GB2515095A

GB2515095A - Generator assembly

Info

Publication number: GB2515095A
Application number: GB1310623.2A
Authority: GB
Inventors: Robert Mackay; Alistair Murray
Original assignee: VEMARINE Ltd
Current assignee: VEMARINE Ltd
Priority date: 2013-06-14
Filing date: 2013-06-14
Publication date: 2014-12-17
Anticipated expiration: 2033-06-14
Also published as: GB2515095B; WO2014199183A3; GB201310623D0; WO2014199183A2

Abstract

A hydropower generator assembly has a bladeless turbine comprising a conical tube 12, and helical ribs which may be attached to an inner conical tube. The turbine has magnets at its periphery, which form a generator with stator coils 110, supported in a housing block 16. The turbine axis may be substantially perpendicular to the river bed. The turbine may be supported on a circumferential ledge on the block. The turbine may be installed by lowering into the mooring block. The entire assembly can be contained in a volume of one cubic metre. The turbine may be installed behind a diverter block 160 effectively forming a weir, so that water flows up towards and into the turbine, and exits from a cut out at the rear of the mounting block.

Description

GENERATOR ASSEMBLY

The present invention relates to turbines and power generators and particularly, though not exclusively, the invention relates to a hydropower generator assembly for mounting turbines on a river bed.

There is currently great interest in developing power generators based on renewable energy. While wind farms are now appearing across the landscape, they have met opposition in terms of their size and environmental impact for the quantity of electricity they can generate. Interest has turned to water power as the UK has an abundance of coastline and waterways.

Hydropower is a renewable energy source where power is derived from the energy of water moving from higher to lower elevations.

Power generation using hydro turbines is a proven, mature, predictable and typically price-competitive technology with amongst the best conversion efficiencies of all known energy sources -about 90% water to wire'.

Hydropower remains the largest source of renewable energy in the electricity sector and, significantly, the sector is continuing to deploy at a rapid pace being situated at the crossroads of two major development issues; water supply and energy. There is a broad range of existing hydropower systems that can be classified by project type, system, head or purpose. These can be designed to suit particular needs and site-specific conditions and are generally known as; run-of-river, storage or reservoir based, pumped storage or in-stream technologies.

I

The majority of current: hydropower systems are large scale installations such as that found at Cruachan Power Station in Scotland which is the world's first high head reversible pumped storage hydro scheme. A 316 metre long dam with a 396 metre hydraulic head gives 440MW through four generators. But around 8O% of dams worldwide do not produce electrical power and many dams, including some where power generation does occur, have the potential for smaller devices to enter the fray either in open channel' or in pipe' situations. Additionally, run of river and in-stream opportunities in flood plains are hugely under-developed in terms of power supply. There is therefore a need to provide small-scale hydropower systems for rural electrification in many parts of the world.

There are a number of tidal device designs currently being developed. These fall broadly into those with a vertical axis rotor, a horizontal axis rotor, oscillating devices and venturi effect: devices.

The devices can also be considered as enclosed or open devices wherein the rotor or prime mover is shrouded to protect it, guide liquid flow to the rotor or increase the effective power of the tidal flow via a swept area, pressure increase stage based on the Bernoulli affect. There are a number of disadvantages in current power generators based on these designs. To generate sufficient power each turbine is a significant size and thus the construction costs are high and the payback period is long. Turbine blades have also been found to fail by the breaking off of the tips when such turbines are used in fast: flowing tides. There is also a difficulty in providing a reliable connection between the rotating shaft and the housing to transfer the generated energy.

To overcome the disadvantages of these prior art tidal devices, the present Applicants provided a turbine which, in contrast to most other water energy conversion systems, comprised the first venturi based prime mover rotating around its own axis and having no central propeller shaft. This is described in WO 2010/109169 and a prior art power generator utilising this turbine is shown in Figure 1.

