September 20th: cleanest air day in Ontario

We don’t usually re-post from blogs, but then there is Scott Luft. Here is his recent posting on emissions in Ontario, and what the situation was last Saturday. Ironically, that was the same day thousands of well-meaning Canadians took to the streets to demand lower emissions and a cleaner environment.

September 20th: Ontario electricity’s cleanest day in my lifetime

Today is The People’s Climate March day. Not being much for marching up and down the square, I thought I’d be better to write about the accomplishments and challenges in my province of Ontario, where this weekend may well be experiencing the lowest emissions from electricity generation in over half a century.

It’s certainly the lowest emissions since I started capturing hourly data, which I have from September 1st, 2010. The reason is the scheduling off of non-utility generators, many of which are fueled by natural gas. Prior to yesterday the lowest value I’d seen for generation fueled by natural-gas was 291 megawatts; yesterday it dropped below that level in hour 3 and just rose above it as I write this (hour 8 of the 21st). I’m not certain the now closed Hearn and Lakeview generating stations would have operated at less than 200MW combined, so this really might be as low emission a day as Ontario saw in the past half a century.

The system operator (IESO) schedules curtailments of non-utility generators when Ontario is expected to have surplus supply for an extended period of time [2]. That is the case this weekend. Yesterday the IESO also required the curtailment of supply from Bruce Power’s nuclear units after exporting as much as possible. [2]

My estimates of the supply Ontario ratepayers will pay for – including the curtailed supply


September 20, 2014, Ontario was a net exporter of more electricity than it has been since the market opened on May 1st, 2002.  The average price was approximately nil. On average, net exports were 3,265 MW – much of it to New York where many of today’s marchers oppose the nuclear source that usually powers their sockets without ever cluttering their air.

The combination of high exports at no price, and curtailed supply, prompted my sometimes collaborator Parker Gallant to e-mail me; “it would be fun to calculate what the cost of generating Ontario “demand” is costing per kWh at this moment.”

There’s lots of problems in accomplishing that, but “fools rush in where angels fear to tread” – and it is fun to utilize this data store I’ve built.
So, for Parker and myself, I’ve done it.

I also summarized hourly data by weekday and month, right back to September 2010.

First, to yesterday. My estimations here assume:

  • capacity payments (net revenue requirement and contingency payments) are distributed evenly to each hour throughout the year)
  • solar output and pricing as described in Estimating production from Ontario’s solar panels [3]
  • I haven’t changed my algorithm for estimated non-utility generator (NUG) curtailment, but I have used costs for curtailed estimated of $110/MWh for wind, $100 for NUGs and $60 for nuclear steam bypass

Read more here.

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