Hydroelectric generator. Generator shaft (large cylindrical structure) and surrounding gantries in a hydroelectric power station. The generator shaft is connected to a turbine beneath it. The hydroelectric power station is on a river, and the turbine is rotated by water flowing through it. This in turn rotates magnets inside the generator, producing electricity. The gantries allow workers to inspect and repair the machinery. Photographed at the hydroelectric power station in Porjus, Sweden. The power station is located on the River Lule. Hydroelectric power, and other non-fossil fuel resources, make up a large proportion of Sweden's energy resources.