Abstract:
Installation for harvesting kinetic energy of ocean currents in deepwaters is based on utilization of a semisubmersible platform and the multiple of vertically oriented Darrieus type hydraulic turbines with funnels. The turbines are located bellow sea level on distance sufficient to exclude them from being affected by wave actions. The electric power generators are located on a structure above water and transmit electric power to the shore utilizing flexible cable from semisubmersible to the sea bottom and underwater cable going to the shore, where it connected to the power distributing network. One of the Embodiments of this invention is designed to harvest energy of tides in deepwaters.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to provisional application Ser. No. 60/300,715 entitled “Installation for harvesting ocean current” filed Jun. 26, 2001, which is incorporated herein in reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to harvesting kinetic energy of ocean currents and tides by utilizing Darrieus type turbine in deepwaters. 
     BACKGROUND—DISCUSSION OF PRIOR ART 
     The search for means to harvest energy of ocean currents and tides has a long history and some successes. Several tidal hydropower installation are already in operation for a prolong time. Their wide use is curtailed by the need to use dams or barrages, which besides having high initial construction cost also are damaging environment. Presently there is ongoing search for the means that allow avoiding use of dams and barrages. This means are designed to harvest kinetic energy of water streams instead of potential energy of water elevated by dams or barrages. 
     There are two major systems for harvesting kinetic energy of water streams—one utilizes propeller type turbines with horizontally oriented axis of rotation the other utilizes Darrieus type turbine, which axis of rotation can be oriented vertically or horizontally. One of the main drawbacks of propeller types turbine is that multiplicator and electric power generators have to be located in waterproof capsule, since axis of propeller rotation is always is underwater. This creates the possibility of this capsule flooding and complicates maintenance service of the generator, multiplicator and related auxiliary systems. One of the advantage of Darrieus type turbine is that in case of vertical orientation of its axis of rotation the multiplicator and electric power generator can be located above water level, thus excluding flooding and simplifying maintenance. The other advantages is that, since Darrieus turbine rotates always in one direction regardless of water stream flow direction, it is better suited for harvesting energy of tide, which frequently changes direction of its flow. The systems utilizing propeller type turbine have to have additional mechanism to entire propeller turbine with multiplicator and electric power generator on 180 degree to accommodate changing direction of tide flow. At the present time it is known about two companies that have projects for harvesting energy of ocean tide and current based on utilization Darrieus type turbine, which was patented in 1927 (U.S. Pat. No. 1,835,018) and was widely used for harvesting kinetic energy of the wind. 
     One of the two mentioned companies—Blue Energy Canada, Inc. is the pioneer of using Darries turbine for harvesting energy of water streams. Their basic design (see their website www.bluenergy.com) utilizes vertically oriented turbine into a frame that is connected to the sea bottom. This limits their use to shallow water straits and rivers. The other company—GCK Technologies Inc. has systems described in the U.S. Pat. No. 6,036,443, issued to Alexander Gorlov. Specific of this patented turbine is in the use of helical blade instead of conventional straight blade of Darrieus turbine. The goal of using helical blade is to provide to turbine self-starting capability. Presently all 2 and 3 blades Darrieus turbines used for harvesting wind energy and converting it to electricity are started by a motor. Since this motor, after turbine reaches synchronous speed of AC power in the grid, starts to operate as generator the absence of self-starting capability is not a problem at all for systems supplying electricity in power grid. 
     Installations for harvesting kinetic energy of water streams shown in Gorlov U.S. Pat. No. 6,036,443 are located underwater, thus making them vulnerable for flooding and are not accessible for frequent maintenance. Gorlov also came up with submerged floating system that can anchored in deep waters to sea bottom by mooring lines. This floating system is described in article “Helical Turbines for the Gulf Stream: Conceptual Approach to Design of a Large-Scale Floating Power Farm”, see Marine Technology, Vol. 35, July 1998, pp. 175-182. 
