Tide turbine

An improved turbine and generating system for generating electrical power from the energy of flowing water, such as a tide, in a water course are disclosed. The turbine features peripheral inward flow and axial outward flow. A flow divider means is provided to ensure that the outward flow is substantially uniform along the turbine shaft in both directions. The turbine wheel is made up of radially extending scoops and generally circular disks, to define chambers. Preferably the chambers are of continuously decreasing cross-sectional area, measured perpendicular to water flow therethrough. Baffles may be provided preventing water from entering certain of the chambers formed between the scoops and disks of the turbine to ensure that a net rotational impetus is given to the turbine by water flow thereagainst. The structure supporting the turbines and generators in and above the watercourse may include a causeway for vehicular traffic.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to turbines for generating electric power. More 
particularly, this invention relates to turbines for generating electrical 
power which are driven by the force of the tides. 
2. Description of the Related Art 
For many years, men have sought a way to harness efficiently the power in 
ocean and river currents, and in the tides, which are governed by 
gravitational forces and are thus not subject to consumption by combustion 
as in the case of petroleum, coal and other natural resources. Numerous 
schemes, have been developed to harness the power in tidal waters and in 
ocean or river currents, but for a variety of reasons, none of these has 
been truly successful. For example, U.S. Pat. Nos. 3,604,942 to Nelson, 
3,912,937 to Lesser, 3,922,012 to Herz, and 3,927,330 to Skorupinski all 
show systems for underwater turbines which involve blades that collapse 
when they are being dragged against the current and are supposed to open 
up again when disposed favorably with respect to the current, so that a 
net torque is produced, which can be used to drive a generator. These 
systems are all relatively complex, and it appears unlikely that they will 
be reliable for any great length of time, especially considering the harsh 
underwater environment of the ocean, which is not only corrosive but, of 
course, is also home to a wide variety of barnacles, kelp weeds and the 
like which attach themselves to mechanical parts and would, over time, 
tend to render them inoperable. 
Other systems concerned with obtaining power from current or tidal flows 
include the devices shown in U.S. Pat. Nos. 4,095,422 to Kurakake (a 
system having very complex arrangement of a number of paddle wheels), 
4,292,535 to Diggs (a complex system involving a number of swinging 
blades, for converting water power into electricity), and 4,023,041 to 
Chappell (a water-powered generator that floats up and down with the water 
level and rotates in response to changes in tide or current flow). All the 
systems shown in these patents are very complex, involving a large number 
of moving parts, and would be costly to manufacture and would appear 
unlikely to be reliable in operation. 
Other patents which show water powered devices that may be of some 
historical significance, but which do not adequately solve the problem of 
obtaining suitable useful power from tides are U.S. Pat. Nos. 204,728 to 
Haskins; 958,467 to Bennett; and 1,320,650 to Pratt. 
Many of the designs shown in the patents referred to above involve 
disposition of electrical generation equipment below the water line, which 
raises a host of difficulties. Similarly, many of these designs would tend 
to macerate fish swimming into them, no escape route for fish being 
provided. 
More recently, in an article in Popular Science, Vol. 226, No. 1 (Jan. 
1985), pp. 56 et seg., there was described a proposed system for obtaining 
electrical power from the tides. In this system, a tunnel was to be dug 
along a waterway having a high degree of tidal activity, such as in the 
Bay of Fundy. The tides are constrained to pass through the tunnel. Water 
is stored in a pond during the incoming tide and used to generate power on 
the outgoing tide only, although generation in both modes would be 
possible. A turbine is mounted for rotation within the tunnel, and is 
driven by water passing therethrough. The stator of a circular generator 
is disposed around the turbine in the wall of the tunnel and the rotor of 
the generator is affixed to the outer extremities of the blades of the 
turbine. This system appears, according to the Popular Science article, to 
have some utility. On the other hand, the turbine design employed places 
the electrical generation equipment in and closely surrounding the tunnel 
through which the water flows. This can be expected at best to pose 
maintenance difficulties, and is a serious constraint on the design of the 
generator. Furthermore, and as detailed in the article, many unpredictable 
environmental changes caused by the variation of the tides will inevitably 
occur if a project of this type having power generating capacity 
sufficient to justify its cost is constructed. Governmental approval may 
therefore not be possible, if the environmental impact appears likely to 
outweigh the benefits of the power provided. 
