Oil-producing Dubai, a key commercial and technological  crossroad in the Persian Gulf region, is taking its first cautious steps towards the eventual production of renewable hydrogen in close cooperation with car maker BMW.  If  the strategy takes hold and succeeds, it could mark a revolutionary shift in the world's  system of energy distribution.  It could signal the beginning of a shift away from carbon-based fuels to solar-derived renewable energy among the world's principal producers of petroleum.  The emirate, part of the United Arab Emirates, was the  departure  point in early February for a six-month tour of a fleet of ten BMW 750hL liquid hydrogen powered  sedans halfway around the globe designed to stir interest and drum up support for this zero-emission transportation technology (H&FCL Jan. 01). Subsequent stops of BMW's hydrogen caravan will be in Brussels, Milan, Tokyo and Los Angeles where the tour is expected to arrive in mid-July.