Blackouts as four power plants shut down

By Dave Cooper and DAN HEALING, Edmonton Journal and CALGARY HERALD July 10, 2012 9:54 AM

EDMONTON – Monday’s rolling power blackouts were caused by a combination of high demand for power and the unexpected outage of several coal power plants in Alberta, made worse by exceptionally poor output from becalmed wind generators.A total of four power generators were down at once on Monday, said Cathy O’Connell, a spokesman for the Alberta Electric System Operator.

TransAlta Utilities’ 362-megawatt Sundance 3 has been out of commission since Friday, but was joined early Monday morning by Atco Power’s Battle River No. 5 and then, in quick succession in the early afternoon by TransAlta’s 406-MW Keephills 1, Capital Power’s 400-MW Genesee 2 and Atco Power’s 385-MW Joffre CT201.

Capital Power said its plant had an instrument malfunction and automatically shut down, but was restarted quickly and back fully on line by 5:15 p.m.

Capital’s three natural gas-fired “peaking” turbine units at Cloverbar were switched on immediately, and were ramping toward their 250-MW capacity within minutes.

“When Genesee went down, and with the other plants off, the province was short 1,200-MW of power,” said Capital spokesman Michael Sheehan.

Atco spokesman Paul Wright said the company isn’t sure what went wrong at Battle River.

“We are still assessing the situation there, but this unit is the newest and largest at Battle River,” he said.

All are coal-fired electricity plants except Joffre, which uses natural gas.

Higher electricity consumption was boosted by consumer demand for air conditioning and refrigeration, leading to a supply-demand imbalance that prompted the AESO to insist that suppliers cut their usage.

Higher temperatures also cause stress on the supply side of the electricity equation, said Evan Bahry, executive director of the Independent Power Producers Society of Alberta.

“These are pieces of equipment in these power plants and they are subject to all sorts mechanical breakdowns and, especially when they are under the stress of the province’s demand growth, each unit then becomes that much more important to the system,” Bahry said.

A chart on the AESO website shows that electricity prices hit their maximum level of $1,000 per megawatt-hour Monday afternoon.

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