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13СОЛНЕЧНАЯ ЭНЕРГЕТИКА
SOLAR ENERGY
Статья поступила в редакцию 17.04.11. Ред. рег. № 967 The article has entered in publishing office 17.04.11. Ed. reg. No. 967
УДК 504.05
СОЛНЕЧНАЯ ЭНЕРГЕТИКА И ЕЕ ЭКОЛОГИЧЕСКИЕ ПРОБЛЕМЫ
С.М. Говорушко
Тихоокеанский институт географии ДВО РАН 690041 Владивосток, ул. Радио, д. 7 Тел./факс: 8(4232)311653, e-mail: sgovor@tig.dvo.ru
Заключение совета рецензентов: 27.04.11 Заключение совета экспертов: 28.04.11 Принято к публикации: 30.04.11
Рассмотрены некоторые вопросы, связанные с солнечной радиацией (понятие, ее типы, спектральная характеристика, особенности распределения по поверхности Земли). Описаны способы получения электричества и тепла из солнечного излучения, показаны типы солнечных электростанций. Проведен анализ экологических проблем солнечной энергетики.
Ключевые слова: солнечная радиация, фотоэлектрические установки, солнечные коллекторы, солнечные электростанции, экологические последствия, отчуждение земель.
SOLAR POWER ENGINEERING AND ITS ENVIRONMENTAL PROBLEMS
S.M. Govorushko
Pacific Geographical Institute FEB RAS 7 Radio str., Vladivostok, 690041, Russia Tel./fax: 8(4232)311653, e-mail: sgovor@tig.dvo.ru
Referred: 27.04.11 Expertise: 28.04.11 Accepted: 30.04.11
Some aspects associated with solar radiation (the concept, its types, the spectral characteristic, features of the distribution on the surface of the Earth) are described. Methods of generation of electricity and heat from solar radiation are given. Types of solar power plants are shown. The analysis of the environmental problems of solar energy is realized.
Keywords: solar radiation, photovoltaic cells, solar power plants, solar collectors, environmental consequences, condemnation of land.
Solar radiation and some peculiarities of its distribution
Solar radiation is the electromagnetic and corpuscular radiation of the Sun. The annual distribution of solar radiation on the Earth's surface is not entirely dependent on latitude, as there are differences in cloudiness and transparency of the atmosphere (Fig. 1).
Solar radiation is the basic and essentially the sole source of energy for atmospheric processes. It is categorized as direct, diffuse, and total solar radiation. Direct solar radiation (i.e., immediately from the Sun disk) reaches the upper limit of the atmosphere. If its value there is taken as 100%, then 42% of this amount is reflected by clouds and dust in the atmosphere, 10% is absorbed and dispersed in the atmosphere, and only 48% of the radiation reaches the Earth's surface [1].
The spectrum of solar radiation is divided into three parts: (1) ultraviolet; (2) visible; and (3) infrared. Ultraviolet radiation has wavelengths of 0.01 to 0.39 micrometre and comprises 9% of the radiant energy from the Sun; it is not perceived by the eye. Visible light is radiation with wavelengths of 0.40 to 0.76 micrometre. The wavelength of 0.40 micrometre corresponds to the colour violet, while 0.76 micrometre corresponds to red. The entire visible spectrum falls between these two wavelengths, 47% of the solar radiant energy falls in this part of the spectrum. Infrared radiation has wavelengths greater than 0.76 micrometre and more (up to several hundred micrometres). Just as with ultraviolet radiation, infrared radiation is invisible. Infrared radiation comprises 44% of all solar radiation [2].
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ISO" 120' 30' 60' 30" 0" 30" 60" 90" 120" 150" ISO' ISO'
150' 130" 90' 60' 30' 0' 30' 60' 90' 120" 150' 130' 150'
Рис, 1. Среднегодовое попгаество садиеяной радиации» достигают« земной поверхности, ккал/см3 (Allaby, 1996)
Уклонные iHHVitUl'ICilllK
-120-линии раиной суммарной солнечной радиации
Fig. L Average annual amount of solar radiaiion reaching ihe I-an I surface in к i] oca lories per square ceniimeire (Allaby, 1996)
Legend:
- . - lines of equal solar radiation
Methods of producing of electricity and heat from solar energy
A solar power plant is an engineering structure used for conversion of solar radiation into electric power. Sunlight can be converted into electricity by using photovoltaics. World solar photovoltaic (PV) installations produced 2.826 gigawatts peak in 2007, and 5.95 gigawatts in 2008, a 110% increase [3]. Photovoltaics have mainly been used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by photovoltaic arrays. For large-scale generation, solar power plants are used. One example of such a facility is a complex of nine solar photovoltaic installations in California's Mojave Desert; the plant was constructed during 1984-90.
Electricity and heat are produced from solar radiation in the following ways: (1) generation of electric power by using photocells (Fig. 2); (2) conversion of solar energy into electricity by means of thermal machines, such as (a) steam engines (piston or turbine) using steam, carbon dioxide gas, propane-butane, or freon and (b) Stirling engines (a kind of external combustion engine that may operate on any heat source); (3) solar power engineering (heating of a surface absorbing sun rays and subsequent distribution and use of the heat for hot-water heating and supply (Fig. 3), or cooking (Fig. 4); focusing
of solar radiation on a vessel containing water for subsequent application of the heated water in heating systems or steam electric generators); (4) thermo-air power plants (conversion of solar energy into the energy of an air stream directed to a turbo-generator); and (5) solar balloon power plants (generation of steam inside a balloon covered with a selectively absorbing coating that is heated by solar radiation).
