Power consumption peaks occur when the demand for electricity is highest in a given period.
In Québec, the biggest peaks occur on very cold winter days, often in the early morning or in the evenings, as a result of heating needs and the intensity of commercial and industrial activity.
As you may know, electricity supply must match demand at every single minute of every day.
The power grid has to respond in real time. If the demand increases, more electricity must be generated and power lines with sufficient capacity are needed to transmit that electricity wherever it is required.
That situation has an important consequence: the power grid must be able to meet any surge in demand, no matter how short, that occurs during the year.
Unless we want to spend a lot of money building equipment that would be used just a few days a year, consumption peaks need to be reduced.
In the future, the power system will have to cope with winter peaks that are likely to become even greater with the higher demand placed on it by heating loads and electric transportation.
However, it also has to deal with the challenges of summer peaks caused by the use of air conditioning when temperatures rise.
Although demand peaks are not as high in summer as in winter, it’s also primarily in the summer that required maintenance work is carried out on generating stations and power lines. This means there are fewer facilities available to supply that peak demand.
Moreover, because the heat given off by transmission lines is dissipated by the surrounding air, this natural cooling is less effective when it is hot out. That in turn reduces the amount of electricity that lines can carry.
Flattening the peak demand curve
To fully appreciate the challenge of flattening the peak demand curve, compare consumption peaks with the current means we have of leveling them. Remember that
in 2019, the maximum anticipated peak (taking into account energy reserves) was around 42,000 MW, while off‑peak consumption that same year was around 15,000
With our customers’ active participation, the current means we have at our disposal to level out the peaks represent approximately 3,000 MW over a roughly