Reliability Outlook Released: Ontario System to Meet Growing Demand with New Generation, Storage Capacity
March 27, 2025
Ontario’s electricity system is expected to see increasing demand over the next 18 months, according to the Q1 Reliability Outlook, and the IESO is planning to meet this with new generation and storage capacity that is expected to connect to the grid during this time.
New storage that is connecting includes the 235 MW Oneida Energy Storage project and about 882 MW procured through the Expedited Long-Term RFP. Storage will add to the diversity of Ontario’s supply mix and help meet capacity needs over the Outlook period. These timely connections, along with more than 2,100 MW cleared in last year’s Capacity Auction for the 2025 summer obligation period, will help meet the projected demand growth forecasted for this year.
New electric-vehicle manufacturing facilities, data centres and electric arc furnaces are all contributing to increasing demand over the Outlook period, and peak demand is expected to increase by about 1,000 MW between summer 2025 and summer 2026. As conditions during summer 2026 are expected to be tight, the IESO will work closely with market participants to co-ordinate outages.
Starting this quarter, the IESO’s demand forecasts used in the Reliability Outlook are informed by weather simulations rather than scenarios based only on historical data. This methodological change reflects industry best practices of employing probabilistic analysis in demand forecast modelling to account for weather.