WO2024180315A1

WO2024180315A1 - A marine vessel and an apparatus therefor

Info

Publication number: WO2024180315A1
Application number: PCT/GB2024/050406
Authority: WO
Inventors: Nigel Stuart BARRETT
Original assignee: Barrett Nigel Stuart
Priority date: 2023-02-28
Filing date: 2024-02-15
Publication date: 2024-09-06

Abstract

A marine vessel having a hull (2) and a hull interior, the marine vessel further comprising a flow tunnel (9) arranged in the hull interior providing a seawater flow path (9'), the flow tunnel having an inlet (6) penetrating the hull under the waterline (7), an outlet penetrating the hull and an impeller (28) arranged in the seawater flow path, the impeller rotating a rotor (29) of an electrical generator apparatus (21,22,23) for producing electricity 10 from rotation of the impeller.

Description

A MARINE VESSEL AND AN APPARATUS THEREFOR

The present invention relates to a marine vessel and an apparatus therefor .

Marine vessels , such as : merchants ships including container ships , oil tankers , chemical carriers and bulk carriers ; and passenger-carrying ships including ferries and cruise ships , are propelled by one or more propulsion means . The propulsion means usually comprises an impeller connected to a prop shaft rotated by a large diesel engine, which may operate in either two-stroke or four stroke . Steam turbines may be used together with or in place of a large diesel engine . The fuel used is generally heavy fuel oil, marine fuel oil, coal or liquified natural gas , which are all generally fossil fuels . Onboard electricity is usually generated by a diesel generator . A biproduct of using such fuels is carbon dioxide, which is a greenhouse gas . It is now desired to minimise such carbon dioxide emissions and improve the efficiency of a ships power usage .

Energy may be captured from tidal flows and wave motion . Capturing energy from tidal flows may involve using fixed barriers arranged transverse to the direction of the general direction of the tidal flows . The barrier may have a series of short sections of tubes arranged therein providing a flow path for the tidal water . The short sections of tubes may each have an impeller arranged therein such that upon tidal waters flowing therethrough, the impeller rotates . The impeller drives a prop shaft driving an electrical generator to generate electricity . These barriers are generally located in areas close to shore in estuaries or water inlets subject to large tidal flows .

Sailing boats may be provided with solar panels , diesel generators or outboard hydrodynamic impellers turning a rotor of an electrical generator to produce a flow of electricity to charge a bank of onboard batteries . Onboard equipment, such as lighting, communications and navigation equipment and galley equipment, such as a fridge, hotplate, dishwasher and washing machine.

The classes of marine vessels which appear to the inventor to be particularly inefficient, using a large quantity of fossil fuels comprise:

Aframax - medium-sized oil tankers with an approximate weight of 120,000 DWT (deadweight tonnage) . The beam of the vessel is restricted to 32.3 metres.

Chinamax - amongst the largest bulk carrier ships in the world and are often classified under Very Large Ore Carriers (VLOC) . Chinamax ships have a Dead Weight Tonnage (DWT) of up to 400,000 tonnes and measure about 360 metres lengthwise with a beam of about 65 metres and a draft of about 25 metres. Valemax vessels are also of a similar size .

Handymax - generally small-sized cargo ships with a load-carrying capacity of up to 60,000 tonnes, typically 150-200m in length. Supermax bulk cargo vessels are also of a similar size.

Capesize - vessels which are too large to pass through the canals of Panama and Suez and thus generally traverse through the Capes of Good Hope and Horn. Capesize vessels usually have 150,000 DWT tonnage capacity and form a majority of bulk carrier ships. Very Large Bulk Carriers (VLBC) and Very Large Ore Carriers (VLOR) with more than 200,000 DWT. Presently, ship sizes with maximum DWTs of about 400,000 tonnes are classified under the Capesize vessel category.

Suezmax - the largest ship that can pass through the Suez Canal. A typical Suezmax vessel has a capacity of 120,000 to 200,000 DWT with a maximum 20.1 drafts with a beam no wider than 50.0m (164.0 ft) or 12.2m (40 ft) of draught for ships with a maximum allowed beam of 77 .5m. Suezmax ships have lengths of about 275 metres stipulated as per the Suez Canal passage requirements .

