Wind Energy Basics

I've been interested in wind energy for some time now. My plan is to use a wind generator to cover some of my electrical consumption of the net-zero energy home I've been building. Wind turbines are a very romantic technology for generating electricity. It's easy to appreciate the concept of harnessing the wind that you can feel on a breezy day and, unlike solar, there is something interesting to watch.

There are 2 main things to consider when trying to determine how much energy a wind turbine will produce on your site. The first is the wind resource itself. If there is not much wind - you will not harvest that much energy. This seems obvious but how many people know what a 10m/s wind feels like? Not many. We tend to be very anecdotal about wind. We think that we live in a very windy area, only to be disappointed when our turbine isn't producing the 1200 kwh a month we were counting on. So how do you know for sure how much wind you really have? For starters, you could go to http://www.windatlas.ca/en/index.php . You can find your location on the map and get a general idea of your wind resource. Notice I said "general" idea. Your specific location and particular spot you want the wind turbine to go, cannot be modelled specifically from the wind atlas. For that matter, if you are in a windy area, your specific location could be less windy(or more windy) than the general area. If you are at the top of a hill, you would likely get more wind than your neighbour at the bottom of the hill. Or, maybe you are at the top of the hill, but you want to place the turbine on a short tower between some large trees and a grain bin which may give you less energy than your neighbour at the bottom of the hill who has a taller tower and an obstructionless location.

If you want to know for sure, you could consider measuring the wind at your site. Best done over a full year, you can buy relatively inexpensive wind dataloggers to let you know for sure. Most of us are too impatient to wait for a full year so at least plan to mount your turbine on a tall tower in an area where there is a minimal amount of obstructions to block the wind and cause turbine-killing turbulence.

The second factor in determining your wind resource is the swept area of the turbine. How much wind is captured by the wind determines how much energy you get. Sounds simple, but you'd be surprised how many wind turbines are sold with power outputs that don't relate to their physical size. Resist the vendors efforts to sway you with comparing the turbines rated output and instead compare the swept area. A bigger wind turbine will make more energy than a smaller one. Sure, the efficiency of the particular machines matter, but if you are comparing legitimate turbines, their efficiencies will be close (typical efficiency will range between 25 and 35%).