The amount is small for Canada's largest independent power generator but could have larger implications for consumers in Alberta's open electricity market, said analysts.
TransAlta late Wednesday said its coal-fired Genesee 3 plant, operated by Capital Power north of Edmonton, would be off-line until Jan.
1, two weeks longer than anticipated.
The 466-megawatt plant was shut down in an unplanned outage mid-November that damaged it turbine/generator bearings.
The outage raises a question about how reliable TransAlta's newest generation plant, the 450-megawatt Keephills 3 will be, said analysts.
The coal-fired plant, which started commercial operations this summer, has similar components as the Genesee plant, noted Patrick Kenny, with National Bank Financial.
"As an Alberta consumer you've got to be a little concerned right now because we don't have any material incremental capacity coming in until Enmax Corp.'s Shepard comes on in 2015-2016," he said.
The 800-MW gas-fired plant is currently under construction on Calgary's southeastern border.
Power prices in Alberta have jumped this year on generation and intertie outages, averaging almost $80 per megawatt-hour over the, compared to $50 in 2010.
Last month power pool prices averaged roughly $114 per MWh.
TransAlta spokesman Glen Whelan confirmed turbines for both Keephills 3 and the downed Genesee 3 plants were the same make, but clarified the outage originated with the backup battery supply rather than turbine issues.
"When the turbine spun down, oil wasn't going to the pumps and as a result the bearings were damaged," Whelan said in a recent e-mail.