Demystifying peak electricity demand

A demand peak is the precise moment (in a day, a month, etc.) at which the greatest load is placed on the Hydro-Québec system. In Québec, this occurs in winter, when we rely heavily on heating (54% of household electricity consumption), whereas in the U.S., it usually occurs in summer, when air-conditioning is used extensively.

-A number of factors contribute to create a demand peak. The main factors are extremely cold weather and wind, as when the temperature falls below -25ºC and/or it is very cold for several days running.

-Demand is particularly likely to peak at two times of day: between 7 and 9 a.m.and between 4 and 8 p.m.

-When those factors combine, power consumption may reach record-breaking levels. During severe cold snaps, Hydro-Québec appeals to the public to use less electricity.

There are some easy ways to conserve electricity:

-Lower the thermostat temperature by a degree or two (Celsius) in all rooms, especially those that are unused. 

-Postpone using major appliances (especially dryers and dishwashers) by a few hours.

-Limit the use of hot water as much as possible.

Hydro-Québec's system aims at satisying Québec's electricity demand.
 
During peak periods of exceptional demand, Hydro-Québec asks for the cooperation of the public to avoid overloading the grid and having to buy electricity from elsewhere.

In other years, appeals to the public have led to reductions of 500 MW.

Hydro-Québec has developed business strategies and the dual-energy and interruptible electricity rate options, for example, with a view to lowering peak demand.

It can import power from neighboring systems.

Only then, if further reductions are needed, will Hydro-Québec appeal to customers to use less electricity during peak hours on those exceptional days.