The bladeless turbine A is in the form of a conduit B providing a fluid flow channel. The part frusto-conical conduit has an inner surface adapted to create a vortex in fluid flowing through the channel. The vortex has sufficient force to cause rotation of the conduit. Spiral fins C are arranged on the inner surface to impel the fluid to form the vortex. A portion of the conduit is located in a housing D having a coil E arranged around the conduit and the conduit includes a magnet F, rotation of the conduit by the vortex causes the magnet to rotate in the coil and generate an electric current. A power generator is realised which can be used as a tidal power generator which delivers greater power output at a considerably reduced size.

The housing is located upon a base G which is weighted to ensure that the generator remains in position on the sea-bed. The housing is fixed in relation to the base with the turbine located in the direction of expected tidal flow. Thus the conduit is arranged to have a central axis I which is parallel to the sea-bed. Fluid entering the channel will cause the turbine to generate electricity which is collected at a battery K and carried to surface for use on a grid L or other supply network.

In order for the conduit to turn successfully within the housing bearings M,N are located at either end of the housing.

Unfortunately, these bearings must hold the weight of the conduit while allowing it to turn within the housing which causes both constructional difficulties in balancing the arrangement and the burden of monitoring these bearings for wear.

It is an object the present invention to provide a hydropower generator assembly which obviates or mitigates at least some of the

disadvantages of the prior art.

According to a first aspect of the present invention, there is provided a hydropower generator assembly for location in or near a river bed comprising: a turbine having a first central axis upon which the turbine can rotate; one or more magnets arranged at a periphery of the turbine; and a first annular bearing surface arranged around and perpendicular to the central axis; a housing having a central bore in which to locate at least a portion of the turbine, the central bore having a second central axis; a stator arranged around the central bore; and a second annular bearing surface arranged at an edge of the central bore; and wherein: at least a portion of the turbine is located within the housing with the one or more magnets aligned with the stator to generate an electric current when the turbine is rotated and the first annular bearing surface is located upon the second annular bearing surface.

In this way, the second annular bearing surface is arranged off the vertical compared to the prior art. In an embodiment, the second central axis being is perpendicular to the river bed. This substantially evenly distributes the weight of the turbine around the bearing surfaces making the assembly easier to construct, as the turbine can be lowered in from above, and provides an even and lower wear on the bearing surfaces.

The system may be located at a barrier head in or near a river bed or can be arranged in an array to create an artificial weir.

Preferably, the one or more magnets are provided on a third bearing surface, the third bearing surface being parallel to the first central axis, and the stator including a fourth bearing surface wherein when the magnets and stator are aligned, the third and fourth bearing surfaces meet to provide a radial guide. In this way, the turbine is centralised in the housing and the first and second central axis are co-linear.

One or more of the bearing surfaces may include roller bearings. In this way, pairs of bearing surfaces can rotate freely with respect to each other while weight distribution is still maintained.

Preferably, the turbine has no central shaft or blades. The turbine may be as described with reference to WO 2010/106169 which is incorporated herein by reference. More preferably, the turbine has a main body with a frusto-conical inner surface, an outer surface having a portion arranged to affix the magnets, and at least one fin arranged on the inner surface in a spiral configuration. The spiral configuration may be clockwise or anti-clockwise. Such an arrangement will produce a vortex to draw water through the turbine and cause the turbine to rotate. Additionally, significantly gravity effects due to the near perpendicular orientation will enhance power outputs.

Preferably, the turbine includes an inner frusto-conical body separated from the main body by the one or more fins. The inner rotor section provides a central conduit which assists in providing rotational movement while providing a safe passageway for marine life through the turbine. In this way, the turbine is fish friendly'.

The one or more fins may sit proud of an end of the main body. In this way, portions of the fins can be arranged to sit proud of the housing so that water flow is directed into the turbine by the fins.

In an embodiment, the inner rotor section sits proud of the end of the main body. In this way, the inner rotor section can support the portions of the fins while providing an additional surface to direct water flow into the turbine. In a preferred embodiment there are three fins equally spaced around the main body.

Alternatively, the one or more fins sit within the main body.

