SPIEGEL cover story: Oil is becoming more and more expensive. The explosion in its price is encumbering economies and stock exchanges. It is not only speculators and the fear of terrorism that are to blame. Though the lubricant for the world-wide growth engine is not yet running out, the thirst for energy is increasing. The battle for the last reserves is becoming correspondingly fiercer. There is now a growing fear that the world could once again face an oil crisis, as in 1973, 1979 and most recently in 1990, with all the devastating effects this would involve for national economies: higher expenses for consumers and industries, increasing inflation and a teetering economy. So far, every recession in the past decades has been preceded by a brief oil shock. This time, however, the price increase may not merely be a passing phenomenon.