Today I pumped petrol into the car at a rate of one euro a liter. That marks the crossing of a major milestone and I doubt we'll return to the other side of the century mark. As I watched the units roll away on the pump, I remembered my days of flying over the vast, rust-red desert of Saudi Arabia, where one-quarter of the world's oil is found. Twenty years ago, I believed we were more than a lifetime away from exhausting that expanse of fossil fuel. Now I'm no longer certain that our modern energy economy has the legs to play out the next forty years. Not that anyone seems to care around Ireland where there are no real incentives to conserve fuel or reduce inefficient uses of transportation.