A wind turbine component, the wind turbine component comprising a laminate of layers with an outer side and an inner side, wherein the outer side faces an exterior of the wind turbine component and the inner side faces an interior of the wind turbine component, the laminate of layers being configured to reflect a radar wave impinging the outer side of the laminate of layers, wherein a reflection loss of the reflected radar wave is below a threshold at a frequency, the laminate of layers comprising: an attenuating layer comprising reinforcing fiberglass or reinforcing carbon fibers, a polymer matrix, and radar absorbing particles; a reflective layer arranged on the inner side of the attenuating layer, the reflective layer being configured to reflect a transmitted portion of the radar wave, the transmitted portion of the radar wave being a portion of the radar wave that has passed through the attenuating layer.

This invention relates to the field of an electromagnetic (EM) field absorbing composition, in particular, those capable of providing absorbance in the frequency of commercial radar. The composition finds particular use as a radar absorbing coating for wind turbines, in particular for use in onshore and offshore environments. There are further provided coated surfaces comprising the composition, methods of absorbing EM radiation, and methods of use of such a composition, such that a surface coated in the composition is capable of absorbing EM radiation. There is provided an electromagnetic radiation absorbing composition comprising elongate carbon elements with an average longest dimension in the range of 50 to 1 000 microns, with a thickness in the range of 1 to 15 microns and present in the range of from 0.5 to 20 volume % dried, in a non conductive binder.

Disclosed is a vertical axis wind turbine air concentration tower with reduced radar cross section. The air concentration tower has a polygonal outer perimeter, a pivot located at each vertex of the polygonal outer perimeter, and an inwardly-positioned rudder blade operatively connected at each pivot. Each inwardly positioned rudder blade has a first wind-neutral position, and is pivotable through a plurality of angles that adjust based on an incoming wind direction, such that the incoming wind is channeled to the vertical axis wind turbine, which is located approximately at a center area of the polygonal outer perimeter. A radar absorbent material is applied to the vertical axis wind turbine air concentration tower to reduce the radar cross section. The air concentration tower is designed to provide higher wind speed to the vertical axis wind turbine than the surrounding ambient air.

Disclosed is a vertical axis wind turbine air concentration tower with reduced radar cross section. The air concentration tower has a polygonal outer perimeter, a pivot located at each vertex of the polygonal outer perimeter, and an inwardly-positioned rudder blade operatively connected at each pivot. Each inwardly positioned rudder blade has a first wind-neutral position, and is pivotable through a plurality of angles that adjust based on an incoming wind direction, such that the incoming wind is channeled to the vertical axis wind turbine, which is located approximately at a center area of the polygonal outer perimeter. A radar absorbent material is applied to the vertical axis wind turbine air concentration tower to reduce the radar cross section. The air concentration tower is designed to provide higher wind speed to the vertical axis wind turbine than the surrounding ambient air.

There is provided a wind turbine rotor blade comprising a rotor blade casing, and a lightning protection system having at least one lightning protection cable and a lighting protection cable holder. The lighting protection cable holder is fixed in or to the inside of the rotor blade casing. The lighting protection conductor holder has a first part and a second part. The first part is fixed to an inside of the rotor blade casing and has a receiving portion for receiving the lighting protection cable. The second part is in the form of a cover or covering means and is placed over the receiving portion. The first and second parts each have a radar-absorbing core or a radar-absorbing layer and an electrically insulating material which surrounds the radar-absorbing core or the radar-absorbing layer.

A wind turbine including a support structure and one or more turbine blades is presented, that incorporates ways for reducing the radar cross section (RCS), wherein the support structure is notionally divided into an upper section in the shadow of the blade sweep area, and a lower section beneath the upper section, wherein the upper section is adapted to have the ways for reducing the RCS, and the lower section does not have the adaptation. The invention makes use of the realisation that the blade masking the tower as it rotates (or the blade being masked by the tower if facing away from a radar), contributes significantly to interference to radar systems, and so localised application of e.g. RAM can give good RCS reduction at a lower cost than treating the whole structure.

A combined omnidirectional flow turbine system includes rotors that are disposed in a vertical position and enclosed in a motionless structure that receives air flows from any external direction which are manipulated by an airfoil to cause the rotors to rotate. The motionless structure is a hollow body and it is formed by a support structure and cover, being said interior space adapted to store electronic components, which can be directly supplied by the energy, produced. On its outer surface, air particles and pollutants filters can be installed, taking advantage of the aerodynamic shape of the motionless structure, which promotes air flow adhesion along its surface, making possible to capture particles along their preferred path.

There is provided a wind turbine rotor blade comprising a rotor blade casing, and a lightning protection system having at least one lightning protection cable and a lighting protection cable holder. The lighting protection cable holder is fixed in or to the inside of the rotor blade casing. The lighting protection conductor holder has a first part and a second part. The first part is fixed to an inside of the rotor blade casing and has a receiving portion for receiving the lighting protection cable. The second part is in the form of a cover or covering means and is placed over the receiving portion. The first and second parts each have a radar-absorbing core or a radar-absorbing layer and an electrically insulating material which surrounds the radar-absorbing core or the radar-absorbing layer.

A wind turbine with reduced electromagnetic scattering includes a wind turbine support structure having a cylindrical shape, a wind turbine blade supported by the wind support structure, and a plurality of multi-layer absorbers to limit the electromagnetic scattering, the absorber including at least cobalt ferrite alloy nano-particles, cobalt ferrite alloy nano-flakes, and air. The wind turbine blade includes a blade root, a blade tip opposite the blade root, and a blade middle part extending between the blade root and the blade tip. The plurality of multi-layer absorbers further includes a planar absorber that covers the wind turbine support structure, and a curved absorber that covers the middle part.

A wind turbine including a support structure and one or more turbine blades is presented, that incorporates ways for reducing the radar cross section (RCS), wherein the support structure is notionally divided into an upper section in the shadow of the blade sweep area, and a lower section beneath the upper section, wherein the upper section is adapted to have the ways for reducing the RCS, and the lower section does not have the adaptation. The invention makes use of the realisation that the blade masking the tower as it rotates (or the blade being masked by the tower if facing away from a radar), contributes significantly to interference to radar systems, and so localised application of e.g. RAM can give good RCS reduction at a lower cost than treating the whole structure.