A visitor passes by the exhibition stand of wind power during the "Hannover Messe" industrial trade fair in Hanover, Germany, on April 20, 2009. Clean energies as solar power and wind power are welcomed during the fair. [Xinhua]

An exhibitor (R) introduces solar power technique to a visitor during the "Hannover Messe" industrial trade fair in Hanover, Germany, on April 20, 2009. [Xinhua]