Wind turbines: is vertical or horizontal best?
Posted by Graham Eastwick on 24 August 2009 at 12:05 pm
There are two main categories of small wind turbines you will see as you travel around the UK today. Horizontal axis turbines look like traditional wind turbines and typically have two or three blades. Vertical axis turbines come in a number of designs, a spiral or some paddles blowing around in the wind.
I am often asked about the relative merits of the two fundamental designs and unfortunately neither the recent Energy Saving Trust field trial or the earlier Warwick Wind Trial study was able to monitor the performance of these turbines.
The key parameter of a wind turbine that determines its maximum theoretical output is the swept area of the blades. For both types of turbine this is easy to calculate from the dimensions provided in the data sheets.
The other important factor is the start-up wind speed. High wind speeds will generate more energy, as the output increases with the cube of the wind speed. Most wind speeds are low, so the lower the start-up speed the longer the turbine will run.
The effectiveness of all wind turbines is reduced in locations where the wind is turbulent and often changes direction. These problems are worst close to buildings so are a big problem in urban environments.
A horizontal turbine needs to face into the wind to extract power, so it has to change direction as the wind changes. A vertical axis turbine does not have this problem so the consensus feeling is that they should be more suited to an urban environment. If you have any data to back this up please post a comment.
More information about wind turbines from YouGen
If you have a question about anything in the above blog, please ask it in the comments section below.
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