The Cost of Wind

On 16 September, an article entitled ‘Environment issues top green debate’ appeared in the Oakville Beaver.  In that, ‘Halton incumbent MPP Ted Chudleigh, of the Tories, said he and his party are not opposed to alternative energy, but believe it has its time and its place.  “The windmills are becoming more and more efficient, more and more economically feasible. The big ones are down to 20 cents per kilowatt hour or less, which is great,” he said.’ … The statement is remarkable on at least two levels:  first, 20 cents per kWh is not particularly ‘great’ (compare to the average price of electricity, as a commodity, recently in Ontario here); and second, although it depends upon the wind resource, a number of sources cite the fact that wind power’s cost is often of the order of 2.5-3.5 cents kWh (e.g., this report from the NREL).

There are other passages in the article – issues of rising costs with smart meters, etc. – but I have addressed that issue in other parts of this blog.

Different 'fuels' at different times

An article entitled ‘We can all do little things for the environment’ appeared in The Kitchener-Waterloo Record on 23 August 2011.  Though the theme was broadly environmental, there was a paragraph’s focus upon electricity issues. Notwithstanding the issue I would take with the comment that ‘On summer weekdays, hydro costs almost double between 7 a.m. and 7p.m.’ (see my earlier posting), the phrase that I will come back on is the following:  ‘In Ontario, if we all run our air conditioning units during the peak time it means Ontario has to start up high polluting coal-fired plants, or buy electricity from American coal plants. Very dirty!’  I thought it would be worthwhile to dig into this.

To do this, I went to the site of a small company called Sygration – harvesting data from the Independent Electricity System Operator in Ontario, these are usefully put into interesting form there.  I pulled out ‘yesterday’ (23 August 2011), as well as 21 July 2011 – a day on which the University of Waterloo weather station says that the temperature reached 37.6°C!  (I was fortunate enough to be in a lake on that day! :>)  Not surprisingly, peak output by Ontario’s power plants was 19,135 MW (hour ending 5pm EDT) on 23 August, but 25,692 MW (same hour) on 21 July – some 34% higher!  In terms of energy, generation on that hot day – across all 24 hours – was 33% higher.  So, across all hours of the day, power plants across the province had to be ‘geared up’ that much more.

That invites a discussion about ‘dispatching’.  Electricity cannot be easily (cheaply) stored.  As such, it needs to be generated when it is needed.  Choices are thus made by system operators as to which plants to ‘call’.  Cheap ones are obviously preferred first, but consideration must also be given to those that are easily (or not easily) ‘ramped up or down’ --  that is, responsive to changes in dispatch instructions from the system operators.  Of the major contributors in Ontario, nuclear is usually run ‘all of the time’; hydropower is generally cheap and ‘rampable’, and thus used often and/or strategically.  The fossil fuels (coal, gas and gas/oil) are not only dirtier, but also often more expensive; they can be, however, responsive to changes in system-wide demand.

So that is meant to help explain the chart below – where the relative contributions of Ontario generators on these two days are listed.  On the ‘lower demand day’ (23 August), nuclear and hydro predominate, and fossil fuels contribute less than 15%.  On the ‘higher demand day’ (21 July), fossil fuels – including the need to operate the Lennox ‘oil/gas plant’ – contribute almost one-third. 

fuel	percentage share to total daily energy on 21 July 2011	Percentage share to total daily energy on 23 August 2011
Nuclear	46.6	65.3
Hydro	18.1	18.9
Wind	2.5	2.0
Woodwaste	0.3	0.3
Coal	11.8	2.2
Gas and gas/oil	20.7	11.3

It might also be useful to think about how the fuels are used during different time-periods – namely, Ontario’s three (summertime) ‘bands’.  I present this in a couple of visuals below – plotting MW generation against time (EST), and then shading the off- (green), mid- (yellow) and on-(red) peak periods.  On 21 July, gas/oil, in particular, plays a relatively predominant role during the on-peak period; the fossil fuels certainly ‘ramp up’ in the morning, but take a while to ‘tail off’ in the evening.  In 23 August, all of those fuels are ‘near the bottom’, given how much nuclear meets all of the needs.

The bottom line? – carbon intensity varies with time, and it is, for the most part, higher during the high-demand/‘on-peak’ periods.

Wind supply and electricity demand

In The Financial Post on Thursday, 4 August 2011, there was an article entitled ‘Energy Rules Change in the Wind’.  I pull out one passage for examination – namely: ‘The Liberals seem not at all upset that wind power is unavailable when needed, as seen during Ontario's relatively warm July, when wind was producing at only 12.6% of capacity.’

First, I wondered about the figure of 12.6% capacity factor in July.  I immediately went to the IESO website on wind, and found data available for the first 27 days of July.  My final figures are listed below.

Windfarm	Nameplate capacity (MW)	Average hourly production, first 27 days of July 2011 (MW)	Capacity factor (percentage)
Amaranth	199.5	26.9	13.5
Dillon	78	11.5	14.8
Gosfield	50	6.67	13.3
Kingsbridge	39.6	4.41	11.1
Port Alma 1	101.2	13.9	13.8
Port Alma 2	101	15.7	15.6
Port Burwell	99	11.3	11.4
Prince	189	26.5	14.0
Ripley South	76	9.27	12.2
Spence	98.9	13.6	13.7
Underwood	181.5	25.0	13.8
Wolfe Island	197.8	26.0	13.2
TOTAL - Ontario	1,411.5	190.7	13.5

My calculated figure of 13.5% is quite close to the author’s.

I also wondered how the wind plants performed – solely during July 2011 – during those times that it was ‘needed’.  I thus looked at three periods:  when time-of-use prices were ‘on-peak’ (i.e., non-holiday weekdays between 11am and 5pm); when Ontario demand was highest; and when Ontario prices were highest.  The table below gives some data regarding the capacity factor (in percentage terms) for each.

Windfarm	OEB on-peak periods         (114 hours)	Top 100 hourly demand periods (21,174 MW to 25,450 MW)	Top 100 hourly price (HOEP) periods ($39.55/MWh to $184.38/MWh)
Amaranth	14.1	22.9	19.2
Dillon	14.9	19.9	16.4
Gosfield	9.63	16.4	12.7
Kingsbridge	11.4	14.6	10.9
Port Alma 1	13.8	18.1	14.4
Port Alma 2	14.1	21.1	17.1
Port Burwell	12.3	17.0	12.9
Prince	7.80	9.35	11.1
Ripley South	11.0	15.6	12.4
Spence	13.1	17.4	13.3
Underwood	13.6	18.7	15.6
Wolfe Island	12.4	22.4	18.9
TOTAL - Ontario	12.4	18.2	15.3

Interestingly, the capacity factor goes up for two of the three ‘critical periods’ above.  More about this can be found in some work we did previously.