Underwater energy generating system

1. An underwater system for generating electricity, the system comprising:

a base for storing generated electricity, comprising:

a spool assembly coupled to a retractable line and configured to wind and unwind the retractable line;

a tension assembly coupled to the spool assembly and configured to maintain a first tension in the retractable line; and

an electrical generator assembly configured to generate electricity by converting rotational motion of unwinding of the retractable line from the spool assembly; and

a submersible controllable apparatus coupled to the retractable line, comprising:

a body;

one or more surfaces coupled to the body and configured to produce a controllable second tension in the retractable line by adjusting the one or more surfaces in a manner sufficient to cause the submersible controllable apparatus to rise toward a surface of a body of liquid in which the submersible controllable apparatus is submersed and thereby generating a force using a current of the liquid as it flows across the submersible controllable apparatus, the second tension having a direction that is modifiable between being either opposite or equal to the direction of the first tension; and

a controller coupled to the one or more surfaces for controlling the one or more surfaces in a manner sufficient to control the controllable second tension;

wherein when the submersible controllable apparatus is controlled to produce the controllable second tension in the retractable line and generate the force using the current of the liquid, and when the generated force is greater than the first tension in the retractable line, the spool assembly rotates and unwinds the retractable line and the electrical generator assembly generates electricity by converting the rotational motion of the spool assembly into electricity; and

wherein the submersible controllable apparatus further comprises an impeller coupled to the body of the submersible controllable apparatus at an end of the body configured to face downstream, and a rotating generator coupled to the impeller for generating electricity based on rotation of the impeller.

2. The system of claim 1 , wherein the one or more surfaces comprise:

at least one lift generating surface coupled to the body and configured in such a way as to provide lift to the body when a fluid flows across the lift generating surface; and

at least one control surface coupled to the body and configured to control a pitch of the body in such a way as to modify lift characteristics of the body between a negative lift and a positive lift.

3. The system of claim 1 , wherein the controllable apparatus further comprises telemetry equipment coupled to the body and configured for wireless communication with at least one remote device.

4. The system of claim 1 , wherein the base further comprises one or more sensors.

5. The system of claim 1 , wherein the controller is configured to operate in one or more of the following modes:

a submersed mode in which the controller controls the one or more surfaces in a manner sufficient to maintain the controllable apparatus at a substantially constant depth below the surface of the body of liquid;

a first transit mode in which the controller controls the one or more surfaces in a manner sufficient to cause the controllable apparatus to rise from the substantially constant depth to the surface of the body of liquid;

a surfaced mode in which the controller controls the one or more surfaces in a manner sufficient to maintain the controllable apparatus at the surface of the body of liquid; or

a second transit mode in which the controller controls the one or more surfaces in a manner sufficient to cause the controllable apparatus to descend from the surface of the body of liquid to the substantially constant depth below the surface of the body of liquid.

6. The system of claim 1 , further comprising a rotatable arm coupling the base to the retractable line, the rotatable arm having freedom-of-movement about a common center point at the base.

7. The system of claim 1 , wherein the base comprises an anchored subsurface float or a dead weight seabed anchor.

8. The system of claim 1 , wherein the submersible controllable apparatus further comprises a swing arm coupling the submersible controllable apparatus to the retractable line, the swing arm being configured to pivot about a pivot point situated in or on the body.

9. The system of claim 1 , further comprising one or more vertical rudder fins coupled to the submersible controllable apparatus for stabilizing the submersible controllable apparatus.

10. The system of claim 1 , wherein the submersible controllable apparatus further comprises an internal buoyancy module and a ballast compartment, the internal buoyancy module and the ballast compartment being sized and positioned in such a way that the submersible controllable apparatus has a net positive buoyancy.

11. A method of operating an underwater system for generating electricity, comprising:

providing a base for storing generated electricity, comprising:

a spool assembly coupled to a retractable line and configured to wind and unwind the retractable line;

a tension assembly coupled to the spool assembly and configured to maintain a first tension in the retractable line; and

an electrical generator assembly configured to generate electricity by converting rotational motion of unwinding of the retractable line from the spool assembly;

providing a submersible controllable apparatus coupled to the retractable line, comprising:

a body;

one or more surfaces coupled to the body and configured to produce a controllable second tension in the retractable line by adjusting the one or more surfaces in a manner sufficient to cause the submersible controllable apparatus to rise toward a surface of a body of liquid in which the submersible controllable apparatus is submersed and thereby generating a force using a current of the liquid as it flows across the submersible controllable apparatus, the second tension having a direction that is modifiable between being either opposite or equal to the direction of the first tension; and

a controller coupled to the one or more surfaces for controlling the one or more surfaces in a manner sufficient to control the controllable second tension;

providing the base configured to be anchored at a subsurface location;

providing the retractable line coupling the body with the base;

an impeller coupled to the body of the submersible controllable apparatus at an end of the body configured to face downstream; and

a rotating generator coupled to the impeller for generating electricity based on rotation of the impeller; and

causing the submersible controllable apparatus to produce the controllable second tension in the retractable line and generate the force using the current of the liquid, and when the generated force is greater than the first tension in the retractable line, the spool assembly rotating and unwinding the retractable line and the electrical generator assembly generating electricity by converting the rotational motion of the spool assembly into electricity and the rotating generator generating electricity from the rotation of impeller.

12. The method of claim 11 , wherein the step of causing the submersible controllable apparatus to rise from an entirely submersed position within the body of liquid to a surfaced position at the surface of the body of liquid comprises controlling one or more attitude control surfaces in a manner sufficient to cause the submersible controllable apparatus to rise from a substantially constant depth to the surface of the body of liquid.

13. The method of claim 12 , further comprising causing the submersible controllable apparatus to descend from the surfaced position to the substantially constant depth below the surface of the body of liquid.