When you flick a switch–and when the source of electricity is hydropower, as in Québec–you're actually requesting that more water drive a turbine in order to generate more electricity and transmit a greater power flow from the generating station to your home appliance.
Turning on a single television set won’t make a big difference. But if everyone in Québec were to turn on their set at the same time, demand would jump way up! And yet, this is exactly what happens every day, for example, when we all turn on the kitchen stove to get supper ready around 6 p.m.
Distributing electric power is like distributing water: it is always better to "have more to be sure to have enough." As soon as a current is generated, it must be used. The reverse is also true: as soon as we turn on an appliance, power must be available. Regardless of the amount required, electricity suppliers must meet demand instantly! Their capacity to respond quickly and cost-effectively to variations in demand will depend on the flexibility of their generating facilities.
If demand rises substantially–for example, because of a cold Québec winter–the supplier must distribute more electricity. When demand drops, as it does during Québec summers, power generators like Hydro-Québec use less water to drive turbines and can therefore store water in their reservoirs.
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