A fresh mystery: what happened to our diesel backup?
With the source of the weekend’s North Slave hydro power outages identified, attention shifts to the question of why diesel didn’t take over.
Late on Sunday evening, the NWT Power Corporation said electricity had been restored in Yellowknife and Edzo after line crews removed fallen trees from sections of power line running from the Snare hydro system.
Those trees had been the primary cause of six separate outages in Yellowknife over 24 hours, but the city’s self-contained power grid is designed to avoid a hydro failure developing into that kind of sustained problem.
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When hydro drops out, diesel generators at the Jackfish power plant exist as a backup and are expected to kick in almost immediately.
This weekend, that didn’t happen.
In a statement on Sunday evening, the NWT Power Corporation seemed as mystified as anyone.
“Staff are still working to identify why the switch over to diesel generation was delayed,” the corporation wrote on Facebook.
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In Rae, where an outage persisted late into Sunday evening, the power corporation again said there had been a diesel generator problem. Power would be restored “once an operator arrives to bring the local generator online,” NTPC wrote.
“Investigation of all of the factors that contributed to the extended outages this weekend will continue.”
Power outages are commonplace in Yellowknife compared to most regions of Canada, in large part because there is no connection to any power source beyond the Snare hydro system and local diesel, so there is no redundancy if those fail. In the south, by contrast, cities and provinces can readily lean on the power generated by neighbours.
Yet the age of the NWT’s power infrastructure is also an issue, as is the fragility of the Snare hydro transmission line (which has no backup) on windy weekends like the one just gone, or if, say, a wildfire threatens the area.
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While outages lasting for hours have occasionally struck the city in years past, Sunday seems likely to have set a Yellowknife record for the number of distinct outages in one day.
“More detailed information on the cause of the outages will be shared once the investigation is concluded,” the power corporation stated.