These days it is comforting to have one thing not to worry about. As the world teeters on the edge of a full-blown depression, and business is crushed between slumping sales and seized-up credit markets, at least the oil price is in retreat. From an historic high of $147 per barrel last July to around $40 today, the price of crude has collapsed so quickly it is tempting to believe it means the end of the energy crisis; that the spike was just some speculative aberration; and that all talk of ‘peak oil’ is so 2008.