 5 - 20 m s h -1 of water from a height of 20 m. The Ministry later ordered ten more pumps of the same type.

    One 5 kW photocell pump has been installed at Garak in Mauritania for irrigation purposes. It was ordered from France at a cost of U.S. $130 000. Solar electricity is being considered for rural settlements also.

    4. Why solar energy in the Arab world?

    In Table 1 the potential amount of renewable energy available every year in the Arab world and the percentages used in the year 1980 are arranged in categories. The energy consumption of the Arab world, both fossil and renewable, is presented in Table 2 [3].

    It must be pointed out here that in 1977 the quantity of flared gas in the Arab world amounted to 840 10 6 MW h year -1, a quantity almost equal to the total energy consumption of the entire Arab world during that year. The total reserves of fossil fuel in the Arab world do not exceed

  • TABLE 1

    Renewable energy sources in the Arab world in 1980

    243

    Energy source Potential energy Consumed energy Consumed energy (X 106 MW h year - l ) a (x 106 MW h year - l ) a (%)

    Solar 27000000 - - 0 Wind 16000000 -- 0 Geothermal 22000 -- 0 Biomass 1700 38 2 Hydraul ic 43 19 43

    Total 43000000 57 1 ppm

    a106 MW h is equivalent to 0.086 mil l ion tonnes of oil, i.e. 0.112 mil l ion barrels of oil.

    TABLE 2

    Energy consumed in the Arab world in 1977 a

    Energy source Energy consumed Consumed energy (x 106 MW h year -1) (%)

    Oil 457 49.7 Natural gas 349 38.0 Coal 6 0.7

    Total fossil 812 88.4

    Biomass 92 10.0 Hydraul ic 15 1.6

    Total renewable 107 11.6

    Total consumpt ion 919 100.0

    a Calculat ions based on Uni ted Nat ions' data.

    4 000 000 X 106 MW h of which 12 000 X 106 are extracted annually, mostly for export. If the probable reserves were taken into account, the above figure could be doubled. As for nuclear energy, the reserves of the Arab world amount to 100 000 tonnes of uranium. There are also large quantities of coal and shale oil in the Arab world.

    In terms of quantity, the Arab world as a whole seems to be well endowed with energy resources. However, there are two facts that could influence its future as far as energy is concerned: (1) fossil fuels are, for the Arab world, as much a source of cash for development as they are a source of energy; (2) the technology of renewable energy sources is yet to be developed. In Table 3 an assessment of the energy consumption of the Arab world in the year 2000 is given on the basis of the most optimistic proposi- tion for renewable sources. In this table two facts are clearly demonstrated:

  • 244

    TABLE 3

    Projected energy consumption of the Arab world for the year 2000 A.D.

    Energy source Energy consumption Total consumed Potential (x 106 MW h year -1) energy (%) energy (%)

    Oil 1800 45 --- Natural gas 1400 35 -- Coal 50 1.3 -- Nuclear energy 500 12.5 --

    Subtotal 3750 93.8 --

    Biomass 170 4.3 10 Hydraulic 43 1.0 100 Solar 17 0.4 -- Wind 5 0.1 -- Geothermal 15 0.4 --

    Subtotal 250 6.2 --

    Grand total 4000 100.0

    (1) the development of renewable energy sources, including solar energy, in the Arab world is necessary to respond to the increasing demand; (2) even if the development of these sources is started now, the Arab world cannot afford to ignore coal and nuclear energy for long.

    5. Economic attractiveness factors

    Solar energy in its electromagnetic form is a raw material which is useless unless it is processed properly, i.e. unless it is converted into a useful form such as electrical energy. To assess the economic feasibility of such a solar conversion system, it is necessary to find a break-even cost model. One such model leads to the break-even cost by calculation of the present value of the average annual saving of a solar energy system compared with a conventional energy system. The solar system is assumed to be f inanced by a mortgage with a predetermined interest rate for a specific period of time. The average annual saving made, if any, due to the uti l ization of the solar energy system will be equal to the annual operating cost of the solar energy system minus the sum of the annual operating cost of the conventional energy system and the cost of maintaining the solar system. Furthermore, the operating cost of the conventional system is assumed to increase yearly at a constant rate. The model could of course be improved to take into account the f luctuation in the value of money with time and the discount value of the yearly energy savings. Other models, slightly different f rom the above, have also been proposed [4, 5] .

    The cost of a photovoltaic system can be divided into two parts: the cost of the land and the cost of the structure. In desert and remote areas,

  • 245

    land cost may be a negligible part of the overall cost while, in densely populated areas, it cannot be neglected. The cost of the structure is basically related to the cost of production of high purity silicon. The cost of silicon more than doubles (U.S. $650 kg -1) when it is processed from an ingot into wafers, since about 50% of the starting material is lost. Development of the edge-defined film growth, producing silicon in the form of a ribbon, should cut down these costs. Lower costs could be exp...