(NL1005542-C2)      A hollow container (1) is placed vertically on the sea bottom (2). There is at least one opening (14) in the wall of the container which allows water to move freely in and out.    A float (7) moves vertically with respect to the container with the movement of the seawater level. The float is connected to the space inside the container so that as it moves the volume of the container changes. This produces a flow of fluid inside the container which is used to drive a propeller which is connected, either directly or indirectly, to an energy generator.    ADVANTAGE -   Improved efficiency of operation    (EP1007843-A1)      A hollow container (1) is placed vertically on the sea bottom (2). There is at least one opening (14) in the wall of the container which allows water to move freely in and out.    A float (7) moves vertically with respect to the container with the movement of the seawater level. The float is connected to the space inside the container so that as it moves the volume of the container changes. This produces a flow of fluid inside the container which is used to drive a propeller which is connected, either directly or indirectly, to an energy generator.    ADVANTAGE -   Improved efficiency of operation    (CN1250507-A)      A hollow container (1) is placed vertically on the sea bottom (2). There is at least one opening (14) in the wall of the container which allows water to move freely in and out.    A float (7) moves vertically with respect to the container with the movement of the seawater level. The float is connected to the space inside the container so that as it moves the volume of the container changes. This produces a flow of fluid inside the container which is used to drive a propeller which is connected, either directly or indirectly, to an energy generator.    ADVANTAGE -   Improved efficiency of operation    (US6216455-B1)      A hollow container (1) is placed vertically on the sea bottom (2). There is at least one opening (14) in the wall of the container which allows water to move freely in and out.    A float (7) moves vertically with respect to the container with the movement of the seawater level. The float is connected to the space inside the container so that as it moves the volume of the container changes. This produces a flow of fluid inside the container which is used to drive a propeller which is connected, either directly or indirectly, to an energy generator.    ADVANTAGE -   Improved efficiency of operation