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How Flexibility, Not Nuclear, Can Secure Ontario’s Electricity Future

Michael Barnard, Clean Technica, 6 Feb 26

Ontario is moving forward with planning for an entirely new nuclear generation site in Port Hope, 100 km east of Toronto, at a moment when its electricity system is already one of the most nuclear-heavy in the world. Nuclear power today provides roughly 55% of Ontario’s electricity, with hydro adding another 25%. Wind, solar, batteries, and demand-side resources together account for a much smaller share, having been cut off at the knees in 2018 when the provincial conservative party took power and summarily cut 758 contracts for renewable generation. Advancing a new site signals how the province understands its future electricity challenge. It reflects an expectation that Ontario will require another large block of firm, always-available capacity to remain reliable as demand grows, particularly during the most constrained hours of the year.

Ontario’s electricity planners, primarily through the Independent Electricity System Operator, frame the case for new nuclear around long-term reliability rather than annual energy supply. Their planning outlook projects electricity demand rising by about 65–75% by 2050—a low energy value not aligned with actual climate or competitiveness goals—with a projected winter peak reaching roughly 36–37 GW. Summer peaks are also expected to rise, but they remain slightly lower, in the range of about 35–36 GW by mid-century. The winter peak, not the summer peak, is treated as the binding constraint, and it is that single cold, dark evening hour that underpins the justification for new nuclear capacity.

This framing matters because of how nuclear is treated in planning models. Nuclear plants supply energy year-round, but the decision to build new nuclear capacity is driven mainly by how much firm capacity planners believe is needed to meet future peak demand. Nuclear units are counted as fully available during peak hours, even though they operate continuously, do not follow demand and are not available when down for maintenance, refueling or refurbishment for months or years. From a reliability perspective, this approach is understandable. System operators are rewarded for avoiding shortages and penalized heavily for blackouts, while overbuilding capacity carries fewer immediate consequences………………………….

The distinction between energy growth and peak growth is critical here. Energy demand, measured in TWh, reflects how much electricity the system produces over a year. Peak demand, measured in GW, reflects the single hardest hour the system must meet. Nuclear plants are not built to follow peaks, but they are sized to peaks. If peaks remain sharp and high, nuclear looks attractive in planning models. If peaks flatten or decline due to significant system component flexiblity, the value of adding large, inflexible, always-on generation falls quickly, even if total energy demand continues to rise.

Electrification without flexibility is genuinely concerning, and planners are right to worry about it……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..

Ontario does not lack clean electricity. It lacks a planning framework that fully reflects how electricity systems are changing, why winter peaks appear hard only under outdated assumptions, and how firm capacity is actually used in a flexible, digitized grid. The choice facing the province is not between reliability and decarbonization, but between building infrastructure sized for a winter peak that no longer needs to exist and building a system designed to avoid creating that peak in the first place. https://cleantechnica.com/2026/02/06/how-flexibility-not-nuclear-can-secure-ontarios-electricity-future/

February 8, 2026 - Posted by Christina Macpherson | Canada, ENERGY