Alberta’s coal phaseout: can wind replace coal?

Last time I started to unpack the inherently dismal performance and underlying economics of wind power in Alberta. The whole reason Alberta has started this dysfunctional relationship with wind is because it has a dream that wind will somehow replace coal for electricity generation. This dream is shared by wind advocates across the globe. Can it ever achieve reality?

Recall last time I showed each grid-connected Alberta wind farm’s output over the period October 24 2018–June 25 2019. I presented the data in the form of non-exceedance curves for each wind farm. I repeat that figure below. (If the individual plots are too small you can enlarge them; they won’t pixelate.)

All the curves have the same general shape: they all slope steadily upward from left to right. They all look pretty much the same. Ho-hum, kind of boring.

Now, let’s look at the non-exceedance curves for each of the sixteen Alberta coal plants, over the same period.

Notice how the coal curves are much different in shape than the wind ones? In particular, look at the plots for the Genessee, Keephills, and Sheerness facilities—those are the ones that, going by the capacity factor (CF) figure in the plot titles, saw most of the action over the sample period. Note the location of the dashed median lines in the plots for those facilities. Compare those positions with the median line positions in every single one of the wind plots.1

That difference in the shape of the curves and the location of the median lines is, in a nutshell, why wind absolutely will not replace coal in Alberta. The location of the median lines in the coal plots is determined by the will of the system operator, instructing the operators of the individual coal plants at time t_1 to put x megawatts of power into the system at or by time t_2. The coal plant operator receives the order from the system operator, and throttles the boiler accordingly—if the system operator wants more power, then more pulverized coal is fed to the firebox.

The location of the median lines in the wind plots, on the other hand, is a function of the inherent intermittence of wind. There’s nothing the wind farm operator can do to change that. Wind blows when wind blows. How much does it blow in Alberta? Look at the wind plots. Wind farm electrical generation is a rough proxy for the fluid dynamics of wind at that location over a period. The non-exceedance curves in the individual plots give probabilities, based on the output values of the sample. That’s how much the wind blew over the roughly 344,000 minutes October 24 2018–June 25 2019 in each of the locations where the Alberta wind farms are.

Wind advocates’ answer to the impossibility of matching wind output to system demand on a timely basis is typically twofold:

  1. Scale up the number of wind farms so they collectively produce as much energy over a year as the coal plants collectively do.
  2. In periods where wind output exceeds demand, store the surplus in batteries. Use the stored energy to cover the shortfall during periods where wind output falls short of demand. That way, non-exceedance curves of the combination of wind plus battery output would, in the aggregate, resemble those of those coal plants that saw the real action over the period.

The first is a political non-starter. Wind turbines occupy around 28 hectares per installed megawatt (Meredith Angwin in her excellent Campaigning for Clean Air arrives at 34.5 hectares, which is likely more reliable; I’ll stick with 28 because all my calculations are based on it and I’m too lazy to change). To replace coal with an 80:20 mix of gas and wind would require over 1,000 square kilometers of territory for just the wind turbines—that’s greater than the amount of land distrurbed by oilsands operations. To completely replace coal’s annual output with wind would require plastering Alberta with 5,000 km\textsuperscript{2} of wind turbines (more if Meredith’s number is the right one). That won’t happen.

And the second part of the twofold wind advocate answer to matching wind to demand—using batteries to store surplus wind output—is even more risible. I’ll explain why next post. For now, recognize that grid-scale battery storage capacity costs around CAN$278 per kilowatt-hour.

NOTE: The recent Alberta provincial election that saw Jason Kenney replace Rachel Notley as premier puts Alberta in line to become one of the federal “backstopped” provinces—i.e. one of the provinces that does not have a carbon tax that is to the liking of the current federal government. All of the aforementioned Alberta coal plants meet the criteria for a “covered facility” under the Output Based Pricing System (OBPS)—i.e., they all emit more than 50,000 tons of CO2 per year. Genessee Unit 1 threw more than 30 times that amount into the air just in the roughly 8-month period studied here. Every coal unit with a mean output greater than 10 MW broke the 50,000-ton limit in the 8 months.2 That’s every plant except Sundance 3 and 5. It will be interesting to see how or whether the Alberta coal plants get tagged with the federal backstop tax.

  1. Recall from the last article that the median lines in these curves are at the output (x-axis) value above or below which there’s a fifty-fifty probability the farm will produce at any given time.
  2. Mean MW \times 5,735 hours (344,112 minutes \div 60 minutes per hour = 5,735 hours) = megawatt-hours over the period. Multiply that figure by 800 grams per kilowatt-hour (the approximate average CIPK of Alberta coal-fired power generation) to find total grams of CO2; divide by 1,000,000 to obtain tons.)

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