A method and apparatus according to which an output of a power generation system is controlled. In one embodiment, the power generation system includes a turbine and a feedback control system. The turbine includes a rotor to which a first portion of a power fluid is communicated, the first portion imparting torque to the rotor; a shaft to which the rotor is connected; a shroud extending circumferentially about the rotor and the shaft; and a bypass gap between the rotor and the shroud, through which a second portion of the power fluid is communicated. The feedback control system axially displaces the shroud relative to the rotor, thereby adjusting the size of the bypass gap and, consequently, the ratio of the first portion relative to the second portion.

An improved system and method of storing water for a closed-loop pumped storage hydroelectric system is provided. The method includes providing a floating reservoir, positioning the floating reservoir in a waterbody, loading the floating reservoir with a volume of water from a source other than the surrounding waterbody, and transferring water from within the floating reservoir to an upper or lower reservoir of a pumped storage hydroelectric system. The floating reservoir includes a flexible membrane defining one or more reservoir cells including a vertically collapsible sidewall, such that each reservoir cell defines a depth varying in proportion to its internal volume of water. Each reservoir cell is buoyed by pontoons adjacent an outer periphery of the reservoir cell and is anchored to the shore or streambed.

Described herein are wave energy conversion systems including actuated geometry components. An example system may include at least one body portion configured to transfer wave energy to a power take off device, and at least one actuated geometry component that is connected to the at least one body portion, the at least one actuated geometry component operable to modify a geometric profile of the system.

This invention relates to an arrangement in a wave energy recovery apparatus and to a method for operating the wave energy recovery apparatus. The apparatus comprises at least a base (1), on which a reciprocating panel (2) is installed, a pivot shaft (7) for the reciprocating panel (2), a control system, and one or more power-take-off (PTO) units (3) to convert kinetic energy of waves or tidal currents to another type of energy. The arrangement comprises adjustment means (5, 5, 5) to set the top of the panel (2) in its vertical position to approximately correspond to the altitude of the surface (8) of the water.

A variable-geometry ducted fan may include an air duct having a longitudinal axis, the air duct including an inlet of the variable-geometry ducted fan, a fan rotatably mounted within the air duct downstream from the inlet, the fan including fan blades defining a fan area, and a variable-area nozzle coupled to the air duct downstream from the fan, the variable-area nozzle including an exhaust of the variable-geometry ducted fan having a variable exhaust area.

An apparatus and method is disclosed for extracting energy from an oscillating working fluid, such as ocean waves. The apparatus (10) comprises an internal flow passage (40) for the working fluid, a turbine (44) and a flow control device (38), each of the turbine (44) and the flow control device (38) being in direct fluid communication with the flow passage (40), wherein in use the flow control device (38) is selectively moveable between a first configuration in which the flow control device (38) is open to allow a flow of the working fluid, such as air, to exit the flow passage (40) therethrough, and a second configuration in which the flow control device (38) restricts a flow of the working fluid therethrough. In such an instance, the working fluid then must enter the flow passage (40) via the turbine (44), which can be harnessed to generate electricity.

A hydroelectric energy system includes a stator including a first plurality of electricity-generating elements. The system also includes a rotor including a second plurality of electricity-generating elements. The rotor is disposed radially outward of an outer circumferential surface of the stator and is configured to rotate around the stator about an axis of rotation. The rotor is a flexible belt structure having a variable thickness and extending along a portion of an axial length of the stator. The system further includes at least one hydrodynamic bearing mechanism configured to support the rotor relative to the stator during rotation of the rotor around the stator. The at least one hydrodynamic bearing mechanism includes a bearing surface made of wood or a composite material.

An axial impeller has a tubular housing mounted on bearings for rotation. The housing is capable of engaging a motor or generator directly or through a drive belt. Interior turbine blades are mounted on the housing wall. The blades may be hinged so they can rotate between a retracted position adjacent to the wall and an extended radial position. Rods penetrate the wall to position the blades between retracted and extended positions. When extended, the blades may be rotated to propel a fluid through the housing; and when retracted natural fluid flow is less restricted.

Wind turbine blades comprising one or more deformable trailing edge sections, each deformable trailing edge section comprising a first and a second actuator, wherein the second actuator is arranged substantially downstream from the first actuator, and wherein the first actuator is of a first type and wherein the second actuator is of a second type, the second type being different from the first type. The application further relates to wind turbines comprising such blades and methods of operating a wind turbine comprising one or more of such blades.

Wind turbine blades comprising one or more deformable trailing edge sections having a multistable sheet comprising a plurality of bistable elements, each bistable element having two stable positions, wherein the multistable sheet is attached in a cantilever manner to a structural portion of the blade and extends in a chordwise direction, and the multistable sheet is connected to a skin of the blade such that upon changing one or more bistable elements from one stable position to the other stable position a shape of the trailing edge section changes. The application further relates to wind turbines comprising such blades and methods of controlling loads on the blades.