Category: 🧱 Foundations
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Electricity systems must continuously balance supply and demand.
Supply refers to the electricity produced by power plants.
Demand refers to the electricity used by homes, businesses, and industries.
Unlike many other products, electricity must be generated at the same moment it is consumed. Because electricity cannot easily be stored at large scale, the electricity system must constantly adjust generation to match changes in demand.
In Ontario, this balancing process is coordinated by the Independent Electricity System Operator (IESO).
⚡ Electricity supply must always equal electricity demand.
If too much electricity is produced, or too little is available to meet demand, the electricity grid can become unstable.
Supply and Demand
In electricity systems, supply is the electricity produced by generators, while demand is the electricity consumed by customers.
Balancing supply and demand is essential for maintaining a reliable electricity system.
Electricity supply comes from a variety of generation resources.
In Ontario, major sources include:
These generators produce electricity that enters the transmission grid and flows to consumers.
Related topic:
Generation Types
Electricity demand is the total amount of electricity being used at a given moment.
Demand is influenced by many factors, including:
For example:
Electricity demand changes constantly throughout the day.
To maintain balance, the electricity system must:
The Independent Electricity System Operator (IESO) coordinates this process to ensure that electricity supply always matches demand.
Related topic:
Independent Electricity System Operator (IESO)
Consider a hot summer afternoon in Ontario.
This continuous balancing process occurs every minute of every day.
➡ Next Topic:
Generation Types
This topic explains the different types of power plants that supply electricity to the grid and how their characteristics influence system operations.
Last Updated: 2026-03-26