Peak Oil, the point at which development and supply of world petroleum resources fall below global oil consumption, is shaping up to be the most controversial issue of this century except it may already be moot. Peak Oil does not mean the end of oil as an energy resource. It is simply the point at which global oil demand exceeds production capacity, which will drive prices higher, make alternative fuel sources more economically viable, and ultimately reduce oil demand. It is controversial because many in industry and among policymakers argue that Peak Oil is decades away, maybe 60 years off. There are even some geologists, according to a web discussion hosted by Chevron Corp., who argue that the planet's oil and gas supplies are not finite at all and are continuously generated by chemical reactions deep in the earth's mantel. Advocates of Peak Oil brush those optimists aside and argue passionately that the tipping point is imminent and that highly developed and hydrocarbon-dependent Western nations are on the brink of economic doom. Maybe not. Matthew Simmons, chairman of energy investment group Simmons & Co. International, contends that Peak Oil may already be at hand, but most people simply don't know that the point has passed.