Also discussed in the Popular Science article is a French project on the 
Rance River in which generators are disposed in bulbs disposed in the 
water stream, coaxial with the turbines which drive them. Apparently, this 
system has been in operation for some time, but the apparatus is quite 
expensive, as compared to that which is the primary subject of the 
article. The Rance River project also has had substantial environmental 
impact in that it relies upon variation of the natural tides for steady 
power, and suffers from many of the same design and maintenance problems. 
The most desirable location for a tide driven turbine generation system 
would clearly be an oceanic area in which a large number of consumers of 
electric power are located in juxtaposition to an area having relatively 
large tidal variation. Such an area is the northeastern portion of the 
United States, where the population density is high, running from 
Washington, D. C. to Boston and beyond, and where the tides are also quite 
high. Several good spots are found along the coast of Maine and between 
Maine and Nova Scotia, in particular between Maine and Grand Manan Island 
which is nine miles off the coast of Maine. The tides in the channel 
between them, which is up to some 300 feet deep, run at up to 
approximately 3.4 mph with a normal variation of approximately 20-26 feet. 
It will be appreciated by those skilled in the art that a supporting 
structure will be necessary to locate turbines and generators directly in 
and above the water respectively. It would be desirable to use such a 
structure for other purposes as well, e.g., as a causeway for vehicular 
traffic between the mainland and an island or other land mass between 
which the tides are relatively high. In this way, maximum utility could be 
provided by the tidal generation system according to the invention. 
OBJECTS OF THE INVENTION 
It is therefore an object of the invention to provide a water driven 
turbine which will generate electric power from tidal movement. 
It is a further object to provide a tidal generator which will provide 
substantial power generation capability without materially affecting the 
natural flow of the tides, so as to avoid adverse environmental impact. 
It is a further object of the invention to provide an electrical power 
generation system which employs the tides for driving generators, in which 
the electrical generation mechanism is disposed above the high water mark 
and is mechanically connected to turbines disposed at all times beneath 
the surface of the water. 
It is a further object of the invention to provide a water-driven turbine 
which allows reasonably free passage of fish and other aquatic life. 
It is a further object of the invention to provide a turbine which will 
generate useful electric power from the tides of the ocean, which is 
relatively simple to install, inexpensive to construct, durable in 
service, and not overly susceptible to fouling by marine organisms or the 
like. 
It is a further object of the invention to provide an improved turbine 
generating system. 
It is a further object of the invention to provide a tidal turbine 
generation system in which the structure used to support the turbines and 
generating machinery are also used to provide a causeway, thereby opening 
up hitherto inaccessible areas to vehicular traffic. 
SUMMARY OF THE INVENTION 
The above needs of the art and objects of the invention are met by the 
present invention, which comprises an improved water turbine and 
generating system employing the same. The turbine of the invention 
comprises at least one rotor unit, which is generally toroidal in 
cross-section. Each turbine rotor unit is made up of a number of generally 
radial scoops, upper and lower generally circular disks having axial 
openings, which together with the scoops define chambers having 
circumferential inlets and axial outlets, and a diverter center hub. Water 
thus enters the turbine from its periphery and exits along the axis. The 
diverter hub splits the flow of water to flow axially along the shaft of 
the turbine in either direction, such that no net axial force is exerted 
on the turbine by the exiting water. Baffles are provided to shroud 
essentially one-third of the surface of the blades which are exposed to 
the incoming current, such that a net rotational force is exerted on the 
turbine by water flow against the uncovered blades on the side of the 
turbine which is exposed to the incoming water, and to increase the flow 
of water against the exposed side of the blades. Similar baffles may be 
provided on the other side of the turbine, so that power is generated 
during tidal flow in both directions. 
The turbine of the invention may be used in an array, so as to be useful in 
connection with a wide range of depths, and may be disposed in a channel 
having a relatively constant flow of water therethrough. 
