A friend of mine who lives a few blocks away from me was without power for over a week--I have no clue why but she had to carry water up 7 flights of stairs to her apartment. Also, I was in Argentina in 2008. I got word my mother was dying and tried to get back to BA for a flight and it was awful. I can't remember how long it took now to get back. Farmers had blocked the highways. It was over the taxes on soybeans. I kept in touch here and heard that food got pretty scarce before that strike was over and people could not get pretty important stuff.
Ever since that happened, and then my friend was without power for that long I have thought about this question McKenna has proposed. I also read a portion of a book by a man who was in B.A. during the 2001 crisis who was without power for a month. It sounded pretty catastrophic. I checked with people in my area who said things went on here in Palermo normally during that time but when you know it has happened elsewhere, it makes sense to take a lesson from it. For my part, I would be in bad shape if that happened tomorrow! So it's a very good question.