A measuring system for determining a torsion of a rotor blade, comprising a reference shaft to be arranged in the rotor blade in the longitudinal direction of the blade, at least one support for the reference shaft, for freely bearing the reference shaft in the rotor blade, so that the rotor blade can twist freely about the reference shaft, so that the reference shaft does not twist when there is twisting of the rotor blade, at least one rotary sensor, arranged on the reference shaft, for detecting a twisting of the rotor blade about the reference shaft in the region of the rotary sensor, the rotary sensor outputting a rotational angle describing the twisting of the rotor blade in relation to the reference shaft, or some other corresponding variable. A method for determining a torsion of a rotor blade, a corresponding rotor blade, a method for arranging a measuring system in a rotor blade and a corresponding wind power installation with a rotor blade and also or alternatively a measuring system.

Various embodiments of an apparatus and method for extracting useful work from a fluid stream are disclosed. Some embodiments comprise balanced hydrofoils comprising upper and lower semifoils joined by a member. Some embodiments comprise an array of removable hydrofoil modules wherein each module is adapted to provide an independent power contribution to an overall system, depending on speed of the fluid stream in the vicinity of the module, and each module is further adapted to provide its power contribution at a substantially consistent pressure to an array-wide high pressure fluid circuit. These and other embodiments are further disclosed herein.

Various embodiments of an apparatus and method for extracting useful work from a fluid stream are disclosed. Some embodiments comprise balanced hydrofoils comprising upper and lower semifoils joined by a member. Some embodiments comprise an array of removable hydrofoil modules wherein each module is adapted to provide an independent power contribution to an overall system, depending on speed of the fluid stream in the vicinity of the module, and each module is further adapted to provide its power contribution at a substantially consistent pressure to an array-wide high pressure fluid circuit. These and other embodiments are further disclosed herein.

A floating type offshore wind power generation facility includes: a wind power generation unit which is installed to be horizontally rotatable about a vertical rotation center while being placed in an inclined state on an offshore structure or installed to be rotatable in two directions about a horizontal rotation center of the offshore structure, and converts rotational kinetic energy of blades caused by sea wind into electrical energy; and a driving unit which is connected to a lower end of the wind power generation unit in a state in which the driving unit is installed on the offshore structure, and changes a pivoting angle or a rotating angle of the wind power generation unit by generating driving power.

Provided are a floating structure fluid dynamic force use system and a wind-propelled vessel which uses the system whereby it is possible to compensate for overturning moment due to fluid dynamic force and to alleviate both tilting and size increases of a floating structure. A floating structure fluid dynamic force use system (1) comprises an assembly (12) which extracts energy from wind or water, and a floating structure (13) which supports the assembly (12). The assembly (12) comprises a wind receiving part (10) which receives fluid dynamic force, and a support column (11) which supports the wind receiving part (10). The assembly (12) is positioned with the center of gravity (15) thereof below the water line and is supported to be capable of tilting in an arbitrary direction upon the floating structure (13).

A power generation apparatus for generating power from water flows is provided. The apparatus has an elongated module having a mechanical side and a hydraulic side, a generator coupled to the mechanical side. The hydraulic side having a set of paddles partially submerged in a water flow. The elongated module has a pivoting point on its mechanical side so that the hydraulic side follows an arc trajectory. The paddles are configured to change positions based on the angular location of the arc trajectory.

A system for hydrokinetic energy conversion of a fluid current is disclosed. The system includes at least two floating platforms, each floating platform has a movable paddle that moves up to an elevated position and moves down to a low position. A transmission mechanism is included to operatively couple floating platforms to a power generator, so that, when in operation, alternatively, a first floating platform, having the movable paddle in low position, is dragged downstream of the fluid current causes the power generator to produce energy and further causes a second floating platform, having the movable paddle in elevated position, be pulled upstream.

A wave energy converter to float in water, including a first body assembly having a first body and a sub-body rigidly connected to the first body by an assembly arm and a second body wherein the first body assembly and the second body being connected to one another via a first arm, the first arm being pivotally connected to at least one of the first body assembly and second body, the first body assembly and the second body also being connected to one another via a linkage that, via movement of at least a part of that linkage, allows for movement of the first body assembly and second body relative to one another in an anti-phase manner, and separation between the first body and the sub-body provides for tunability to tune the wave energy converter for use in a particular wave field.