WO2011138749A1

WO2011138749A1 - Plant for the exploitation of marine or river currents for the production of electricity

Info

Publication number: WO2011138749A1
Application number: PCT/IB2011/051978
Authority: WO
Inventors: Marco Gatti
Original assignee: Marco Gatti
Priority date: 2010-05-05
Filing date: 2011-05-04
Publication date: 2011-11-10

Abstract

This invention concerns a system to exploit sea/ocean or river currents for the production of electric energy, comprising at least one turbine (2) to transform the kinetic energy of moving water into mechanical energy and at least one generator (3) to transform said mechanical energy into electrical energy, characterised by the fact that said turbine (2) is located on the sea or river bed and said generator (3) is located on land, with a system (4) to transfer the mechanical energy from the turbine to the generator (3).

Description

TITLE

PLANT FOR THE EXPLOITATION OF MARINE OR RIVER CURRENTS FOR THE PRODUCTION OF ELECTRICITY DESCRIPTION

This invention concerns a system to exploit sea or river currents for the production of electrical energy, in particular a system where the equipment to transform the kinetic energy of the fluid is located on a sea or river bed.

There are different types of systems for producing electrical energy which use the kinetic energy of sea currents or waves, or else river currents.

The first are generally installed near the coast or on special off-shore platforms and are fitted with turbines, blades or similar just under the water's surface. These take the kinetic energy from the moving liquid and turn it into mechanical energy, which is in turn transformed into electrical energy by alternators or similar.

Such systems present numerous disadvantages, however.

Indeed, being subject to the forces of storms or rough seas, they can suffer temporary interruptions to service. In the worst cases permanent damage can even be caused to the system's structure /components.

Moreover, the presence of floating or protruding structures has a significant environmental effect, as well as causing problems for shipping if there are sea lanes in the area where the system is installed.

There are also two principal types of system to exploit river currents: traditional (dam) and run-of-the-river.

Both, however, require significant engineering works, particularly for the construction of dams, with very high construction costs and environmental impact.

Completely submerged systems are also common, which can be located on the bottom of marine channels or rivers.

These systems, while partially obviating the above-mentioned problems, have various drawbacks themselves.

Indeed in these types of installation, the devices used to transform the mechanical energy produced by the turbines or similar into electrical energy (alternators or similar) are directly connected to the turbines and so are also submerged.

This leads to a significant increase in construction costs, as the system must be designed to protect these components, as well as greater difficulty in their maintenance, as the generators are amongst the most delicate of the system's components and require greater periodic maintenance.

In light of all this, the scope of this invention is to present a system to exploit sea/ ocean or river currents for the production of electrical energy which overcomes these technical problems.

In detail, this invention's purpose is to present a system to exploit sea/ ocean or river currents for the production of electrical energy which has a minimum environmental impact.

In greater detail, this innovation's aim is to present a system to exploit sea/ ocean or river currents for the production of electrical energy which does not have structures floating in or protruding from the water.

Another of the innovation's aims is to present a system to exploit sea/ ocean or river currents for the production of electrical energy which can be easily and cheaply realised. In still greater detail, the scope of this innovation is to present a system to exploit sea/ ocean or river currents for the production of electrical energy with greater efficiency than current systems.

The above-mentioned aims and goals are substantially met with a system to exploit sea/ ocean or river currents for the production of electric energy, comprising at least one turbine to transform the kinetic energy of moving water into mechanical energy and at least one electrical device to transform said mechanical energy into electrical energy, characterised by the fact that said turbine is located on the sea or river bed and said generator is located on land, with a system fitted to transfer the mechanical energy from the turbine to the generator.

Thanks to the turbine located as such, the system has a much more limited environmental impact and proves safer and more reliable than surface-based systems.

Furthermore, the electrical device installed on dry land allows for a simpler system, inasmuch as it does not necessitate the technical workarounds required for submerged systems, with consequent savings in design and construction costs.

In detail System under claim 1 , characterised by the fact that said devices for the transfer of mechanical energy to the generator comprise at least one hydraulic pump connected to the output of said turbine and at least one hydraulic motor connected to an input shaft of said generator.

