JudasIscariot: Still need oil to either make the batteries or extract the rare earth metals, not to mention the fact that the batteries will wear out and have to be replaced which will result in more oil being used.
Sielle: True, it's unlikely that we'll every be able to stop using petroleum based products completely but we can cut down our use quite a bit.
You're vastly underestimating the amount of energy the average American burns daily. That Mars Oil field that everyone talks about? If we could somehow pump it out tomorrow it would be gone in 46 days at current usage rates of oil (presuming no imports). There is no domestic production that can hope to keep up. We have around 30 years of coal left at current production rates (which have peaked and are falling off) and we're topping mountains to get at what's left.
Renewables are great but they don't do baseload (save hyrdo and that's limited) and you mention batteries but can you imagine the sheer amount that it would take produce enough chemical energy to power one single city during the night? Yeah, you can make hydrogen with excess energy during over production and then burn that but it won't compensate.
No one is saying there won't be electricity left, clearly there will be, but there won't be much. Farming alone is burning (depending on who you believe) between 3 and 8 calories per calorie of food produced. In 2000 the US estimated 10% of domestic energy was burned in farming and as production rates have climbed the energy burned has increased far more!
It takes something ridiculous in acreage per US citizen to support them (sewer, electric, food production, etc.); something like 20-25 I think; the home where they plant their ass for the night is actually the least space consuming. Building out enough wind and and solar to even get 50% of what we get from fossil fuels today could well increase that by an order of magnitude take more space than the US has.
Of course shit won't get burned out at every increasing rates as it gets rare, it'll get expensive instead (like those 250 dollar per barrel oil prices 2-3 years ago), that will happen more and more often... and then what will we do when we want to turn on the lights?