Zevco, a small Anglo-Belgian firm, has just launched the world's first taxi to be powered by smooth, silent fuel cells. Zevco's taxi is actually a hybrid vehicle. The cells that power it, generate their electricity by reacting hydrogen and oxygen together in the presence of a catalyst. When the cab is moving, this electricity turns the motor. When the cab is stationary, it is used to charge a battery that acts as a supplementary power source.