Thus, the shear forces on the rotor blade are greater when it is in the top position. Wind shear is a function of wind speed, which increases with height above the surface. Variability leads to wind shear and wake forces. It is necessary to measure the characteristics of the wind in great detail, including how often winds of certain speeds occur (see Figure 1) and how the surrounding terrain affects the stability of air flow.Ī stable flow with a consistent speed is important for both generating efficiency and structural integrity. Understanding this variability is key to siting wind-power generation, because higher wind speeds mean higher duty cycles (i.e., longer periods of active power generation). Both direction and speed are highly variable with geographical location, season, height above the surface, and time of day. (Courtesy: Sentient Science Corp.)Īlthough there may be a prevailing wind direction, it is not the only wind direction. Figure 1: Plot of the frequency of occurrence of different wind speeds over a period of a year. At night, the water is warm relative to the land, so air is warmed over the water and rises the resulting low pressure draws cool air from land out to sea: the land breeze. One such effect, familiar to anyone living near the ocean, is the land breeze.
As a result, different regions of Earth have different prevailing wind directions.Īt the other end of the spectrum, local geographical features can have specific effects. As cool air flows from higher to lower pressure areas, it is deflected by the Coriolis force the direction of deflection depends on latitude. Global patterns are in part the result of the Coriolis force, which arises from the Earth’s rotation. Wind is shaped by both global and local forces. Hot air rises, reducing the local atmospheric pressure nearby cooler air flows into this region of lower pressure this air flow is wind. The sun’s energy creates temperature differences that drive air circulation. Wind arises from processes driven by solar energy. The global capacity for generating power from wind energy has grown continuously since 2001, reaching 591 GW in 2018 (9-percent growth compared to 2017), according to the Global Wind Energy Council.
Wind turbines are the fastest-growing renewable energy source, and wind energy is now cost-competitive with nonrenewable resources. Wind energy is expanding both onshore and offshore with bigger, more powerful turbines, creating new demands and markets. We are seeing an unparalleled enthusiasm, demand, and growth in renewable energy production, wind energy being at the forefront. The rising concerns over climate change, environmental pollution, and energy security have increased interest in developing renewable energy.
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