Abstract:
Normally hydroelectric dam powerhouses use river flow once before discharging it as turbulent tailwater, ineffective to spin turbines. The present invention uses tapered channels to confine and constrict turbulent tailwater into laminar flow that drives turbines both submersible and floatable utilizing the same water three times concurrently to generate new electricity. Channels originate adjacent to draft tube outlets, constrict in the downstream direction to create narrow necks where turbine/generators benefit from debris free, increased velocity and laminar flows to generate electricity. Hydroelectricity uses zero fuel, creates zero waste and has zero carbon dioxide emissions. Structures are uncomplicated, construction is within project boundaries minimizing environmental impacts and speeding projects coming online. New facilities are protected by existing dam security. Hydroelectricity replaces less dependable renewable energy systems.

Description:
BACKGROUND OF THE INVENTION 
   Applicant/Inventor was a designer for twenty-two years and Value Engineering Officer (hereinafter VEO) for nine years with the Walla Walla District U.S. Army Corps of Engineers. In that period eight new hydroelectric dams were built on the Columbia, Snake, Boise and Clearwater rivers. Applicant/Inventor was involved with several of them and as VEO, he led studies on many until retiring in 1982 to continue his career in Value Engineering (hereinafter VE) as an international consultant. That included occasional VE studies on dams, such as five potential projects in Nepal and several more in the United States. 
   McNary Dam on the Columbia River is first Applicant/Inventor encountered with the Corps. The 1340 foot long powerhouse has fourteen generators. The total rated capacity of the powerhouse is 1,120,000 kilowatts. One hydropower turbine at McNary Dam produces as much electricity as two hundred and eleven 660 KW wind turbines. In addition, McNary&#39;s hydroelectricity is dependable, unaffected by wind, daylight or oceanic conditions. 
   Applicant/Inventor led a VE study on a planned second power-house for the McNary Dam. It would have duplicated the existing powerhouse by abutting and extending it on the Oregon side of the Columbia River. Complications mired the effort; it was never built and finally de-authorized. Leading the latter study embedded in Applicant/Inventor an interest to creatively increase hydroelectric dam&#39;s generation of electricity. 
   BRIEF SUMMARY OF THE INVENTION 
   Normally hydroelectric dam powerhouses use river flow once. In accordance with the present invention, the same flow is used two additional times to generate electricity without negative impact on existing generating capability plus leaves precious water in storage reservoirs, such as Lake Mead. 
   Water emerging from draft tubes is free of debris but roiling and churning renders it ineffective to spin turbines. In accordance with the present invention, that turbulent water is confined and constricted to both accelerate and convert it toward laminar flow useable to generate electricity. The conversion to laminar flow may evacuate water faster from the draft tube outlets thereby eliminating a rise in tailwater elevation from the new addition. In any event newly generated electricity must exceed any loss of existing output for a profitable net gain. 
   In accordance with the present invention tapered compartments or channels formed from one or more segments of two structural walls extend from draft tube outlets into tailwater and from river bottom to well above the maximum tailwater elevation. The compartments or channels are arranged in side-by-side relationship and each is contained on three sides but could be lidded for complete enclosure if hydraulic modeling indicates a potential benefit. Each compartment or channel converges in a direction from an upstream or uppermost origin adjacent the draft tube outlets toward a narrowest downstream channel portion which may be a simple opening or in which walls become parallel for a length (throat) then diverge to produce a venturi effect of accelerating laminar flow to drive one or more turbine/generators of submerged or floatable types located partially to fully inside the throat. Whenever possible flow should be further laminated and accelerated by frusto-conical flow acceleration tubes each surrounding each turbine/generator unit. 
