Wind power has been a valuable tool throughout the history of civilization. We’ve used it to propel our boats across the oceans and to spin wind turbines to grind our grain. In the modern age we are using wind power to generate electricity.
Wind power systems work well in locations with wind speeds in excess of 7 mph. This wind should be available on a frequent basis. Wind turbines are somewhat of a specialty, however, since they can be used only in locations with constant patterns of winds. These patterns are often related to mountain Chinooks, coastal climates, and locations in the Great Plains under the influences of the jet stream.
Wind power systems are usually coupled to an AC or DC generator and battery bank, and may be outsourced to the electrical grid. Since wind speeds often change, then so too our wind turbine rotational speed will want to change. Wind turbines have an ideal operational speed based on their aerodynamics. Modern load control and variable pitch blade systems are often used to help maintain the turbines within this operating range.
Horizontal axis wind turbines are the most dominant design in the wind power market today. These are the traditional style of windmill with two to four blades facing head on into the wind stream. Sizes range from small home units that will generate a few kilowatts, on up to large industrial units in excess of 1 Megawatt.
Vertical axis wind turbines have seen limited time in the market place. They take on the flow tangentially and use a different style of blades. Historically, their design was compact and easy to install, but at the expense of some output and efficiency. They are nice for someone considering a smaller output roof mounted wind power unit, however very few designs are available on the market today. Some newer designs are under development, however, and so with some time market conditions may change.
Mathematically speaking, the amount of wind power we generate is proportional to the wind velocity cubed. And so once can imagine the difference between a 15 mph and 7 mph wind source can be huge. When installing our wind turbine systems, we should try and keep them at the highest elevation that is possible. This reduces the effects of trees, structures, and other land based obstructions on wind velocity.
An additional thing to keep in mind is too much wind. Extreme gusts and high velocities could overload the wind turbine, and so we must have a way to protect from this. Variable pitch (self adjusting) blades are helpful, but in the stronger storms we may have to decommission the turbine, lock down the rotor, and reorient to the lowest stress position.
The decision whether to use wind can be pretty easy. Just by experience, you should know your local wind patterns and couple of measurements should tell if you are in excess of 7 mph. In certain locations, wind power works nicely hybridized with solar panel installations.
Using the local wind patterns is an ancient practice for obtaining energy. If you have the right weather conditions, then wind power is a good choice for you. There will be some planning and forethought in the type of system you select. But once in place, you will have an energy source that is clean, reliable, and free for generations to come.
Walter Hull is a mechanical engineer with expertise in green power production. Walter continues to design and build off grid power generation systems utilizing wind power and solar power.