Similarly the inner rotor section may sit within the main body. The one or more fins may be level with an end of the main body as may the inner rotor section. These embodiments provide additional protection to the rotor section and the fin(s).

In this way, the fins provide a foreshortened logarithmic screw helix. Additionally with the weight at the rim of the rotor section, it operates akin to a flywheel as the mass is distributed at the edges and in combination with the venturi effect a wing lift' occurs reducing the apparent mass and thus the load is reduced is operation.

Advantageously, a majority of the outer surface of the main body is frusto-conical. In this way, the turbine presents a narrower end to act as a pilot for assisting in locating the turbine within the housing.

Optionally, the assembly includes a mooring block, the block comprising at a first end an inlet profiled to accept the housing, at an opposing end, a base for locating on a river bed, and an outlet from a side thereof providing a fluid passageway through the block from the inlet to the outlet. In this way, the mooring block can be provided at a location and the housing together with the turbine can be mounted later. Preferably the mooring block comprises a dense, heavy material such as concrete. More preferably, the mooring block is of single piece construction, being lifted into place.

Preferably, the profile includes a circumferential ledge at the inlet, to allow the housing to locate into and be supported by the mooring block. Preferentially, the ledge is arranged to lie parallel to the base. In this way, the first and second central axes will be perpendicular to the base. Optionally, the ledge is arranged to be at an angle with respect to the base. In this way, the first end is at an angle so that the housing and turbine are at an angle to the river bed. In this way, the turbine can be directed into the water flow.

Preferably the angle is less than 45 degrees. More preferably, the angle is less than 20 degrees. In a preferred embodiment the angle is about 17 degrees. Preferably also, the assembly includes a diverter block, having a planar first end arranged at the angle to a base. In this way, positioning the diverter block beside the mooring block can assist in mounting the mooring block. The diverter block would then be removed and used elsewhere.

Preferably, the mooring block includes connection means to collect the generated electricity. The mooring block may also include means to store the generated electricity. Alternatively, the mooring block may include connections to transfer the electricity generated to land.

According to a second aspect of the present invention there is provided a method of deploying a turbine onto a river bed, comprising the steps: (a) lowering a mooring block onto the river bed; (b) anchoring the mooring block in position; (c) locating a turbine into a housing; (d) lowering the housing into the mooring block.

In this way, a simple deployment system is provided.

Preferably the mooring block, turbine and housing are according to the first aspect.

The method may include the step of locating a diverter block beside the mooring bock to assist in diverting flow to the turbine. The method may further include the step of removing the diverter block once the turbine has been started up.

The method may include repeating steps (a) -(d) to provide an array of power generators on the river bed.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a power generator mounted on the sea-bed according

the prior art;

Figure 2 is a three quarter section through a power generator assembly according to an embodiment of the present invention; Figure 3 is a plan view of the power generator assembly of Figure 2; Figure 4 is a cross-sectional view through the power generator assembly of Figure 2; Figure 5 is an isometric view of the turbine of the power generator assembly of Figure 2; Figure 6 is a cross-sectional view of the turbine of Figure 5; Figure 7 is a plan view of the turbine of Figure 5; Figure 8 is an exploded isometric view of the housing of the power generator assembly of Figure 2; Figure 9 is a three quarter section through a power generator assembly according to a further embodiment of the present invention; Figure 10 is an isometric view of a deployed power generator assembly according to a further embodiment of the present invention; and Figure 11 is an isometric view of an array of hydropower generators located on a river bed according to a further embodiment of the present invention.

Reference is made to Figure 2 of the drawings which illustrates a hydropower generator assembly, generally indicated by reference numeral 10, including a turbine 12 and a housing 14 according to an embodiment of the present invention. The assembly 10 is located within a mooring block 16 for positioning on a river bed 18.

This provides a substantially cubic structure which can have dimensions of one cubic metre, making it relatively small compared

to prior art generators.

