Method and a wave-power aggregate to extract energy from wave motion in a fluid and the use of a wave-power aggregate

Abstract

The present invention relates to a wave-power aggregate and a method of extracting energy from wave motion in a liquid by means of a wave-power aggregate. The wave-power aggregate comprises a container which is situated at least partially in the liquid and also comprises an inflow and an outflow. The container is arranged to, under the influence of said wave motion, to let a first part of the container arrange itself in a first position and a second part of the container in a second position, where the first and second position corresponds to different potential energy states. The method comprises the steps of: alternately supplying the container with at least a first and a second fluid respectively via the inflow, where the density of the fluids differs. at least during an initial stage of the method controlling a flow resistance in at least one of the first and second fluids through the container.

I claim: 
     
         1 . A wave-power aggregate for extracting energy from wave motion at a surface of a first fluid, said aggregate comprising:
 at least one flexible elongated container essentially assuming a wave shape of said surface in such a way that portions of said container are moved up and down by waves at the surface of said first fluid, the container being equipped with an inflow and an outflow wherein said container has an extension in an extension direction between said inflow and said outflow;   a fluid supply for alternately supplying the first fluid and a second fluid to said container, the first fluid and the second fluid being transported through said container from the inflow to the outflow by the wave motion at the surface of the first fluid;   a measurement arrangement for measuring said wave motion;   a flow controller connected to said measurement arrangement for controlling at least one of fluid speed and flow resistance through said container based on information from said measurement arrangement; and   a converter connected to said outflow and/or inflow for converting an increase of pressure and/or flow rate in at least one of said first and second fluids into usable energy.   
     
     
         2 . The wave-power aggregate according to  claim 1 , wherein the first fluid is water and the second fluid is air. 
     
     
         3 . The wave-power aggregate according to  claim 1 , wherein said measurement arrangement is arranged and configured to measure at least a propagation direction and a speed of said waves. 
     
     
         4 . The wave-power aggregate according to  claim 1 , wherein said measurement arrangement includes at least one of a wave radar and a wave buoy. 
     
     
         5 . The wave-power aggregate according to  claim 1 , wherein said flow controller is arranged and configured to control both said fluid speed and said flow resistance. 
     
     
         6 . The wave-power aggregate according to  claim 1 , wherein said flow controller comprises control gear fitted at said inflow of the container for controlling said fluid speed as a function of said wave motion. 
     
     
         7 . The wave-power aggregate according to  claim 1 , wherein said flow controller is arranged and configured to control said fluid speed through the container to substantially correspond to a propagation speed of the wave motion in said extension direction of the container. 
     
     
         8 . The wave-power aggregate according to  claim 1 , wherein said flow controller is arranged and configured to control said fluid speed through the container to substantially correspond to a multiple of the propagation speed of the wave motion in said extension direction of the container. 
     
     
         9 . The wave-power aggregate according to  claim 1 , wherein said aggregate further comprises:
 a fluid separator arranged at said outflow for separating said first and second fluids; and   a return conduit connected to said fluid separator for returning the second fluid from the outflow towards the inflow.   
     
     
         10 . A method of extracting energy from wave motion at a surface of a first fluid using a wave-power aggregate comprising:
 at least one flexible elongated container essentially assuming a wave shape of said surface in such a way that portions of said container are moved up and down by waves at the surface of said first fluid, the container being equipped with an inflow and an outflow wherein said container has an extension in an extension direction between said inflow and said outflow;   a fluid supply means for controlling supply of said first fluid and a second fluid to said flexible elongated container; and   a converter connected to said outflow and/or inflow for converting an increase of pressure and/or flow rate in at least one of said first and second fluids into usable energy,   wherein said method comprises the steps of:
 measuring said wave motion; and 
 controlling at least one of fluid speed and flow resistance through said container based on information from said measurement arrangement. 
   
     
     
         11 . The method according to  claim 10 , further comprising the steps of:
 separating said first and second fluids at the outflow using a fluid separator arranged at said outflow; and   returning the second fluid from the outflow towards the inflow using a return conduit connected to said fluid separator.