Energy is harvesting from fluids with different densities, such as water (34) and air (38) with a rotor (12) that is selectively above and below a water surface (30). The rotor (12) has cavities (31,32) inside tubes (18) with apertures (24) in walls (22) of the tubes (18). In a submerged mode, with the rotor (12) in the water (34), air is trapped in tubes (18) on one side of the rotor (12), which has apertures (24) facing down and air is released from the tubes (18) on the opposite side of the rotor (12), which has apertures (24) facing up. The opposite happens in an elevated mode.

A root bushing for a wind turbine rotor blade is provided, including a plurality of fiber material layers and an insert, wherein the insert is embedded in the fiber material layers, and wherein at least a part of the fiber material layers forms a double scarf joint for transferring loads from the insert to the fiber material layers and vice versa. Due to the double scarf joint it is possible to transfer high loads from the fiber material layers and vice versa. A less load resilient joint like double lap shear joint or the like can be omitted.

Wave energy conversion (WEC) systems and methods for harvesting wave energy by use of the systems are described. WEC systems incorporate a plurality of submerged oscillating water columns (SOWC) that encourage oscillating water motion within each submerged column to mimic the motion of waves passing the SOWC system. A WEC system includes multiple SOWC connected to one another via air pockets within each submerged column. Each SOWC includes a float connected to a power take-off. The oscillations of the floats are converted to useful energy by the power take-off of the system.

Provided is a blade mounting arrangement at the interface between a hub and a rotor blade of a wind turbine, which blade mounting arrangement includes at least an annular bearing including a stationary part mounted to the hub and a rotating part mounted to the root end of the blade; and a reinforcing ring arranged between the bearing rotating part and the root end of the blade, which reinforcing ring includes a cylindrical body portion shaped as an extension of the root end of the blade. A wind turbine including a hub and a number of blades mounted to the hub, and with such a blade mounting arrangement at the interface between the hub and each rotor blade is also provided. A method of realizing an interface between a hub and a rotor blade of a wind turbine is also provided.

A vertical axis wind turbine with improved safety, production efficiency and greater functional wind speed range. A vertical axis wind turbine comprises turbine blades having geometric characteristics of a “yin yang” symbol when viewed from the top down. The turbine blades are configured to form a scoop portion for catching wind. The surface area of the scoop portion may be dynamically configured to accommodate power production in higher wind speed ranges by dynamically furling the blades to reduce the surface area of the scoop portion as RPM begins to exceed a safe limit. First and second permanent magnet rotor arrays are dynamically positioned above and below an array of stator coils to maximize power generation.

Wave energy conversion (WEC) systems and methods for harvesting wave energy by use of the systems are described. WEC systems incorporate a plurality of submerged oscillating water columns (SOWC) that encourage oscillating water motion within each submerged column to mimic the motion of waves passing the SOWC system. A WEC system includes multiple SOWC connected to one another via air pockets within each submerged column. Each SOWC includes a float connected to a power take-off. The oscillations of the floats are converted to useful energy by the power take-off of the system.

Aspects of the disclosure include a tidal power generator comprising a first container, at least one second container pivotably coupled to the first container, a frame pivotably coupled to the first container, a first valve, associated with the first container, configured to selectively control ingress of a first volume of a first fluid into the first container, and a second valve, associated with the first container, configured to selectively control egress of a second volume of the first fluid out of the first container.

A turbine having a rotor assembly with substantially cylindrical blades. A scoop may be used to direct a fluid flow into the turbine, thereby causing a pushing force and/or a suction force to be exerted on at least some of the cylindrical blades. Accordingly, the rotor assembly may rotate within the turbine. In an example, the rotor assembly may include a plurality of magnets, which may cause a magnetic field to fluctuate. Copper discs on the turbine enclosure may be used to generate electricity based on the changing magnetic field. In another example, the turbine enclosure may have one or more openings, which may generate a suction or pressure force as the rotor assembly rotates.

A renewable-energy power plant including a first structure, a second structure, a first flue, a second flue and a turbine arrangement comprising at least one turbine, wherein the first structure includes a primary fluid inlet and the second structure includes a secondary fluid inlet and a primary fluid outlet, wherein the secondary fluid inlet is connected to the first flue, wherein the primary fluid inlet is located lower than the secondary fluid inlet and the primary fluid outlet is located lower than the secondary fluid inlet, wherein the turbine arrangement is provided inside the second flue, wherein the power plant includes wetting means arranged to discharge an additive fluid to the working fluid passing through the secondary fluid inlet, wherein the turbine arrangement is arranged to generate power due to the working fluid flowing in a downwards direction inside the second flue and passing through the turbine arrangement.

Provided is a blade mounting arrangement at the interface between a hub and a rotor blade of a wind turbine, which blade mounting arrangement includes at least an annular bearing including a stationary part mounted to the hub and a rotating part mounted to the root end of the blade; and a reinforcing ring arranged between the bearing rotating part and the root end of the blade, which reinforcing ring includes a cylindrical body portion shaped as an extension of the root end of the blade. A wind turbine including a hub and a number of blades mounted to the hub, and with such a blade mounting arrangement at the interface between the hub and each rotor blade is also provided. A method of realizing an interface between a hub and a rotor blade of a wind turbine is also provided.