I've seen some of your coal mining heritage, great stuff. But since the electricity grid is linked from Ceduna to Hobart to Cairns these days there will be plenty of paths to take up little variations in load not dependent on coal. Energy companies keep up their profits by quickly moving power to demand. I have been told by wind energy boffins that up to 20% renewables is safe with this amount of grid interconnection, so earth hour will show up less than a coffee break during the AFL grand final.