At the centre of the assembly 10 is the turbine 12. Turbine 12 is based on the turbine design described in WO 2010/106169 to the present Applicant's which is incorporated herein by reference. The turbine 12 is best described with reference to Figures 5 to 7.

Turbine 12 has an outer rotor section 20 which is part frusto-conical presenting a curved inner surface 22 from a wide circular inlet end 24 to a narrower circular outlet end 26. The outer surface 28 is also frusto-conical to provide a trumpet form to the outer rotor section with the exception that towards the inlet end 24, a mounting portion 30 is located around the periphery 32.

The mounting portion 30 provides a right-angled mount with an outer surface 34 being a smooth ring whose face is parallel to a central axis 36 of the turbine 12. An under surface 38 of the mounting portion 30 provides an annular ring whose face is perpendicular to the central axis 36.

Located within and co-linear to the outer rotor section 20 is an inner rotor section 40. The inner rotor section 40 takes up the same shape as the outer rotor section 20 being part frusto-conical presenting a curved inner surface 42 from a wide circular inlet end 44 to a narrower circular outlet end 46. The outer surface 48 is also frusto-conical to provide a trumpet form to the inner rotor section and is spaced apart from the inner surface 22 of the outer rotor section 20 to provide an annular conduit 50 therebetween. Note that the inner rotor section 40 is located only partly within the outer rotor section 20 so that the inlet end 44 sits proud of the inlet end 24 and the outlet end 46 is enclosed by the inner surface 22.

In an embodiment, the outer rotor section has a height of 750mm along the central axis 36. The inner rotor section 40 has a height of 500mm and sits proud of the outer rotor section 20 by a distance of 250mm. Thus half of the inner rotor section 40 is located within the outer rotor section 20. Additionally, the diameter of the inlet end 24 and outlet end 26 of the outer rotor section 20 are greater than the diameter of the inlet end 44 and outlet end 46 of the inner rotor section 40. The diameter of the inlet end 44 of the inner rotor section 40 is greater than the diameter of the outlet end 26 of the outer rotor section 20. However, the diameter of the inner rotor section 40 at the inlet end 24 of the outer rotor section 20 equals the diameter of the outlet end 26 of the outer rotor section 20.

Located in the conduit 50 between the inner surface 22 of the outer rotor section 20 and the outer surface 48 of the inner rotor section are three rotor fins 52a-c. The rotor fins 52a-c are equally spaced around the inner rotor section 40. Each rotor fin 52 is a substantially rectangular panel with first 54 and second 56 long edges, first 58 and second 60 short edges, an upper surface 62 and a lower surface 64. With the second short edge 60 arranged towards the outlet 46 of the inner rotor section 40 across the conduit 50, each fin 52 is positioned to spiral around the outer surface 48 of the inner rotor section 40. As each spiral is formed, with the first long edge 54 mating with the outer surface 48 of the inner rotor section 40 and the second long edge 56 meeting and mating with the inner surface 22 of the outer rotor section 20 until it reaches the inlet end 24, the long edge 56 is then exposed and curves into the short edge 58 to provide a rounded fin 66 around the inner rotor section 40 at the inlet end 44.

The outer rotor section 20 and mounting portion 30 may be cast as a single piece, preferably in a metal or metal alloy which is non-corrosive. Alternatively, a plastic, composite or ceramic material may be used provided it can bear its own weight upon the under surface 38. The inner rotor section 40 may be cast as a single piece and the fins 52 joined to each rotor section 20,40 respectively.

Alternatively, the entire turbine can be cast as a single piece with materials as described hereinbefore for the outer rotor section 20.

On the face 34 of the mounting portion 30 there are arranged magnets 68. There are a plurality of magnets 68 equidistantly spaced around the circumference of the face 34. Each magnet is held in a recess 74. In an embodiment, the magnets are neodymium magnets with dimensions of 5Ox2SxlOmm and are held in place by screws 70 locate through the face 72 of each magnet 68. By using multiple small magnets 68, the cost can be kept low as the magnets 68 need not be curved in shape to match the face 34.