These inexpensive and reliable devices allow the two components, the turbine and generator, to be located separately, even at distances of over a kilometre, with no constraints owing to the makeup of the sea/ river bed or banks. In particular, the turbine comprises a case accommodating at least one runner supported by a support shaft and fitted with a flotation device to generate sufficient force to counterbalance the weight of the runner when it is immersed in the water.

It is thus possible to reduce friction between the shaft and its supports in the case, decreasing dissipated energy and so increasing the system's output.

Other characteristics and advantages will be clarified in the description of an ideal, but not exclusive, example of the invention's realisation. The description is indicative and therefore not limiting, and is illustrated in the enclosed figures in which:

• Figure 1 is a schematic view of the system to exploit sea or river currents for the production of electric energy, according to the invention

• Figure 2 is a perspective view of the turbine of the system in figure 1

• Figure 3 is a sectional plan view of the turbine in figure 2

• Figure 4 is a side view of the turbine in figure 2

• Figure 5 is a side front view of the turbine in figure 2

• Figure 6 is a schematic perspective view of the runner of the turbine in figure 2

• Figures 7 and 9 are also detail views of the runner in figure 6

With reference to the enclosed figures, the system to exploit sea/ocean or river currents for the production of electric energy 1 comprises at least one turbine, indicated overall with no. 2, and at least one electric device (generator) 3.

In detail, said turbine can be located on the sea bed in an area with currents of at least 0.2 - 0.3 m/s velocity, or else on a river bed, as schematically illustrated in figure 1.

Said turbine 2 has the job of transforming the kinetic energy of the moving fluid, generally water, into mechanical energy through the movement of a mechanical member.

The electrical device (generator) 3, according to the invention, is instead located on dry land, on the sea shore or river bank.

Said electrical device is made up, for example, of an alternator or similar able to convert the mechanical energy produced by the turbine into electrical energy which can be supplied to the grid network via well- known equipment.

According to the invention, the system also consists of a system, indicated overall with 4, to transfer the mechanical energy produced by the turbine 2 to the electrical device 3.

Said system 4 preferably comprises hydraulic equipment to transform the mechanical energy output by the turbine into pressure energy and to transform said pressure energy back into mechanical energy to transfer it to the electrical device.

According to a preferred realisation, said hydraulic equipment 4 comprises a hydraulic pump 5 connected to the output of the turbine 2 suitable to pressurise hydraulic fluid sent via tubing 7 to a hydraulic motor 6 connected to the electrical device 3.

Said hydraulic motor in turn transforms the pressure energy of the hydraulic fluid into mechanical energy which can be utilised by the electrical device 3.

The hydraulic pump 5 can comprise, for example, one or more hydraulic cylinders activated by a crank gear connected to the turbine 3, or else one or more piston, gear or lobe pumps or similar.

The hydraulic motor 6 can, in the same fashion, be made up of one or more hydraulic cylinders which operate a crank gear, or one or more piston, gear or similar motors.

Through a second tube 8, said hydraulic fluid is returned at low pressure to pump 5. Preferably said second tube 7 is fitted with at least one accumulator tank to replenish any losses to the circuit and to guarantee the fluid is always carried correctly inside the pump.

The hydraulic fluid used is preferably biodegradable and non toxic, such that any dispersion in the water or on land does not constitute a source of pollution for the fauna and flora in the area of the installation.

With reference to figures 2 to 5, the system's turbine is illustrated, indicated overall as no. 3.

In detail, said turbine comprises a case 10, fixed to the sea or river bed, inside which at least one runner is housed, indicated overall as no. 1 1.

Said case comprises a body with a first opening 12 for the intake of water directed at the runner 1 1 and a second opening 13 for the output of the water from said runner.

The case 10 is fitted with a convergent conduit 14a, preferably corresponding with the first (intake) opening 12, to accelerate the flow of water directed at the runner 1 1 to increase its effective work and thus also its output.

To the same end, the second (output) opening 13 of the case 10 is fitted with a divergent conduit 14b in order to reduce the velocity of the water flow output from the runner 1 1.

Usefully the intake opening 12 of the case 10 is fitted with a net 30 to prevent the entrance of foreign bodies to the turbine.

Preferably said net 30 is fitted around a pair of motorised rollers 31 which are able to pull it.

This way, if an object or foreign body comes to rest in the net 30 in proximity to the intake opening 12, it can be moved away towards the outside by the movement of the net imparted by the rollers and then carried off by the current.