Q-Max - the vessels are colloquially referred are the biggest known LNG tanker ships . The Q-max' s have been specifically built to suit the entryway of the Liquefied Natural Gas depot of Ras Laffhan in the middle-east Asian country of Qatar . These cargo ships have a capacity to carry about 266, 000 cubic metres of LNG .

Malaccamax - the largest size of ship which is capable of passing through the Strait of Malacca . These vessels are often associated with Very Large Crude Carriers (VLCCs) , though a specific assignation to their ship size has been annotated . These ship sizes measure about 400 metres lengthwise with a DWT up to 165 , 000 DWT . Used for both bulk carriers and supertankers .

Very Large Crude Carriers (VLCC' s) - Supertankers that have a maximum DWT of 320 , 000 tonnes are classified as VLCCs .

Ultra Large Crude Carriers (ULCC' s) - Cargo carrying supertankers having DWT range of 320 , 000 to 550 , 000 are classified as ULCCs . These cargo vessels are the biggest carrying tanker vessels with select areas of operation extending to European, Northern American and certain Asian harbours and port facilities .

Seawaymax - the Saint Lawrence Seaway forms an important sea passage between the water routes spanning linking United States and Canada . Seawaymax vessels are thus those vessels that can easily pass through this important waterway . Such kinds of vessels have lengths of about 226 metres with widths of about 24 metres and drafts up to eight metres .

Panamax and New Panamax - ships that are designed to travel through the Panama Canal . The ship classification indicates the minimum dimensions required by the ship to be able to pass smoothly through the Panama Canal . The sizes of Panamax ships are determined by considering the dimensions of the smallest lock of the canal . Those ships which do not fall under the dimension criteria of Panama' s vessel are known as Post-Panamax Vessels .

The inventor has noted that energy can be captured from moving water in which the marine vessel floats . The inventor has noted that energy can be captured from moving water in which the marine vessel moves or floats when stationary, such as when at anchor, moored or docked . The inventor has noted that energy can be recovered when the marine vessel is decelerating . A marine vessel of a significant size moving at full speed has a considerable amount of momentum which could be recorded and used for power generation .

In accordance with the present invention, there is provided a marine vessel having a hull and a hull interior, the marine vessel further comprising a flow tunnel arranged in the hull interior providing a seawater flow path, the flow tunnel having an inlet penetrating the hull under the waterline, an outlet penetrating the hull and an impeller arranged in the seawater flow path, the impeller rotating a rotor of an electrical generator apparatus for producing electricity from rotation of the impeller .

Optionally, a selectively openable door is arranged to substantially cover the inlet opening in the hull . The door may simply facilitate flow of water thereover to minimise skin friction over an opening in the hull which may otherwise unduly increase overall friction between the hull and the seawater in which the vessel travels . The door may also be water-tight to inhibit ingress of seawater, so that the flow tunnel can be evacuated of water when the electrical generator apparatus is not in use . Thus , the marine vessel does not carry extra weight unnecessarily when travelling the oceans . Optionally, the flow tunnel is provided with a shut-off valve to selectively open and close the seawater flow path . The shut-off valve may be activated to close to inhibit ingress of seawater, so that the flow tunnel can be evacuated of water through drain points , when the electrical generator apparatus is not in use . Thus , the marine vessel does not carry extra weight unnecessarily when travelling the oceans . Optionally, the flow tunnel is provided with a control valve to regulate the flow of seawater through the seawater flow path . The control valve may regulate the flow rate of water therethrough by restricting the size of an opening through which the seawater passes or may use other known techniques to reduce the pressure of the seawater flowing in the flow path . This may reduce the chance of overloading the electrical generator apparatus and damage or cavitation occurring to the impeller .

