It's an interesting sort of sci-fi though experiment to imagine what the world would be like if power was cheap. Really really cheap, like lets say we came up with a workable form of fusion, and the average electricity bill was say $25/month, but if you left everything you had on all the time, like 24/7, your bill might be $50.
The infrastructure would have to be upgraded, no doubt, because people would be using a lot more power. You could set your air conditioning to 60 degrees or lower and not worry about it, ditto with heat in the winter. Insulation would be a lot less of a concern, heck you could air condition your porch. Efficiancy in appliances and electronics would also be much less of a concern (except in portables). Electric cars would get more development if recharging them was nearly free. Dads everywhere would have to learn to stop yelling "shut the damn refrigerator door!" Probably ton of other unforseen benefits/consequences too - it'd be damn nice to be able to run my computers, X360 & PS3 24/7 and not worry about it, then turn down the AC enough so they don't heat up the house too much.
I read something about a proposal to generate electricity using the earth's orbital momentum a while ago, the upside is that it's a clean and nearly free source of power. The downside is that as soon as we use too much, everybody dies.
