Jérôme, I have only recently (in the last couple of days, really) noticed you mentioning the fact that energy prices are set by gas prices because the latter are marginal. While this is elementary once one is introduced to the concept, most people have never heard of it. Given that this was one of the few points that Adam Smith made repeatedly in his Wealth of Nations, public misunderstanding of how marginal sources set the price of commodities must rank up there with people not knowing about Newton's laws of motion (a topic more dear to me personally). I would write a diary about it were it not that you are probably better equipped that I am to write it (including access to hard data), unless you think there is value in having a non-economist write about it and reserving your sharp wit for smoothing out my corners.

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman