Accurate Control of Depths and Easier Installations and Recoveries

On November 7, 2007, US Patent No. 7,291,936 was issued for important improvements for the Gulf Stream Turbines. The first of these adds a second depth control system that is controlled by the hydrostatic pressures going either above or below any preset limits. This system adjusts the lifting forces as required to keep the machines operating within any pre-set range of depths. This system also simplifies the installation process by permitting entire strings of Gulf Stream Turbines to be simultaneously submerged and returned to the surface while they are still generating electricity. When recovering individual units, once all of the still generating machines would be floating just at the surface, shallow diving would be required to disconnect the machine to be removed and to purge its buoyancy tank.

            The new patent application also includes a ballast-water purging system that permits the Gulf Stream Turbines to be quickly raised to the surface with their buoyancy tanks empty, both individually or entire strings.

Precise Depth Control

            In the preceding side view of the Gulf Stream Turbine, the center of buoyancy (the center of gravity of the displaced water) is represented by the red dot and the adjustable centers of gravity by the two blue dots and the connecting blue line.  Depending on how the ballast water is distributed between the buoyancy tank’s front and rear compartments, the structure’s center of gravity can be located at either blue dot or anywhere between them.  Extending from the center of buoyancy (the red dot) are two angled lines (257 and 258) that radiate downward from that center of buoyancy and pass through the two blue dots.  Because a free-floating submerged object will always float with its center of gravity directly under its center buoyancy, if the center of gravity were moved forward to the front blue dot, the downward angled line (257) would become vertical and cause the structure’s front end move lower and its rear end to move higher, giving the hydrofoils a negative angle of attack that would produce a downward force.  Conversely, if the center of gravity were moved aft to the rear blue dot, the second downward angled line (258) would become vertical.  This would cause the structure’s front end to move higher and its tail end to move lower, giving the attached hydrofoils a positive angle of attack to produce a lifting force.

New Depth-Control System Complements the Low-Hitch-Point System

            The forces produced by moving of the Gulf Stream Turbine’s center of gravity longitudinally by transferring the ballast water between the buoyancy tank’s end compartments will be superimposed upon those other forces that are produced by the structure’s anchor line’s (3) attachment point (21) being located below its center of drag (22, the black dot).  A dark green line extending upward and to the right from the anchor line’s hitch point (21), continuing at the same angle as the anchor line (3).  A yellowish green line extends downward from the center of drag (the black dot) to meet the darker green line at a right angle.  The length of this yellowish-green line is the length of the “lever arm” through which the changing tensions on the anchor line, caused by the changes in the horizontal drag, will place rotational forces on the structure.  If the height of the anchor line’s hitch point (21) were properly adjusted, this leverage system will use those same horizontal drag forces that produce the downward vector forces to rotate the entire structure to change the hydrofoil’s lifting forces to balance those same downward forces.  With this low-hitch point system, changes in the downward vector forces produced by changes in either the current’s velocity or in the demands on the generators, will instantly adjust the hydrofoils’ lifting forces to keep the generating units operating at approximately the same depth.  The new depth control system, controlled by the hydrostatic pressures, will make any additional adjustments in the lifting forces that may be required to keep the Gulf Stream Turbines operating at precisely the proper depths. 

System Permits Simultaneous Submersions of Gulf Stream Turbines

In addition to accurately controlling the Gulf Stream Turbines' operating depths, the new pressure-activated-depth-control system will also make it possible for the simultaneous submerging of any number of Gulf Stream Turbines that are linked together into strings. While floating on the surface, the submersible generating plants can be formed into staggered lines, each machine connected to its two neighbors by the electricity collecting cable. Before starting the submersion process, all of the switches will be in the off position so that there will be no electricity flowing either to or from the grid. Because the asynchronous generators will not be receiving any 60-Hz current from the grid to magnetize their stators, the generators will be producing no electricity and their rotors will be spinning freely, producing little drag and little downward vector force. When the ballast water is added to all of the buoyancy tanks, their rear compartments will be loaded with more water than their front compartments. This heavier loading at the rear compartments will place the centers of gravities for the structures at those locations that are represented by the rear blue dot (222) in Fig. 2. Having the centers of gravity at the rear of the buoyancy tanks will cause the Gulf Stream Turbines' rear ends to float lower than their front ends to float higher to maximize the hydrofoils' lifting forces to keep the ballasted Gulf Stream Turbines at the surface.