Рис. 2. Солнечная фотоэлектрическая станция в г. Серпа (Португалия). Производимой электроэнергии достаточно
для энергоснабжения 8 тыс. домов. Фото: http://en.wikipedia.org/wiki/ Serpa_solar_power_plant, март 2006 г. Fig. 2. Solar power plant in Serpa, Portugal, that use photovoltaic cells. The plant provides enough electricity to supply approximately 8,000 homes. Photo credit: http://en.wikipedia.org/wiki/ Serpa_solar_power_plant, March 2006
International Scientific Journal for Alternative Energy and Ecology № 5 (97) 2011
© Scientific Technical Centre «TATA», 2011
С.М. Говорушко. Солнечная энергетика и ее экологические проблемы
Рис. 3. Солнечные коллекторы для обеспечения горячей водой в северо-восточном Китае. Фото: С.М. Говорушко, Тихоокеанский институт географии ДВО РАН, 25 августа 2007 г. Fig. 3. Solar collector panels used to provide a hot water supply in north-eastern China. Photo credit: S.M. Govorushko, Pacific Geographical Institute, Vladivostok, Russia, 25 August 2007
Рис. 4. На снимке: солнечная кухня в Ауровиле, Индия. Солнечная энергия используется для приготовления пищи. Полусферическое зеркало диаметром 15 м и расположенное на высоте 7 м над уровнем земли концентрирует солнечные
лучи на цилиндрическом котле. При ясной погоде этой энергии достаточно, чтобы приготовить еду два раза в день для 1000 человек. Фото: http://en.wikipedia.org/wiki /Auroville Fig. 4. This photo shows the Solar Bowl in Auroville, India. It used solar energy for cooking. The ferrocement base of this stationary faces south. It is 15 metres in diameter and 7 metres above ground level. The sun's rays, trapped by a huge hemispherical mirror, focus on a cylindrical boiler that follows the sun's position by means of a computerized tracking device. On a clear day, sufficient steam at a temperature of 150 °C can be generated in this boiler to cook two meals a day for 1,000 people. Photo credit: http://en.wikipedia.org/wiki/Auroville
Рис. 5. Солнечная электростанция башенного типа в Испании. Фото: http://en.wikipedia.org/wiki/Renewable_energy, 3 сентября 2007 г. Fig. 5. Tower-base solar power plant in Spain. Photo credit: http://en.wikipedia.org/wiki/Renewable_energy, 3 September 2007
The methods of solar radiation conversion are different and depend on the power plant construction. All solar power plants (SPPs) are subdivided into several types: (1) tower-base SPPs (Fig. 5); (2) dish-shaped SPPs; (3) SPPs using photovoltaic cells; (4) SPPs using parabolic concentrators; (5) combined SPPs; and (6) balloon SPPs.
As of October 2009, the largest photovoltaic power plants in the world are (1) Olmedilla Photovoltaic Park, Spain (60 megawatts); (2) Strasskirchen Solar Park, Germany (54 megawatts); (3) Lieberose Photovoltaic Park, Germany (53 megawatts); (4) Puertollano Photovoltaic Park, Spain (50 megawatts); and (5) Moura Photovoltaic Power Station, Portugal (46 megawatts) [4].
Among the advantages of solar power plants are availability and inexhaustibility of the energy source. In order to meet today's needs of mankind for electric power, only 0.0004% of incoming solar radiation to the Earth is sufficient [5].
The often-declared environmental cleanness of solar power engineering is an illusion. From an environmental point of view, only the operation stage can be recognized to be relatively clean, and even that assertion is made with reservations.
Environmental consequences of solar power engineering
The negative effects of solar power engineering become apparent in the following [6]: (1) condemnation of land; (2) contamination of natural media in manufacturing materials for plants; (3) contamination of the environment with highly toxic chlorates and nitrites from working fluid leaks; (4) influence on vegetation and soils when they are shaded by solar concentrators; (5) changes in the heat balance and humidity in the vicinity of plants; (6) climatic effects of SPPs in space; (7) television and radio noises; and (8) thermal effects on the environment of cooling a condensate.
In addition, there is a theoretical probability that the all-round application of solar power engineering may change the albedo of the Earth surface and cause climate change (however, it is extremely unlikely at the current level of energy consumption).
The construction of solar power stations needs large areas of land. A power plant producing 1,000 megawatts in a hot, dry locality (such as west or central Australia) will need a total collector area of 13-25 square kilometres. This area is more than that occupied by an ordinary thermal power plant but less than the territory used for a plant and coal open-cut [7].
The indirect impact of solar power engineering on the environment lies in the fact that it demands considerable resources. Enterprises manufacturing concrete, glass, steel, and other materials are needed to support the construction of solar power plants, The making of photoelectric cells for solar batteries demands
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a number of substances (silicon, cadmium, arsenidegallium) that are hazardous to produce. In the case of wide development of solar power engineering, such indirect effects on the natural environment could be considerable.
References
1. Allaby M. Basics of Environmental Science. London: Routlege, 1996.
2. Khromov S.P., Petrosyants M.A. Meteorology and climatology. Moscow: MGU, 2001 (in Russian).
3. http://en.wikipedia.org/wiki/Photovoltaics#Overview.
4. http://www.pvresources.com/en/top50pv.php.
5. Grachev Yu.G. Ecology of buildings. Perm: State technical university, 1995 (in Russian).
6. Govorushko S.M. Influence of economic activities on the environment. Vladivostok: Dalnauka, 1999 (in Russian).
7. Strauss W., Mainwaring S.J. Control of air environment pollution. Moscow: Stroiizdat, 1989 (in Russian).
International Scientific Journal for Alternative Energy and Ecology № 5 (97) 2011
© Scientific Technical Centre «TATA», 2011
