I've been without a computer this past week and a half, so I haven't been able to field my comments on the windmill thing.
Having read over the comments made by the various entrants onto this thread, I've noticed a glaring omission that contributes in a major sense to the cost effectiveness and practicality of windmills as a serious power source. That that omission is the effect of windmills and other such alternate energy power sources on the power system (grid to many). Electrical power systems are run on a generation matches load scenario. That is, you turn on a light motor, whatever, there has to be a generator in the system to adjust upward to supply that extra load. If this is not done, the power system frequency ultimately slows down. If the frequency reduction is enough the grid's clocks will slow down (this means any clock driven by electricity that is not on a battery. Slow the frequency even more, and the electrical power system becomes unstable and , hopefully, automatic load shedding takes place to balance and stabilize the system again.
Most of our electrical systems are traditionally supplied by one or more of the following, nuclear, fossil or hydraulic power. Nuclear power is a base load power source, that is, it takes a long time to change load,particularly in a downward direction, and therefore is kept at a base or constant load, usually at or near full power. Fossil plants are designed to be the same for efficient operation, but can change power outputs relatively quickly. Hydraulic generation is very maneuverable, but is usually run a maximum when the water is available because it is so cheap. This leaves fossil fired plants to look after most rapid load changes inn the power system.
If we go back to windmills, they are subject to the vagaries of the wind. The wind can change hour by hour and minute by minute. Those changes up or down have to be compensated for by the traditional power sources as I mentioned above. The only one capable of doing it and maintaining the system stable are fossil fired plants. This means fossil generation, with the capacity available equal to that of the windmills, has to be on line at all times to adjust for swings in windmill loadings, which is frequent. Therefore, what are we saving from a carbon , fuel consumption or cost standpoint when we can't rely on a constant reliable out put from windmills.
In the Ontario power system, it is seen that windmills only produce about 14 percent of their capacity of the course of the year. Winter has the highest winds, but the windmills still don't approach anywhere near full power output. In summer,when the load requirement is highest, the windmill output is at its least.
Ontario windmills are still being pushed because the government pays for half of their cost and guarantees the builder income regardless of whether the machine produces or not. The farmers want them on their property because they get paid rent regardless of whether the machine produces or not. Who gains, certainly not the consumer and neither does the environmentalist whether you agree with their opinions or not.
Its all a smoke screen for big money from our taxes.
To get an idea of what Ontario's windmills put out on an hour by hour basis check out this web site
http://www.ieso.ca/imoweb/siteShared/windtracker.asp?sid=ic What are my qualifications? I was a power system dispatcher for 15 years.
John