Wind Energy

eolica 1Wind is the result of air flowing across different pressure zones, which in turn is a byproduct of incident solar radiation variations on the atmosphere and troposphere.

Wind characteristics (velocity, direction and turbulence) are hard to predict due to globalized phenomena interacting with one another, as well as local phenomena: earth's rotation, Coriolli's acceleration, the moon's relative position, differences between local and global average temepratures, terrain topography, surface roughness, obstacles, among others.

Only exhaustive studies and measurements and statistical wind data analysis are valid tools for predicting energy yield accurately. Site analysis is key in wind potential determination.
 
If a potential site is found, energy may be extracted from the wind by means of wind turbines. These may be used for electricity production, water pumping, water production and mechanical work (for grinding).

There are several kinds of wind turbines, depending on rotor shapes and sizes. Large wind turbines are mostly Horizontal Axis Wind Turbines (HAWT's), with the rotor facing directly the wind and a mechanical or drag-induced mechanism rotating the nacelle into the wind. For small applications, Vertical Axis Wind Turbines (VAWT's) are the most used; they have lower efficiencies and output capacities than VAWT's, but are not as affected by interference of other turbines and achieve reliable yield independent of wind direction.
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Steps for wind power assessment:
 
  1. Obtain or elaborate reliable wind data (wind rose)
  2. Recognize the terrain's topography, roughness and obstacles
  3. Determine nacelle height
  4. Choose final location
  5. Choose a wind turbine that maximizes yield and operates correctly under given site conditions
Wind Data:
 
  • Main wind data to assess potential are wind velocity (m/s) and direction (degrees)
  • The wind rose is essential for adequate site assessment
  • Statistical tools including Weibull-distribution fitting helps characterize and predict wind regime
  • Reliable wind data allows for an accurate prediction of energy yield on site, as a function of wind direction and velocity
Advantages of Wind Power:
 
  • Allows for the electrification of non-interconnected zones
  • Generates distributed energy on a micro scale, reducing transmission costs and losses
  • Energy is produced on site, taking advantage of the particular characteristics present in the chosen location
  • It is a scalable solution, meaning that arrays of turbines may be organized and installed without significant power losses
  • May be combined with solar photovoltaic in hybrid systems
Applications:
  • Lighting
  • Electricity supply
  • Reduced energy consumption
  • Water pumping and irrigation
  • Recharging batteries for off-grid applications