One thing that I've noticed in reading news and reports is how easy it is to be confused by the terms "installed capacity" (measured in MW) and "electricity produced" (measured in kWh). So I felt that maybe I should explain the difference.
In layman's terms, when you build an electricity generating station there is a maximum amount of electricity that the station can produce at any given point in time. That is the "installed capacity". If the station operates at 100% capacity, producing the maximum amount of electricity every hour of every day over a year, then we can use the "installed capacity" in order to easily calculate the total electricity that the station has produced.
As an example:
In one day a 1MW station will generate (assuming a 100% capacity)
1 MW x 24 hours / 1 day = 24 000 kWh /day
In one year,
1 MW x 24 hours / 1 day x 365 days / year = 8 760 000 kWh / year
But lets use a real life example and go a little further. It was reported that in 2007, the Chinese had an installed capacity of 6.06 GW of wind power and produced 5.6 billion kWh in that year.
So, assuming a 100% capacity:
6 060 MW x 24 hours / day x 365 days / year = 53 085 600 000 kWh / year
Which can also be written as 53.1 billion kWh /year.
So, if Chinese wind farms are operating at 100% capacity every day for a year they would be able to produce 53.1 billion kWh. In reality, they only produced 5.6 billion kWh. That means that the actual capacity of the Chinese wind farms was around 10.5%.
Now, there are plenty of limitations with this simple analysis but the question this raises is why should we use "installed capacity" rather than "electricity produced" when talking about wind power? The answer is politics. Talking about larger numbers makes the 'achievements' sound more impressive than they really are.
If Ontario installs 2500 MW of wind power but only receives electricity as much as a 250 MW coal fired power plant then are we really getting our money's worth?