Electricity emissions contained as Ontario nuclear unit comes back online

After a three-month maintenance shutdown, Darlington generating unit #1 came back into service at five a.m. today. Not a minute too soon. Southern Ontario is heading into its first serious heat wave of 2008, and every air conditioner in the province is poised to leap into action.

In the last few days, total Ontario electricity generation has been inching into the 19,000–20,000 megawatt range during the mid-day peak (see June 3 output on Electric Power Statistics). I predict that today’s peak will be around 22,000 MW. Tomorrow, when temperatures are expected to hit 30 degrees, it will be at least 25,000 MW.

Emissions corresponding to June 3’s output went over 5,000 tonnes per hour during the mid-day peak, according to the EmissionTrak™ engine on Electric Power Statistics. As you can see, the emission curve is much more pronounced than the output curve. When output rose by 10 percent between six a.m. and seven a.m. on June 3, emissions rose 37 percent. When output increased by 2 percent between noon and one p.m., emissions went up 347 tonnes.

That is because prior to today at 5 a.m., every increase in output above roughly 14,000 megawatts was met by fossil generators. (Coal is emission intensive but cheap, so it is the dominant and price-setting fossil fuel.) The return of Darlington 1 moves that base threshold to around 14,800 MW.

If the remaining three nuclear units re-entered service, that threshold would move to well over 16,000 MW. This would sharpen the emission curve, which during the summer is good because there would be more hours in the day when electricity demand is met by non-emitting generators.

Those three remaining nuclear units are part of the Bruce–Pickering fleet of CANDUs. Darlington unit 1 is in what we can call the post-Pickering CANDU fleet. As I mentioned in mid-May, the performance of the post-Pickering CANDU fleet, in Canada and around the world, has been very good.

I asked in that post which CANDU manufacturer will show up in the Ontario reactor competition. Well, it’s a hot day in June, and Darlington unit 1 is back in action.

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