Southwest Ontario Bulk Planning

Electricity demand in Southwest Ontario is growing. This growth is primarily driven by economic development in the greenhouse sector. The Windsor-Essex and Chatham-Kent areas are the primary drivers of this change and are projected to reach a demand of 2,300 MW by 2035 - the equivalent of adding a city the size of Ottawa to the electricity grid.

To meet this growing demand, the IESO undertook extensive electricity planning and engagement with local and regional communities and stakeholders to address current and future electricity needs.

Electricity plans were developed to recommend solutions that support this growth and infrastructure and upgrades are already underway that include two new sets of transmission lines and a new switching station. These projects, plus other planned initiatives and ongoing dialogue with communities and stakeholders, will support current and future economic growth in the region.

Southwest Ontario Bulk Planning Initiatives

A map of transmission line projects planned for Southwest Ontario

West of London Bulk Report

This report examines emerging electricity needs, evaluates options and recommends actions required to reinforce the bulk system in parallel with regional electricity planning for the Windsor Essex and Chatham-Kent/Lambton/Sarnia regions. This new bulk transmission plan outlines recommendations to ensure the adequacy and reliability of supply up to the year 2035, including:

  • A new 230 kV transmission line from Lambton to Chatham to be in-service no later than 2028 (see March 2021 news release);
  • The continued operation of the Brighton Beach Generating Station to support immediate local need in the near-term until the Lambton to Chatham transmission line is in-service;
  • A new 500 kV transmission line from Longwood to Lakeshore to be in-service in 2030; and
  • 550 MW of local resources needed by 2035 that can be met by reacquiring resources whose contracts have expired or by acquiring new resources.

Engagement meetings were held to inform interested parties about plan development and solicit feedback. You can view meeting materials, feedback received and the IESO’s responses on the engagement webpage.

Supporting Materials and Resources

Windsor-Essex Bulk Report

A planning study was undertaken to asses the adequacy of the bulk transmission system in the Windsor-Essex Region. This study was triggered by forecast electricity demand growth in the Kingsville-Leamington area, which is expected to double over the next five years. It recommends two transmission reinforcements, a switching station at the Leamington Junction (Lakeshore TS) and a new West of Chatham transmission line (Chatham to Lakeshore line).

A companion Integrated Regional Resource Plan (IRRP) was also completed. It focused on providing customers in the region with adequate line connection, step-down transformation capacity and maintaining a level of reliability consistent with planning standards. Information from the IRRP, such as demand forecasts and plans for new connection facilities, informed this bulk planning study.

The IESO recently completed an addendum study to the Windsor-Essex IRRP focused on meeting the future needs in the Kingsville-Leamington area and will continue to monitor the progress of developments in the area while studying future system needs through subsequent regional planning cycles.

Supporting Materials and Resources

Switching Station at Leamington Junction

The IESO issued a hand-off letter to Hydro One requesting that they undertake work to establish a new switching station at the Leamington Junction along the Chatham to Windsor transmission corridor. This new station will be located in the Municipality of Lakeshore is expected to be completed as early as 2022. It will help meet electricity needs in the area by supporting additional consumer connections and is an integral part of the reliable long-term plan to improve supply for the Windsor-Essex region.

Supporting Materials and Resources

Transmission Line from Chatham to Lakeshore

The IESO issued a hand-off letter to Hydro One requesting that they initiate work, including Environmental Assessment and Leave-to-Construct approvals, for the construction of a new 230 kV transmission line from Chatham to the new Lakeshore TS. This line is expected to be completed prior to the winter of 2025/2026.

Supporting Materials and Resources

Transmission Line from Lambton to Chatham (St. Clair Line)

The IESO issued a hand-off letter to Hydro One requesting that they initiate the work associated with developing a new 230 kV transmission line from Lambton to Chatham. This is expected to be in service in 2028 and is one more step that will support rapid agricultural growth in the Windsor-Essex and Chatham areas.

The IESO encourages Hydro One to meaningfully engage with Indigenous communities in Southern Ontario in a way that recognizes the unique interest of each community in this project and to discuss their concerns about potential impacts to their Aboriginal or treaty rights.

Supporting Materials and Resources

Transmission Line from Longwood to Lakeshore

The IESO published the West of London bulk report, which recommended a new 500 kV transmission line from Longwood to Lakeshore. This is expected to be in service in 2030 and is one more step to ensure the adequacy and reliability of supply in the area up to the year 2035.

Supporting Materials and Resources