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2010 - Diverse Supply Mix Provides Flexibility in Operating Ontario's Power System - Integration of Renewable Resources Well Underway

Ontario's diverse supply mix continues to provide the flexibility needed to respond to changing economic, weather and grid conditions, the Independent Electricity System Operator (IESO) reported today in its annual release of supply, demand and price data for the preceding 12 months.

As in previous years, Ontario's nuclear units provided more than half the energy required by Ontario consumers. However, unusually low water levels last spring and summer resulted in reduced hydroelectric output. The reduced availability of hydro power coincided with an increase in demand triggered by hot, humid summer conditions, resulting in greater reliance on gas- and coal-fired generation compared to 2009. Although coal-based output was up in 2010, it was still 45 per cent lower than in 2008 and roughly one-third what it was in 2003. Four coal-fired units were removed from service in 2010 without impacting reliability and the move to eliminate coal-fired generation is on track for completion in 2014.

Total electricity consumption for 2010 reached 142 TWh, up from 139 TWh in 2009. A marked increase in summertime temperatures pushed peak hourly demand to 25,075 megawatts (MW), up almost 700 MW from 2009 but still shy of Ontario's all-time peak demand of 27,005 MW set in 2006. At the same time, hydroelectric output fell by 20 per cent to 30.7 TWh.

Output from Ontario's wind generators continued to grow as more units came online, resulting in total annual production of 2.8 TWh in 2010, up from the 2.3 TWh recorded in 2009. Wind generation is starting to play an important role in meeting Ontario's energy needs, and nine of the 10 highest output days for wind power were in November 2010. In fact, wind generation on November 26 averaged more than 1,100 MW over the entire day - a record for total daily output.

"Energy production from new renewable resources is accelerating, and we are revising our operating policies and processes to integrate this new supply," said Paul Murphy, President and CEO of the IESO. "At the same time, we remain reliant on conventional sources of electricity, which provide the flexibility we need to manage the grid."

Total electricity output by fuel type is listed in the table below.









82.9 TWh
55.0 %

30.7 TWh
20.4 %

12.6 TWh
8.3 %

20.5 TWh
13.6 %

1.3 TWh
0.8 %

2.8 TWh
1.9 %


82.5 TWh
55.2 %

38.1 TWh
25.5 %

9.8 TWh
6.6 %

15.4 TWh
10.3 %

1.2 TWh
0.8 %

2.3 TWh
1.6 %


84.4 TWh
53.0 %

38.3 TWh
24.1 %

23.2 TWh
14.5 %

11.0 TWh
6.9 %

1.0 TWh
0.6 %

1.4 TWh
0.9 %

The cost of power in 2010 was 6.52 cents per kilowatt hour (kWh), as compared to 6.22 cents/kWh in 2009. This cost includes the average weighted wholesale market price of 3.79 cents/kWh and the average Global Adjustment of 2.73 cents/kWh (preliminary). 

Ontario's electricity imports increased to 6.4 TWh, up from 4.8 TWh, while exports rose modestly from 15.1 TWh to 15.2 TWh.