            All of the Gulf Stream Turbines in the string can then be submerged simultaneously by simply closing those switches that magnetize the generators' stators and that connect the generators' output to the grid - as well as activate the new pressure-activated control system. The instant that the Gulf Stream Turbines begin to produce electricity, there will be an increase in the horizontal drag that will produce an equally abrupt increase in the downward vector forces, which will immediately pull all the Gulf Stream Turbines beneath the surface. The machines will then descend quickly to that depth where the downward vector forces will be balanced by those greater than normal lifting forces produced by the heavy loading of the rear compartments. All of the pressure-activated depth-control systems in all the Gulf Stream Turbines will continue to continue transferring more ballast water from the buoyancy tanks' rear compartments to the front compartments. The transfer pumps will continue operating until the movements of the centers of gravity forward will cause the nose ends of all of the Gulf Stream Turbines to drop sufficiently that their hydrofoils' lifting forces become in perfect balance with the downward vector forces, at the desired operating depths.

How the New Pressure-Controlled System Works

            This subsection describes its operation in some detail. The buoyancy tank is divided into compartments 68, 77, 101, 80, and 69. Vent holes 255 are located at the top of the bulkheads 360, which will allow air to pass between the compartments to equalize air pressures. There is a ballast water transfer system 305 that can transfer ballast between the buoyancy tank's front and rear compartments. This water transfer system consists of a first pump 250, a first pipe 306 and a first special check valve 253, capable of transferring ballast water from the front compartment 68 to the rear compartment 69. The second part of this transfer system consists of a second pump 251, a second pipe 307 and a second special check valve 254 that is capable of transferring ballast water from the rear compartment 69 to the front compartment 68. The two pumps 250 and 251 are controlled by a pressure switch 259 that is activated by the ambient hydrostatic water pressures going either above or below those preset limits that are determined by the desired water depths.

            The special check valves 253 and 254 will not only not allow water to flow in the wrong reverse directions through the pipes 305 and 307, they also will not allow water to flow through the pipes in the right direction - unless the pipes' water pressure is above a minimum. This is to prevent the water from siphoning between the end compartments due to differences in their water levels. Each special check valve is extremely simple and failure proof, consisting of a heavy ball 275 that rests upon the valve's intake port 276 to prevent low-pressure water from flowing from 278, through the valve to 282. However, when the pump starts running, the greater pressure will lift the heavy ball off the valve's water inlet port 276 to allow the water to pass through the special check valve to 282.         



The Ballast Water Purging System

            At the time when GE Power Systems studied the patent, the most profitable product they were producing was the combined-cycle gas-turbine generators. Although I was told that they believed that my invention would operate as I had described in my patent, their engineers were unable to imagine how the Gulf Stream Turbines could be installed and later removed for servicing and repair. As a result of these legitimate concerns, I developed those methods for installing and recovering that are described in the sections Installing the Gulf Stream Turbines and Replacing the Gulf Stream Turbine. Although those methods would work, they would require divers to be transported in submersible vehicles to the turbines' operating depths (probably be less than 250 feet).

            The key to the ballast-water-purging portion of the system is that the buoyancy tanks must be pre-pressurized to pressures greater than the hydrostatic pressures at the machines' operating depths. Previously it was stated that there are vent holes 255 (Fig. 10) located near the tops of the bulkheads 360 to equalize the air pressures in the buoyancy tank's compartments. There is a hose-connection and valve combination 262 located on the top of the buoyancy tank through which the air inside the tank can be pressurized to a pressure that is greater than the hydrostatic pressures at those depths where the machines will be operating. Each of the compartments has a drain hole 287 that is connected to a separate drainpipe 124 that goes to a separate special valve 264 that permits only the passage of liquid and not air.

