Wind turbines failed Nova Scotia during the weekend cold snap; what that means for the grid as our reliance on electricity grows

On Sunday morning, Nova Scotia wind turbines were generating 350 megawatts; by Sunday evening that had dropped to 75 megawatts. The cause of the power drop hasn’t been confirmed. Photo by File photo

When the mercury plummeted over the weekend and Nova Scotians needed electricity the most, wind generation dropped out.

Despite the shortfall, Nova Scotia Power didn’t have to resort to wide-scale rotating electricity shutdowns.

But it was close.

“While there were some localized issues and outages related to the cold on Sunday, our teams were able to avoid system-wide issues that could have required load shedding — or proactive, short, rotating outages across the province,” reads a written response from Nova Scotia Power.

The episode is a warning of how renewable energy sources can suffer in extreme cold as they are built to replace coal, while at the same time our reliance on electricity for all aspects of our lives, from home heating to transportation, is increasing.

Nova Scotia Power calls for conservation

Many Nova Scotians were surprised Saturday and Sunday to be asked by their energy provider to avoid non-essential electricity usage during peak demand periods from 5-9 p.m. The power corporation warned this was so there could be enough electricity to meet basic demand across the province.

With temperatures dropping to -21 C, with windchills around -35 C over the weekend, electricity demand had the potential to offset supply.

“For electricity suppliers like NSP and NB Power, it’s very expensive to pay for the winter peak in demand,” said Larry Hughes, a retired Dalhousie University professor and energy analyst.

“Because if your winter peak only lasts 30-40 hours out of an entire year of almost 9,000 hours, it’s expensive to buy the equipment for that. So what you do is buy power from your neighbour. But the problem for this region is what happens if we all enter the winter peak at the same time?”

Evan Bezanson uses a snowblower to clear out his driveway in north-end Halifax on Monday. On Sunday evening demand on the grid reached an all-time high of 2,481 megawatts. Photo by Ryan Taplin

The weekend’s power shortages resulted from renewable electricity generating shortfalls.

Ice clogged the intakes at Newfoundland and Labrador’s Bay D’Espoir hydroelectric generating facility on Friday, creating a shortfall in a province that usually sends electricity to Nova Scotia via the Maritime Link. As residents across that province were being asked to turn their thermostats down during a deep freeze, Nova Scotia and New Brunswick were sending electricity back to Newfoundland and Labrador across the Maritime Link.

But the Maritime provinces, Quebec and the New England states were facing the same cold snap and demand peaks.

Drop in wind turbine generation

Nova Scotia has an estimated total electricity generating capacity of 2,700 megawatts, some 2,400 megawatts of which is produced by Nova Scotia Power.

About 600 megawatts is wind, but that’s only when it’s blowing and the turbines are working at capacity.

The average daily demand in the winter months is 1,700 megawatts. On Sunday evening, as Nova Scotians were cooking supper and heating their homes, demand on the grid reached an all-time high of 2,481 megawatts.

Meanwhile, wind generation was dropping out.

On Sunday morning, Nova Scotia turbines were generating 350 megawatts; by Sunday evening that had dropped to 75 megawatts. The cause of the power drop hasn’t been confirmed.

According to Environment Canada, wind speeds at Halifax Stanfield International Airport were 35 kilometres an hour at 7 a.m. on Sunday but dropped to 17 kilometres by 5 p.m.

Natural Resources Canada notes that wind turbine generation is susceptible to power loss during deep cold due to icing and, in some cases, shuts down to prevent equipment failure.

“That’s a loss of 80 per cent; that’s huge,” said Hughes.

He notes that while we are seeking to get off coal and move to 80 per cent renewables by 2030, we need to also be wary about the resilience of our grid to peak demand and equipment failures.

The federal and provincial governments have sought to build grid resilience by investing heavily into tying the grid to neighbouring provinces, while also investing in renewables. Most of those renewables, like wind and solar, are intermittent power sources; we can’t turn them on or off and open up the throttle like at a coal or natural gas plant.

Meanwhile, all of Atlantic Canada and Quebec hits peak demand in January.

“If our neighbours are all going full out, they’re not going to be able to supply us,” said Hughes.

Those interties can also be damaged by ice storms and other weather events. The issue of hardening them and building enough reserve generation from sources such as natural gas, Hughes warned, becomes more acute as we become more reliant on electricity to heat our homes and charge a growing fleet of electric vehicles.

“While Nova Scotians are no stranger to cold weather, this weekend posed a unique challenge,” reads a written statement from Nova Scotia Power, citing the drop in wind generation.

“During this time, other energy sources — along with support from neighbouring utilities and our two new grid-scale battery sites — played a critical role in keeping power flowing to your homes and businesses.

“As Nova Scotia continues to experience more extreme weather — from prolonged cold snaps to powerful hurricane-force winds — we are planning, investing, and implementing new technology and strategies to strengthen our generation facilities and grid infrastructure. These efforts are part of our five-year reliability plan and are focused on building a more resilient energy system for the future.”