An energy emergency alert issued by the Alberta Electric System Operator has ended, after the province's extreme cold snap caused a spike in demand for electricity Monday evening.

A Level 1 alert was issued at 5:18 p.m., meaning all available resources in the energy market were used to meet the load but that some reserves were still available.

That alert was upgraded to a Level 2 at 7:20 p.m., stating those reserves were being used and emergency energy was being requested from neighbouring areas.

The website's event log also stated shortly after 6:30 p.m., one coal generator suddenly went offline. A second coal generator had an unplanned outage at 7:25 p.m.

"At this point we would also ask customers … to lower their demand on the system," the alert reads, referring not to residential customers but energy companies across the province.

At 9:31 p.m., the AESO alerts ended, as supply was once again enough to meet demand.

If alert hit Level 3, power outages would happen

Tara de Weerd, AESO's spokesperson, said Albertans shouldn't need to worry about power outages unless an alert is raised to a Level 3.

"It's more from a system controller perspective … they're monitoring the grid 24/7," she said.

The entire province of Alberta is currently under an extreme cold warning, something de Weerd said likely led to the alert.

Both Calgary and Edmonton's forecasts called for a high of –28 C for Tuesday, with the wind chill expected to make it feel colder than –40 C.

"In extreme weather … that's when we'll see typically the greatest draw on the grid, and when we hit an all-time record it has been historically always in the winter."

Energy load may have surpassed all-time high

She said the system's record consumption was on Jan. 11, 2018, when the load was 11,697 MW.

AESO has yet to officially confirm that record has been surpassed but the operator's website showed the load passed 11,700 MW at around 6 p.m. Monday.

de Weerd said peak hours are typically between 4 and 7 p.m. on weekdays, so while AESO isn't yet issuing a public plea for energy conservation, it would be wise to refrain from running the dishwasher or washing machine during those hours while the deep freeze continues. She said 13 per cent of energy use in Alberta is residential, so industrial use is likely playing a factor in demand as well.

Prices per megawatt-hour hit the province's cap of $999.99 at 7 p.m. Monday. But short term price spikes will likely only have a small impact on the regulated rate option that many Albertans are on.

AESO's peak load forecast shows demand is likely to be nearly as high in the days ahead, with the system expected to reach 101 per cent capacity during peak hours Tuesday through Thursday.

The electricity system isn't the only system on alert in Alberta due to the weather.

Canada Post issued a yellow alert Monday, stating that severe weather conditions were impeding delivery and some customers would not be receiving mail.