   The turbine/generator units include both submerged and floatable types, are distinctive and comparatively selected by performance factors matched to hydropower and afterbay conditions of the particular dam whose hydroelectric power production is expanded by the present invention. Sound support structures are tailored for each turbine/generator unit including appropriate fish protection. A structure and its supported unit become one when various combinations of turbine/generator types plus vertical and horizontal locations of both submerged and floatable units are judged for the most effective combination and arrangement of units to maximize electricity production at lowest life-cycle costs. Coupling submersible and floatable turbine/generator units is one cornerstone of the invention. Most effective utilization of laminar flow distributed between submerged and floatable turbine/generator units depends upon depth of tailwater; efficiency of channel design and construction in creating/maintaining laminar flow; type, size, shape and placement of submerged turbine/generator units whose impact on upper laminar flow utilized by floatable generator/turbine units can vary from minor to major. Shallow tailwater tightens and deep tailwater expands leeway in the design process of selection, placement and relationship of turbine/generator units. The submerged turbine/generator units are located as far below the maximum tailwater elevation as practical to utilize lowermost laminar flow because the invention couples the latter turbine/generator units with barge-mounted electricity generating units that utilize uppermost surface laminar flow. The barge-mounted electricity generating units are, for example, undershot water wheels which are driven by the water&#39;s kinetic energy just immediately downstream of the submerged turbine/generator units which themselves disturb the lower laminar flow, yet with little disturbance caused thereby to the upper surface laminar flow under relatively high tailwater depth conditions. 
   In this manner the once unsuitable turbulent water emerging from draft tubes is converted into laminar flow that drives both submerged and floatable electricity generating units to create maximum electricity generation under project specific flow rates by minimizing impacts of submerged turbine/generator units on performance of floatable turbine/generator units. 
   The barge supported electricity generating units are aligned with a centerline of each of the channels, and the barges extend the entire length of the powerhouse, as do the compartments or channels and the turbine/generator units associated therewith. The barges are preferably moored to downstream pilings which in part define each of the channels or compartments, and each barge individually can be moved immediately adjacent the channel outlets to access optimum hydraulic surface flow conditions. Each barge may be positioned as need be at the channel outlets such as not to hinder access to the lowermost submerged turbine/generator units inside each converging channel/compartment. 
   Unlike isolated and scattered wind, tide, wave and other renewable energy systems at risk for sabotage or vandalism, the present invention lies within the protected cordoned-off area in the tailwater limiting access to project personnel. It abuts the powerhouse and is covered by its in-place security system. The invention uses no fuel, creates no waste and sends no carbon dioxide into the atmosphere. Construction occurs within project boundaries, is uncomplicated and has limited environmental impact. Its environmental assessment should be very focused and satisfied faster than usual. 
   Construction mostly occurs in relative shallow water; requires limited excavation; channel/compartment components are few; supports, beams and associated steel or concrete members are either readily available or can be pre-fabricated on site; or in concrete casting facilities in the region readily moved by truck, rail or barge; and channel/compartments can be assembled concurrently working from readily-relocated solid platforms, such as drill barges with spuds. The invention thereby lends itself to rapid construction that substantially and quickly boosts renewable electricity production at existing hydroelectric dams. 
   With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following several views illustrated in the accompanying drawings, the detailed description and the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  is a vertical cross-section taken through a conventional hydroelectric dam and illustrates downstream of a draft tube a wall which in part defines one of several side-by-side channels which convert turbulent tailwater flow into laminar flow, a lowermost submerged turbine/generator unit which benefits from bottommost flow and downstream therefrom a barge supported electricity generating units each efficiently driven by respective river bottom and upper surface laminar flow. 
       FIG. 2  is a fragmentary top plan view of  FIG. 1 , and illustrates four converging compartments/channels, two submerged turbine/generator units within downstream outlets of each channel and two floating barges each carrying electricity generating units utilizing undershot water wheels aligned with the converging channels outlets to generate electricity utilizing uppermost surface flow. 
       FIG. 3  is a fragmentary top plan view similar to  FIG. 2 , and illustrates enlarged details of supports, posts or pillars having vertical slots into which panels can be lowered to construct adjacent converging compartments/channels. 
       FIG. 4  is a fragmentary cross-sectional view looking upstream taken along line  4 - 4  of  FIG. 3 , and illustrates pairs of submerged turbine/generator units supported within the converging outlet ends of each compartment/channel and adjacent walls of adjacent compartments/channels at downstream posts being spanned and closed by panels. 