     Objects and Advantages 
     The main objective of IHOC invention is to create a new and more practical system for harvesting kinetic energy of ocean current and tides in deepwaters, by overcoming the drawbacks of the known systems utilizing Darries type turbine. 
     At the present time there is no one system in operation that can harvest kinetic energy of ocean or tidal currents in deepwaters. The known systems addressing this subject, which conceptual description are published in special magazines, are of submerged type and floating type. Submerged type can withstand stormy weather but makes regular maintenance and small repairs so complicated that it makes entire system unreliable for continuous operation. The floating type, that provides capability to service power generating systems on a regular basis, are subject to waves actions, which can at one time fully destroy them. 
     The IHOC advantage is in its capability to solve this problem by employing special semisubmersible floating platform, which can be anchored in deep waters and allows to locate turbine on a sufficient depth bellow sea level and have multiplicator and electric power generator located on the upper deck of the semisubmersible platform out of reach by waves. Thus provides it with the advantage of being capable of harvesting energy of powerful ocean currents such as Gulf Stream near Florida, Kurashiwo near Japan and tides in deep water straits such as Strait of San Bernardino in Philippines, Strait of Messino in Italy, etc. Also, sine the gigantic dimensions of the ocean current opens up an opportunity to have the hydraulic turbines also of gigantic dimensions. Since large turbines and generators are more efficient than small ones, this leads to the advantage of having higher efficiency of the entire system for harvesting ocean energy. Larger turbines and generators are more efficient. In case of IHOC the maximum size of hydraulic turbine would be determined by the manufacturing industry capability and by the magnitude of the torque transmitted through its central shaft. 
     Among other objects of IHOC is the increase in the entire system efficiency through the increase of turbine efficiency. This is achieved by employing two blade turbine wheels, which have the highest efficiency, in an innovative way that excludes their drawback—vibration due to pulsation of the torque on the turbine shaft. 
     SUMMARY OF THE INVENTION 
     The IHOC utilizes semisubmersible floating platform for installing hydraulic turbines on a significant depth, out of the zone of significant wave actions, and perpendicular to the current. Semisubmersible platform also allows to locate electric power generator assemblies above water level and above the zone of wave actions. 
     The present depth limits for semisubmersible platform installation is about 3 km. When IHOC will be installed in a zone of permanently acting current the anchor-mooring arrangements are needed only from one side. This is because the wind forces acting on the above water part of IHOC and wave forces acting on a sparsely located vertical column are much smaller than the constant hydraulic pressure of the ocean current acting on the submerged turbines and their funnels. When IHOC will be installed in the zone of tide, where current is alternate on 180 degree the anchor-mooring arrangements are needed from opposite side of IHOC. 
     As a means for converting kinetic energy of the water stream, the IHOC utilizes concept of the Darrieus type reaction turbine (U.S. Pat. No. 1,835,018). 
     There are three preferred Embodiment of IHOC. 
     Embodiment A is the IHOC design, which takes-off the torque developed by turbine from several points on the turbine wheel outer diameter, that serves as a tooth-pin gear. 
     Embodiment B is the IHOC design, which takes-off torque developed by turbine from its central shaft. 
     Embodiment C is the IHOC design that has inlet funnels and anchor mooring systems located from both sides, thus permitting their use for harvesting the kinetic energy of tides that alternating direction of their movement on 180 degrees. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       FIG.  1 —Elevation. 
       FIG.  2 —Side view. 
       FIG.  3 —Plan, section A—A from FIG.  2 . 
       FIG.  4 —Section B—B from FIG.  3 . 
       FIG.  5 —Section E—E from FIG.  4 . 
       FIG.  6 —Section C—C from FIG.  4 . 
       FIG.  7 —Section D—D from FIG.  4 . 
       FIG.  8 —Drive, Section F—F from FIG.  5 . 
       FIG.  9 —Drive, Section H—H from FIG.  5 . 
       FIG.  10 —Drive, Detail I from FIG.  5 . 
