Abstract: A multirotor wind turbine (1) comprising a tower structure (2) and at least one load carrying structure (3, 4), each load carrying structure (3, 4) being arranged for carrying two or more energy generating units (5, 7) comprising a rotor (6, 8). At least two of the rotors are upwind or downwind rotors (6), the energy generating units (5) comprising upwind or downwind rotors (6) being arranged with their centres of gravity at a first distance behind the tower structure (2) along a direction of the incoming wind, substantially at the same vertical level, and at opposite sides of the tower structure (2) at substantially the same second distance to the tower structure (2) along a direction substantially perpendicular to the direction of the incoming wind. The multirotor wind turbine (1) is self-yawing, even under turbulent wind conditions.

Abstract: A rotor apparatus for extracting energy from bidirectional fluid flows comprises a first rotor (7) mounted for rotation about an axis of rotation (4) in a first direction of rotation, the first rotor (7) having at least one helical blade (2) with a pitch that decreases in a direction along the axis of rotation (4); and a second rotor (8) mounted for rotation about the same axis of rotation (4) in an opposite direction of rotation and having at least one helical blade (2) with a pitch that increases in the same direction along the axis of rotation (4), wherein fluid exiting the first rotor (7) is passed to the second rotor (8).

Abstract: An electrodialysis unit 8 comprises a plurality of cathodes 68, a plurality of anodes 70 and a plurality of membranes 71; wherein the cathodes 68 and anodes 70 are arranged alternately in an electrode stack, with membranes 71 in between each cathode 68 and anode 70; and wherein the cathode 68 and the anode 70 are each formed of a single conductive plate such that both surfaces of the cathode plates and anode plates enclosed within the electrode stack are, in use, in conductive contact with the water being treated.

Abstract: The present invention relates to a filter arrangement comprising a plurality of elongate hollow filtration elements, each containing a back-washing mechanism. The back-washing mechanisms comprise at least one debris receiving portion having a cross-section corresponding to the cross-section of the hollow filtration element.

Abstract: An electrodialysis unit 8 for treating water, such as a treatment in order to kill microorganisms, comprises: a membrane cell, an anode flow path 52 for directing a portion of an incoming water flow to an anode side of the membrane cell, a cathode flow path 50 for directing a portion of an incoming water flow to a cathode side of the membrane cell, a temperature monitoring device 9a for monitoring the temperature of the water and a heater 9b for increasing the temperature of the water in the anode flow path 52 before it reaches the membrane cell, wherein the heater 9b is arranged to operate to increase the temperature of the water in the anode flow path 52 when the original water temperature is below a predetermined level. A membrane 71 is located between the electrodes (cathodes 68 and anode 70).

Abstract: An electrodialysis unit comprises a plurality of cathodes, a plurality of anodes and a plurality of membranes; the cathodes and anodes being arranged alternately in an electrode stack, with membranes in between each cathode and anode, anode flow paths formed between the membranes and anodes and cathode flow paths formed between the membranes and cathodes; the electrodialysis unit further comprising: an inlet manifold for distributing water to the anode flow paths or to the cathode flow paths, wherein the inlet manifold comprises a first tube provided with holes along its length, the holes being connected to the flow paths, and a second tube located within and enclosed by the first tube, the second tube having an inlet at one end and being closed at its second end and the second tube being provided with holes along its length that open into the first tube.

Abstract: An electrodialysis unit 8 comprises a cathode 68, an anode 70, a membrane 71 between the cathode 68 and the anode 70, a cathode flow path 72 for water flow along the membrane 71 on the cathode side, an anode flow path 74 for water flow along the membrane 71 on the anode side, and a reaction zone formed between the membrane 71 and the cathode 68 where the cathode 68 faces the anode 70, wherein the cathode flow path 72 is arranged for laminar flow in the reaction zone and wherein the electrodialysis unit 8 comprises flow conditioning elements 64 arranged to promote laminar flow in the incoming water flow to the cathode flow path 72.

Abstract: A liquid or water treatment apparatus comprising one or both of an electrodialysis cell and a cavitation unit. The cavitation unit generates cavitation in the liquid by flow of the liquid into a constriction where cavitation bubbles are formed and then to an outlet where cavitation bubbles implode, and the constriction includes an aperture formed by walls which are long and narrowly spaced in a plane normal to the flow direction. The electrodialysis cell is arranged with an inlet flow path for directing only part of a quantity of water to be treated through the electrodialysis cell, and an outlet flow path for returning a product of the electrodialysis cell to the remainder of the water.

Abstract: A liquid or water treatment apparatus comprising one or both of an electrodialysis cell and a cavitation unit. The cavitation unit generates cavitation in the liquid by flow of the liquid into a constriction where cavitation bubbles are formed and then to an outlet where cavitation bubbles implode, and the constriction includes an aperture formed by walls which are long and narrowly spaced in a plane normal to the flow direction. The electrodialysis cell is arranged with an inlet flow path for directing only part of a quantity of water to be treated through the electrodialysis cell, and an outlet flow path for returning a product of the electrodialysis cell to the remainder of the water.

Abstract: A cleaning head for a filter backwashing mechanism, the cleaning head comprising: a nozzle for contact with a filter element wall 1 and for receiving a flow of backwash fluid 8, 9, wherein the nozzle comprises a rotor 3 for generating a torque when exposed to the flow of backwash fluid 8,9, and wherein the cleaning head is arranged such that at least a part of the nozzle will move toward and/or apply a force to the filter element wall 1 as a result of the torque generated by the rotor 3.