       FIG. 5  is an end elevational view taken along line  5 - 5  of  FIG. 3 , and illustrates the manner in which the undershot water wheels carried by the barges which drive turbine/generators are aligned each with an associated compartment/channel to access optimum upper hydraulic surface laminar flow conditions. 
       FIG. 6  is a perspective view, and illustrates the manner in which panels are lowered into vertical slots of supports, columns, piers or posts to form adjacent side-by-side compartment/channels converging in a downstream direction toward the submerged and buoyantly supported electricity generating units. 
       FIG. 7  is an enlarged fragmentary side elevational view partially in cross section and illustrates a frusto-conical water flow acceleration tube surrounding a submerged self-supported turbine/generator unit to increase laminar flow velocity incident to driving the turbine. 
       FIG. 8  is a fragmentary top plan view similar to  FIG. 3 , and illustrates one of several venturi compartments/venturi channels which convert turbulent tailwater flow into laminar flow, and the electricity generating turbines within a parallel channel portion of the venturi channel. 
       FIGS. 9 through 12  are fragmentary enlarged plan views detailing in  FIG. 8  the respective encircled connections using H-piles to obtain smooth uninterrupted surfaces at sliding connections between edges of panels slid downwardly into vertical slots of associated H-piles/end supports. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A conventional hydroelectric dam  10  ( FIG. 1 ) generates electricity through the utilization of water head of its reservoir R. The hydroelectric dam  10  and its associated powerhouse  15  contain from one to several bays per turbine  13 . Each bay contains the following elements in various numbers and configurations: trash rack  11 , fish screen (not shown), gated intake  12 , and penstock  14 , which together control and transfer water flow through the turbine  13  to generate torque that transfers to a generator  16  whose electricity is transmitted by power lines  17  to a power system  18  and from the latter via power lines  20  to sources of utilization. Many dams use multiple intakes  12  and draft tube outlets  21  for each turbine  13  which pass water emerging from the draft tube outlets  21  which is free of debris but its roiling and churning condition renders it unsuitable as a turbine driving power source. Therefore, one the major challenge to utilize tailrace water exiting draft tube outlets  21  to drive turbines of hydroelectric dams is that of converting the turbulent tailwater flow exiting from draft tube outlets  21  into laminar flow. 
   Another substantial problem associated with utilizing existing hydroelectric dam sites for creating or extracting new electric energy are special interest efforts whose foremost “weapon” against run-of-the-river hydroelectric projects being the presence of anadromous fish (live in salt water and spawn in fresh water, such as Pacific and Atlantic salmon, shortnose sturgeon and American shad) and/or catadromous fish (live in freshwater and spawn in saltwater, such as eel). Water that exits a conventional powerhouse, such as powerhouse  15 , has been sieved by trashracks  11 , fish screens plus massive efforts to bypass or rebuild turbines to minimize fish injuries plus removable spillway weirs and reduction of nitrogen super-saturation at spillways. Thus, any utilization of existing hydroelectric dams must protect migratory fish that miss bypassing. 
   Adult salmon migrating upstream to spawn intuitively avoid swimming into strong currents and follow paths of least resistance. At a dam they seek passageways to fish ladders or similar features, but water exiting draft tubes is churning, eddying and up-boiling without well-defined paths for migrating fish. Fish can mill about wasting precious energy for several days seeking an entry to ladders or similar features. Laminar flow may accelerate fish passage. 
   Smolt traveling downstream have several aids in their journey to either bypass or mitigate impacts of going through turbines. However, smolt moving downstream that enter and survive large turbines  13  having flow velocities up to mid-double digits per second near the turbines will exit the draft tube outlets  21  at relatively slow flow of approximately 6-8 ft. (1.83-2.44 m) per second which, coupled with the use of new small slow revolving turbines with fish screens, are much less likely to injure fish. 
