I've completed one year of gathering and presenting Ontario's wind turbine production, and I figured it was time to put that data to more use than just the reports. So I visited the IESO web site to get more information on demand patterns so I could compare the demand vs. the wind production. Of course mission creep occurred and I created some other charts that might be of interest as well.

The first of these charts is the daily Ontario electric demand for the year starting August 1, 2007 and ending July 30, 2008. There's several things I feel obligated to mention. The vertical axis is the daily demand in mw-hr's - roughly 15-20,000 mw times 24 hours. The horizontal axis is days, starting with August 1, 2007. Each number represents about 1 month. The little bumps are each week, with the dips occurring on the weekends. The overall peaks are in the winter and in the summer, with the summer being slightly higher. It used to be reversed, by the way. Notice the weekly bump around day 151 is missing - that's the Christmas holiday. Also notice how in the summer the peaks are sharper and more jagged, due to air conditioning use.

Next is the Ontario wind farm production for the same period. The horizontal axis is the same as the first chart, while the vertical axis is in percent of total capacity. To give you some perspective, the 90% line was about 10,000 mw-hrs for most of the year - it varied as new wind farms came online, which is why I used percents. The most obvious thing is the wide variability in the daily output. You can see there are days when not much wind blows anywhere in Ontario. There is an increase in wind production in the winter, which helps out with the winter demand peak. There is very little wind production in the summer, which doesn't help at all with the higher summer peak. But the overriding factor is the variability. On an hourly basis, this requires other dispatchable energy generators to be kept at the ready. On a yearly basis, it requires a complete set of alternative generators to be built.

For a longer-range look at Ontario demand, this chart goes back to 2002. Each number on the horizontal axis represents about one year. Here you can see the two peaks each year more clearly. To me the most interesting thing about this chart is that overall Ontario demand is not increasing.

This chart shows the difference between what is generated in Ontario and what is demanded over the same period as the chart above. Any positive difference represents electricity that can be exported to other provinces and especially to the U.S. What is not shown is any imports, and I don't know how accurate my numbers are - for example, from my chart, Ontario would have exported 17tw-hr in 2007, but the IESO reports only 12.3. Still, in the last few years both this chart and the web site note that net exports have increased dramatically. Of the roughly 150tw-hr that Ontario uses in a year, the net exports have grown to about 5tw-hr, or 3% of the total.