A de-icing and anti-icing arrangement for a Wind Energy Converting System (WECS), a WECS comprising a de-icing and anti-icing arrangement and a method for preventing and eliminating ice accretion on the rotor blades of a WECS are provided. The WECS comprises a tower, a rotor having a plurality of blades that rotate due to wind force, a nacelle including a first means for transforming the rotor's rotational movement to electric power, and a second means for permitting the flow of fluid from volumes defined by the rotor blades, the rotor blades comprising an external surface having openings in fluid connection with the volumes inside the blades for permitting the flow of fluid to the outside of the blades to fluid-thermodynamically interact with the wind hitting the part of the blade surface, and thereby prevent or eliminate the accretion of ice on the external surface of the blade.