   In keeping with the foregoing the invention provides in combination three cooperative and interactive mechanisms, namely, means  30  ( FIGS. 1-3 ) for converting turbulent tailwater flow exiting the draft tube outlets  21  into laminar flow, first means  50  for generating electricity from the bottommost laminar flow adjacent river bottom and second means  70  downstream from the first generating means  50  for generating additional electricity from uppermost laminar flow. 
   The means  30  for converting turbulent tailwater flow exiting the draft tube outlets  21  into laminar flow include a plurality of channels or compartments  30   a  through  30   d  ( FIGS. 2 and 3 ) each of which converges in a flow direction toward the first electricity generating means  50  and toward the second electricity generating means  70 . The following description of the channel or compartment  30   c  applies to the channels  30   a ,  30   b ,  30   d  and all other similarly constructed channels located along the length of the powerhouse  15  ( FIG. 2 ). 
   The channel  30   c  is formed by four pairs of supports, posts, columns  31 ,  31 ;  32 ,  32 ;  33 ,  33  and  34 ,  34  ( FIG. 3 ). The upstream or uppermost pair of vertical supports  31 ,  31  are spaced furthest from each other and the downstream outlet pair of vertical supports  34 ,  34  are located closest to each other. The pair of vertical supports  31 ,  31  include two vertical slots  35 ,  36  ( FIG. 3 ). The next downstream pair of vertical supports  32 ,  32  each include two pair of oppositely directed slots  37 ,  37  and  38 ,  38 . The next downstream pair of vertical supports  33 ,  33  each include oppositely directed pairs of vertical slots  39 ,  39  and  40 ,  40 . The downstream-most pairs of vertical supports  34 ,  34  each include vertical slots  41 ,  42  with the vertical slots  42 ,  42  being in opposing relationship to each other. The vertical slots  35 ,  37 ;  37 ,  39  and  39 ,  41  of the vertical supports  31 ,  32 ,  33  and  34  are in alignment with each other as are the vertical slots  36 ,  38 ;  38 ,  40 ; and  40 ,  41  of the respective vertical supports  31 ,  32 ,  33  and  34 . 
   Concrete panels  43  through  45  ( FIGS. 1 ,  3  and  6 ) are consecutively lowered between the opposing vertical slots  35 ,  37 ;  37 ,  39  and  39 ,  41  of respective vertical supports  31  through  34 . Similar panels  43  through  45  are lowered consecutively within the slots  36 ,  38 ;  38 ,  40  and  40 ,  41  of the respective vertical supports  31 ,  32 ,  33  and  34 . Shorter panels  43   a ,  44   a  and  45   a  ( FIGS. 3 ,  4  and  6 ) are lowered consecutively between opposing slots  42 ,  42  of adjacent pairs of vertical supports to close the opening between them. The lower half of panel  43   a  and upper half of panel  44   a  shall include screened openings (not shown) below lowest water elevation to balance the water pressure between tailwater, channels and triangular enclosed areas or “V”-segments  49 . Screened openings must be sufficiently shallow to utilize pole/brush equipment to clean them and avoid using divers. The stacked panels  43  through  45  ( FIG. 1 ) thereby define converging walls  46 ,  47  ( FIG. 3 ) which converge from the furthest spaced pair of vertical supports  31 ,  31  toward the closest spaced vertical supports  34 ,  34  defining respective upstream or uppermost and downstream or lowermost portions of the channel compartment  30   c  and each of the identically constructed remaining illustrated compartments  30   a ,  30   b  and  30   d . Due to the converging nature of each of the channels  30   a  through  30   d , the roiling and churning water leaving the draft tube outlets  21  is progressively confined and constricted between the converging walls  45 ,  46  of the channels  30   a  through  30   d  to both accelerate the flow and convert it toward laminar flow useable to generate electricity both well below water surface level and also adjacent thereto by the respective first and second electricity generating means  50 ,  70 , as will be described more fully hereinafter. 