       FIG.  11 —Drive, Section G—G from FIG.  10 . 
       FIG.  12 —Elevation. 
       FIG.  13 —Side View. 
       FIG.  14 —Plan. 
       FIG.  15 —Enlargement of Elevation from FIG.  12 . 
       FIG.  16 —Enlargement of Side View from FIG.  13 . 
       FIG.  17 —Section K—K from FIG.  16 . 
       FIG.  18 —Section L—L from FIG.  15 . 
       FIG.  19 —Section M—M from FIG.  16 . 
       FIG.  20 —Section N—N from FIG.  16 . 
       FIG.  21 —Turbine wheel. 
       FIG.  22 —Section O—O from FIG.  21 . 
       FIG.  23 —Section P—P from FIG.  21 . 
       FIG.  24 —Section R—R from FIG.  21 . 
       FIG.  25 —Section S—S from FIG.  22 . 
       FIG.  26 —Detailed I from FIG.  17 . 
       FIG.  27 —Detailed II from FIG.  25 . 
       FIG.  28 —Section T—T from FIG.  27 . 
       FIG.  29 —Illustrates Embodiment C design. 
     
    
    
     Embodiment A 
     The Embodiment A illustrates a design for harvesting energy of ocean current in deep waters. By this design the torque from the turbine wheel is transmitted to several (two) power generator assemblies through several (two) vertical shafts which by their low ends are engaged with tooth-pin wheel attached to upper part of the turbine wheel. When a large size turbine rotates with a low speed of a few RPM it generates a two big torque for conventional gearboxes to accommodate it. The Embodiment A is an illustration of a design that spreads this torque to a manageable level by uptake of the power from rotating turbine from several, at least two, points on its perimeter. For this purpose along the turbine upper ring is located tooth-pin wheel. The two tooth-gears, which are engaged with the tooth-pin wheel, have special provisions that keep the engagement between wheel and gear constant, thus compensating the horizontal and vertical deviation of the point of contact between wheel and gear. These deviations are inevitable because of manufacturing and assembling tolerances, which on the diameter of 20 meters can amount to several centimeters at the point of contact. 
     Because the turbine height is significant (about 20 meters), what effects the stability and strength of the blades, the height of each blade is reduced to half of the turbine height. For this purpose the turbine has three outer rings—upper, middle and lower. The blades are located between two rings. This allows to shift position of blades on the level between middle and lower rings on 30 degrees, in comparison with blades positions between upper and middle rings. This, besides reducing the blade height, will allow to smooth pulsation of the developed torque by factor of 2, assuming that the total number of blades is 6 and they are equally distributed along the perimeter of the ring. The use of semisubmersible platform as a support for turbines creates an opportunity to install funnels for directing additional volume of water through the turbine, thus increasing its energy output. 
     All structural elements of semisubmersible platform and the turbines are from pipes, which internal volume is sealed and filled with a substance lighter than water. The blades internal volume is also sealed and filled with the same substance. Thus will provide to the IHOC sufficient positive buoyancy to compensate its weight and current pressure. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 through 3  show general arrangement of the IHOC in Elevation, Side View and Plan. The IHOC  21  consist semisubmersible platform  23 , turbine  25 , turbine drive  27 , electric power generator assembly  29 , two anchor-mooring arrangements  30 ,  31 , each consisting of pair of mooring lines  32  and  33 , which are attached to anchors  34 . Generated power is transmitted to shore through a flexible cable  35  to anchor  36  and further through underwater electric cable  37 . 
     The semisubmersible platform  23  consists of upper structure  40 , intermediate section  42  and lower frame  44 . 
     The upper structure  40  houses the electric power generator assembly  29  and also has room for temporally accommodation maintenance and repair crew. 
