Scheduling electrical power supplies - the effect of on-demand TV

When a popular TV programme comes to an end, viewers rush to put the kettle on for a hot drink.  For some programmes, the resulting surge in demand for electricity put a strain on the power system, and so the power companies had generators ready to be brought online to meet the demand.  One of my industrial contacts worked for a power supplier, and we discussed the problem that his business faced.  It was an interesting application of O.R., and like so much O.R., it was hidden from view.  The company needed to know TV schedules, and forecasts of viewer numbers and the step in numbers between programmes, and what fraction of those who stopped viewing would use high wattage equipment. Occasionally, I used this as an example for students to consider how they would tackle such a forecasting and scheduling problem.
However, changing habits in TV viewing have reduced the size of "end-of-programme" surges.  Many people watch programmes on catch-up TV, so want their hot drinks at a time which bears no resemblance to the end of the original programme.
Fifteen years ago, the surge (called a "pick-up" in the power companies) after an episode of the popular soap, EastEnders, could be up to 660Megawatts.  Now there is still a surge, but only 200Megawatts.
Jeremy Caplin, the Energy Forecasting Manager for the National Grid, has the overall responsibility for developing models for forecasting demand.  He was recently quoted as saying: "We see as many spikes in demand, but they are much, much smaller than they were.  The way that people watch TV has meant that they have come down in size."  Nonetheless, during the summer's Olympic Games, there were many sizeable spikes, because so many people wanted to see events as they happened.
From an O.R. perspective, the integration of forecasting and resource allocation is an interesting case of several techniques coming together to deal with a problem, and it is one which occurs several times each day.
Besides forecasting the surges, the forecasters at the National Grid have had to forecast the effect on solar farms of a partial eclipse of the sun, and there is an infographic available (below) of the changed demand during the 1999 total eclipse of the sun when crowds of people stopped using power to watch the eclipse.

Putting on the kettle is not the only activity that follows a popular TV programme.  I met an engineer who had studied the variation in the flow in sewers during advertising breaks and at the end of TV programmes.


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