A water mill, power generator, for use underwater, has a flexible support shaft which permits the water current to orient the turbine axis substantially parallel to the direction of flow so that the force of the water on the blades is optimized for a given turbine, without the need for slip ring style connections between the generator at the turbine and the 5 anchored base. Optionally, the design features fins or cowlings on the flexible support shaft to further improve reorientation of the turbine with the water current or flow acting as the source of power; and/or output power links or power conditioning systems at the anchored base. The generators may be selected to meet low rotation operating conditions, and the entire system may be designed for particular ocean bottom and/or current parameters applicable to the 10 deployment.

A water mill, power generator, for use underwater, has a flexible support shaft which permits the water current to orient the turbine axis substantially parallel to the direction of flow so that the force of the water on the blades is optimized for a given turbine, without the need for slip ring style connections between the generator at the turbine and the 5 anchored base. Optionally, the design features fins or cowlings on the flexible support shaft to further improve reorientation of the turbine with the water current or flow acting as the source of power; and/or output power links or power conditioning systems at the anchored base. The generators may be selected to meet low rotation operating conditions, and the entire system may be designed for particular ocean bottom and/or current parameters applicable to the 10 deployment.

Some geographies have tide ranges above 15 yards, but most do not. The wider the tide range, the more hydroelectric power can be generated per cycle of low tide to high tide and then high tide to low tide, using a tidal barrage. Methods of raising the high tide above the measured level to fill the storage ponds to an even higher level and a method to empty the storage ponds to a lower than low tide level, provide means to expand the tide range significantly, enabling many more planet geographies to have economically feasible hydroelectric power.

A submersible power plant and a method for providing a submersible power plant. The submersible power plant includes an anchoring provided at a minimum depth and a vehicle including at least one wing. The vehicle is arranged to be secured to the anchoring of at least one tether rotatably attached to the anchoring by an anchoring coupling and attached to the vehicle by at least one vehicle coupling. The submersible power plant is completely submerged in a body of fluid both during operation and non-operation of the submersible power plant and the tether has an unextended tether length between 2-20 times a wingspan of the wing, specifically between 3-12 times the wingspan of the wing, more specifically between 5-10 times the wingspan of the wing.

The invention relates to a method for controlling the operation of a submersible power plant (1) and a submersible power plant (1). The submersible power plant (1) comprises a structure (2) and a vehicle (3). The vehicle (3) comprises at least one wing (4). The vehicle (3) is arranged to be secured to the structure (2) by means of at least one tether (5). The vehicle (3) is arranged to move in a predetermined trajectory by means of a fluid stream passing the vehicle (3). The vehicle (3) is arranged to change the angle of attack of the at least one wing (4). The method comprises: I: determining if the speed of the fluid passing the vehicle (3) is higher than a predetermined value; or II: determining if the speed of the fluid passing the vehicle (3) is lower than the predetermined value. The vehicle (3) changes the angle of attack for different situations depending on if the speed is higher or lower than the predetermined trajectory.

A tidal power generation and storage system (10) comprises a lagoon (12) and a plurality of reservoirs (14) separating the lagoon from an area of tidal water (16). Each reservoir (14) comprises a seawall (20) surrounding a reservoir chamber (22). The system has a first flow channel (30) in communication between the area of tidal water (16) and the lagoon(12) which directs flow through a turbine (32)to generate electrical power. The system also has a second flow channel (40) to allow communication between two adjacent reservoirs and a third flow channel (90) to allow communication between a reservoir and the first flow channel. The seawall (20) of each reservoir (14) comprises a gravity structure comprising a plurality of layers of a mixture of sand and/or other seabed material with a hydraulic binder. The system can be built using material sourced at the point of construction, and allows storage and pumping of water in the reservoirs (14) and lagoon (12) to maximise the period over which power can be generated.

The invention relates to a tidal wave powered device and a method thereof for producing potential energy from the movement of tidal waves in a water mass, the device comprising a cylinder (18) anchored to the bed (22) of the water mass with a piston (16) located in the cylinder to define a pumping chamber (25) therein. A storage tank (23) is located at an elevated height for storage of water delivered from the cylinder pumping chamber (25). A docking unit (30) anchored to the bed of the water mass is connected to a floater (10) such that when the floater (10) attains an optimal height, the docking unit (30) is locked in to hold the floater (10) in an elevated position. The docking unit (30) is opened to release the floater (10) from the elevated position so that the weight of the floater pushes the piston (16) downwards to deliver water from the pumping chamber (25) of the cylinder (18) into the storage tank (23).

An underwater structure includes a power generation unit, which includes a main body, a mounting portion which extends from the main body and which defines a mounting axis, and a support structure adapted for engagement with a bed of a body of water, and support housing. The mounting portion defines a substantially continuous mounting surface which extends substantially completely around the mounting portion, and the support housing defines a substantially continuous support surface which extends substantially completely around the support housing. The mounting surface and support surface are arranged to abut one another substantially continuously when the power generation unit is mounted on the support structure. The mounting portion and the support housing are adapted to cooperate with one another for mounting of the power generation unit on the support structure in any polar orientation about the mounting axis.

An accelerated and/or redirected flow arrangement, optimally serving as a wildlife and/or debris excluder (WDE), is used in combination with a turbine-like device having an inlet end and an outlet end for fluid flowing therethrough, e.g., a hydro-turbine. The arrangement includes at least a forward part designed to be placed in front of a fluid inlet of a turbine-like device and configured to produce at least one of the following effects on the fluid: (a) imparting a re-direction of the fluid; and/or (b) accelerating the flow velocity of the fluid, as it flows through the forward part. Turbine-like devices having both a forward part and a rearward part of flow arrangement are disclosed, as well as a method of enhancing turbine performance.

A rotor shaft unit for a tidal system, which tidal system includes a main frame and a rotor and a housing connected to the rotor, includes a rotor shaft configured to be connected to the main frame, at least one bearing unit for rotatably supporting the housing for rotation relative to the rotor shaft, and a sleeve configured to be mounted in the main frame, the sleeve being disposed around a first end portion of the rotor shaft and connected to the rotor shaft by a friction connection. Also a tidal system including the rotor shaft unit.