GB2456798A

GB2456798A - Power generation apparatus using buoyancy of inflatable bags

Info

Publication number: GB2456798A
Application number: GB0801274A
Authority: GB
Inventors: Misikir Dawit Sisahun
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-01-23
Filing date: 2008-01-23
Publication date: 2009-07-29
Also published as: GB0801274D0

Abstract

An electrical power generation apparatus 10 comprises inflatable devices 18, 20, 30, 32 arranged such that alternate inflation and deflation causes them to move, arranged to drive a generator. The devices may be inflated with hydrogen extracted from water in which the apparatus is situated.

Description

Electrical Power Generation Apparatus

Field of the Invention

The invention relates to the generation of electrical power using renewable energy sources.

Background to the Invention

It is now considered desirable to produce electrical power by means that do not involve burning fossil fuels. Two known methods of generating electrical power without using fossil fuels make use of energy contained in moving bodies of water.

Known hydro electric power stations make use of the potential energy in water falling from a significant height or tidal water movement. Typically, these methods involve investment in large and expensive infrastructure and may give rise to environmental issues. Other known methods of generating electrical power that do not require the use of fossil fuels make use of wind turbines or solar panels.

Summary of the Invention

The invention provides electrical power generation apparatus comprising generator apparatus operable to generate an electrical output in response to an input drive force and a drive apparatus for providing said input drive force, said drive apparatus comprising at least one inflatable device arranged such that sequential inflation and deflation thereof causes movement of the inflatable device that provides said input drive force.

The invention also includes a method of generating electrical power comprising sequentially inflating and deflating at least one inflatable device to cause movement of the inflatable device that provides an input drive force to a generator that is operable to generate electrical power in response to said input drive force.

The invention also includes electrical power generation apparatus comprising electricity generator means, float body means connected with said generator means such that movement of the float body means provides an input drive force for the generator means and means for inputting to said body means a fill gas that is less dense than an environment in which the float body means is to be located such that, in use, said movement of the float body means is obtained by inputting then expelling the fill gas from the from the body means.

Brief Description of the Drawings

In order that the invention may be well understood, some embodiments thereof, which are given by way of example only, will now be described with reference to the drawings in which: Figure 1 is a schematic illustration of an electrical power generation apparatus; Figure 2 is a schematic illustration of an connection unit of the electrical power generation apparatus of Figure 1; and Figure 3 shows the electrical power generation apparatus of Figure 1 on the bed of a body of water.

Detailed Description of the Illustrated Embodiment

Referring to Figure 1, an electrical power generating apparatus 10 comprises a generator apparatus in the form of a dynamo set 12 that is operable to generate an electrical output in response to an input drive force provided by a drive apparatus 14.

The drive apparatus 14 includes a first drive unit 16 comprising a first float body 18, a second float body 20 and an elongate flexible connection device in the form of a chain 22 to which float bodies are connected. The float bodies comprise respective inflatable bags 18, 20 connected to respective ends of the chain 22. The chain 22 runs around and engages a suitable toothed drive wheel 24. The drive apparatus 14 also includes a second drive unit 28, which corresponds to the drive unit 16. The drive unit 28 comprises two float bodies in the form of inflatable bags 30, 32 connected to respective ends of a chain 34. The chain 34 runs around and engages a suitably toothed drive wheel 36.

The toothed drive wheels 24, 36 are connected by shafting 38, 40 to a transmission unit 42. The transmission unit 42 is configured to convert bi-directional rotation of the shafting 38, 40 into uni-directional rotation of an output shaft 43. The output shaft 43 is connected to the dynamo set 12 such that its rotation provides an input drive force to the dynamo set 12.

The dynamo set 12 is electrically connected to an electricity storage apparatus in the form of a suitable battery unit 44. The battery unit 44 stores electrical power output by the dynamo set 12 for use in powering components of the electrical power generating apparatus 10. A suitable regulator 46 is provided between the dynamo set 12 and battery unit 44 to allow the flow of electricity to be controlled so as to prevent overloading of the battery unit.

The drive apparatus 14 additionally comprises a filling, or inflation, system for filling the inflatable bags with a gas that will allow them to float. The inflation system includes a hydrogen extraction apparatus 48 for extracting hydrogen from water to provide a supply of hydrogen gas for filling the inflatable bags. The hydrogen extraction apparatus 48 is powered from the battery 44 and is connected to a reservoir in which the hydrogen extracted from the water is stored. A pump 52 is arranged to pump hydrogen from the reservoir 50 into a conduit system 54 that includes four outlet valves 56, 58, 60, 62. The hydrogen extraction apparatus 48 includes a sensor 64 that outputs signals indicative of the pressure in the reservoir 50 to a controller 66.