In a particularly preferred embodiment, a number of tidal turbines are 
disposed beneath a causeway extending between different land masses, so as 
to render accessible previously inaccessible areas. A number of the 
turbines of the invention are connected by a common shaft which drives a 
generator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Tide turbines incorporating the principles and concepts of the present 
invention which may take the form of any of several possible embodiments 
are referred to in the accompanying drawings by the reference numeral 10. 
As FIGS. 1A-1D illustrate, each tide turbine 10 rotates on a shaft 12 
having a vertical axis. As detailed below, typically a number of turbines 
10 will be mounted on a common shaft which transmits the rotational force 
they develop to a generator 14 mounted above the water level. The tide 
turbines 10 are preferably formed of a durable plastic or 
corrosion-resistant metals such as aluminum or stainless steel for 
durability in sea water. They may be provided with antifouling coatings as 
known in the art. Preferably, the turbines 10 are at all times completely 
submerged underwater and operate on the flow of water on both the incoming 
tide and the outgoing tide. As shown, a number of turbine and generator 
assemblies may be used. Maintenance ladders are indicated at 15 (FIG. 1A). 
A flywheel (not shown) may be provided on the shaft 12 to keep generator 
14 spinning during the period of the slack tide. A clutch (not shown) may 
be incorporated to allow the turbines to remain still during this period. 
In FIG. 1A the tide turbines 10 are shown positioned underneath an oil 
drilling platform 16, but their placement beneath a bridge, a causeway, a 
fishing dock, or any other sturdy structure that facilitates the use of 
the tide is within the scope of the invention. 
Referring now more particularly to FIGS. 1B-1D, which show a single turbine 
10, the tide turbine 10 rotates in the same direction (clockwise in FIGS. 
1B-1C) when driven by either the incoming or outgoing tide. The turbine 
comprises a number of "scoops" 28 against which the flowing water entering 
from the periphery of the turbine "wheel" exerts a force, causing the 
turbine to rotate. The axially outer edges of the scoops 28 are shrouded 
by upper and lower ringlike disks 32 and 34, respectively; upper and lower 
axial outlets 24 and 26 in the centers of the disks 32 and 34, 
respectively, provide an "escape route" for the water as well as for any 
fish, etc., which may enter the turbine. Preferably the outlets are ringed 
by upstanding shoulders or lips 32a and 34a which provide additional 
surface area against which the flowing water can exert force. 
Disposed about central hub 18 is a divider 22 which rotates with the 
turbine and which splits the water as it passes by scoops 28. The divider 
22 comprises mating curved surfaces. Sections through the divider 22 
perpendicular to the shaft 12 are all circular, being of largest radius 
where the surfaces of the divider meet and smallest near the shaft, i.e. 
at its upper and lower ends. The water is split by divider 22 so that 
approximately half flows upwardly through the upper axial outlet 24 and 
half flows downwardly through the lower axial outlet 26. By splitting the 
water, the divider 22 prevents an unbalanced axial force from being 
exerted on the hub 18 in either direction. This simplifies the design of 
the bearings in which the turbine rotates, as well as that of the other 
supporting structure required. 
The dividers may also have upstanding members formed on their surfaces, 
particularly near their portions of maximum radius, against which the 
flowing water can exert further force. These members are discussed below 
in connection with FIG. 4. 
As mentioned, the tide turbine 10 includes an array of scoops 28 which 
extend radially from the hub 18. As shown in FIG. 1C, the scoops 28 have 
smooth inside walls and are concave on one side and convex on the other 
side, so as to have force exerted thereon by the incoming water, whereby 
the turbine is rotated as the water passes by toward the divider 22. In a 
typical arrangement, the scoops 28 may be 8 inches wide and 30 inches 
long, and their shape and the radius of the openings 24 and 26 is so as to 
thrust the water into the divider 22 and out through openings 24 and 26 at 
approximately twice the speed at which the water enters the space between 
the outer peripheral edges of scoops 28 and the disks 32 and 34. 