Alternatively, a magnetic band could be arranged as a single piece or in sections around the circumference of the face 34.

Turbine 12 is positioned within housing 14. Referring now to Figure 8, there is shown a housing 14 comprising a cylindrical body 76 suspended from a top plate 78. Top plate 78 a metal panel with a circular aperture 80 located centrally thereon. The plate 78 is formed as a square with nibbed corners to provide four upwardly facing securing areas 82a-d. At each securing area 82 there is located a lifting eye bolt 84 so that the housing 14 can be raised and lowered. The body 76 has an upper section 86 with a greater diameter than a lower section 88. Where the sections 86,88 meet there is a ledge 90. This can be seen in Figure 4 also. Extending from the inner surface 92 of the lower section 88 at the ledge 90, is a first plate 94 having an upwardly facing bearing surface 96. Plate 94 is an annular ring whose surface 96 is perpendicular to the central axis 36. Supports 98 are located under the plate 94 so that the plate 94 can be weight-bearing. Positioned in the plate 94 are rollers 100. Preferably there are six rollers 100 equidistantly spaced around the plate 94, but any number of rollers could be used.

Extending from the inner surface 102 of the upper section 86 above the ledge 90, is a second plate 104 having an upwardly facing bearing surface 106. Plate 104 is an annular ring whose surface 106 is perpendicular to the central axis 36. Plate 104 has a width equal to the width of the ledge 90. Positioned in the space between the ledge 90 and the plate 104 are rollers 108. Preferably there are six rollers 108 equidistantly spaced around the circumference of the body 76. Rollers 100 are arranged to rotate on an axis which is perpendicular to the central axis 36 whereas rollers 108 are arranged to rotate on an axis which is parallel to the central axis 36.

Positioned on the surface 106 is a stator 110. Stator 110 is a ring having an inner surface 112 on which is arranged coils 114. The stator 110 is sized to fit against the inner surface 102 of the upper section 86, rest on the plate 104 and present a surface of inwardly facing coils 114 at a diameter equal to the diameter of the lower section 88. Bolts 116 can be used to hold the stator 110 within the housing 14.

Referring now to Figures 2 to 4, the entire assembly 10 can be seen located within a mooring block 16. Block 16 is a concrete structure being approximately one cubic metre is size. In a preferred embodiment the block has side lengths of 1500mm. The block 16 has four square walls 118 with a circular throughbore 120. At least one of the walls 118 has a cutaway 134 at a base 136 thereof to provide a passageway from the through bore 120 to an outer surface 138 of the mooring block 16. The bore 120 is stepped to provide a ledge 122 between an upper section 124 having a wider diameter than a lower section 126. The bore 120 is sized so that the housing 14 can be lifted into the mooring block 16, using the lifting bolts 84; the ledge 90 rests on the ledge 122; the lower section 88 of the body 76 sits within the lower section 126 of the bore 120; the upper section 86 of the body 76 sits within the upper section 124 of the bore 120; and the top plate 78 rests on the upper surface 128 of the block 16. The housing 14 can be screwed 130 to the mooring block 16 at the securing areas 82. In this way the housing 14 is totally supported in the mooring block 16.

Either prior to or after mounting the housing 14 in the mooring block 16, the turbine 12 is located in the housingl4. As the turbine 12 has a tapered outlet end 26 positioning in the housing 14 is simplified with the turbine 12 being dropped in the aperture 80 from above. The turbine 12 is lowered until the under surface 38 of the mounting portion 30 rests upon the bearing surface 96 of the first plate 94. The turbine will be centralised by virtue of the rollers 108 acting as radial guides against the outer surface 34 of the mounting portion 30. The spaced rollers 100 will evenly bear the weight of the turbine 12 and, in combination with rollers 108 will create the correct spacing between the magnets 68 and the coils 114 while allowing the turbine 12 to rotate relative to the housing 14 around the central axis 36.