The dynamo set 12 is also electrically connected to transformer apparatus 68 from which electrical power generated by the electrical power generation apparatus 10 is conducted to a load, grid or storage apparatus 70 via heavy duty electrical cabling 72.

For ease of reference, in the description that follows, item 70 will be referred to as a load.

The controller 66 includes a computing unit 72 that is programmed to control the operation of the electrical power generation apparatus 10. The controller 66 includes input/output devices for outputting command signals in a form suitable for receipt by components of the electrical power generation apparatus 10, such as the hydrogen extraction apparatus 48, and for receiving input signals from the sensors used to monitor the operation of parts of the electrical power generation apparatus. The controller 66 is powered from the battery unit 44.

Referring to Figure 2, each inflatable bag 18, 20, 30, 32 includes a connection unit 74 located at the base region of the bag where the bag is connected to the respective chain 22, 34. The connection units 74 each comprise a normally closed inlet valve 76 that is configured to engage a respective one of the conduit outlet valves 56, 58, 60, 62. As will be described in more detail below, in use, the inflatable bags 18, 20, 30, 32 make a reciprocating movement as they are sequentially inflated and deflated.

When deflated, the inflatable bags are pulled onto their respective outlet valves 56, 58, 60, 62 to be inflated by hydrogen pumped from the reservoir 50. The connection units 74 are each provided with guide devices 78 that cooperate with respective guides (not shown) associated with the outlet valves 56, 58, 60, 62 to align and guide the inlet valves 76 into engagement with the respective outlet valves. The guide equipment can take any suitable form that will assist in guiding the connection units 74 into position with respect to the outlet valves 56, 58, 60, 62. In the illustrated embodiment, the guide equipment comprises guide devices 78 in the form of conical skirts (shown partly cutaway) that are configured to cooperably engage suitable conical surfaces associated with the respective outlet valves.

The connection units 74 additionally comprise an exhaust valve 80, an onboard pump 82 that is arranged to pump gas from the inflation bag via the exhaust valve and a sensor 84 that provides signals indicative of the gas pressure in the inflatable bag for the controller 66. The connection units 74 are connected with the battery unit 44 and the controller 66 by suitable cabling 86 such that they can receive electrical power from the battery unit and command signals from the controller and the controller can receive signals from the sensor 84. As an alternative to a wired connection, the controller 66 could communicate with the connection units 74 via a suitable wireless communication system (for example using a Bluetooth connection).

As shown in Figure 3, in use, the electrical power generation apparatus 10 is located underwater on, for example, the seabed 100. The parts such as the dynamo set 12, transmission unit 42, battery unit 44, hydrogen extraction apparatus 48 and controller 66 are typically provided on a common structure or frame (not shown) that can be secured to the seabed 100. The inflatable bags 18, 20, 30, 32 are able to float in the sea 102 and are effectively tethered to the structure on the seabed 100 by means of the chains 22, 34.

Under control of the controller 66, the hydrogen extraction apparatus 48 opens suitable valving to let in seawater as indicated by arrow 112 (Figure 1) and extracts hydrogen from it, exhausting the hydrogen depleted water back into the sea 102 as indicated by arrow 114 (Figure 2). The hydrogen extracted from the seawater is received in and stored in the reservoir 50. The controller 66 controls operation of the hydrogen extraction apparatus 48 such that a set gas pressure is maintained in the reservoir 50. The controller monitors the pressure in the reservoir 50 by reference to signals provided by the sensor 64.

Except in cases in which the electrical power generation apparatus is used in a body of water in which there is little or no water movement, it is envisaged that it will be desirable to provide guides for guiding the movement of the inflatable bags 18, 20, 30, 32. In the illustrated embodiment, the guides would be arranged to constrain the inflatable bags to essentially vertical movement (ie limiting lateral movement that might be caused by cuirents or tides). Respective guides 104, 106, 108, 110 for the inflatable bags are shown schematically in Figure 3. The guides 104, 106, 108, 110 could be respective perforated sleeves within which the inflatable bags would be free to move up and down but prevented from making substantial lateral movements.

Alternatively, the guides could take the form of an open frame. For example, a group of three or more upright elongate members may be arranged to define a path within which inflatable bag can rise and fall, but lateral movement is limited. The upright members may be interconnected by bracing members.

At the commencement of an operation cycle of the electrical power generation apparatus 10, the inflatable bag 18 is positioned at the lowermost point of its movement path, or stroke, with its inlet valve 76 engaging the conduit outlet valve 56.