            Two versions of these special valves are shown in the following drawings. The drawings Figs 13a and 13b are reproduced from the patent. Fig. 13b shows how the buoyant ball 265 will prevent air from flowing through the valve's outlet 276 when there is no water in the valve's casing 264 to support the ball. The drawings on the right show a simpler version where the buoyant ball is located inside a cage that is positioned over the compartments' drain holes 278. These fluid-only valves are to conserve the pressurized air to purge the ballast water from all the buoyancy tank's compartments.   


From these special valves, the exiting water flows through conventional valves 123 to a common pipe 308 (see schematic Fig 10), through a conventional valve 312, through a conventional check valve 294, to the buoyancy tank's nose, where the water is ejected forcibly downward. The conventional valves 123 prevent the ballast water from siphoning between the compartments when the machines are not being brought to the surface. They can also be used to set different flow rates so that, when the machines are being brought to the surface, they will cause the structure's front end to raise faster than its rear end. Valves 123 should remain closed, except for when the ballast water is being purged. When bringing a submersible generating plant to the surface, the conventional valve 312 in the line 266 should stay closed until after the conventional valves 312 have been opened the desired amounts to allow the divers sufficient time to open the conventional valves 123 before opening the valve 312 to start the machine's ascent. The check valve 294 is for the purpose of preventing sea water from flowing backwards through the pipes of the purging system to flood the compartments in the event that the buoyancy tank's interior air pressures should be allowed to drop while a Gulf Stream Turbine is floating while the valves 123 open.   

Raising a Single Gulf Stream Turbine to the Surface

When bringing a single Gulf Stream Turbine to the surface, the first thing that must be done is to turn off the waterproof switch 7. The electricity extension cable 4 can then be disconnected from the electricity linking cable 43 at the junction box 6. The electrically collecting cable 5 is then disconnected from the underside of the anchor line 3. Because the generators will no longer be producing any electricity, the reductions in the horizontal drag and in the resulting downward vector forces will tend to cause the Gulf Stream Turbine to ascend to the surface.

With the anchor line 3 disconnected from the electricity collecting cable 5 and the electrical extension cable 4 disconnected from linking cable 43, the structure will be ready to be raised. With the conventional valve 312 still closed, the diver would open the valves 123, opening those from the forward compartments more than those from the rear. The divers will then open the conventional valve 312, which will start the Gulf Stream Turbine's ascent.

Opening the conventional valves 123 more from the front compartment than those from the rear compartment will cause the buoyancy at the structure's nose end to increase faster than its rear end. This faster increasing buoyancy at its nose - combined with the reaction from the ballast water being forcibly ejected downward from the nose - will lift the structure's front end faster than its rear end, which will - in turn - increase the angle of attack of the attached hydrofoils to increase their lifting force. As these forces are driving the Gulf Stream Turbine to the surface, the widening spread between the slower dropping pressures inside the tank and the faster dropping hydrostatic pressures outside the tank will be increasing the rate of the ballast water's discharge, increasing the machine's ascent. After the Gulf Stream Turbine bursts to the surface, the pressurized air inside the tank will continue to push out the remaining ballast water. After a float has been attached to the anchor-line's end, the anchor line can then be detached from the Gulf Stream Turbine. The machine then can be removed from the water.  

Raising a String of Turbines Without Disconnecting the Electric Cables.

There are two methods that can be used to bring entire strings of the Gulf Stream Turbines to the surface. The first system will bring them all to the surface with their generators stopped and their buoyancy tanks purged. The second system described will permit all of the machines to rise to the surface with their buoyancy tanks still containing the proper amount of ballast water and with the generators still producing electricity.