   However, reference is made to  FIG. 1  of the drawings which illustrates electricity generating means  50  located submerged and closely adjacent a river bottom RB and substantially within the downstream end portion of the channel  30   c  ( FIG. 3 ), while the second electricity generating means  70  in the form of undershot water wheels  71  carried by barges  72  are driven by the water&#39;s kinetic energy closely adjacent maximum tailwater elevation TE. Because the second electricity generating means  70  is located well above the first electricity generating means  50 , any turbulence created by the latter adjacent the river bottom RB is under high tailwater depth conditions substantially ineffective to disturb the laminar flow in the upper water surface adjacent the tailwater elevation TE. 
   The first electricity generating means  50  are a plurality of turbine/generator units conventionally supported adjacent the river bottom RB within the downstream end portion of each of the channels  30   a  through  30   d , particularly as illustrated with respect to the channels  30   a  through  30   d  of ( FIG. 2) and 30   c  and  30   d  of ( FIG. 3 ). Though the turbine/generator units  50  are located in pairs within the downstream-most converging portions of the channels  30   a  through  30   d , more or less than two turbine/generator units  50  can be utilized. The turbine/generator units  50  are connected by a power line  51 , ( FIG. 1 ) to the power system  18 . Preferably, each turbine/generator unit  50  is provided with means  55  ( FIG. 7 ) for further accelerating the laminar flow incident to driving the turbine/generator unit  50 . The accelerating means  55  is a substantially frusto-conical water flow acceleration tube which surrounds each turbine/generator unit  50 . However, reference is made to  FIG. 1  of the drawings which illustrates the first electricity generating means  50  RB located submerged and closely adjacent the river bottom RB and substantially within the downstream end portion of channel  30   c  ( FIG. 3 ), and the second electricity generating means  70  which include undershot water wheels  71  carried by barges  72  driven by the water&#39;s kinetic energy closely adjacent maximum tailwater elevation TE. 
   Each barge  72  of the second electricity generating means  70  include buoyancy chambers (not shown) which can be utilized to locate the undershot water wheels  71  to the most efficient depth beneath the tailwater elevation TE, and electricity generated thereby is delivered by power lines  73  ( FIG. 1 ) to the power station  18 . The barges  72  are connected at opposite ends thereof by U-shaped supports  75  which slidably embrace selective ones of the vertical supports  34  and can slide vertically upwardly and downwardly relative thereto to accommodate for variations in tailwater elevation TE. The U-shaped supports  75  and particularly a pair of parallel legs  76  of each can utilize mechanical means to permit the barges  72  to be advanced toward or moved away from the vertical supports  34  depending upon upper laminar flow conditions adjacent the tailwater elevation TE. The water wheels  71  are also centered along a centerline CL ( FIG. 5 ) bisecting the various channels  30   a  through  30   d  to achieve optimum performance. Thus, by locating the water wheels  71  well above the submerged turbines  50  coupled with the orientation thereof with respect to the center lines CL of all of the channels  30   a  through  30   d , the upper surface location of the water wheels  71  access the surface velocity of the upper laminar flow without affecting the laminar flow of the submerged turbine units  50 . 
   It is to be understood that the converging channels or compartments  30   a  through  30   d , the turbine/generator units  50  and barges  72  and their associate water wheels  70  extend the entire length of the powerhouse  15  with the size and numbers thereof, as well as the length and height of the channels  30   a  through  30   d , being dependent upon the dam  10  with which the invention can be associated. The various heights and lengths, entrance ends and discharge ends of the channels  30   a  through  30   d  and the first and second electricity generating means  50 ,  70 , respectively, would be comparatively selected using performance factors matched to the hydraulic conditions of a specific hydroelectric dam  10 . Most importantly, however, the laminar flow adjacent the river bottom RB which efficiently drives the turbine/generator units  50  does not detract from or reduce the efficiency of the water wheels  71  subjected to the laminar flow at the fastest surface velocities adjacent the tailwater elevation TE. 
