spot on - all power provided is on a pro-active basis, that is, its supplied before its used
so if the power companies estimate 1,000 killowatt units and VIC only uses 9400 killowatt units then the 600 units are wasted.
ie: they dont get stored up, reused later on or saved in batteries etc. so earth hour is void, becuase they estimate $x units and provide, the rest is wasted.
usually when a power blackout occurs the company has under-estimated so there isnt enough actual power, so suburbs black out.
had you have seen suburbs style blackouts on saturday night, then it would say that earth hour was a direct impact as
the companies mega low estimated the use and basically ran it too low. i mean they would have lowered the expecatation, but they can't just black out subrubs to save power. and there are very big pentalities for companies who under-estimate and black out suburbs etc. its not like internet where an outage is acceptable
im not saying its a waste of time, but a misconception perhaps like ziad said
its just some poeple believe its a massive impact, its probably not that big, but a good step, certainlty better than doing nothing