Ontario’s system operator reports 200% rise in annual wind curtailment

The IESO has updated its 2016 year-end supply data page to include annual totals for “wind dispatch” and “Nuclear Manoeuvres and Shutdowns.”

Added to data from OPG on “hydroelectric generation due to [surplus baseload generation] conditions” this provides a more complete picture of annual curtailment.

annual curtailment.png

The IESO’s provides this Wind Dispatch Overview:

With the implementation of the dispatch of renewable generation in fall 2013, wind generation facilities in Ontario help support ramping and balancing on the system. In particular, the wind dispatch helps avoid nuclear shutdowns during periods of surplus baseload generation (SBG).

The wind dispatch is just one tool used by the IESO to provide operational flexibility. The integration of hourly centralized forecast into the IESO scheduling tools as well as enhanced visibility of renewable output have also been instrumental in managing a system with increasing levels of renewable generation with greater efficiency.

In 2016, the total amount of wind energy that was dispatched down was 2,244.23 GWh, representing 19 per cent of the total amount of wind energy produced in the province. A greater proportion of wind energy was dispatched down in 2016 compared to 2015, due to a Market Rule change on February 18, 2016 for the floor price of renewables. Renewables are a flexible, 5-minute dispatchable resource, and therefore wind is dispatched down before manoeuvring nuclear during surplus baseload conditions. See Floor Price Review for a history of the stakeholder initiative.

This summary seems less than useful.

Totaling only the IESO’s reported curtailment shown above reveals an increase of 78% over 2015 (integrating OPG’s reported lost hydro makes the annual change a still steep 58%). The summary they provide indicates they were unable to accommodate much more supply in 2016 due to multiple tools providing operational flexibility.

Is that what the IESO’s multiple tools are doing?

Multiple tools don’t seem to be “managing a system with increasing levels of renewable generation with greater efficiency.”

Approximately 65% of all contracting of industrial wind capacity was done under feed-in tariffs or the Samsung deal offering the same rates – most of these contracts would be at $135 per mega-watt hour (some are more).

At $135/MWh the cost of dispatched down, or curtailed, wind in 2016 is over $300 million.

Which may not seem efficient to you, but to the multiple tools at the IESO it shows as considerably less than their 2016 spend on efficiency (conservation) in 2016.



I regularly update some spreadsheets with query results on curtailment from my tracking database. Parker Gallant has cited my estimates frequently, so I’ll briefly note how the IESO’s figures compare to my estimates.

The IESO’s now posted total for 2016 “wind dispatch” for 2016 is 3.5% less than I’d estimated.

Close enough for me.

Last March I wrote on my methodology in a post inspired by the variance between my 2015 estimate and the IESO’s posted figure for 2015: Ontario’s curtailed wind energy.

In that post I noted, “The IESO claimed in 2014 5.3% of potential wind energy was dispatched down, growing to 7.5% in 2015.” For 2016 the IESO claims 19%.





3 thoughts on “Ontario’s system operator reports 200% rise in annual wind curtailment

  1. OK the 2,200 GWh of wind at > $135,000.00 / GWh that the IESO curtailed/refused cost $300 million
    The 4,800 GWh of wasted water spilling unused over dams at $???,???.00 cost lost $????
    Same calculation for nuclear ?
    This graph would reveal, even more, the outrageous nature of the dreamers who created this Ontario fiasco, called electricity. I’m guessing so. Thanks for all you insightful analysis to push back the spin.
    Looks like SMRs hold some hope.


    • I’ll provide some answers/guesses.
      It is my understanding curtailed nuclear costs more than the contracted rate, which was around $66/MWh in 2016 (for Bruce Power).
      For hydro my understanding is Hydro One will receive rate riders to compensate them for curtailed supply, and I expect the rates used in calculating that omit water taxes. I’ll ignore that and simply use an estimate of OPG’s 2016 hydro rate at $45/MWh.
      Nuclear – $44 million
      Hydro – $212 miillion
      total (with wind) approximately $558 million.


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