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.

Baseload 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.

Distribution-connected (embedded) generation

Evolutions in technology and the electricity marketplace are expanding opportunities for participation in Ontario’s electricity system and are driving a transition towards a system characterized by two-way energy flows and growing prevalence of smaller-scale distribution-connected, or embedded, generation.

Embedded generators supply electricity to local distribution systems, which reduces demand on the transmission grid. This capacity is continuing to grow.

The largest capacity of embedded generation comes from solar power, followed by wind and waterpower. Embedded resources pose some unique operational challenges to the IESO in that the magnitude and timing of their energy output is less visible and less predictable than that of conventional generation. Despite the added complexities, embedded generation can improve the efficiency of delivery of power closer to its end-users, resulting in cost savings associated with line losses and transmission.

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.

Role of energy efficiency

The role of energy efficiency in meeting Ontario’s electricity demand is growing. It provides the cleanest and most cost-effective alternative to building new generation. The IESO delivers innovative programs and educational resources to Ontario businesses and residents to help them manage energy usage.

Read more about the province’s efforts to reduce electricity consumption through energy efficiency.

Role of electricity imports and exports

Ontario's electricity grid is part of a greater network that spans North America. Ontario currently has interconnections with five of its neighbours: Quebec, Manitoba, Minnesota, Michigan and New York. By importing and exporting energy on a continual basis, the IESO has an important tool to help it balance the system. Electricity trades between these neighbouring jurisdictions provide operational and planning flexibility, as well as enhance the reliability and cost effectiveness of the Ontario electricity system.

Learn more about Ontario's annual imports and exports.

Role of demand response

Through demand response, consumers reduce their electricity use in response to system needs and prices, providing a highly flexible resource. While large consumers have always played an important role to help meet system needs in real time, the opportunities for consumers to participate in demand response programs has grown. Through the IESO’ s Demand Response Auction large consumers, as well as aggregators of smaller institutional, commercial and industrial customers, can compete to provide demand response capacity.

Since 2013, through an aggregated load provider, ENBALA Power Networks, a number of large institutional, commercial and industrial consumers are able to deliver up to 4 MW of regulation service, a grid-balancing function traditionally provided by generators. Participants in this aggregated load program increase and decrease their power use in response to real-time system needs.

Read more about the role of demand response.

Role of energy storage

Emerging energy storage technologies are allowing electricity to be captured and stored and then re-injected back into the grid when it is required. Energy storage can help to smooth out fluctuations of variable resources and absorb surplus baseload generation when the output is higher than minimum demands.

The IESO has contracted 50 MW of a variety of energy storage technologies in order to understand how storage can be integrated into the power system and used to support day-to-day operations of the system and market. The IESO is already using storage technologies as a source of "regulation" − a specialized service that maintains second-by-second balance on the grid.

Learn more about energy storage technologies and how they work.

Emerging Technologies Across North America

All across North America, system operators are working to integrate renewable generation, and Distributed Energy Resources (DERs) to ensure a nimble, efficient and robust electricity system. Together, through the ISO/RTO Council (IRC), they’ve released this report which sets out strategic approaches and goals to integrating these emerging technologies.