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Earth hour! Page 3
Quote: Aaron @ March 27 2009, 6:32 PM GMTBlimey. That really is wastage on a major scale.
One of those lines is available capacity, not actual generated electricity. But you have to generate much more than is actually used or there will be shortages. The power companies look ahead at weather forecasts and can predict demand very accurately. The national grid is old and in need of upgrades, but the companies do a good job of shipping excess capacity to neighboring states, etc. I can only imagine that oil/gas-powered plants are doing all they can to minimize the wasting of expensive fuel.
I work for tree huggers and litter pickers. It gets my bills paid and free t-shirts. 
I'll turn off my stuff, it's ok, I can just record my shows.... 
Quote: DaButt @ March 27 2009, 6:18 PM GMTMy brother is an electrical engineer for a major power company and he says that short exercises like this do nothing to actually save electricity - the generators are still turning.
There's a lot of excess power generated at night that just gets wasted. My brother told me about a plant that uses the excess electricity at night to pump a small lake uphill to a reservoir. The lake is drained during peak electricity consumption periods and the water generates electricity as it falls. Then the cycle is repeated the next evening.
There's one in Wales that's used I think (might be: http://www.fhc.co.uk/dinorwig.htm ). Essentially when there's a sudden surge in demand, they let the water flow down and spin the turbines. Then when off-peak pump it back up for when next needed. Advantages being it's quick to get the turbines going compared to "normal" ones (as below).
Massive amount of effort goes into accurately predicting demand for electricity. Weather, sporting events, etc. - everything basically calculated in advance as it takes a crazy amount of time (6 hours seems to ring a bell) to start a turbine and get it up to speed (50Hz in UK is the frequency used). So need to know if there'll be a surge early or there's trouble. But continually monitoring and adjusting to keep the load variation within limits.
As Dabutt says, the turbines will likely be going still, they can't just turn them off and on, or after the hour's up there won't be enough power - and it takes too long to start turbines as stated.
I seem to recall normally they'll have other turbines going that aren't connected to the National Grid, which are used if, say, another one has a problem.
Isn't there an England friendly on tomorrow night? Seems might be a bad night to choose considering they'll have to ensure there's enough power. But if loads switch off then that'll mess up the load too
My brother's job is to model future needs for the power company. He spends all his time simulating "what if" situations and decides when/where/how additional facilities should be constructed.