   The invention as thus far described, including details in  FIGS. 1 through 7 , may be sufficient for many projects; however, the abrupt open exits from channels  30   c ,  30   d  ( FIG. 3 ) produce eddies that may be counter productive for turbine/generator units  71  carried by floatable segments (not shown) supported by stable platforms  72  or other turbine/generator units (not shown) supported by or suspended under stable platforms  72  ( FIG. 3 ). The embodiment of the invention of  FIGS. 8 through 12  eliminates eddy formation concerns. Reference is first made to  FIG. 8  of the drawings which includes first means  50 ′ for generating electricity from the laminar flow at river bottom RB and second means  70 ′ downstream from the first generating means  50 ′ for generating further electricity from upper surface laminar flow. The first and second electricity generating means  50 ′,  70 ′, respectively, are identical to those heretofore described with respect to  FIGS. 1 through 7  of the drawings, but the turbulent tail water flow converting means  30  of  FIGS. 1 through 7  constructed as a continuously converging channel is instead constructed as a venturi channel  30 ′ to eliminate eddies at the exits. Structure corresponding to comparable/equivalent structure heretofore described with respect to  FIGS. 1 through 7  is primed, such as a venturi channel or compartment  30   c ′ ( FIG. 8 ) which is but one of many side-by-side venturi channels corresponding to the channels or compartments  30   a  through  30   d  located along the length of the powerhouse  15  ( FIGS. 2 and 3 ) and  15 ′ ( FIG. 8 ). 
   As in the case of the channel  30   c , the venturi channel  30   c ′ is formed by four pairs of vertical supports, H-piles, posts, columns or piers  31 ′,  31 ′ ( FIGS. 8 and 9 );  32 ′,  32 ′ and  33 ′,  33 ′ ( FIGS. 8 and 10 );  34 ′,  34 ′ ( FIGS. 8 and 11 ) and  80 ,  80  ( FIGS. 8 and 12 ). The upstream or uppermost pair of vertical supports  31 ′,  31 ′ are spaced furthest from each other, while the next two pair of vertical supports  32 ′,  32 ′ and  33 ′,  33 ′ are located closer to each other. The pairs of vertical supports  33 ′,  33 ′ and  34 ′,  34 ′ are parallel to each other and downstream thereof the pair of vertical supports  80 ,  80  are spaced midpoint the structure end columns  34 ,  34  (not shown) and downstream half that distance  80 ,  80  ( FIG. 8 ). 
   The venturi channel  30   c ′ further includes a plurality of concrete panels  43 ′ through  45 ′ corresponding to the concrete panels  43  through  45  which are consecutively lowered between the opposing vertical slots of the vertical supports  31 ′,  32 ′ and  32 ′,  33 ′ which collectively define a converging channel portion  86  of the venturi channel  30   c ′ which transitions to a further downstream parallel channel portion  87  defined by parallel spaced panels  43 ′- 45 ′ supported between the pairs of H-piles  33 ′,  34 ′ ( FIG. 8 ). 
   A divergent channel portion  88  ( FIG. 8 ) is defined by the two pairs of panels  43   a ′- 45   a ′,  43   a ′- 45   a ′ slidingly assembled between the last two pairs of H-pile vertical supports  34 ′,  80 ;  34 ′,  80  ( FIGS. 8 and 12 ). 
   It is to be particularly noted that the first electricity generating means  50 ′ ( FIG. 8 ) are located in the parallel laminar flow channel portion  87  of the venturi channel  30   c ′. Thus, in addition to the laminar flow created during water flow through the converging channel portion  86 , the laminar flow velocity/kinetic energy is further augmented/increased by the venturi effect created by the venturi channel  30   c ′ and released without eddies through a diverging exit at the divergent channel portion  88 , thereby further increasing the power generating efficiencies of the first electricity generating means/turbines  50 ′. 
   As is most readily apparent between a comparison of  FIGS. 3 and 8  through  12  of the drawings, the vertical supports  31  through  34  are rounded and portions thereof project into the various channels  30   c ,  30   d , for example, which tends to create flow disturbances, such as small eddies. The latter undesired effects are substantially eliminated or reduced by the construction and assembly of the panels  43 ′- 45 ′ and the associated channels or vertical supports  31 ′ through  34 ′ and  80 . 
