The Ontario government and City of Toronto announced on June 4 that they will work together to bring a third electricity transmission line into downtown Toronto to ensure the city has the power it needs to support new homes, economic growth and major infrastructure like transit.

“We are acting now to protect Ontario families, workers and businesses by ensuring our province’s largest city has the power it needs to grow,” said Energy Minister Stephen Lecce. “By planning for and investing in this critical infrastructure, we’re securing the electricity needed to power new communities like the Port Lands and East Harbour in downtown Toronto, as well as supporting major transit expansions like the Ontario Line and securing a reliable and affordable energy supply without relying on other jurisdictions.”

Toronto’s electricity demand is expected to roughly double by 2050, with the greatest need being projected in the downtown core.

The City of Toronto is currently supplied by two transmission supply paths, one from the west at Manby Transmission Station (TS) near Kipling Road and Dundas Street and the other from the east at Leaside TS near Overlea Boulevard and Millwood Road. These pathways will start to reach their capacity in the early 2030s.

Following more than a year of technical analysis and public engagement, Ontario’s Independent Electricity System Operator (IESO) has confirmed a third transmission line will be required to meet Toronto’s growing demand.

“Toronto is growing. As we build more housing, transit, and create more jobs, we’re going to need the power that fuels and sustains economic growth," said Mayor Olivia Chow. "With our electricity needs doubling over the coming decades, we’re ready to work with the provincial government to advance a third transmission line that will help power our growing city.”

The IESO has identified three potential options for new transmission supply in Toronto, each of which has been designed to minimize land-use impacts by using existing infrastructure corridors, underground segments or underwater routes:

• An overland route from Pickering to Leaside in Toronto. This line would connect Cherrywood TS to Leaside TS using an existing transmission corridor.
• An overland route from Pickering to the Port Lands in Toronto. This line would connect Cherrywood TS to Hearn TS via Warden TS, using an existing corridor to Warden TS, then possibly transitioning to an underground cable from Warden TS to Hearn TS.
• An underwater cable from Darlington or Pickering to the Port Lands in Toronto. This line would connect underwater through Lake Ontario.

The IESO will conduct further engagement this summer with the goal of providing a recommendation to the government by the end of August.

Once a final recommendation is made, the Ontario government will evaluate what actions must be taken to kickstart its development. Depending on the option selected and the necessary approvals, construction and commissioning could take between seven to 10 years to complete.

In addition to a third transmission line, the IESO will also continue engagement to identify complementary solutions to meet electricity demand across Toronto. This could include small-scale generation and storage, such as rooftop solar and battery systems, as well as expanded energy efficiency programs to reduce strain on the grid and help manage peak demand.

Peak electricity demand in Toronto is currently 4,700 megawatts, which is approximately 20 percent of peak demand for all of Ontario. According to the IESO, after 20 years of flat electricity demand in the city, Toronto’s peak demand is expected to roughly double by 2050 due to economic growth, new construction, and the electrification of transit lines.