Wind Energetics

a branch of science and technology that develops the theoretical foundations, methods, and facilities for using the energy of the wind to produce mechanical, electrical, and heat energy and determines the areas and extent of expedient use of wind energy in the national economy.

Wind energetics consists of two principal parts: wind technology, which develops the theoretical foundations and practical methods for planning technical facilities (aggregates and installations); and wind use, which includes theoretical and practical problems of the optimal use of wind energy, rational exploitation of installations and their technical-economic indexes, and theoretical generalization of experience in the use of these installations in the national economy. Wind energetics also uses the results of aerological research, on the basis of which the wind-energy cadastre is developed. The data of the wind-energy cadastre serve not only to reveal regions with favorable wind conditions but also to determine the types of operations in which the use of wind energy is expedient and economically profitable in comparison with other energy sources. The use of wind energy is indicated above all in types of manufacturing processes in which interruptions in the flow of energy are permissible or in cases where the product of processing can be stored (drawing of water, irrigation, drainage, milling of grain, fodder preparation, charging of electrochemical storage batteries, and so on). Taking into account the importance of this branch, V. I. Lenin, in his first Draft of a Plan for Scientific-Technical Operations (April 1918), included operations that would use wind and water energy generally, and in particular for farming; in a letter to A. P. Serebrovskii (April 1921), Lenin emphasized the important value of using wind engines for irrigation and for the development of farming in the Baku region.

Wind energy, along with solar and water energy, is one of the perpetually renewable and, in that sense, eternal sources of energy that owe their origin to the activity of the sun. As a result of uneven heating of the earth’s surface and the lower layers of its atmosphere by the sun’s rays, movements of large masses of air occur in the surface layer and also at altitudes of 7 to 12 km—that is, wind is generated. The wind carries a colossal quantity of energy: 96 x 10²¹ joules (J) or 26.6 x 10¹⁵ kilowatt-hours (kW-hr), which is almost 2 percent of the energy of all the solar radiation reaching the earth. The force of the wind, which depends on its velocity, changes within very broad limits, from a light puff to a hurricane with a velocity up to 60-80 m/sec. The potential resources of wind energy over the whole territory of the USSR have been determined at 10.7 gigawatts (GW; million kW), with a possible annual yield of 65 x 10¹⁸ J (18 x 10¹² kW-hr). It would be possible to satisfy a significant portion of the country’s requirements by using even a small percentage of this energy. The type of wind installation and its economic characteristics are determined according to the economic, wind, and other zonal conditions.

Some of the most important advantages of wind energy are its availability and ubiquitous distribution and the practical inexhaustibility of its resources. It is not necessary to extract and transport the source of energy to its place of use: the wind comes on its own to the wind engine that has been set up in its path. This property of wind is extremely important for inaccessible regions (arctic regions, steppes, deserts, mountains, and so on), which are distant from sources of centralized energy supply, and for relatively small (up to 100 kW) users of energy who are spread over extensive areas. The principal obstacle to the use of wind as a source of energy is the variability with time of its velocity and consequently of its energy. The wind has not only perennial and seasonal variability (see Figure 1), but also changes its activity

Figure 1. Seasonal variability of wind velocity

Figure 2. Diurnal variation of wind velocity

Figure 3. Character of variations in wind velocity over a short time interval

in the course of a day (see Figure 2) and over very short time intervals (momentary pulsations of velocity and wind gusts; see Figure 3).

The potential of wind energy depends on the average annual or average periodic values of velocity and on the recurrence of various wind velocities. It is evaluated according to the quantity of energy that may be obtained in a given locality by means of a wind engine. In zones of moderate wind regime (average annual wind velocity, 5 m/sec) it is possible to obtain an annual output of electrical energy of approximately 3.6 × 10⁶ megajoules (MJ; 1 million kW-hr or 1 GW-hr).

The power of the wind current is proportional to the cube of its velocity. For this reason, even relatively small changes in velocity lead to significant fluctuations in power developed by a wind engine, within a range of velocities from the minimal operating velocity (at which a wind engine will begin to produce usable power) to the rated velocity (which corresponds to the rated power for a wind-power installation). The design and means of regulation of the rotation frequency and power of wind engines ensure their reliable operation at gale velocities (40-50 m/sec) and the limitation of developed power so that the maximum power usually does not exceed the rated power by more than 15-20 percent. In order to diminish or avoid fluctuations in power, wind energy is accumulated when there is surplus power and is then used during periods of calm or of insufficient wind velocity. The difficulties of using wind energy and the reasons for its still insufficient practical use may be explained to a significant degree by the specificity of its accumulation.

