the ends of this driving shaft 13 being connected at least to one generator 14 comprised in the body of the float 3 said guiding means 12 may notably be a roller a wheel or a pinion meshing with a rack not shown extending vertically on the surface of the guiding support 2 advantageously in order to prevent water from passing into the body of the float 3 the latter may comprise seal gaskets which may be o rings 15 which are positioned so as to partly cover said orifices 11 of said sidewalls 10 and to clasp said driving shafts 13 further the device according to the invention 1 may also comprise means not shown allowing pressure of the guiding means 12 to be exerted on the surface of the guiding support 2 so as to prevent untimely sliding of these guiding means 12 the generators 14 are dc or ac current generators however according to an alternative embodiment of the invention they may be replaced with hydraulic pumps not shown advantageously the device according to the invention 1 may comprise several generators 14 which are preferably sealed and which may each operate alternately in one direction and in the other advantageously the heat energy released by the generators 14 during their operation may allow water to be heated making it thereby possible to recover energy as electricity but also as hot.