Wind power in Ontario, June 2019: Dances with… Hydro

Last time I noted the operation of one particular Ontario gas-fired generating plant in relation with provincial electrical demand, total in-province generation, “market” price, and aggregate wind output. I showed that although through the month of June 2019 total generation exceeded Ontario demand in every hour, that particular gas plant (Goreway, near Brampton) also produced power during the daily demand ramps up and down, albeit with each unit never exceeding half power.

I wondered and still do if Goreway’s operation in that manner was necessitated by the significant amount of intermittent wind supply. Along with roughly 5,000 megawatts of wind, there’s also significant solar supply, most of which is located inside distribution grids and is non throttlable by the system operator. Both wind and solar are extremely expensive sources, not only because they must fetch high per-kilowatt-hour rates in order to make their operators profitable but also because they require additional connections to the grid and especially because they require conventional generation to cover the operational upshot of their inherently uncertain output.

If that conventional generation is combustible-fired then the putative zero-CO2 benefit of renewable energy—and hence the claims of avoided tons of CO2 you see written onto the securities, i.e. “green bonds,” through which more and more renewable energy facilities are financed and refinanced these days—is undone to some extent, perhaps entirely. Moreover, if this conventional generation is itself zero-CO2—as appears to be the case in Ontario—then what is the point of renewable energy, other than to provide profit to renewable energy operators at the expense of the operators of the zero-CO2 power required to cover renewable energy?

Both wind and solar are extremely expensive sources especially because they require conventional generation to cover the operational upshot of their inherently uncertain output.

I left off that post by wondering if, while Goreway’s output in all its operating hours appeared superfluous—given the persistent systemwide oversupply through every hour of June 2019—it was necessary to smooth out the erratic, jagged output of wind. Arguing against, or at least complicating, this hypothesis is the fact that there were other periods in the month when Goreway didn’t operate but there was significant wind increase/decrease. I wondered if there might be a connection with the 8,000-or-so megawatts of hydro capacity in Ontario.

Well, it looks like there was.

The 56 facilities that make up the Ontario hydroelectric generation fleet can be separated into three broad categories, based on the nature of their supply.

  1. Baseload—facilities whose output mean is at least 10 times output standard deviation. In the 720 hours of June 2019 there were 12 such facilities.1
  2. Ramping—output mean-to-std is between 1.5 and 10, non-inclusive. 28 in June 2019.2
  3. Peaking—less than 1.5. 16 facilities.3

Here’s how those hydro groups performed in June 2019:

Notice that when wind output collapsed significantly June 6 and 7 and again June 17 to 20, peaking hydro picked up, and when wind picked back up after its two lulls peaking hydro dropped.

Notice also that what I call “Ramping” hydro produced in a distinct daily pattern roughly following demand.

If wind displaces hydro on an electricity grid, how much CO2 does wind avoid? On the Ontario grid in June 2019, the Peaking portion of the 56-facility hydro fleet appears to have followed wind’s erratic journey through the month. The great variability of the output of this 16-facility portion of the hydro fleet permits the system operator to essentially mirror wind output with relatively fast-reacting supply. I said last time that Wind proponents would argue that wind displaces fossil generation; I also showed that it did not seem in June 2019 to have displaced the Goreway plant, which produced, albeit at much less than full power, in accordance with demand.

I pointed out last post what everybody knows—Ontario has over the past years been overproducing electricity, and dumping the oversupply to export markets for next to nothing. Here we are throttling hydro plants in reaction to wind, so if wind is displacing anything it is displacing hydro.

In which case green bonds financing Ontario wind projects cannot claim to have avoided any CO2 at all.

Solar output of course has a pattern similar to diurnal demand, though significantly out of phase with demand. Demand peaks around eight p.m.; solar in June 2019 peaked between ten a.m. and three p.m. See the following plot.

Might that warrant running gas plants and the ramping hydro plants even with an oversupply? By far most solar in Ontario is embedded, inside distribution grids. The plot above shows the daily maxima of transmission-connected solar; the total embedded maxima were some multiple, in the neighborhood of four to five times, of the amounts shown.