As shown in FIG. 1B, the circular disks 32 and 34, which together with the 
scoops 28 and divider 22 define the water flow pathways, are generally 
frustoconical in shape to provide a smooth flow of water between the 
scoops and out along the axis of the turbine, and to provide the correct 
variation in cross-sectional area of the chambers formed between each of 
the scoops and the circular disks 32 and 34. In general, the water flow 
pathways decrease smoothly in cross sectional area from inlet to outlet in 
slope note #2. Water flowing through these passages, being incompressible, 
is accelerated. A force is thereby exerted on the turbine, causing it to 
be rotated. 
FIGS. 2A-2C show, as mentioned, a somewhat different form of the turbine 
according to the invention, in which the upper and lower disks 32' and 
34', instead of being smooth as in the embodiment of FIG. 1, are formed to 
comprise a number of conoids 61, which are indentations having a 
semi-circular face at one end, against which the flowing water exerts 
force. The disks again may comprise shoulders or lips 32a, 34a, as shown. 
The conoids 61 taper more or less to a point at their other end. The 
result is to provide an additional torque generation capability. The 
conoids 61 are readily visible in FIG. 2A. The conoids 61 provide 
resistance to the flow of water past the disks and should therefore aid in 
causing the turbine to rotate, thus improving the power generated, for a 
given flow of water. As shown, each of the conoids includes a generally 
flat reaction surface against which flow of water exerts force; the rear 
of the flat surface is faired into the major surface of the turbine wheel, 
so that a net rotational force is provided by water flow into and past the 
wheel. As also shown in FIG. 2B, the struts 48 which support the turbine 
assembly (detailed below in connection with FIG. 5) are preferably shaped 
as shown to control the water flow. Fin deflectors can also be provided at 
42, to further channel the water flowing towards the turbine, and to 
prevent larger fish and the like from being caught in the turbine blades. 
The leading edges of the struts 48 are desirably relatively sharp to cut 
any floating debris or marine life which might otherwise tend to become 
tangled in the rotating turbines. 
As shown, a pair of baffles 56 is desirably provided. Baffles 56 may also 
be used in connection with the other embodiments of the turbine of the 
invention. 
Their function is to prevent water from impacting the "backs" of the scoops 
28, e.g. on the right lower quadrant of the turbine wheel in FIG. 2A, when 
the current is flowing in the direction shown by the arrows A. Otherwise 
the rotation of the turbine 10 would be impeded. The baffles may desirably 
be controllably movable between the position shown in full at 56 and that 
shown in phantom at 56b, to "tune" the water flow characteristics. 
FIG. 2B also shows a possible alternative shape of the baffle 56, which is 
generally C-shaped in cross-section, but which may have an indentation 56a 
at its central portion, to assist in deflecting flow of water into the 
turbine. 
FIGS. 3A-3B show how a plurality of turbines according to the invention can 
be supported on a framework comprising uprights 48, as shown in 
cross-section in FIG. 2A. FIG. 3A shows the lowermost turbine of a group 
of turbines, preferably connected by a common shaft 12, and an exemplary 
base construction, while FIG. 3B shows a turbine located in an 
intermediate position. The disposition of plural turbines in juxtaposition 
to one another on a common shaft may further aid in obtaining useful 
energy from the flow of water. A number of X-shaped radial brace 
assemblies 76 provide stabilization for bearing housings 74. Bearing 
housings 74 carry elements of a common shaft 12 joined by couplings 75 in 
order to connect a number of turbines 10 according to the invention. Thus, 
a large number of turbines 10 can be mounted on essentially modularized 
bearing and brace sub-assemblies for convenient assembly. Their total 
output is effectively summed by the shaft 12 for supply to generators 
which sit on a platform well above water level, e.g. at 16 in FIG. 1; also 
note the discussion below in connection with FIG. 5. preferably, each 
bearing housing 74 is provided with tide deflectors 98 which serve to 
direct the water away from them and onto the turbines 10, thereby lowering 
the loading on the structure and increasing the efficiency of the 
turbines. Means may be provided for remotely monitoring the bearing 
temperature and for remote lubrication, both for convenience and 
timeliness of maintenance. 
