Thirst for power

Tuesday, 10 July 2012 02:00 May, Katie

Katie May
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Some Lethbridge residents were left in the dark Monday afternoon as a heat wave across the province put pressure on Alberta’s electricity grid, forcing blackouts in several communities.
Lethbridge, along with other cities including Calgary and Edmonton, had to power down amid humidity warnings and 30-degree weather because the province’s electrical system was in danger of overloading. The Alberta Electric System Operator (AESO) – the body that looks after the provincial grid – pleaded with Albertans to cut their electricity consumption for fear of a widespread blackout, blaming increased use of air conditioners and irrigation equipment.
“We’ve identified that there is a supply shortfall and so we’ve notified all of the transmission facility owners and it’s up to them to decide what they need to do to ease the load,” said AESO spokesperson Erin Powell.
Around 2:30 p.m. Monday, the AESO told the City of Lethbridge it needed to immediately shut down four megawatts of electricity – enough to power 4,000 homes. For the next three hours, the city saw rotating power outages, mainly in westside residential neighbourhoods such as Paradise Canyon and RiverStone that don’t have traffic lights. Lethbridge College and some southside homes were also affected by the outages, which lasted about 30 minutes each.
Randy Doyle, the city’s electric operations distribution manager, had to figure out how to comply with the provincial order without disrupting too much of the city’s 150-megawatt peak power usage.
“We try to spread the pain, so to speak. We’re somewhat limited in our ability to do that because we try not to drop big commercial customers. If we drop the power at a bank, say, that’s a real problem,” said Doyle. “We try to stay with residential as much as we can, but ultimately if the province says we have to shut stuff off, we just have to start opening circuit breakers and dropping everyone who’s attached to that line.”
Such a widespread over-usage outage is rare in the Lethbridge area, Doyle said.
“I don’t think this has happened in probably a decade,” he said. “Today the system is definitely under stress.”
Power companies serving central and southern Alberta also shut down electricity to several communities Monday afternoon, though they had no estimation of how many customers were affected.
FortisAlberta said it pulled the plug on customers throughout its service area, including rural areas near Medicine Hat and Taber.
AltaLink, which supplies power to most of southern and central Alberta, had powered down at least 14 substations, most serving oilfield operations in those areas of the province to try to lessen the burden on residential customers, according to AltaLink spokesperson Scott Schreiner, who said that in addition to the sweltering heat, a few generators went offline, meaning the province didn’t have enough power supply to meet the demand.
“It’s pretty rare for something like this to happen, but fortunately the Alberta Electric System Operator has the contingency plans in place that allow us to do the systematic removal of load from the system so that it prevents a larger scale outage from happening,” he said.