The document discusses a visit by students and teachers to the Portile de Fier I hydroelectric plant on the Danube River in July 2013 as part of a Comenius bilateral project on renewable energy. It provides details about the hydroelectric plant, which is one of the largest hydroelectric constructions in Europe. It transforms the force of water into electricity using huge generators. The students learned about how navigation on the Danube is facilitated through locks on both sides of the river. Construction of the dam raised the water level by 35 meters, requiring the evacuation of several villages.