Hydrogen fuel cell bus, Stuttgart, Germany. This bus is part of the CUTE (Clean Urban Transport Europe) project. This is a demonstration project that is testing 27 hydrogen fuel cell buses, three each in nine European cities. The project started in 2002, and Stuttgart's three buses arrived in November 2003. The buses are Mercedes-Benz Citaro hydrogen fuel cell buses made by Daimler Chrysler, and are being used on the number 44 route. Hydrogen fuel cells combine hydrogen and oxygen to generate electrical power, emitting water vapour as an exhaust gas. This method of generating power is cleaner than burning fossil fuels to form carbon dioxide and other pollutant gases. Photographed in June 2005.