   As is best illustrated in  FIGS. 9 through 12  of the drawings, all of the panels  43 ′- 45 ′ have stepped vertical edges which when lowered downwardly in the various slots  35 ′,  36 ′;  37 ′,  39 ′;  38 ′,  40 ′; etc., place panel surfaces Ps of the opposing panels  43 ′- 45 ′ in substantially the same vertical plane as inboardmost surfaces Vs of the channels with which the panels  43 ′- 45 ′ are connected. Since all of the surfaces Vs, Ps merge smoothly and uninterruptedly in the convergent channel portion  86  and the parallel channel portion  87  in particular, the laminar flow created thereby and flowing therein is not adversely affected by flow variations, as described heretofore, caused by the rounded vertical supports  31 ,  32 ;  32 ,  33 ; etc., of the channels  30   a  through  30   d . In this manner, the substantially seamless coextensive surfaces Vs, Ps in the convergent channel portion  86  and the parallel channel portion  87  of the venturi channel  30   c ′ and like side-by-side arranged venturi channels optimize the electricity generated by the turbines  50 ′. 
   Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined by the appended claims. 
   For example, in keeping with the invention designers and contractors will apply new insight and innovations to tailor the invention to site specific parameters with the objective to produce a facility that generates maximum electricity from existing tailwater flows. The solution must not diminish existing electricity production unless the new addition generates sufficient additional power to make up the difference with a profitable return on investment. 
   It should be noted walls may be formed several ways including casting the “V” segments ( 49 , FIGS.  3  and  49 ′,  FIG. 8 ) as complete reinforced concrete monolithic units that are set in place and connected in sequence. 
   Converging walls  45 ,  46  of channels  30   a  through  30   d  are smooth but the river bottom RB is not ( FIGS. 1 ,  6 ,  7 ). Surface irregularities beyond a point will diminish efforts to generate laminar flow and must be eliminated. This is especially true within the downstream reach containing submerged turbine/generators  50  ( FIGS. 2 ,  3 ) and within the parallel walled venturi channel  87  ( FIG. 8 ). 
   Drill barges with spuds or similar structures with permanent pile supports become stable platforms well above high water elevation and wave effects that contain and control rectangular floatable segments for turbines/generators. Each rectangular segment moves vertically by floatation with water elevation and horizontally by controls to and fro along channel centerlines CL. Platforms connect to downstream pilings ( FIG. 8 ) to maintain relationship of floatable segments with channels. Platforms can be intermittent ( FIG. 2 ) spanning two or more channels or continuous ( FIG. 8 ) like a pier for access from shore for construction and future operations and maintenance. In either case they run full length of the powerhouse  15  and its draft tube outlets  21 . Platforms are positioned to ensure floatable sections directly face and match narrowest widths of downstream channel openings so floatable turbine/generator units can extend into the openings and utilize most favorable flow conditions and when necessary retract to allow access to submerged units. Special variations are required for floatable units  71  ( FIGS. 1 ,  3 ,  5  and  8 ) such as horn intakes for individual rectangular channels enclosed on sides and bottom. 
   Stable platforms containing floatable segments with turbine/generators may serve as cover for smolt against aerial or other predators as smolt reorient themselves from passage through turbines. 
   Multiple submerged turbine/generator units  50 ,  50 ′ may occupy each lower channel outlet area depending upon type, size, spacing, support structures and hydraulic impacts on uppermost laminar flows which floatable turbine/generator units  79  ( FIGS. 1 and 3 ) rely on. Numbers of floatable turbine/generator units  70  also rely upon type, size, spacing and hydraulic impacts on each other. Submersible turbine/generator units  50 ,  50 ′ consume laminar flow and could impact uppermost flows. Therefore, relative usage of submerged and floatable turbine/generator units must be juggled to achieve highest efficiencies of electricity generation for both types.