Abstract: The present invention relates to a filter arrangement comprising a plurality of elongate hollow filtration elements, each containing a back-washing mechanism. The back-washing mechanisms comprise at least one debris receiving portion having a cross-section corresponding to the cross-section of the hollow filtration element.

Abstract: An electrodialysis unit 8 comprises a cathode 68, an anode 70, a membrane 71 between the cathode 68 and the anode 70, a cathode flow path 72 for water flow along the membrane 71 on the cathode side, an anode flow path 74 for water flow along the membrane 71 on the anode side, and a reaction zone formed between the membrane 71 and the cathode 68 where the cathode 68 faces the anode 70, wherein the cathode flow path 72 is arranged for laminar flow in the reaction zone and wherein the electrodialysis unit 8 comprises flow conditioning elements 64 arranged to promote laminar flow in the incoming water flow to the cathode flow path 72.

Abstract: An electrodialysis unit 8 comprises a plurality of cathodes 68, a plurality of anodes 70 and a plurality of membranes 71; wherein the cathodes 68 and anodes 70 are arranged alternately in an electrode stack, with membranes 71 in between each cathode 68 and anode 70; and wherein the cathode 68 and the anode 70 are each formed of a single conductive plate such that both surfaces of the cathode plates and anode plates enclosed within the electrode stack are, in use, in conductive contact with the water being treated.

Abstract: A rotor apparatus for extracting energy from bidirectional fluid flows comprises a first rotor (7) mounted for rotation about an axis of rotation (4) in a first direction of rotation, the first rotor (7) having at least one helical blade (2) with a pitch that decreases in a direction along the axis of rotation (4); and a second rotor (8) mounted for rotation about the same axis of rotation (4) in an opposite direction of rotation and having at least one helical blade (2) with a pitch that increases in the same direction along the axis of rotation (4), wherein fluid exiting the first rotor (7) is passed to the second rotor (8).

Abstract: An electrodialysis unit for treating water comprises a membrane cell, a temperature monitoring device for monitoring the temperature of incoming water and a heater for increasing the temperature of the incoming water before it reaches the membrane cell; wherein the heater is arranged to operate to increase the temperature of the incoming water when the original water temperature is below a predetermined level.

Abstract: An electrodialysis unit comprises a plurality of cathodes, a plurality of anodes and a plurality of membranes; the cathodes and anodes being arranged alternately in an electrode stack, with membranes in between each cathode and anode, anode flow paths formed between the membranes and anodes and cathode flow paths formed between the membranes and cathodes; the electrodialysis unit further comprising: an inlet manifold for distributing water to the anode flow paths or to the cathode flow paths, wherein the inlet manifold comprises a first tube provided with holes along its length, the holes being connected to the flow paths, and a second tube located within and enclosed by the first tube, the second tube having an inlet at one end and being closed at its second end and the second tube being provided with holes along its length that open into the first tube.

Abstract: A deformable trailing edge section (3) of a wind turbine blade (1), at least part of said section (3) being formed in a deformable material. The blade section (3) comprises one or more cavities (5) being in connection with or connectable to a fluid source in a way that allows fluid to stream from the fluid source to the cavity or cavities (5), so that the shape of the deformable trailing edge section (3) and thereby the camber of the blade cross-section (3) is changeable by the pressure of fluid in the cavity or cavities (5) with insignificant changes of the thickness and chord wise length of the deformable trailing edge section. Furthermore a wind turbine blade (1) is described, having at least one of such trailing edge section (s) (3) and to a system (11) for mounting a blade section (3) on a main blade (2) of a wind turbine. In addition a method of manufacturing a deformable trailing edge section (3) of a wind turbine blade (1) is disclosed.

Abstract: The purpose of the invention is to reduce the contribution of wind power installations to frequency errors on the grid, and preferably to contribute to the elimination of such errors. Thus, the method involves the use of PID control and/or control with hysteresis so as to regulate the active power injected into the grid, in view of the deviation between a measured grid frequency and the nominal grid frequency.

Abstract: A liquid or water treatment apparatus comprising one or both of an electrodialysis cell and a cavitation unit. The cavitation unit generates cavitation in the liquid by flow of the liquid into a constriction where cavitation bubbles are formed and then to an outlet where cavitation bubbles implode, and the constriction includes an aperture formed by walls which are long and narrowly spaced in a plane normal to the flow direction. The electrodialysis cell is arranged with an inlet flow path for directing only part of a quantity of water to be treated through the electrodialysis cell, and an outlet flow path for returning a product of the electrodialysis cell to the remainder of the water.

Abstract: A liquid or water treatment apparatus comprising one or both of an electrodialysis cell and a cavitation unit. The cavitation unit generates cavitation in the liquid by flow of the liquid into a constriction where cavitation bubbles are formed and then to an outlet where cavitation bubbles implode, and the constriction includes an aperture formed by walls which are long and narrowly spaced in a plane normal to the flow direction. The electrodialysis cell is arranged with an inlet flow path for directing only part of a quantity of water to be treated through the electrodialysis cell, and an outlet flow path for returning a product of the electrodialysis cell to the remainder of the water.