The Role of the IESO:
Ontarios Electrical Power System
Ontarios electrical power system is one of the largest in North America,
serving the power needs of more than 12 million people in a market that is 1.1
million square miles in size.
- Transmission - Electric power is transmitted across the province
on 29,000 kilometres of high-voltage transmission lines, most of which are
owned by Hydro One. Ontario's high-voltage lines interconnect with lines from
Manitoba, Quebec, New York, Michigan and Minnesota, allowing up to 4000 MW
of electricity to be imported into and exported out of Ontario.
- Distribution - Transformers are used to link electric power from the
high-voltage lines to low-voltage lines. Hydro One, municipally owned utilities
and private companies then distribute the electric power at low voltage to
- Generation - Ontario currently has the capacity to generate 30,000
megawatts of electric power from 94 generating stations across the province.
These include hydroelectric, fossil-fuel and nuclear generating plants. OPG
currently provides about 70 per cent of the electricity produced in the