The inlet opening may be arranged perpendicular to the flow natural flow of seawater when the marine vessel is underway . Optionally, the opening may be arranged at an oblique angle to the natural flow of seawater when the marine vessel is underway . Optionally, the opening is planar with the portion of the hull the opening is located in . Optionally, the inlet opening is arranged in a bow end of the hull . Openings in the side of the hull may allow water currents and tidal flows to push seawater therethrough, rotating the impellers in the flowpath to generate electricity, whilst the ship is underway or at anchor . Flow of water through the openings in the hull particularly but not exclusively in a side of the hull may affect the directional stability of the ship when underway, but may be compensated for by computer controlled adjustment of the rudder, with an appropriate directional feedback system. Furthermore, flow of water through the openings in the hull particularly but not exclusively in a side of the hull may affect the roll, pitch, yaw, surge, sway and heave of the ship when at anchor or underway, but may be compensated for by computer controlled adjustment of known stability control surfaces around the ship, with an appropriate feedback system.

Optionally, at least one further electric generator apparatus is provided in the flow tunnel . Optionally, the at least one further electric generator apparatus is in series with the electric generator apparatus , the at least one further electric generator apparatus has an impeller which is rotated by seawater which has already rotated the impeller of the electric generator apparatus . Optionally, the electric generator apparatus further comprises a second impeller on a common rotor, such that the two impellers are arranged in parallel to the flow of seawater therethrough .

Optionally, there is provided a debris control apparatus in the seawater flow path . Optionally, the debris control apparatus comprises a series of blades to shred any large pieces of debris , such as seaweed to inhibit binding of the seaweed in the impeller of the electric generator apparatus . Optionally, the debris control apparatus comprises a filter element .

Optionally, the flow tunnel comprises at least a portion of circular cross-section . Optionally, the flow tunnel comprises at least a portion of rectangular crosssection . The rectangular section may be oblong or square .

Optionally, the marine vessel comprises a battery bank to store electric energy produced by the electric generator apparatus . Optionally the marine vessel comprises a desalination plant powered directly or indirectly by the electric generator apparatus .

Optionally, the marine vessel comprises a side inlet opening distant to the inlet opening . Optionally, the side inlet and inlet opening feed a common electric generator apparatus . Optionally, the side inlet opening is arranged in a side of the hull . Optionally, the side inlet comprises a scoop for facilitating flow of seawater into the tube of the flow tunnel . Optionally, the scoop comprises a door for selectively closing off flow of seawater through the side inlet opening .

Optionally, the outlet opening is located in a stern wall of the hull . Optionally, the outlet opening is located behind a propeller of the marine vehicle . Optionally, the opening is located to allow seawater to flow therefrom above and into a wake of the marine vessel .

Optionally, the apparatus further comprises an electrolysis apparatus for producing hydrogen from clean water, the power for the electrolysis apparatus provided by the electrical generator . The apparatus may further comprises a desalination plant , power for the desalination plant provided by the electrical generator .

Optionally, the flow tunnel is made of thin walled tubing or circular or square section . The thin wall may be steel, stainless steel, aluminium, chrome, or composite material such as carbon fibre and may comprise several layers of different materials , and may be rigid or flexible and may have a wall thickness in the order of between 1mm and 100mm.

The present invention also provides an apparatus for use in a marine vessel, the apparatus comprising a flow tunnel arrangeable in a hull interior of a marine vessel, the flow tunnel for providing a seawater flow path, the flow tunnel having : an inlet and an inlet valve; an outlet and an outlet valve; a drain point valve; and an impeller arranged in the seawater flow path, the impeller rotating a rotor of an electrical generator apparatus for producing electricity from rotation of the impeller .

An apparatus for capturing energy from flowing water, the apparatus comprising a flow tunnel providing a water flow path, the flow tunnel having : an inlet and an inlet valve; an outlet and an outlet valve; an optional drain point valve; and an impeller arranged in the seawater flow path, the impeller rotating a rotor of an electrical generator apparatus for producing electricity from rotation of the impeller . Optionally, the apparatus is located in a river or an estuary . Optionally, the marine structure is fixed to a bed of the river or estuary or tethered to a riverbank . Optionally, the apparatus is arranged on a pad on the seabed, the pad optionally fixed to the bed on piles . The marine structure may be suitable for use in freshwater rivers or brackish water estuaries . Optionally, the apparatus is sized to be containerized . Optionally, the apparatus is sized to fit into a single ISO container, optionally a 40 ' and optionally a 20 ' ISO container, wherein the apparatus may be dismantled into two or more parts to fit into one or two such containers . Optionally, the apparatus is lifted into position of use using a crane .

