Abstract: The low head energy in for example a river flow is used to provide electrical energy by directing the water through a duct (70), and by inducing air into the duct to create an air flow which is drawn over an air turbine (76) to excite same, and thereby produce electrical energy. The air can be introduced into the flowing water in the duct by a switching arrangement to ensure that no bubbles or pockets of air travel along with the water, which impairs efficiency. The duct may be in the shape of an anti-gravity course (70) to prevent the bubbles from travelling.

Abstract: The invention provides for the generation of electrical power from low head water, such as the flowing water of rivers or the like, the electrical power is generated by passing the water in sequence over flexible bags or membranes to displace air under the flexible bags or membranes. The displacement of the air is utilized for the driving of a power generator such as an air turbine, and smooth power flow is achieved by diverting air displaced from the underside of one membrane into the cavity under the other membrane. The water flows over the membranes in sequence so that a self oscillating system is set up with the air being displaced back and forth from the cavities, and the displacement air being used to drive the air turbine. Preferably a bi-directional air turbine such as a Wells turbine is used.

Abstract: The invention describes an energy extractor for extracting energy from waves in the sea. A ring spine is disclosed and on the spine, spaced circumferentially thereof are flexible membranes which flex back and forth under the influence of the waves. The back and forth flexing deflects air back and forth and the air movement is used to drive air turbines and electrical generators. Arranging for the spine to be in a ring and spacing the membranes around the ring ensures efficient energy extraction regardless of wave direction.

Abstract: A wedging assembly for steering or branching a borehole comprises a wedge defining the steering or branching angle, a locking device for locking the wedge in a desired position, and an actuator for actuating the locking device, the locking device including cooperable male and female locking members which are relatively moveable to cause an annular locking surface on the female member to lock firmly about the wall of the borehole.

Abstract: A device for generating power from the energy of waves in a body of liquid employs a buoyant reaction element and at least one displacement element which can move back and forth to react against the reaction element. The movement of the displacement element which is caused by the cyclic application of wave forces is converted into a more readily usable form by a turbine driven by the flow of air or hydraulic fluid caused by the movement of the displacement element. Where the air or hydraulic flow is bidirectional, the turbine can be of the self-rectifying type so that it is driven unidirectionally. The turbine may, for example, drive a generator that produces electrical power. Where a plurality of displacement elements are employed, some of the displacement elements are arranged to be out of phase relative to others of the displacement elements.

Abstract: A wave energy conversion system is disclosed and comprises a spine and a plurality of wave driven pump units each comprising a pillow shaped flexible bag arranged with its length direction horizontal and mounted on the spine so that the water in which the system is located flows to both sides of the bag so that in use the bag is kept out of abrading contact with the spine. The lower edges of the bags are attached to the spine and the upper edge of each bag has a common outlet/inlet passage through which air is pumped back and forth by the bag collapsing and expanding under the influence of the waves. The common passage is at one top corner of the bag and at the other top corner is a dummy passage which enables the bag to be fabricated in such a manner that the corners are not stressed significantly in use. Also, a common pipe can be used to define the common passage of one bag and the dummy passage of the adjacent bag.