Ever wonder how much energy a wind turbine produces, or how you would even calculate such? Let’s first break down how exactly a wind turbine produces energy. Wind turbines function by capturing wind through their blades and converting this energy into electricity with generators.
The shape of the blades is designed so that pressure differences across the surfaces causes them to rotate. This rotation turns an internal shaft that leads to the generator inside the turbine.
Calculating Wind Energy
While the basic function of a wind turbine is quite simple, the amount of power that a turbine produces is based on many factors. The three most important of these factors that influence the power produced by a turbine are: air density, blade length (rotor radius), and wind speed. The power availability in wind is calculated by the following equation:
ρ=air density, kg/m3
v=wind speed, m/s
r=blade/rotor radius, m
As you can see, wind speed and blade size have a profound effect on the energy output of a turbine. In fact, doubling the wind speed will increase the power output eight fold. Likewise, doubling the rotor radius will increase the output by four.
As a result, even small increases in wind speed or rotor length can vastly increase the amount of energy produced. This is why the location of wind farms is so important.
Planning for Wind Production
Before construction even begins on a project, extensive analysis of the site and its wind resources must occur to determine what turbines are best to use, and where exactly to place them. The planning process for wind turbine installation can be rather lengthy.
Engineers will record wind speed statistics from meteorological towers – sometimes two years before any development begins. These figures, compared against past data gathered from the site, topographic information and locations of obstacles in nearby areas are placed into a computer program that’s specifically designed for wind farm design.
The program then provides engineers with a detailed analysis, calculating the Annual Energy Production in megawatt hours (MWh) to aid in financing the future wind farm. It’s not until after all of these calculations have been completed that construction can begin on the wind turbines.
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