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference will now be made, by way of example, to the accompanying drawings , in which :

Figure 1 is a schematic top view of an apparatus in accordance with the present invention in a marine vessel in accordance with the present invention, with some hidden parts of the apparatus shown;

Figure 2 is a schematic side view of the apparatus shown in Figure 1 ;

Figure 3 is a schematic end view of a biological and debris control device of the apparatus shown in Figure 1 ;

Figure 4 is a scrap sectional end view of an electric generator apparatus in the apparatus shown in Figure 1 ; Figure 5 is a side view of the electric generator apparatus in the apparatus shown in Figure 1 ;

Figure 6 is a top view of the electric generator apparatus in the apparatus shown in Figure 1 ;

Figure 7 is a view taken from line VII-VII of Figure 6;

Figure 8 is a schematic top view through a section of a marine vessel of the invention comprising an apparatus of the invention; and

Figures 9A and 9B shows an optional detail of the present invention shown when in-use and in a stowed position .

DETAILED DESCRIPTION

Referring to Figure 1 there is shown a marine vessel 100 floating in seawater 5 , the marine vessel 1 comprising an apparatus for capturing energy 1 .

The marine vessel 1 comprises a hull 2 having a bow end 3 and a stern end 4 . The hull 2 is generally made from rolled steel plate with T-bars (not shown) welded thereto to provide rigidity . The hull 2 is shaped to reduce displacement of marine vessel 1 when floating in the seawater 5 . The bow end 3 comprises an opening 6 in the hull 2 below waterline 7 through which seawater 5 selectively flows through an open door 8 (shown closed in Figures 1 and 2 ) into a tube 9. The door 8 is provided with an electrically controllable motor (not shown) and door opening mechanism (not shown) to selectively open and close the door 8 . The tube 9 is of circular outer cross-section defining a circular inner surface defining a circular cross-section flow path 9' , but may be of any suitable inner and out cross-sectional shapes , such as square, rectangular, pentagonal, hexagonal, heptagonal, octagonal or any other suitable cross-section . The tube 9 is made from a steel, which may be galvanised, but may be made of any suitable material for conveying seawater, such as stainless steel, coated steel, plastics or composite pipe . The tube 9 is optionally provide with a valve 10 to control the flow of seawater 5 . The valve 10 is optionally a quarter turn ball valve, needle valve or plate valve . The flow path continues through the valve 10 into an optional converter 11 . The converter 11 coverts the circular cross-section of the tube 9 to a rectangular cross-section conduit 12 .

An optional biological and debris control apparatus 13 is provided in the flow path in conduit 12 to filter out any debris and biological material, such as seaweed from the seawater 5 flowing therethrough . The biological and debris control apparatus 13 comprises a rectangular inlet connector section 14 connected to the rectangular section conduit 12 , a slot 15 for receiving a biological and debris control device 16 and a rectangular outlet connector section 17 for connection with a rectangular section conduit section 18 . The debris may be collected and disposed of at harbour . A drain point 18 ' is provided to enable the system to be drained of seawater and debris for maintenance .

Referring to Figure 3 , the debris control device 16 may comprise a frame 19, optionally made from a metal or plastics material . The frame 19 has a central opening in which are arranged offset blades 20 for slicing pieces of debris , such as seaweed . The debris control device 16 may be removable from the slot 15 to enable cleaning, replacement and servicing .

The flow path continues through rectangular conduit 18 to one or more (three shown) generator apparatuses 21 , 22 and 23 . Each generator apparatus is substantially identical . Generator apparatus 21 is shown in detail in Figures 4 to 7 . The rectangular conduit 18 has an opening 24 in a top surface 25 which is provided with a bell cover 26 completely enveloping the opening 24 . A pair of impellers 27 and 28 are arranged to rotate about an axis substantially perpendicular to the direction of flow of fluid through the conduit 18 . The impellers 27 and 28 are spaced apart a distal end of a common rotor 29 arranged substantially in line with the top 25 of the conduit 18 , such that impeller blades 30 are subject to direct flow of seawater through the flow path on an under side 31 and to a longer path through the bell housing on an upper side 32 . Each blade 30 may be shaped and may include a scoop portion 30 ' to facilitate transfer of energy from the flow of seawater thereover into rotating the common rotor 29. In an alternative embodiment , only one impeller or several impellers may be used in place of the two rotors shown in the figures .

