Ontario’s $149/MWh Darlington SMR Estimate May Be Much, Much Higher

October 5, 2026 | Ontario

Ontario Power Generation’s projected $149/MWh levelized cost of electricity for its four planned Darlington small modular reactors is already below the low end of several independent estimates, according to York University professor Mark Winfield.

Winfield told Energi Media that independent analyses have put mature, nth-of-a-kind SMR electricity at roughly $250/MWh, with first-of-a-kind costs potentially reaching the mid-$400/MWh range. That makes OPG’s estimate difficult to assess without more information about its assumptions.

“This seems implausibly low,” Winfield said, arguing that financing assumptions, investment tax credits and other supports could materially affect the calculation.

The debate matters because Canada expects electricity demand to rise sharply as transportation, buildings and industry electrify. Electricity cost will increasingly shape both household affordability and industrial competitiveness.

SMRs And The Economies Of Scale

Winfield said one of the core problems with SMRs is scale. Large nuclear reactors spread fixed costs across much more generating capacity. Smaller reactors were supposed to compensate through standardized designs, factory manufacturing and repetition, but he said the evidence so far has not demonstrated that those savings will overcome the lost economies of scale.

Ontario is currently the only OECD jurisdiction proceeding with a commercial grid-scale SMR project of this kind, he said, while other jurisdictions have reconsidered similar plans as costs became clearer.

Comparing Complete Electricity Systems

The alternative is not simply replacing nuclear with intermittent wind and solar. Firm, low-carbon electricity has additional system value.

But Winfield said governments should compare entire portfolios — renewables, storage, transmission, demand management and emerging firm technologies such as advanced geothermal — rather than treating nuclear expansion as the default.

He argued that Ontario’s planning structure makes that comparison difficult. OPG and Bruce Power are deeply embedded incumbents, while the province lacks an independent regulatory process that rigorously tests whether the government’s preferred electricity pathway is the lowest-cost or lowest-risk option.

Winfield, who serves on the executive committee of the Energy Modelling Hub, said Canada has comparatively weak public modelling capacity and few forums where competing electricity pathways can be openly tested and challenged.

That institutional problem becomes more important as electricity systems confront rapid technological change. Wind, solar, batteries, distributed energy and geothermal have advanced quickly, while traditional utilities were largely designed to deliver stability rather than continuous technological innovation.

Affordability And Competitiveness

For Winfield, the consequences ultimately come back to cost. Ontario already spends roughly $7 billion to $8.5 billion from general revenues each year to suppress electricity bills, he said, insulating consumers from the full cost of the system while shifting the burden to the provincial budget.

As Canada builds much more electricity supply, those costs will become harder to hide. “The question of costs has to come home to roost,” Winfield said. “That goes directly to affordability. That goes to competitiveness.”