The case 10 can be attached to the sea or river bed with a pair of poles or posts 34, anchored to the bottom in proximity to the side walls 35 of the convergent conduit 13.

Thanks to the force applied by the sea or river current, the case is pushed in such a way that the convergent walls push against said poles 34, blocking the movement of the case itself.

With reference to figure 6, the runner 1 1 housed in the case 10 of the turbine 2 is illustrated schematically.

The runner can be arranged in the case 10 with its axis of rotation Y being substantially vertical or substantially horizontal.

In greater detail, said runner comprises a number of blades 15 joined to a shaft 16 supported in the case 10.

The number of blades on the runner is preferably between 3 and 10.

According to the invention, said runner 1 1 is fitted with flotation devices 17 in order to apply an opposing force to the weight of the runner when it is immersed in the water.

In this manner it is possible to reduce the forces applied to the supports of the shaft 16 and consequently also the friction and dissipated power.

According to a preferred form of realisation, said flotation devices comprise a hollow, closed body 17, filled with air or another gas.

In detail, said hollow body has a substantially flat disc shape and is mounted centrally on shaft 16.

In detail, the body 17 can be joined to shaft 16 and thus to blades 15, or can be mounted on said shaft with a bearing (not visible in the figure) in such a way that there is no transfer of torque between them but only buoyancy, thus reducing friction and the runner's inertia.

Usefully, the outside of said disc-shaped body 17 can comprise teeth (not shown in the figure), making up a crown wheel to mesh with a pinion mated to an input shaft of the hydraulic pump 5.

In greater detail the blades 15 of the runner 1 1 each comprise a number of sectors 18, hinged on at least one edge to a shaft 19 fitted to the support shaft 16.

In this fashion said sectors can rotate from an active position in which they are substantially perpendicular to the direction of the runner's Peripheral Velocity PV to an inactive position in which they are substantially parallel to the PV direction.

In the active position, said sectors form a substantially flat and continuous blade surface able to receive and transmit the pushing force of the moving water.

In the inactive position on the other hand, said sectors are hit by the fluid along a perpendicular direction, thus presenting minimal resistance to the advancement of the fluid.

In the active position, or when the velocity of the blade is substantially in the same direction as that of the water flow, it is able to receive the full force of the movement of the water flow. In the inactive position, on the other hand, in other words when the velocity of the blade has a direction substantially perpendicular to or against that of the water flow, the blade offers minimum resistance to the advancing water, increasing the efficiency of the runner and thus the system's output.

To this end a system is foreseen, indicated overall with no. 20, to control the rotation of said sectors based on the angular position of the blade with respect to the turbine case.

In this fashion each blade 15 will be in the active position only along the portion of the runner's arc of rotation where it can receive thrust from the water, while it will remain in the inactive position for the remaining portion so as not to provide resistance to the runner.

With reference to figures 7 to 9, said system 20 to control the rotation of the sectors 18 is illustrated.

In detail, said system comprises:

- A cam-profile track 21 attached to the case 10 of the turbine with a variable radial distance from the axis of rotation Y of the runner

- A sliding pin 22 inside said track

- An arm 23 attached to said pin 22 mounted and sliding on shaft 19 which supports the sectors

- A rack 24 attached to said arm 23 to mesh with toothed wheels 25 affixed to the blade's sectors

During rotation of the blade 5, pin 22 slides in the track 21 varying its radial distance from the axis of rotation Y of runner 1 1 and moving the arm 23, attached to it, with respect to shaft 19.

Rack 24, meshing with toothed wheels attached to each sector 19, controls its rotation. In detail, the cam profile of track 21 comprises a first section A in which pin 22 remains at a lesser radial distance from the axis of rotation Y and a second section B in which said pin stays at a greater radial distance.

When sliding in the first section A the sectors will be oriented in the active position, while in section B they will remain in the inactive position.

Said pin 22 and said arm 23 are preferably mounted respectively in track 21 and on shaft 19 with bearings 26 to reduce friction.

Thanks to the present invention it is therefore possible to realise a system for the production of electrical energy which, thanks to the turbine located on the sea or river bed, has a minimal environmental impact and does not affect shipping in the area around the installation.

