Abstract: A tower (1) for wind power installations, on which at least one rotor (2) that can be driven by wind can be rotatably supported, has an especially low mass relative to its load-bearing capacity, stability, and rigidity, if it has a tower portion (3), tapering toward the top, with a bulging outer wall (4) that is convex in longitudinal section.

Abstract: A wind energy system, having a wind-drivable rotor (3) with angularly adjustable rotor blades (4), a generator, connected directly or indirectly to the rotor, for generating electrical energy, in which the power output of the generator is possible at variable rotor rpm, and a facility management system, which is embodied, within a predetermined wind speed range, to regulate the rotor rpm by adjustment of the rotor blade angles and to turn off the operation of the system above a shutoff speed, can advantageously be produced economically, with economies of material and energy costs, if the facility management system is embodied to regulate the rotor rpm and the power output downward, by adjustment of the rotor blade angles, in a range between a predetermined limit speed and the shutoff speed.