I'm strongly against the option to just disable your power plants to avoid it, though - that indeed would be gamey - just imagine turning off electricity all of a sudden in developed countries. And you could get rid of the consequences of your doings on the first place (which is building those coal plants...)
If would be nice to turn off buildings, though. Currently, It seems as though a city is fully powered and gets all of the powered building benefits or its unpowered and gets none of them. I'd like to be able to turn off my Research Labs, Broadcast Towers, etc. when I'm low on power because of disasters or war or whatever.