     The intermediate section  42  consists of vertical columns  54 ; cross beams  56  and braces  58 . All of these elements are from hermetically sealed large diameter pipes, which provide to the submerged platform additional buoyancy. The vertical columns  54 , which are located parallel and on some distance apart, are protruding through water level and by this forming water plane area that provides to semisubmersible platform required stability. The vertical columns  54 , through which the vertical shafts  111  (see  FIG. 10 ) are going to electric power generating assembly  29 , have an internal pipe  130 . Pipe  130  is welded to column  54  bottom and top plates  134 , thus keeping internal space of column  54  sealed. 
     The lower frame  44  (see  FIGS. 4 ,  6  and  6 ) consists of vertical elements  66 , horizontal elements  68  and braces  69 . Two rows of vertical elements  66 A and  66 B in conjunctions with horizontal elements  68 A and  68 B form a chamber  70 , which houses the turbine  25 . For this purpose in the middle of chamber  70  are located coupling-bearings  75 . The funnel  80  is formed by vertical elements  66 , horizontal elements  68  and braces  69 . The flat spaces between these elements form panels  71 , which are covered by a thick synthetic film  72  and are reinforced by a grid of synthetic ropes  74 . These panels are directing additional flow of water into turbine  25 . 
     The turbine  25  consists of a central shaft  90  with two coupling-bearing  75  on its ends; horizontal spokes  92 , upper ring  94 , middle ring  96  and lower ring  98 . The rings  94  and  96  are interconnected by 6 equally spaced blades  100  having hydrofoil profile (see FIG.  6 ). The rings  96  and  98  are interconnected by 6 equally spaced blades  101 , but they are shifted on 30 degrees (see  FIG. 7 ) to reduce pulsation of developed torque. 
     The ring  94  of includes a pin-wheel  102  consisting of a number of equally spaced pins  104 , hosed by 2 rings  106 , which are welded to a cylinder  108  (see FIGS.  10  and  11 ). The turbine drive  27  (see  FIGS. 10 and 11 ) consists of a vertical shaft  111 , having its end in a form of square shaped bar and tooth-gear  113 , having its central opening matching the shape of the vertical shaft  111  end. It also includes a guiding roller  115  and its support  117 , connected with tooth-gear  113  through a cylindrical bearing  119  and fixed in this position by a stopper  121 . 
     During turbine rotation guiding roller  115  follows the cam-cylinder  108  deviation in vertical and horizontal direction, thus keeps pin-wheel  102  engagement with tooth-gear  113  constant. This is required to accommodate manufacturing tolerances and misalignments during assembling. Adjustment in vertical in direction is done under the weight of the vertical shaft  111 , which keeps guiding roller  115  always in contact with cylinder  108 . Adjustment in horizontal direction is possible due to springiness of the long vertical shaft  111 . 
     The anchor-mooring arrangements  30  and  31  are of catenary type. Arrangements  30  are attached symmetrically to upper part of the semisubmersible platform  23  and arrangements  31  are attached symmetrically to the lower part of the platform  23 . By this they are taking horizontal force of the current and providing to platform vertical stability. The underwater electric cable system  35  consists of a flexible cable  36 , concrete anchor  37  and sea bottom cable  38 . 
     Embodiment B 
     The Embodiment B illustrates a design that differs from Embodiment A by the way how torque is transmitted to power generator assembly. Also one of the specifics of this design is in the structure of turbine wheel, which consists of three sections each having only two opposite locating blades. All these three sections are shifted in plane on 120 degrees in relation to each other. One of the others specifics is in the structure of the anchor mooring system that has means for controlling semisubmersible platform in vertical position in case the length of anchor mooring lines do not elongate equally. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 12 through 14  show general arrangement of the IHOC in Elevation, Side View and Plan. The IHOC  221  consist semisubmersible platform  223 , turbine  225 , electric power generator assembly  229 , two anchor-mooring arrangements  230 ,  231 . The anchor-mooring arrangement  230  consists of two 90 degrees wire ropes guides  232 , attached to the lower part of the semisubmersible platform, one wire rope  233 , which is rived through wire ropes guides  232  and connected by its both ends to two anchors  234 . The anchor-mooring arrangement  231  consists of a pair of mooring lines  235  each consisting of anchor chain  236  and wire rope  237  connected to each other. The mooring lines  235  are attached by wire ropes end to anchors  234  and by anchor chain ends to chain tensioners  238  through guide  238 A. In case of a slack developed in any of mooring lines the tensioneer  238  will adjust their length and will keep floating semisubmersible platform  223  always in vertical position. 