Typically the central axis 36 is arranged to be perpendicular to the river bed 18, but may be located at an angle off the vertical. This is achieved by angling the mooring block 16, providing a leading wall 140 with a shorter height and an angled base 142. In this arrangement, the cutaway 134 is on the opposing wall 144. Such a tilt on the turbine 12 positions the inlet ends 24,44 in the direction of water flow.

Referring to Figure 9 there is illustrated an alternative embodiment of a hydropower generator, now indicated by reference numeral 10'.

Like parts to those of Figure 2 to 8 have been given the same reference numeral but are suffixed with an apostrophe. In generator assembly 10', the inner rotor section 40' of the turbine 12' does not sit proud of the inlet end 24' of the outer rotor section 20', but instead the inlet ends 24' and 44' are aligned with each other and the top plate 78 of the housing 14'. Equally the inlet ends may sit below the level of the top plate. The stator 110', as before, is aligned with the inlet end 24' and thus the upper section 124' of the block 16' and the upper section 86' of the housing 14' are only as deep as the stator 110' and the rollers 108'. The generator assembly 10' is constructed in the same manner as the assembly 10.

In use, the generator assembly 10,10' is located at a river bed, see Figure 10 for example. Advantageously the generator assembly 10,10' could be located at a natural barrier in the river. In a narrow waterway 148, a mooring block 16, is sized to locate between the river banks 150a,b. The block 16' is preferably a square block, cut at an angle as described hereinbefore with side lengths of around 1000mm. The mooring block 16 is lifted into position by crane and secured to the river bed 152 using anchor rods 154 as are known in the art. With the mooring block 16 in place the water will flow against the front face 156 and want to come over the top and into the throughbore 120, where it can exit through the cut away 134 at the rear 158. To assist in the deployment, a diverter block 160 is located directly in front of the mooring block 16. The diverter block is a cube of similar material to the block 16, with an upper surface which is sloped to direct the water flow across the top of the mooring block 16. The diverter block 160 can be removed after installation of the generator assembly 10. The generator assembly 10 is lifted into the mooring block 16 and secured at the areas 82.

Wat:er flow into the turbine 12, will impinge on the rotor fins 52 causing them to rotate with vortices being created in both the inner and outer 20 rotor sections. This rotation will be on the entire turbine 12 relative to the housing 14. Bearings 100 will assist in a balanced rotation as the weight of the turbine 12 is substantially evenly distributed over the bearings 100 as they are arranged to be close to parallel with the river bed 152. The turbine 12 remains centred on the axis 36 with the assistance of the radial bearings 108. By the rotation of the magnets 68 inside the coils 114, an electric current is generated. Although not illustrated, it will be apparent to those skilled in the art that suitable connections such as a battery and/or power lines will take the power onto the river bank for onward delivery.

A number of hydropower generator assemblies 10,10' can be arranged on the sea or river bed to provide an array of generators.

This is illustrated in Figure 11 where two rows of five generator assemblies are arranged between the river banks. The array of generators may be electrically coupled to assist in collecting the generated power.

An additional feature of the generator assembly 10,10' is the unimpeded flowpath which exists from the inlet 44 of the inner rotor section 40 to the cut away 134 of the mooring block 16. This flow path is sufficient to allow marine life to pass through the turbine 12 without risk of harm to themselves or damage to the turbine 12 operation. Thus the generator assembly 10,10' can be considered as fish friendly.

The principle advantage of the present invention is that it provides a hydropower generator assembly which is relatively small and easy to assemble on or near a river bed.

A further advantage of the present invention is that it provides a hydropower generator assembly in which the rotational axis is perpendicular to the river bed so that the weight of the turbine is evenly distributed over the bearings and gravity assists in operation of the turbine.

A yet further advantage of the present invention is that it provides a hydropower generator assembly which uses a bladeless turbine and gives a fish friendly arrangement.

It will be appreciated by those skilled in the art that various modifications may be made to the invention herein described without departing from the scope thereof. For example, there need not be a second inner rotor section. There may be a greater or smaller number of rotor fins. The mooring block may provide the support to the first plate providing the bearing surface.

