Device and process generating electrical power from flowing medium. Device includes turbine generator units connected to form module(s), and at least two fixed-position structures arranged to form a waterway. Module(s) are arranged between the fixed-position structures to be raised and lowered. In this way, high water level is produced upstream of the at least one module and low water level is produced downstream of module(s). An auxiliary apparatus provided on each fixed-position structure extends above upper edges of fixed-position structures, and a lifting device is arranged to lift the module(s) that are guided, at least partially, by the at least one auxiliary apparatus. In a lifting procedure, module(s) are raised above the upper edges of the fixed-position structures. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.