I have copied this discussion from the Biodiesel Forum, where it was Off Topic.
Quote:
Way OT I know, but there isn't a direct linear relationship between electricity use and coal burnt. Huge amounts of power get dumped to ground overnight in baseload power stations because it takes hours to take a generator module down then reheat & synchronise it to the grid. So a heap of excess power is generated and dumped overnight.
2 corollaries to this are:
1. "Earth hour" does not reduce CO2 emissions by any amount despite the warm glow it gives the participants.
2. A significant number of plug-in hybrids can be recharged overnight without increasing CO2 emissions from power stations... they would just use up the excess off-peak electricity that gets wasted now... and the same amount of coal would still be burnt.
There would therefore be a nett benefit from replacing dino-fuelled cars with plugin hybrids.
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- Coal fired power stations do take time to come up to full power. Power authorities do study the TV programs to know when to add more generation during commercial breaks.
- Electricity is never "dumped to ground ", as this would damage the equipment, it is much easier than that, they vent steam to prevent the generator speeding up too much at low load.
- At low load times, they do not put as much coal on the fire, so there is less steam being generated.
- They know when to build up steam at any time of day or night, due to employment patterns, schools, industry starting up, etc. There is a long history of power supply and demand management, and they are good at it.
- Gas fired power stations can be started from cold and be running at full power much faster and are used for load peaking management.
- There IS a direct relationship between power consumed and CO2 emissions.
- Earth Hour does reduce emissions, but the effect is very small due to the short time frame and the small number of participants, as well as the fact that industry does not often participate.
I would like to know how you developed the idea that power was dumped to ground overnight.
I hope this explains the power industry a little better.
Regards,
Tony