This might be of interest either to techie types or to anyone who is just curious about the amount of power we use.
The link below to the National Grid website gives a continually updated view of the current electrical power consumption throughout the U.K. along with a graph of demand over the last hour. At the moment, for example, the nation is consuming approx. 38,200 megawatts of power (or for
Back to the Future fans, that's more than 30 times as much power as the 1.21 gigawatts that Doc Brown needed for his time machine!
).
If you look back at the page at various times of day you'll see fairly clearly the periods of peak demand, and even the way the demand jumps up dramatically at certain times (e.g. at midnight GMT/1 a.m. BST when Economy 7 heating comes on, or at the end of very popular TV shows when half the nation then goes out to the kitchen to turn the kettle on!).
Also to the right of the graph and below the current demand figure you can see the exact frequency of the power on the grid. This frequency -- nominally 50 Hertz -- is dependent upon the speed of the generators. When demand for electrical power increases, more mechanical power is needed to keep the generators turning at the same speed. If insufficient power is available, then the generators will slow slightly and the frequency will drop (and conversely, when demand drops power has to be reduced to keep the generators from rotating too fast).
Thus the frequency of the grid at any given moment gives a good idea of how well the generating stations are keeping up with demand. The normal permitted range allows for a variation of 1% from nominal, i.e. 49.5 to 50.5 Hz, although most of the time it's regulated much more closely than that. If the frequency ever starts dropping below about 49Hz the U.K. grid is in serious trouble as it means that the power stations just cannot cope with demand, and at this point we'd start to see areas blacked out.
Enjoy!
http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Demand/Demand60.htm