The Ontario government is taking a deep dive, approving the Independent Electricity System Operator’s (IESO) recommendation to build a new underwater electricity transmission line from near the Darlington Nuclear Generating Station in Bowmanville, Ont. to the downtown core and eastern portion of Toronto.
The first-of-its-kind high-voltage underwater transmission line in Ontario is being constructed in order to keep up with growth as electricity demand in Toronto is expected to double by 2050, a release reads.
Currently, the City of Toronto is supplied by two transmission lines, one from the west at Manby Transmission Station (TS) and one from the east at Leaside TS. These pathways will begin to reach their capacity in the 2030s. The third transmission line will deliver 900 MW of additional power, equivalent to all the power generated from three small modular reactors, or power for 900,000 new homes.
With news of the approval, the government is proposing the IESO launch a competitive procurement process to select a transmitter, which will be informed by a consultation on the procurement design.
The province states the reason for an underwater line is because it is less vulnerable to extreme weather events such as flooding or ice storms.
“The underwater cable will also deliver more capacity than any other option and meet the system needs beyond 2044, reducing the need for additional, costly upgrades and expansions,” the release notes. “The third line will also alleviate strain on the bulk power system by avoiding bulk system reinforcements elsewhere in the GTA which could result in an estimated preliminary savings of $100 to $300 million.”
The development, construction and commissioning could take between seven to 10 years to complete.
The IESO’s recommendation follows analysis of multiple options, prioritizing routes that minimize land-use impacts by leveraging existing corridors, underground infrastructure and pathways, the release adds. The proposal is detailed in the 2025 Toronto Integrated Regional Resource Plan.
The province notes underwater transmission lines have been used in Newfoundland and Labrador, Nova Scotia and Prince Edward Island.
news.ontario.ca