Engagement with the outlet valve 56 opens the normally closed inlet valve 76 to allow inflation of the inflatable bag 18. On receipt of a command from the controller 66, the outlet valve 56 is opened and the pump 52 operates to pump hydrogen from the reservoir into the inflatable bag 18.

Once the inflatable bag 18 reaches a preset fill level, indicated by signals from the sensor 86, the output valve 56 closes. When the inflatable bag 18 is close to being fully inflated, the controller 66 signals the exhaust valve 80 and pump 82 of the inflatable bag 20 to operate. Hydrogen is then pumped from the inflatable bag 20 and once the inflatable bag 20 is sufficiently deflated, the inflatable bag 18 is able to float upwardly due to its relatively increased buoyancy and the relative loss of buoyancy of the inflatable bag 20. Due to their connection by the chain 22, as the inflatable bag 18 floats upwards, it pulls the deflated bag 20 down towards the seabed 100. The arrangement of the electrical power generation apparatus 10 is such that the inflatable bag 18 can float far enough upwards to pull the inflatable bag 20 down to the seabed for its connection unit 74 to move to a position at which its inlet valve 76 can engage with the conduit outlet valve 58. The movement of the chain 22 as the respective inflatable bags 18, 20 rise and fall causes rotation of the drive wheel 24, which in turn rotates the shafting 38. This rotation is transmitted to the dynamo set 12 via the transmission unit 42 and output shaft 43 to provide an input drive force for the dynamo set. In response to the drive force input by the output shaft 43, the dynamo set 12 generates an electrical power output, which is delivered to the load 70 via transformer 68 and the cabling 72 (and when needed to the battery unit 44).

Once the inflatable bag 18 has reached its full height and the inflatable bag 20 is at the bottom of its stroke with its inlet valve 76 engaging the conduit outlet valve 58, inflation of the inflatable bag 20 can commence. The previously described process is then repeated, but with the roles of the inflatable bags 18, 20 and the associated equipment reversed. This sequential inflation and deflation of the two inflatable bags 18, 20 provides for a reciprocating motion of the two inflatable bags, which causes them to impart a back and forth rotation to the shafting 38. The transmission unit 42 converts that rotation into a uni-directional rotation of the output shaft 43, which provides the input drive force to the dynamo set 12. The drive unit 28 operates in exactly the same way as the drive unit 16, with the inflatable bags 30, 32 being sequentially inflated and deflated to provide back and forth rotation of the shafting 40.

The drive unit 28 is controlled to operate out of phase with the drive unit 16 so that between the two drive units, a substantially continuous input drive force is provided to the dynamo set 12.

It will be appreciated that the connection between the float bodies and the shafting does not have to be via a single chain. A set of chains arranged side-by-side and engaging respective side-by-side sprocket wheels could be used. As an alternative it is envisaged that for some applications a connection device comprising rigid portions extending from the float bodies and interconnected by a flexible portion could be used. Such rigid portions could be used to cooperate with guides to guide movement of the float bodies. It is also envisaged that for some applications, most likely in a relatively still body of water, it may be appropriate to use a rigid connection between the float bodies and the input shafting. It will be appreciated that in such an arrangement the rigid connection would pivot about an axis defined by the shafting and that this arrangement is likely to limit the length of the reciprocating movement of the float bodies.

In the embodiment, the float bodies are inflated using hydrogen. However, this is not essential. The float bodies may in principle be inflated using any suitable gas to provide the buoyancy necessary to cause them to reciprocate. An advantage of using hydrogen is that in cases in which the apparatus is located underwater, the hydrogen can be readily extracted from the surrounding water.

For some embodiments, it may be desirable to provide securement of the float bodies while they are being filled. Securement can be provided in any convenient manner and may be achieved by using one or move suitably positioned electro-magnets.

While it is currently envisaged that at least the float bodies will be located in a body of water, this is not essential. The electrical power generation apparatus could be entirely land-based. In that case, it would be necessary to ensure that the float bodies are filled using a gas that is less dense than ambient air. The fill gas may be heated air. However, it will be understood that it is advantageous to have the bodies located in a body of water due to the significantly increased difference in the density of water and a gas as compared with the difference between two different gases.

It will be understood that instead of being inflatable bags, the float bodies may comprise lightweight rigid or semi-rigid bodies. In this case, the float body would need to be configured to admit a replacement fluid as the fill gas is expelled. For example, where the float body is to be located in a body of water, it may be provided with a valve that opens to admit water as the fill gas is expelled. Some embodiments, employing such an arrangement may dispense with the pump on the connection unit and rely on the water to push the fill gas out of the float body. It may be desirable to have a free floating separation member within the float body that during gas tilling and expulsion would move in the float body according to the opposing pressures acting on it as the fill gas is input and expelled.

