Ontario’s energy transition is creating critical transmission system development opportunities, as indicated in the IESO’s recently released its 2024-2043 Annual Planning Outlook, and Pathways to Decarbonization report. 
The demand forecasts in the Annual Planning Outlook reaffirms the IESO’s Resource Adequacy Plan including the need to procure over 4,000 MW of new effective capacity beginning in 2025 and up to 10,000 GWh of energy beginning between 2029 and 2043, in order to comply with reserve margin requirements and to meet anticipated future demand needs.
The IESO expects the increase in procured supply – both in terms of volume and diversity of technology - will create new transmission system reliability needs which must be addressed concurrently.
The Annual Planning Outlook identifies for the first time some of these transmission system needs that must be implemented over the next two decades. The Annual Planning Outlook also includes a three year planning road map to signal priority areas on the transmission system grid.
Transmission system refurbishment or expansion projects that are sufficiently far along in their planning and development and that have received regulatory approval from the Ontario Energy Board are treated in the Annual Planning Outlook as completed assessments and are included as ‘Planned Transmission Projects’ in the IESO’s base cases with expected in-service dates between 2023 to 2029.
However, the Annual Planning Outlook also identifies a series of constraints on the bulk transmission system that currently hinder the ability to supply forecasted residential, commercial and industrial demand growth across Southwestern Ontario.
These potential problem areas include the Greater Toronto Area, Essa and near Cornwall, due to certain transformer stations, circuits and lines expected to reach their respective thermal limitations and/or end-of-life beginning as early as year 2027.
Increased interest in potential commercial, manufacturing and agricultural development also raise possible future constraints on the bulk transmission system between East of London (Buchanan TS) and Hamilton-Brantford (Middleport TS).
This ‘unplanned’ transmission system build-out is estimated in the Pathways to Decarbonization report to cost up to $2.1 billion by 2035, that is over and above Planned Transmission Projects.
Further, the Pathways to Decarbonization report states that in order to achieve just a “starting point” for a system that is capable of incorporating the wide array of non-emitting resource types – including the anticipated surge in storage and hydrogen resources – a “significant build-out of Ontario’s existing 500 kV network would be required, focusing on paralleling the existing network where possible … as well as additional 230 kV of bulk reinforcements” with an overall estimated cost of $20 billion to $50 billion.
Studies remain ongoing by the IESO concerning the future impact of increased transmission reinforcement in Northeastern Ontario, and of possible intertie equipment failure, particularly on the Manitoba-Ontario interconnection. If 500 kV reinforcement through northwestern Ontario to Manitoba is determined to be needed, it could cost between an additional $7 billion to $16 billion.
However, given the lead time required for these types of electricity system build-outs, regulatory permitting and approvals processes must be streamlined. Hence the Ministry of Energy issuing an Order-in-Council in April 2022 declaring certain of the Planned Transmission Projects as priorities and thereby effectively streamlining the Ontario Energy Board’s regulatory approval process for transmission system development.
Yet more must be done to ensure the required transmission grid build-out is implemented in time to support the anticipated energy transition - particularly with respect to electrification of transportation and electric vehicle charging - if Ontario’s net zero goals are to be achieved.
The author remains hopeful that the necessary legislative and regulatory changes to expedite current permitting and approvals processes will form part of the set of recommendations the Electrification and Energy Transition Panel is to submit to the Ministry of Energy later this year, as part of the government’s development of a long-term plan to implement electrification and the energy transition in Ontario.