The daily maxima of just the Tx-connected solar was highly variable, as you can see, not only in the magnitude of output but its distribution through the times of day. The embedded “fleet” is comprised of literally hundreds of installations, geographically scattered though concentrated mostly in southern Ontario towns and cities. We shouldn’t be surprised if its daily maxima are similarly varied. Moreover, the entire solar fleet contributes no inertia to the homogeneity of electricity supply on the grid.

So I ask again: is Ontario’s seemingly systematic oversupply the system operator’s proactive way of covering not just for uncertainty of renewable energy output but also its lack of inertia?

I’ll take this up next post.

I mentioned that demand peaks around eight pm. While several demand daily peaks in June 2019 occurred around 8pm, half the days of the month saw demand maxima occurring closer to 7pm. Plus there was greater variability in the sizes and times than I indicated. Here’s how it looked:


  1. Baseload hydro:
    1. Abkenora
    2. Alexander
    3. Apiroquois
    4. Cameronfalls
    5. Carmichael
    6. Decewfalls
    7. Earfalls
    8. Fortfrancswc
    9. Littlelong
    10. Peter Sutherland Sr
    11. Redrock
    12. Saunders

  2. Ramping hydro:
    1. Aguasabon
    2. Aubreyfalls
    3. Beck1
    4. Beck2
    5. Cariboufalls
    6. Chatsfalls
    7. Chenaux
    8. Clergue
    9. DA Watson
    10. Decewnd1
    11. Desjoachims
    12. Gartshore
    13. Harris
    14. Holden
    15. Holingswth
    16. Kakabeka
    17. Longsaulte
    18. Lower White River
    19. Mackaygs
    20. Manitoufalls
    21. Mission
    22. Nagagami
    23. Silverfalls
    24. Steephill
    25. Umbatafalls
    26. Upper White River
    27. Wells
    28. Whitedog

  3. Peaking hydro:
    1. Arnprior
    2. Barrett
    3. Beck2 PGS
    4. Canyon
    5. Harmon
    6. Harmon 2
    7. Kipling
    8. Kipling 2
    9. Littlelong 2
    10. Lowernotch
    11. Mtnchute
    12. Otterrapids
    13. Pineportage
    14. Rayner
    15. Smoky 2
    16. Stewartvle

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James R. Baerg
3 years ago

OK I’m convinced (& have been for long time) that we need lots of nuclear. I’m wondering under what circumstances (if any) are wind or solar worth bothering with?

3 years ago

It’s possible that there are ramp rate (up and down) restrictions on Ontario’s hydro, such that a gas plant is required to be active in the middle of its range of responses.

Most grids require “spinning reserve” active which can ramp up quickly in the event of loss of a major facility (e.g. failure of transmission link to Ontario’s nuclear plant). Hydro is normally ideal for this as it has a fast response time, but if there are ramp rate restrictions maybe gas is also needed to provide the total ramping rate.

“If wind displaces hydro on an electricity grid, how much CO2 does wind avoid?”

The output (in MWh or GWh) of most hydro systems with some large capacity dams is constrained by the total volume of water, rather than the nameplate capacity (MW or GW) of the generators.

So, reducing the output of hydro when wind power is available will typically not waste hydro output (e.g. by spilling water with no generation), but will normally defer it.

Norwegian hydro and Danish wind operate synergistically like this. When Danish wind is blowing strongly, Denmark exports power to Norway cheaply, and Norway reduces hydro output, saving water. When Danish wind stops blowing, Norway increases hydro output and exports power to Denmark (at a higher price than it pays for the wind imports). Clearly the arrangement is constrained by the maximum output of the Norwegian hydro.

Norwegian hydro storage is 88 TWh of storage, or about 6 months supply, which would be enough to power the whole of Europe for 10 days.

So my guess is that curtailing Ontario hydro when wind power is plentiful results in saving water and deferring, not wasting, hydro generation. To that extent, all the wind power contributes to a reduction in CO2 emissions from the back up gas plants.

3 years ago

if keeping that supply high quality means burning gas, then wind and solar are the cause of the emissions, no?

That is a killshot that “Greens” refuse to acknowledge.  It destroys everything they purport to believe.