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Home wind farm: good or whim?
With the use of wind energy, mankind has been familiar from time immemorial. Once an unknown inventor adjusted the sail to an unpretentious floating vessel, and with its help, centuries later, the entire Earth was examined by inquisitive navigators. Windmills, even in our time in many countries, regularly serve man.
But today, the use of wind implies, above all, the generation of electricity. Let's try to figure out how simple, cheap and convenient it is. For those who want to immediately hear the outcome, the conclusion: wind power will never be cheaper than energy received from other sources: thermal, nuclear or hydroelectric power plants.
Therefore, it makes sense to engage in wind power plants for the home only to those who have itchy hands to adapt a ready-made generator they got "on occasion", or to enthusiasts of clean energy who fanatically want to save the planet from environmental disaster. Other reasons to use wind energy when powered by external electric networks simply can not imagine.
First, some information about the possibilities of using wind energy. When the wind acts on the turbine blades, the energy extraction efficiency (Efficiency) cannot exceed 59%. This value was obtained in their works by a number of scientists (Lanchester, Betz, Zhukovsky) as early as 1920. Since then it has been known as the “Betz limit”.
Does it make sense to consider efficiency wind generatorif it is powered by a gratuitous source of unlimited power? Of course have! Knowing the conversion efficiency, you can estimate the required power of the power plant, and then how much your wallet will lose weight after its purchase.
The maximum power that can be "taken away" from the wind is equal to the area on which it acts (the area of the propeller’s reach), multiplied by the wind speed in the cube and the efficiency mentioned above, equal to 0.6. Having expressed all the values in the SI system, we get that 1m2 of the turbine at a wind speed of 2 m / s takes power as much as ... 4.8 watts. With a wind speed of 8 m / s (the nominal speed of most wind generators), selection per unit area will increase to 307 watts.
Now, information for consideration: the real efficiency for home installations should be taken no more than 0.3. Working hours wind farms at the optimum wind speed, it ranges from 10 to 15% per year in the climatic conditions of the CIS countries.
Therefore, the power of a wind power station obtained from the formula must be increased by another 4-5 times. In practice, it is recommended to install a wind power plant, focusing not so much on technical indicators as on financial capabilities, on the principle: "The more, the better." With a dream to establish a powerful and, at the same time, compact installation, you must immediately part. One contradicts in principle.
The design of a wind power plant, in general, consists of a generator, a rectifier, a battery and an inverter for converting voltage to the usual value of 220V. The control and management of all units and elements of a power plant is performed by a microprocessor controller or simpler logic circuits.
Studying technical characteristics of wind farms, preference must be given to those in which the speed of the beginning of the movement of the rotor, the initial charging speed of the batteries and the speed at which they enter the operating mode, are minimal. The wider the range of operating wind speeds, the more likely it is to get energy. In this case, the cost plays a secondary role: why take the unit cheaper if it will work in your region for several days a year?
Now it's time to ask the price of the products of companies offering ready-made sets of equipment.We will not talk about home-made wind farms here at all. Even the best examples of industrial production have an efficiency of no more than 30%, and home-made constructions from auxiliary materials can only produce noise.
The whole variety of designs of wind generators can be reduced to two large groups: with a horizontal arrangement of the rotor of the generator and generators with a rotor of a vertical type.
Horizontal vane type generators have higher efficiency, less material consumption. But they require the use of masts of greater height, have a complex mechanical part and are inconvenient to maintain. Stations of the vertical type are less economical, they have greater material consumption, but operate in a larger range of wind speeds and are more compact.
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Consider one sample of the most interesting representatives of the wind power plants of each group. Of greatest interest from power plants with a horizontal rotor is gearless contour generator "Windtronics".
In it, aerodynamic drag is reduced due to the special design of the turbine, in which strong permanent magnets are fixed at the ends of the blades, and 68 stator coils are mounted along the rim. With this solution, the rotor is also a generator of electrical energy. Special flaps on the blades allow the turbine to start moving at a wind speed of 0.2 m / s. Today, this value is a record for generators.
At a speed of 0.9 m / s. the turbine begins to generate electricity. Other types of generators at these wind speeds cannot even budge. The weight of the product is about 110 kg, the diameter is 1.8 meters, the noise level is no more than 35 dB.
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Thanks to its rigid construction, the turbine can withstand wind speeds of up to 62.6 seconds. Annual output is from 1500 to 2750 kW / h of electricity. The American company Honeywell Wind Turbine, complete with a turbine, supplies all the necessary electronics, designed to connect 2 generators or an additional solar panel. A serious and only drawback of a wind power plant is its price - $ 5,750 with a nominal generator power of only 1.5 kW.
A promising representative of power plants with a vertical type generator can be considered Urban Green Energy turbines Eddy. The generators are very compact, almost silent and can be mounted even in urban environments. With a generator weight of 95 kg, it occupies an area of slightly more than 2.5 m2.
The turbine can be mounted in an hour, and it serves up to 20 years. The generator withstands wind loads of up to 193 km / h and generates, depending on the modification, from 2000 to 4000 kW / h of energy per year. The main disadvantage is the high initial wind speed for the turbine - 3.2 m / s. Information on the cost of the generator is not yet available.
The original turbine shape, reminiscent of rose petals, prompted architects to create a power plant in the form of a tree with 3 to 12 turbines mounted on its branches. The project was named "Power Flowers" - "flower tree" and attracted wide public attention by creating good advertising for Eddy generators and UGE.
One can talk about various designs and models of power plants for a very long time, but one thing unites them: a very high price. From an analysis of the proposals of firms, one can derive a certain unit cost of 1 kW of equipment power. It is approximately $ 2,000 without installation work. Adding another $ 500 for installation and commissioning, we get the average cost of equipment that will produce 2000-3000 kW / h of electric energy per year.
According to experts, the electricity received from environmentally friendly sources is 3-4 times more expensive than usual.When using low-power wind farms, the cost of energy can be an order of magnitude (10 times) higher than that obtained from traditional sources. This is associated with large one-time equipment costs and the installation, commissioning and maintenance of wind power plants.
In order to hide this fact, they often use the statement that with the increase in energy prices, environmentally friendly sources will become profitable. At the same time, the consideration is ignored that with the growth of energy prices, the cost of equipment that has significant material consumption will also increase. And the prospects for a reduction of such a “fork” is not expected even in the distant future.
If you have an irresistible desire to establish a wind farm, then first you need to get acquainted with the archive of weather reports for the last few years in your area. Such information is now available online and will immediately clarify the real possibilities for using wind energy.
See also at e.imadeself.com
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