Looking at electricity generation from windfarms in Ontario from last month reveals some interesting details. As always, the data that I am using is publicly available on the IESO website.
Figure 1: Wind generation for Ontario in June, 2010 - Datapoints are hourly.
As I've come to expect, sometimes the windfarms produce large amounts of electricity and sometimes they produce nearly nothing. The average capacity factor this last month was a dismal 18.8%. The most output for any one hour was 746 MW, and the least was 0 MW.
No, that wasn't a typo. In fact, there was a period of two hours where not one MW was recorded as being produced. Since the markets are required by law to include wind power where possible, its safe to say that this is because of the wind turbines themselves and not because regulatory limits. If I recall there was some nasty weather around that time but that wouldn't explain why none of the wind turbines were producing useful electricity.
In any case, I'm not sure there can be a much clearer illustration of why wind power doesn't work in Ontario. Sure, you can produce electricity maybe 18.8% of the time on average, but the other 81.2% of the time you require another source of electricity, like coal.
That doesn't mean that wind power is a bad idea everywhere all the time, but we need to have an honest discussion about the drawbacks of generating electricity via the wind. Something that environmentalists and many politicians are unwilling to do.
While someday in the future someone may figure out a way to 'smooth' the inherent instabilities of windpower to make it a viable option while making it cheap enough for us to afford, that day isn't here yet, and it might never come. And we shouldn't pretend that if we just wish and hope hard enough that it will.