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Power Output of Homemade Wind Turbines:
Just as it is with other homemade or do it yourself turbine projects, one of the most crucial things to consider, if not the most crucial thing is the power output. And the same goes with homemade wind turbines. Many beginner DIY enthusiasts usually fail to consider the power output factor when building their own projects. Initially they start out with all the excitement in the world, putting all the niceties and bells and whistles in their project, only to find out later on that their turbine’s power output just does not meet their standards. And most often than not, the project has to be redone from scratch.
Determining the power output of the wind turbine is not as insanely difficult as one might initially think. However, it does require a bit of patience and a bit of calculation. However, to keep things simple, there are just some basic guidelines to follow when computing for the power output of homemade wind turbines:
1.) The power output of the wind turbine is directly proportional to the area swept by the rotor. This means that if the wind turbines swept area is doubled – due to perhaps a much larger rotor blade, the power output will also effectively double. 2X Rotor = 2X Power.
2.) The power output of the wind turbine is proportional to the cube of the wind velocity. Essentially, when the wind doubles in strength, the power output of the turbine will also increase by a factor of eight! 2X Velocity = 2x2x2 Power.
3.) Another factor of computing for wind power is air density. Air has a density of around 1.23 kilograms/m3 at sea level – and the air density varies depending on how high or low the area is when compared to the sea level. But to keep things simple, we will be using the sea level data as a reference point. (1.23 kg/m3)
Now for the formula: To sum it all up, the theoretical power that a wind turbine can generate is equivalent to velocity multiplied by swept area and then multiplied by air density. (Power = Velocity x Area x Density). This is supposedly the maximum power the turbine can generate.
Getting the theoretical maximum power for homemade wind turbines however, will not be applicable in real world application. This is one of things that get a lot of DIY enthusiasts off track. This is because the computation in theory does not consider limitations of wind energy and also the equipment used. A good example for this is the computation for the world’s largest wind turbine. The turbine, when computing for its maximum power, should have a power of 21 Megawatts. However, the actual power rate is only at 5 Megawatts. The reason for this is that there are other factors to be considered like turbine efficiency, drag, and heat transfer. There is also such a thing as the Betz limit (or the Betz law). This law is a theory about the maximum possible energy to be derived from a “hydraulic wind engine”, or a wind turbine. It states that no turbine can extract more than 59.3 percent of the kinetic energy in wind.