Short history of the development of wind energetics. From most ancient times man has used the energy of the wind—at first in navigation and then as a substitute for his muscle power. The first and most simple wind engines were used in earliest antiquity in Egypt and China. In Egypt (near the city of Alexandria) the remains of stone windmills of the drum type constructed as early as the second and first centuries B.C. have been preserved. In the seventh century A.D. the Persians built windmills of more advanced (vane-type) construction. Somewhat later, apparently in the eighth and ninth centuries, windmills appeared in Rus’ and in Europe. Beginning in the 13th century, wind engines became widely distributed in Western Europe—especially in Holland, Denmark, and England—for drawing water, grinding grain, and driving various machines. Before the Great October Socialist Revolution there were approximately 250,000 windmills on peasant farms; they milled half of the harvest (approximately 33 million tons or 2 billion poods of grain) annually. With the invention of steam engines and then of internal-combustion and electric motors, the old, primitive wind engines and windmills were supplanted in many areas and remained chiefly in agriculture. At the beginning of the 20th century the Russian scientist N. E. Zhukovskii developed the theory of a high-speed wind engine and laid the scientific foundations for the creation of high-production wind engines capable of using the energy of the wind more effectively. They were built by his students after the organization in 1918 of the Central Aerohydrodynamics Institute. Soviet scientists and engineers laid the theoretical bases for designs that were new in principle and created various types of wind-power installations and wind-power plants of advanced construction, with capacities up to 100 kW, for the mechanization and electrification of agricultural production processes and for other purposes. Contributions of great merit in creating the foundations of wind energetics and wind use were made by the Soviet scientists N. V. Krasovskii, G. Kh. Sabinin, and E. M. Fateev. The industrial production of wind engines for mechanical machine drives was set up at the beginning of the 20th century, and the production of electrical wind aggregates with low-capacity generators began approximately in the 1920’s.

The construction of wind-power plants achieved intensive development in the 1940’s and 1950’s in the USSR and abroad. In Denmark during World War II, several dozen wind-power plants were operating; their output exceeded 80 million kW-hr. During the years of Soviet power, lot production of specialized and general-use wind engines with capacities of 0.7-11 kW (1-15 horsepower)—mainly with mechanical and electrical transmissions—was instituted. In the postwar period more than 40,000 wind motors were produced—mainly types TV-8, TV-5, D-12, and VE-2, which were used with great effectiveness on kolkhozes and sovkhozes.

The status of wind energetics at the end of the 1960’s. In the USSR new types of improved, standardized high-speed wind-power units (VBL-3, VPL-4, Berkut, Veterok, and others)—using new types of pumps and generators; pneumatic, electrical, and other types of drives; and improved regulatory systems—have been created. Most wind engines are used to mechanize the drawing of water, especially in pastures and isolated farms along the Volga, in the Altai, and in the Chernye Zemli region, the Kazakh, Turkmen, and Uzbek SSR’s, and in other zones, where they operate 250-300 days a year. The development of the theoretical foundations and creation of new constructions of wind-power units for various uses are under way in the Soviet Union (the All-Union Scientific Research Institute for the Electrification of Agriculture, the All-Union Scientific Research Institute of Electromechanics, the Central Aerohydrodynamics Institute, and others), the Federal Republic of Germany (the Stuttgart School of Wind Power Engineers), the USA, Great Britain, France, Denmark, and other countries. In those countries of the world where wind energetics is widely developed, more than 600,000 wind-power installations are in use (according to incomplete data—UNESCO materials for 1967). In 1968 in Australia more than 250,000 wind-power installations, predominantly of the pump type, were in operation. In the USSR the number of operating wind engines (not including homemade engines) is 8,000-9,000.

Prospects for development. The role of wind energetics in the Soviet Union is increasing, with the implementation of a large program of irrigation and land reclamation and the solution of the most important problems of the developing mechanization of animal husbandry and the electrification of agriculture. Wind-power installations can be used successfully for the mechanization of water supply to consumers, drying of swamp areas, small-oasis irrigation of melon, forage, and garden crops in newly reclaimed desert or semidesert zones, for energy supply to distant objects, and so on. It is presumed that for these purposes tens of thousands of wind-power installations will be used, which will provide a severalfold decrease in expenses for the drawing of water. As the famous Russian scientist K. A. Timiriazev wrote as early as the 1930’s, this will be the ideal solution to the problem of drought control. Early experiments have shown that wind-power aggregates can also be used expediently for feeding energy to installations for the purification of mineralized ground waters and for so-called cathode protection of pipelines and maritime structures from corrosion, and that wind-pneumatic aggregates can be used for the aeration of bodies of water in the winter by pumping air under the ice. The possibility of building larger wind-power plants (in particular, in the Philippines, up to 5 MW) for the supply of power to isolated consumers in inaccessible regions (arctic, mountainous, and so on) and on islands, where the delivery of fuel is difficult and expensive, is being studied. The use of such wind-power plants for parallel or joint operation with other electric power plants is most promising. A more distant prospect is the use of high-altitude wind-power plants with a capacity of 3-5 MW, which would use the energy of air currents in the tropopause.