Abstract: The invention relates to a rotor blade (22) for a wind energy installation (10), with the rotor blade (22) having at least one cavity (28). The cavity (28) is sealed to be gas-tight and is filled with gas, in particular air, in order to prestress the rotor blade (22), with the pressure of the gas being greater than or less than the average air pressure to be expected at the point of use of the rotor blade.

Abstract: A wind energy installation (10) and a method for operation of a wind energy installation (10), with the wind energy installation (10) having a rotor (18) which can be driven by wind, having at least one rotor blade (22), a generator for conversion of the mechanical energy of the rotor (18) to electrical energy, as well as a tower (14) on which the rotor (18) is arranged. At least one measurement variable is measured, preferably more than once, by means of a suitable measurement device during. operation of the wind energy installation (10), which measurement variable is a measure of the bending of the rotor blade (22) in the tower direction as a result of a given wind load, and is thus a measure of the risk of the rotor blade (22) colliding with the tower (14) of the wind energy installation (10) as it passes the tower, with at least one operating parameter of the wind energy installation (10) being adjusted as a function of this measurement variable for determination of the rotor blade bending.

Abstract: A method for operating a wind energy installation, in particular for adapting a wind energy installation (10) to given wind conditions, the wind energy installation (10) having a rotor (16), which can be driven by wind, with at least two rotor blades (20), whose respective angles of incidence of the wind can be adjusted by means of at least one adjustment device, and having a generator for converting the mechanical energy of the rotor (16) to electrical energy. During operation of the wind energy installation, parameters are measured with spatial and/or temporal resolution on the side of the wind energy installation (10) facing the wind, said parameters describing the wind conditions in the measurement region, preferably the wind speed and/or the wind direction.