A system (1) designed to generate energy with the aid of, primarily, sea currents, comprising a rotation body (4) having a front inlet side (2) and a rear outlet side (3), and at least one transfer member (6) connected between the inlet side (2) and a generator (5). The rotation body has a conical and/or bulb shaped, tapering section (8, 9) extending from a substantially cylindrical waist section (7) in direction towards the inlet side, and a conical and/or concave or flat portion extending in the opposite direction from the outlet side, said waist section being along its circumference provided with close to each other mounted blades (10) for the purpose of maintaining a rotation of the rotation body, the free, front end of which is at the same time secured to the transfer member (6) in order to transfer a rotational movement to the generator (5).