Category: The characteristics and origin of wind energy
The characteristics and origin of wind energy
Terrain classification and ground airflow
Topographical features can have such a large effect on wind turbine energy output that the economics of the entire project depend entirely on the appropriate selection of the site. In the previous article, two methods for modeling vertical wind profiles (logarithmic wind profile and power exponential wind profile) were described. But these methods were developed for…
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Steady Wind: Variation of wind speed with altitude
As shown in Figure 1 (van der Tempel, 2006), the actual wind speed varies with space and time. Due to turbulence effects, the actual wind speed at any location will always vary around its average value with time and direction. Most importantly, the graph clearly shows that the average wind speed increases with height, a…
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Turbulence
Turbulence in the wind results from the continuous creation and disappearance of small eddies (or gusts), which convert the kinetic energy dissipation of the wind into thermal energy. Turbulent winds may have relatively stable averages over time spans of an hour or longer, but over shorter periods of time (minutes or less) it may vary…
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Atmospheric lapse rate
The lapse rate of the atmosphere is usually defined as the rate of change of temperature with altitude. As shown in the analysis below, the lapse rate is easily determined by calculating the change in pressure with altitude using conventional thermodynamic relationships. If the atmosphere can be approximated as a dry ideal gas (no water…
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Characteristics of the atmospheric boundary layer
The atmospheric boundary layer, also known as the Earth’s boundary layer, is the lowest part of the atmosphere whose properties are directly affected by the Earth’s surface. Here, physical quantities like speed, temperature, relative humidity can vary drastically in time and space. For example, an important parameter of wind resource characteristics is the variation of…
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Estimates of world wind resources
Based on wind resource data and estimates of the efficiency of actual wind turbines, many researchers have made estimates of potential wind power in several regions of the world, as well as for the entire planet. The maximum theoretically obtainable power output from the kinetic energy of the wind is 60% of the available power.…
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Temporal characteristics of wind
Atmospheric motion varies both in time (from seconds to months) and in space (from centimeters to thousands of kilometers). The previous article discussed the spatial characteristics of wind, which generally depend on height from the ground, global and local geographic conditions. Change of time According to common practice, changes in wind speed over time can…
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Other atmospheric circulation models and the spatial characteristics of wind
Other atmospheric circulation models The aforementioned general atmospheric circulation model is a good model for smooth spherical surfaces. But in reality, the earth’s surface varies greatly, with large areas of ocean and land. These different surfaces affect air flow due to differences in pressure fields, solar radiation absorption and moisture content. The ocean is like…
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Global generation mode and movement mechanism of wind
Global generation mode of Wind All renewable energy sources on Earth, including wind resources, come from the sun. Global winds are caused by pressure differences across the Earth’s surface caused by uneven heating of the Earth by solar radiation. For example, the Earth’s surface absorbs far more solar radiation in the equatorial regions than in…
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Alternative energy: wind energy and its historical development
Wind energy has once again become an important resource of the world’s energy is one of the significant developments in the energy industry at the end of the 20th century. The invention of the steam engine and the emergence of other industrial technologies that convert fossil fuels into useful energy sources seem to make wind…
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