Ontario’s nuclear and renewable resources generate more power during some off-peak hours than Ontario has been able to use. Ontario cannot save money by turning off this power, because:

• Renewable power (e.g., wind) has extremely low operating costs; and

• Nuclear plants cost virtually the same whether they are making power or not.

Instead, Ontario curtails (i.e., turns off and wastes) or exports some of its surplus clean electricity. The electricity that Ontario curtails (5% of potential production in 2016) or exports (8%) is a resource that Ontario could make better use of. For 2017, preliminary data indicates that the province curtailed 7% and exported (net) 9% of the electricity produced.

More than half of the surplus is exported for more than it costs to produce that power (its marginal cost), but the rest cannot presently be exported at a financial benefit and so is curtailed.

Curtailment of surplus low-carbon power provides no financial, environmental or other benefit to Ontario. Yet the Independent Electricity System Operator (IESO) projects that it will continue to curtail surplus clean electricity for many years. (Source: Environmental Commissioner of Ontario: 2018 Energy Conservation Progress Report, Volume One).