It will be understood that the float bodies can be connected with a reservoir for receiving the expelled fill gas. The fill gas could then be recycled by pumping it up to pressure for refilling the float bodies in subsequent cycles. In embodiments using a hydrogen extraction apparatus as shown in Figure 1, this would reduce the need to operate the hydrogen extraction apparatus. The connection for return of the fill gas can include a flexible conduit or make use of passages defined by the guides. As an alternative to recycling the hydrogen, it may be stored in this way and then collected for other uses.

Claims

Claims I. Electrical power generation apparatus comprising generator apparatus operable to generate an electrical output in response to an input drive force and a drive apparatus for providing said input drive force, said drive apparatus comprising at least one inflatable device arranged such that sequential inflation and deflation thereof causes movement of the inflatable device that provides said input drive force.
2. Electrical power generation apparatus as claimed in claim 1, comprising a plurality of inflatable devices connected by an elongate connection device such that said sequential inflation and deflation causes reciprocating movement of said connection device.
3. Electrical power generation apparatus as claimed in claim 2, wherein said drive apparatus comprises a plurality of drive units, each said drive unit comprising a said elongate connection device connecting a plurality of inflatable devices.
4. Electrical power generation apparatus as claimed in claim 3, wherein said drive units operate out of phase so as to provide a substantially continuous input drive force.
5. Electrical power generation apparatus as claimed in claim 2, 3 or 4, wherein the elongate connection device comprises a flexible connection device.
6. Electrical power generation apparatus as claimed in any one of the preceding claims, comprising an inflation system for inflating the or each said inflatable device, the or each said inflatable device comprising a connection unit for releasably connecting with the inflation system to facilitate inflation of the inflatable device.
7. Electrical power generation apparatus as claimed in claim 6, wherein said connection unit comprises a guide device for guiding the connection unit into engagement with the inflation system.
8. Electrical power generation apparatus as claimed in any one of the preceding claims, wherein the or each said inflatable device comprises a pumping system for deflating the inflatable device.
9. Electrical power generation apparatus as claimed in any one of the preceding claims, comprising hydrogen extraction apparatus for extracting hydrogen from water to provide a supply of hydrogen for inflating said inflatable devices.
10. Electrical power generation apparatus as claimed in claim 9, wherein said hydrogen extraction apparatus is powered by said generator apparatus.
11. Electrical power generation apparatus as claimed in any one of the preceding claims, comprising guides defining a movement path for the or each said inflatable device.
12. Electrical power generation apparatus as claimed in any one of the preceding claims, wherein the or each said inflatable device is an inflatable bag.
13. Electrical power generation apparatus as claimed in any one of the preceding claims, wherein said movement of the or each said inflatable device is a reciprocating movement and comprising a transmission unit for connecting said reciprocating movement into a rotational input drive force.
14. An installation comprising an electrical power generation apparatus as claimed in any one of the preceding claims, wherein the or each said inflatable device is located in a body of water.
iS. An installation as claimed in claim 14, wherein the or each said inflatable device is inflated with hydrogen.
16. A method of generating electrical power comprising sequentially inflating and deflating at least one inflatable device to cause movement of the inflatable device that provides an input drive force to a generator that is operable to generate electrical power in response to said input drive force.
17. A method of generating electrical power as claimed in claim 16, comprising inflating said at least one inflatable device with hydrogen gas.
18. A method of generating electrical power as claimed in claim 17, wherein said hydrogen gas is extracted from a body of water.
19. A method of generating electrical power as claimed in claim 16, 17 or 18, wherein the or each said inflatable device is disposed in a body of water.
20. Electrical power generation apparatus comprising electricity generator means, float body means connected with said generator means such that movement of the float body means provides an input drive force for the generator means and means for inputting to said body means a fill gas that is less dense than an environment in which the float body means is to be located such that, in use, said movement of the float body means is obtained by inputting then expelling the fill gas from the from the body means.
21. Electrical power generation apparatus as claimed in claim 20, comprising a plurality of interconnected float body means arranged such that sequential inputting then expelling said gas provides a reciprocating movement.
22. Electrical power generation apparatus as claimed in claim 21, comprising transmission means for converting said reciprocating movement into a rotational input drive force.
23. Electrical power generation apparatus as claimed in claim 20, 21 or 22, comprising means for recirculating the expelled fill gas.
24. Electrical power generation apparatus substantially as herein described with reference to the drawings.
25. A method of generating electrical power substantially as herein described with reference to the drawings.