FIGS. 4A-4D show some variations on the shape of the scoops which may be 
employed. In this case it is desired that the turbine be rotated in a 
clockwise direction by a current which is moving in the reverse direction 
with respect to the embodiments of FIGS. 1-3, that is, as shown by the 
arrows B. In this case, the flow divider 22 is still shown, (see FIG. 4B) 
but riveted or otherwise affixed to the circular frustoconical disks 34 
and 36 are a number of additional deflectors 68 which serve to derive 
additional power from the current. These may be simply openended as shown 
at 68 in FIG. 4C, or they may have their ends closed as shown at 68A in 
FIG. 4D. FIG. 4D also shows in phantom conoids 22a formed on the flow 
divider 22, which may be provided in order to generate additional force. 
In this embodiment the flow divider rotates with the turbine wheel. Again 
the conoids comprise generally flat reaction surfaces perpendicular to the 
flow of water, for receiving rotational energy therefrom, the rear 
portions of the conoids serving to fair the flat surfaces into the 
generally smooth surface of the flow divider. 
FIG. 5 shows the overall configuration of a generating system according to 
the invention. A number of turbines 10 according to the invention are 
mounted on a structure made up of a number of the uprights 48 shown in 
FIG. 1, mounted on concrete piers 75 in the bottom of a channel through 
which oceanic tides flow. These uprights 48 generally are arranged in a 
grid pattern, such that the turbines are supported by struts 76 disposed 
on several sides of the turbines, for rigidity. It may be useful to heat 
the uprights in winter to prevent ice formation. 
A platform 100 is mounted on the top of the uprights. Other parts of the 
system such as generators 102, observation platform 104, control room 108 
and the like, may be mounted on platform 100. In one preferred embodiment, 
it is contemplated that platform 100 would comprise part of a causeway 
connecting two land masses separated by the body of water being tapped for 
power. One or more wind generators according to the inventor's U.S. Pat. 
No. 4,465,929 may be provided as well. The normal maximum tidal wave is 
shown in phantom at 120; as shown, the platform 100 is located above this 
height. Flywheels 114, planetary gearing, clutches and brakes, as needed, 
indicated generally at 112, may be disposed beneath the platform 100. The 
clutches can be used to disconnect the turbines from the generators during 
slack tides so that the flywheels can continue to rotate the generators at 
these times, and for repair. The planetary gearing allows the generators 
and fly wheels to spin faster than the turbines. 
Preferably, the relative height of the turbine assembly is such that all of 
the turbines are under water at substantially all times, regardless of the 
state of the tide. As mentioned, flywheels can also be added to the shafts 
to ensure that the generators continue to spin, even during the slack 
tide. The number of turbines can be multiplied as desired. 
As discussed above, the most desirable location for an electrical power 
generation tide turbine according to the invention is at a location where 
power demands are heavy and where the tides are strong. The coast of Maine 
is such a place; the huge metropolitan area extending from Washington, 
D.C. to Boston and beyond is accessible by power lines and provides ample 
electrical demand, while the tides between Maine and some of the islands 
of New Brunswick and Newfoundland are very high; the Bay of Fundy tides 
are the highest in the world. 
The inventor has realized that the particularly advantageous location for a 
tide turbine might be in the channel separating Maine and Grand Manan 
Island, a distance of some nine miles in which the tides move at up to 
some 3.4 mph and have a variation of over 20 feet. At present Grand Manan 
is accessible from the mainland only by boat or helicopter. If a causeway 
were built connecting the two, the turbines according to the invention 
could very conveniently be supported therebeneath, as could generating 
equipmemt placed between the roadway and the banks of turbines in the 
water, as shown in FIG. 5. The flywheels mentioned above could also be 
provided on the various shafts 12 underneath the causeway. In this way, 
the structure required to support the turbines would do double duty, and 
would connect the relatively inaccessible Grand Manan Island with the 
mainland. 
In this way power could be provided without combustion of nonrenewable 
resources and without requirement of construction of unsightly, dangerous, 
expensive and unpopular generating plants. Nor need the flow of the tides 
be significantly affected. 
It will be apparent to those skilled in the art that numerous modifications 
and improvements can be made to the turbine and generating system of the 
invention. Therefore, the above exemplary disclosure should not be 
considered as a limitation on the scope of the invention, but only as an 
illustrative embodiment thereof.