Ontario’s ambition to build two of the world’s largest nuclear power plants could cost between $221-billion and $294-billion, more than double the cost of expanding its renewable energy supply, according to a new study.
The estimate by Power Advisory LLC, a consulting and analysis firm focused on the electricity sector, examined the proposed facilities known as Bruce C and Wesleyville. They’re promoted by private-sector power producer Bruce Power and publicly owned Ontario Power Generation, respectively, and to be located in Tiverton and Port Hope. Both projects are at early stages; according to an “illustrative” schedule published by the government last summer, construction of the units might take place between 2031 and 2046.
Power Advisory estimated that if the government instead built renewable facilities but maintained its existing nuclear fleet (including a new plant already under construction in Clarington) the cost would be substantially less – between $104-billion and $126-billion.
A typical residential customer would pay between $240 and $456 more for electricity per year if the nuclear plants were built instead of renewables, the study found.
Power Advisory declined an interview request to discuss its methodology and conclusions. Environmental Defence, a non-governmental organization, hired the company to prepare the study and supplied it to The Globe and Mail.
“I don’t think that the government is going to halt the plans at Wesleyville and Bruce as a result of this analysis, but that is what they should do,” said Keith Brooks, Environmental Defence’s program director.
“Moving forward without a thorough investigation of the costs of all of this, and without a discussion about alternatives, is a big mistake.”
Ontario’s existing reactor fleet, built between the 1970s and the early 1990s, has a generating capacity slightly greater than 12,000 megawatts. The province’s Independent Electricity System Operator (IESO) suggests that as much as 17,800 megawatts of new nuclear capacity could be required by mid-century.
OPG recently began constructing a new 300-megawatt small modular reactor (SMR) at Darlington. It’s the first of four planned for the site, at a total estimated cost of $20.9-billion. But their combined output would represent less than one-10th of what the IESO thinks is needed – hence the desire for much larger stations.
Bruce C would feature four new reactors producing up to 4,800 megawatts. PG’s Wesleyville could be even larger, with as many as eight reactors generating up to 10,000 megawatts. The existing four-reactor Darlington station’s output is 3,500 megawatts.
Together, the total production of Bruce C and Wesleyville would come close to meeting the IESO’s estimated requirement.
Ontario’s plan is sprawling in its ambition. The Ford government envisions as many as eight reactors under construction simultaneously at the two plants by the late 2030s. By mid-century, nuclear fission would provide roughly three-quarters of the province’s electricity, up from about half today.
This is strikingly different than what most jurisdictions are doing.
According to a report published earlier this year by the International Energy Agency, renewables have accounted for the vast majority of new generation brought online in recent years globally, growing by 9 per cent last year. This is expected to continue between now and 2030. The IEA expects nuclear generation will grow modestly (by 2.8 per cent per year) over the same period, driven by rapid construction in China. The lack of growth of nuclear power generation in developed countries has much to do with long-standing concerns about its cost, and the long duration of construction and tendency to miss deadlines.
Neither Bruce Power nor OPG has published estimates on how much the plants might cost. The IESO, for its part, has offered seemingly contradictory guidance.
In 2025, the IESO recommended the government build the Darlington SMRs because it believed their cost compared favorably to a portfolio of renewables. Part of its reasoning was that Ontario would need to build as much as seven times more wind and solar capacity paired with battery storage to match the SMRs’ output, accounting for the fact that wind and solar facilities generate electricity intermittently.
This dovetailed with the government’s own view. Although the IESO has procured small amounts of wind and solar in recent years, the government of Premier Doug Ford has generally disfavoured renewables. Energy Minister Stephen Lecce contends that nuclear power is cheaper; he has also emphasized the much larger land footprint of wind and solar installations.
Yet last summer, the IESO prepared another paper which compared the cost of building SMRs against wind and solar coupled with batteries. It found that should the province face a future of high peak demand, a portfolio of renewables would cost between $44.1-billion and $52.9-billion, less than half what SMRs would cost.
The Ontario Clean Air Alliance, a non-governmental organization which consistently opposes nuclear expansion, has estimated the cost of Wesleyville alone at $230-billion. Jack Gibbons, the organization’s chair, said the organization arrived at the figure by multiplying the cost per kilowatt of the only new nuclear reactors completed in North America so far this century (at Georgia’s Alvin W. Vogtle Electric Generating Plant) by the plant’s planned maximum capacity. Applying the same logic, Bruce C would cost $110-billion.
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Wind and solar cost less than one-third that amount, the organization asserts.
Estimating the cost of future power generation requires making assumptions about a range of factors including future electricity demand, how long plants can operate and more – all of which influence the conclusions.
Power Advisory’s study, for instance, did not account for the cost of stringing new transmission lines. These costs could be substantially higher for wind and solar facilities, which are likely to be located far from existing transmission lines, major cities and industrial users.
On the other hand, the consultancy derived its nuclear cost estimates from a recent report by the New York State Energy Research and Development Authority. Georgia’s Vogtle units cost substantially more and are regarded by some as a more realistic benchmark because they were actually built.
Power Advisory also assumed new nuclear plants will last 60 years, and amortized their cost over that long period. Ontario’s existing Candu plants have generally operated for 30 years or so before requiring overhauls, costing billions of dollars per reactor.