The system is also cheaper and simpler to realise compared to common submerged systems in that the electrical device or devices used to transform the mechanical energy into electricity, located on dry land, do not need ad-hoc design and planning for use in water.

The turbine runner, thus configured, also allows a notable reduction in dissipated power contributing to an increase in the system's output.

The present invention, as described and illustrated herein, is susceptible to numerous modifications and variants all included in the concept of the invention; moreover, all details may be substituted by other, technically equivalent elements.

Claims

1. Invention of a system to exploit sea/ ocean or river currents for the production of electrical energy, comprising at least one turbine (2) to transform the kinetic energy of moving water into mechanical energy and at least one electrical device (generator) (3) to transform said mechanical energy into electrical energy, characterised by the fact that said turbine (2) is located on the sea or river bed and said generator (3) is located on land, with a system (4) to transfer the mechanical energy from the turbine to the generator (3).

2. System, under claim 1, characterised in that said devices (4) comprise at least one hydraulic pump (5) connected to the output of said turbine (2) and at least one hydraulic motor (6) connected to an input shaft of said electrical device (3).

3. Systems, under any of the preceding claims, characterised in that said turbine (2) comprises a case (10) containing at least one runner (1 1) supported by a support shaft (16), said case (10) being fixed to the sea or river bed.

4. System, under claim 3, characterised in that the case (10) comprises a body with a first opening (12) for the intake of water directed at the runner (11) and a second opening (13) for the output of the water from said runner (1 1).

5. System, according to any of the preceding claims, characterised in that said runner (1 1) is fitted with a flotation device (17) in order to apply an opposing force to the weight of the runner (1 1) when this is immersed in the water.

6. System, according to any of the preceding claims, characterised in that said flotation device (17) comprises at least one hollow, closed body filled with air or another gas.

7. System, under claim 6, characterised in that said body has a disc shape and is connected to the support shaft (16) of said runner.

8. System, according to claim 7, characterised in that there are teeth on the edge of said disc- shaped body to mesh with a pinion attached to an intake shaft of said hydraulic pump (5) .

9. System, according to any of the preceding claims from 3 to 8, characterised in that said runner (1 1) comprises a number of blades (15), each blade comprising a number of sectors (18), hinged on at least one edge to a shaft (19) attached to the support shaft (16), said sectors (18) being able to rotate from an active position in which they are substantially perpendicular to the peripheral velocity (PV) of the runner and forming a substantially flat and continuous surface, to an inactive position in which they are substantially parallel to the PV, with a system (20) provided to control the rotation of said sectors (18) based on the angular position of the blade (15) with respect to the case (10).

10. System, according to claim 9, characterised in that said system (20) comprises:

- A track with a cam profile (21) attached to the case (10) of the turbine (2) with a variable radial distance from the axis of rotation (Y) of the runner

(1 1)

- A sliding pin (22) inside said track (21)

- An arm (23) attached to said pin (22) mounted and sliding on the shaft (19)

- A rack (24) attached to said arm (23) to mesh with toothed wheels (25) affixed to the sectors (18) of the blade (15)

11. System, according to any of the claims from 2 to 10, characterised in that said system (4) to transfer mechanical energy from the turbine (2) to the electrical device (3) comprises at least one primary tube (7) for the sending of pressurised hydraulic fluid from the hydraulic pump (5) to the hydraulic motor (6) and at least one secondary tube (8) for the return of low pressure hydraulic fluid from said hydraulic motor (6) to said hydraulic pump (5), said second tube (8) being fitted with at least one accumulator tank (9).

12. System, according to any of the claims 2 to 1 1, characterised in that the hydraulic fluid used is non toxic and biodegradable.

13. System, according to any of the preceding claims from 3 to 12, characterised in that there is a convergent conduit (14a) in order to accelerate the flow of water towards the runner (11) in correspondence with the first opening (12) of the case (10).

14. System, according to any of the preceding claims from 3 to 13, characterised in that there is a divergent conduit (14b) in order to decelerate the output flow of water in correspondence with the second opening (13) of the case (10).

15. System, according to any of the preceding claims from 3 to 14, characterised in that it comprises a net (30) located in correspondence with the first opening (12) of the case (10), said net (30) being fitted around a pair of motorised rollers (31) which are able to pull it.