Many people living in cities are itching to take advantage of residential wind turbines, but this may prove to be difficult. Cities are some of the least hospitable places for wind turbines to be located. Turbines work most efficiently when placed in undisturbed airflow. Any large obstacles nearby, such as buildings will greatly affect the amount of power that a turbine can produce.
To find a suitable residential wind turbine, the best option may be a vertical axis wind turbine or VAWT. You may have seen these turbines before, most commonly they are shaped like large egg beaters and spin around a pole mounted vertically. This is in contrast to traditional turbines which have propeller-like blades.
VAWTs have much better performance than traditional wind turbines when used in turbulent environments. This means that in a residential wind turbine application, a VAWT will provide more power than a traditional turbine. There are many different styles of VAWTs and each has its own advantages and disadvantages.
Savonius type turbines are completely solid, and don’t have blades as you are used to seeing. Instead, a Savonius turbine has two (or more) curved surfaces which face the wind full on, and spin the turbine about its axis. These turbines are large and heavy compared to other aerodynamically-driven machines and are also less suitable for use as residential wind turbines due to their size.
Darrieus type turbines are the egg-beater style VAWTs mentioned earlier. These turbines have curved or even more complex blades to take advantage of turbulent wind conditions. Traditionally, these turbines have been very large. This means that their suitability as residential wind turbines is limited; however they are more suitable than Savonius type turbines. These turbines do have several issues which make their design more complicated. Specifically, the turbines generate maximum torque at two points in their rotation, and thus the power they generate is not “smooth” as it would be in a traditional wind turbine. Additionally, these turbines have issues with vibration that could cause the blades to fail prematurely.
Finally, airfoil based turbines, which are a subset of Darrieus turbines. Instead of curved blades, the blades of these turbines are parallel to the main shaft. This means that they generate more constant power than Darrieus turbines, much closer to traditional wind turbines. These turbines are the closest match to the requirements of residential wind turbines. Much research into this type of turbine is ongoing and new developments are happening in this field every day.