Claims

CLAIMS1. A hydropower generator assembly for location on a river bed comprising: a turbine having a first central axis upon which the turbine can rotate; one or more magnets arranged at a periphery of the turbine; and a first annular bearing surface arranged around and perpendicular to the central axis; a housing having a central bore in which to locate at least a portion of the turbine, the central bore having a second central axis; a stator arranged around the central bore; and a second annular bearing surface arranged at an edge of the central bore; and wherein: at least a portion of the turbine is located within the housing with the one or more magnets aligned with the stator to generate an electric current when the turbine is rotated and the first annular bearing surface is located upon the second annular bearing surface.
2. A hydropower generator assembly according to claim 1 wherein the one or more magnets are provided on a third bearing surface, the third bearing surface being parallel to the first central axis, and the housing including a fourth bearing surface adiacent the stator wherein when the magnets and stator are aligned, the third and fourth bearing surfaces meet to provide a radial guide.
3. A hydropower generator assembly according to claim 1 or claim 2 wherein one or more of the bearing surfaces include roller bearings.
4. A hydropower generator assembly according to any preceding claim wherein the turbine is a bladeless turbine.
5. A hydropower generator assembly according to claim 4 wherein the turbine has a main body with a frusto-conical inner surface, an outer surface having a portion arranged to affix the magnets, and at least one fin arranged on the inner surface in a spiral configuration.
6. A hydropower generator assembly according to claim S wherein the turbine includes an inner frusto-conical body separated from the main body by the one or more fins.
7. A hydropower generator assembly according to claim 5 or claim 6 wherein the one or more fins sit proud of an end of the main body.
8. A hydropower generator assembly according to claim 5 or claim 6 wherein the one or more fins sit entirely within the main body.
9. A hydropower generator assembly according to any one of claims 5 to 8 wherein there are three fins equally spaced around the main body.
10. A hydropower generator assembly according to any one of claims 5 to 9 wherein a majority of the outer surface of the main body is frusto-conical.
11. A hydropower generator assembly according to any preceding claim wherein the assembly includes a mooring block, the block comprising at a first end an inlet profiled to accept the housing, at an opposing end, a base for locating on a sea or river bed, and an outlet from a side thereof providing a fluid passageway through the block from the inlet to the outlet.
12. A hydropower generator assembly according to claim 11 wherein the mooring block comprises a dense, heavy material such as concrete.
13. A hydropower generator assembly according to claim 11 or claim 12 wherein the profiled inlet includes a circumferential ledge to allow the housing to locate into and be supported by the mooring block.
14. A hydropower generator assembly according to claim 13 wherein the ledge is arranged to lie parallel to the base.
15. A hydropower generator assembly according to claim 13 wherein the ledge is arranged to be at an angle with respect to the base.
16. A hydropower generator assembly according to claim 15 wherein the angle is less than 45 degrees.
17. A hydropower generator assembly according to claim 16 wherein the angle is less than 20 degrees.
18. A hydropower generator assembly according to any one of claims 15 to 17 wherein the assembly includes a diverter block, having a planar first end arranged at the angle to a base.
19. A method of deploying a turbine on a sea or river bed, comprising the steps: lowering a mooring block onto the river bed; anchoring the mooring block in position; locating a turbine into a housing; lowering the housing into the mooring block.
20. A method of deploying a turbine in a river bed according to claim 19 wherein the mooring block, turbine and housing are according to any one of claims 1 to 18.
21. A method of deploying a turbine in river bed according to claim 19 or 20, including the step of locating a diverter block beside the mooring block to assist in diverting flow to the turbine.
22. A method of deploying a turbine in a river bed according to claim 21, including the step of removing the diverter block once the turbine has been started up.
23. A method of deploying a turbine in a river bed according to any one of claims 19 to 22, including repeating steps (a) -(d) to provide an array of hydropower generators on the river bed.
24. A method of deploying a turbine in a river bed according to any one of claims 19 to 23, including the step of locating the turbine at a barrier on the river bed.