The preceding drawings show a modified purging system that will permit the simultaneous raising of a string of Gulf Stream Turbines while they are all still connected to the electricity collecting cable. The conventional valves 123 in the first version have been replaced by special check valve 453, which can be identical to the special check vales 253 and 254 that are in the ballast water transfer system 305. The special valves 264, which prevent the loss of air pressure, remain. The conventional valve 312 is replaced with an electrically controlled valve 412. Valve 412 can be operated either manually or electrically from a distant location. Fig. 14a shows the special valve 264, special check valve 453, and the electrically control valve 412 when the generating structure is operating at its proper depth. Note that the valve 412 is closed. Fig. 14b shows the valve system with electrically controlled valve 412 open and the ballast water flowing out through all the valves, driven by the pressurized air in the buoyancy tank. The water entering the special check valve 453 has more than enough pressure to lift the heavy ball 475 off the intake port 476 to allow the water to flow from the valve's intake port to its outlet 477. Fig. 14c shows the special check valve and the special valve after the ballast water has been purged from the compartment. Because the special valve 264 no longer contains water, the buoyant ball 265 drops to cover the special valve's outlet 279, cutting off the outflow of pressurized air through the valve's outlet 279. Because there is no water passing through the pipe 295, the heavy ball 475 drops down to again cover the valve inlet 476. The simultaneous opening of all of the electrically controlled valves 412 on all the generating structures in a string of machines will cause them all to ascend together while their anchor lines remain connected to the electricity collecting cable 5, and while the electricity extension cables 4 are still connected to the linking cables 43. Just as it is for the conventional valves 123 described for the first version of the water purging system, valves 482 can also be adjusted to permit the valves draining the forward compartments 68 to be opened the most and the valves 482 for the compartments 77, 101, 80, and 69 to be opened by decreasing amounts.

Because the electrically operated valve 412 in the second version of the purging system can be controlled either electrically from a remote location or manually at the underwater work site, the second version of the water purging system can be used exactly like the first version to remove individual machines from a submerged string without interfering with the other turbines' ability to generate electricity. In both versions, the divers must be transported in a submersible vehicle to the underwater work site to detach the electricity collecting cable 5 from the anchor line 3, and the electrical extension cable 4 from the linking cable 43.

As previously described, the second version's electrically controlled valves will also permit an entire string of Gulf Stream Turbines to be brought to the surface without being disconnected from the electrical collecting cable and the electrical extension cable. Although this would provide an extremely easy way to recover all the machines in a string, it will result in all of them floating at the surface, with their buoyancy tanks empty.    

The Best Method or Raising the Machines for Removing Machines

            The simplest method for removing a single machine from a string of machines would be to simply reverse the installation process.  This would require a remote means for overriding the depth control system so that the water-transfer pumps on all of the submerged machines will simultaneously transfer all of the ballast water from the buoyancy tanks’ front compartments to the rear compartments.  This simultaneous movement of the centers of gravity to the back end of all the machines will lower their rear ends and raise their front ends, increasing the angles of attack of their hydrofoils.  This will increase their hydrodynamic lifting forces, causing all of the submersible power plants to rise simultaneously to the surface.  Those machines that are to be removed can  then be disconnect from the anchor and electric lines, purged of their ballast water, and hoisted from the water – all while the other machines in the string remain at the surface, generating electric power.  After the replacement machine has been attached to the anchor line and the electrical connecting cable, the rear compartment of its buoyancy tank should be loaded with all the ballast water that will be placed inside the buoyancy tank.  When all the work has been completed, the switch would then be thrown to remove the override to the depth control system, which would turn on those pumps on all of the machines that move the water forward.  Those pumps would continue operating until the forward movements of the machines’ centers of gravity have reduced the hydrofoils’ hydrodynamic lifting forces to balance the downward vector forces when it reaches their preset depths.     

If the movement of the ballast water to the rear compartments of all the ballast tanks is not sufficient to lift the string of turbines completely to the surface, the individual machines can be removed by either of two different methods.  The first method would be to throw a switch that would stop the generators from producing electricity and allow the turbines’ rotors to spin freely.  The resulting decreases in the downward vector forces would cause of the still fully-ballasted machines to raise all the way to the surface, where the still ballasted machines would float low in the water, nose high.  The buoyancy tanks of those machines that are to be removed from the string can then be purges by opening valve 412 (Fig. 14b) to allow the pressurized air in the buoyancy tank to purge the remaining ballast water.  After both the electrical connecting lines and the anchor lines have been disconnected, the machines can be lifted from the water.  After the machines have been replaced and the proper amounts of ballast water has been added to the rear compartments of those replacement machines, the switches can be thrown to re-activate the depth control system and to magnetize the stators.  Then, just as it was when the turbines were originally submerged, they will all descend to their proper depths while generating electric power.