     Generated power is transmitted to shore through a flexible cable  239  to anchor  240  and further through underwater electric cable  241 . 
     The semisubmersible platform  23  consists of upper structure  242 , intermidiate section  243  and lower frame  244 . 
     The upper structure  242  houses the electric power generator assembly  229  and also has room for temporally accommodation maintenance and repair crew. 
     The intermediate section  243  consists of vertical column  254  and longitudinal beams  256  and cross beams  255  and  257 . All of these elements are from hermetically sealed large diameter pipes, which provide to the submerged platform additional buoyancy. The vertical columns  254 , which are located parallel and on some distance apart, are protruding through water level and by this forming water plane area that provides to semisubmersible platform required stability. 
     The lower frame  244  consists of vertical elements  266 , horizontal elements  268  and braces  269 . Two rows of vertical elements  266  in conjunctions with two horizontal elements  268  form a chamber  270 , which houses the turbine  225 . 
     The funnel  280  is formed by vertical elements  266 , horizontal elements  268  and braces  269 . The flat spaces between these elements form panels  271 , which are covered by a thick synthetic film  272 , which are reinforced by a grid of synthetic ropes  274 . These panels are directing additional flow of water into turbine  225 . 
     The turbine  225  consists of a turbine wheel  290  having central shaft  291  and three equal horizontal section  292 ,  293  and  294  each shifted in plane on 120 degrees in relation to each other and each having a pair of blades  295 , each connected to shaft  291  through a pare of spokes  296  and 180 degrees apart. The adjacent turbines are connected to each through an intermediate shafts  297  and by couplings  298 . The central shaft of upper turbine  225  is connected to power generating assembly  229  by shaft  299 . The vertical position of turbine wheel  290  is guided by upper and lower set of bearings  275 . Each set of bearing  275 , consist of number of rollers  276  equally distributed by circumference of guiding disc  277 . 
     Embodiment C 
     Embodiment C differs from Embodiments A and B by having inlet funnels and anchor-mooring systems from both sides thus allowing their use for harvesting energy of tides, which are alternating direction of their movement on 180 degree and which are occur in deepwater straits. 
     Drawing  FIG. 29  illustrates Embodiment C design. 
     Conclusion and Scope of Invention 
     The innovation of the instant invention is in a new combination of elements already known and used in variety of applications. This new combination creates a positive effect—capability of harvesting kinetic energy of ocean current and tides acting in deepwaters. As of now there are no known or existing systems that have this capability. The main elements of which IHOC is consisting are: a floating semisubmersible platform, a Darrieus type hydro turbine, an anchor-mooring system and funnel incorporated with turbine and semisubmersible platform. 
     The floating semisubmersible platform adapted for instant invention has a special underwater frame for housing Darrieus turbine and funnel, which makes it unique in comparison with others known application of semisubmersible platform. 
     The anchor-mooring system for the floating semisubmersible platform also has an unique features, such the capability of adjusting vertical orientation of semisubmersible platform in cases when elongation of anchor-mooring lines are not equal. 
     The use of Darrieus type turbine for harvesting kinetic energy of water streams is known. The innovative feature of it in application for instant invention is in the design of the turbine wheel, which consists of three sections each containing a pare of blades located opposite to each other. These pares of blades are shifted in relation toward each other on 120 degrees, thus forming a turbine wheel having high efficiency of two blades turbine and self starting capability of six blade turbine. 
     While the invention has been particularly shown and described with reference to preferred embodiments therefor, it will be understood by those skilled in the art that the foregoing and other changes in form and details maybe made therein without departing from the scope of the invention.