Managing A Diverse Supply of Energy
Diversity in the type of energy resources strengthens the reliability of Ontario’s power system as different energy resources serve different functions.
No single energy resource option can meet all system needs at all times. Maintaining a diverse supply mix, where the different resources are complementary to each other, is an effective way to provide the services necessary to balance the supply and demand of electricity and maintain the reliability of Ontario’s power system.
The province’s demand for energy throughout the day can vary by more than 10,000 MW – requiring different energy resources to perform different roles. Some generators are needed to produce a constant supply of energy, while others are needed to increase or decrease output in step with second-by-second changes in demand.
As the sources of generation evolve, the IESO must adapt how it manages the power system to effectively coordinate the operating characteristics of the different forms of generation.
Nuclear power plants and run-of-the-river hydro facilities with little or no storage capabilities provide a constant and steady output of electricity, 24 hours a day. While some of these facilities may be able to adjust their output to a limited degree, these manoeuvres typically take place when total demand for electricity is forecast to be less than the usual output from these baseload generators.
Peaking and intermediate generation
Some generators are designed to increase and decrease energy output as needed − these include natural gas facilities and hydroelectric generators with reservoirs for storage. Generators relied upon to meet the "peaks" on the highest demand days are referred to as peaking generation. These generators can also step in quickly should another generator break down unexpectedly. Others act as intermediate generation − working throughout the day by adjusting output as consumer demand moves up and down.
Variable but controllable generation
Wind and solar facilities produce energy depending on how strong the wind blows and how bright the sun shines. While their output is variable, these generators are highly flexible and can change output very quickly in response to system signals. The IESO is able to instruct transmission-connected solar and wind facilities to decrease or increase their output in response to system conditions, such when there is more baseload generation than needed to meet demand or when there is congestion along transmission lines in certain areas of the province.
Using meteorological data in addition to operational and facility data for variable wind and solar generators greater than 5 MW, the IESO is able to forecast the amount of hourly energy to be provided from variable resources in regions across Ontario.
See hourly forecasts of wind output: Wind Power in Ontario Map.
Learn more about how growing distributed energy resources (DERs) are creating a more decentralized electricity system – presenting both new opportunities and challenges for the operation of the power system.
See current capacity by fuel type for generators connected on Ontario's distribution systems.
Read more about the province’s efforts to reduce electricity consumption through energy efficiency.
Learn more about Ontario's annual imports and exports.
Read more about the role of demand response.
Learn more about energy storage technologies and how they work.