Generation outages, high temperatures force AESO to import power from other provinces

The unplanned outages of a number of generating resources in Alberta, including the loss of some baseload generation resources, during a period of near-record-setting temperatures forced the Alberta Electric System Operator (AESO) to import power from neighboring provinces.

The grid operator issued its first appeal for conservation on Friday, June 28, because “a number of generators are out of service for planned and unplanned maintenance, and wind generation is very low.”

“The issue we had … was because we lost some of our baseload coal plants,” John Esaiw, AESO’s director of market analytics and forecasting, told TransmissionHub July 1.

AESO restated its appeal for conservation on June 29, as near-record high temperatures resulted in increased demand, exacerbating the generation outages. Environment Canada  forecast highs that could reach 90 degrees Fahrenheit on Tuesday in Calgary. Average highs during July in Calgary range from 69 degrees to 72 degrees Fahrenheit.

To help make up for its power shortfall, AESO turned to utilities in British Columbia and Saskatchewan for the power it needed. While transmission ties from Alberta to the two provinces are limited, they were sufficient to meet the immediate need. A tie to B.C. has been operating at its rated capacity of approximately 650 MW, while a tie to Saskatchewan has been transporting about 153 MW, Esaiw said.

The need for supplemental, imported power is expected to be very short-term, he added. 

“Two did come back, and we’re expecting one more back between today and tomorrow,” Esaiw said. “The others that tripped were just short-term outages. They did quick turn-arounds and came back.”

The challenges come on the heels of what is being called the worst flood ever to strike Calgary, Alberta. The flooding that struck the week of June 21 claimed at least four lives and knocked out part of the city’s electrical infrastructure. Although the municipal grid has been restored, individual buildings will need to be deemed safe before their electricity is turned on, local officials said.

Since the onset of the flooding, the AESO issued at least four statements reassuring stakeholders that “the provincial electricity grid is continuing to operate normally throughout this state of emergency.”