An electric generator 33 is arranged on a proximal end of the common rotor 29. The electric generator 33 may comprise a rotor (not shown) connected to the common rotor to rotate therewith and a stator (not shown) static with electric generator housing 34 and associated electric wire coils and magnets , as known in the art . Ends of the generator coil (s) (not shown) end in a connection box 35 for onward connection to a battery bank 36.

Alternatively, the electric generator 33 may be replaced with an electric generator 37 , having a rotor (not shown) connected to a proximal end of the common rotor 29 via a knuckle joint 38 , so that the electrical generator 37 is arranged at right angles to the common rotor 29. Alternatively, or additionally, a gearbox may be arranged between the common rotor 29 and the rotor (not shown) of the electric generator 33 , 37 . The electric generator 33 , 37 may be an AC generator producing AC voltage and may be provided with an inverter (not shown) to convert AC to DC for changing batteries in the battery bank 36.

Figures 4 and 5 show details of the electric generator apparatus 21 . The bell cover 26 comprises a front planar plate 40 and a semi-cylindrical roof portion 41 . Lifting lugs 42 are provided to facilitate inspection, repair and replacement of the electric generator apparatus 21 and parts thereof . Bearings 29' are provided in front planar plate 40 and rear wall 43 of the bell cover 26, through with common rotor 29 is rotatable . Interior and exterior corners of 44 of the conduit 18 are curved, which may reduce skin friction and improve flow of seawater therethrough over square corners . It is preferred that the speed of seawater through the conduit 18 is maintained in a laminar flow state, although it is envisaged that there may be some turbulent flow therein .

The conduit 18 extends closer to the stern of the marine vessel 1 , at which point an end of the conduit 18 is provided with a converter 45 which converts the rectangular section to a circular cross-section . A valve 46 is connected between the converter 45 and a circular cross-section tube 47 leads to an opening 48 in the stern 4 of the marine vessel and is welded about the perimeter of the tube 47 to provide with a water-tight seal about the tube 47 . A stern door 49 may be provided to selectively open and close the flow path 9' . The stern door may simply be a flap hinged at a top of the stern door 49.

In use, an initiation instruction is sent to a controller 52 to open door 8 . The initiation instruction may be entered manually into a computer device 50 via a user input interface 51 , such as a keyboard, mouse, microphone or joystick or may be an automated instruction from a computer program executed within the computer 50 . The instruction may be sent at any time during a voyage, but may be sent when the marine vessel 1 is slowing down to enter a harbour, or when at anchor in a tidal flow, or underway in a current or tidal flow . Once the door 8 is open, the controller 52 opens valves 10 and 46 or confirms the valves 10 and 46 are open . Seawater flows through the flow path 9' from the bow 3 into tube 9, through open valve 10 , through biological and debris control apparatus 13 and on to impellers 27 and 28 of the electric generators 21 , driving the impellers , rotating common rotor 29 and thus rotor of the generator 34 producing an electric current , which flows through wires 36' into the battery bank 36. Impellers of electric generator apparatus 22 and 23 similarly rotate and produce electric current for charging batteries in a battery bank or other onboard uses , such as running a desalination plant or powering electrodes in the production of green hydrogen gas from water . Optionally, the electric generator apparatus 22 and 23 powers such uses directly without the need to store the produced electricity in a battery bank 36. If the energy is transferred from momentum in the ship to electrical energy .

Referring to Figure 8 , there is shown a further embodiment of the invention, similar parts of the marine vessel 101 will be referred to by the same reference numerals in the 100 series . The marine vessel 101 , which may be a container vessel, comprises a hull 102 having a bow end 103 and a stern end 104 . The bow end 103 has a pair of doors 108 : one door 108 on the port side and one on the starboard side . The pair of doors 108 is located in the hull 102 below the waterline of the vessel 101 when fully loaded and optionally, when carrying no load (no ISO containers) . Each door 8 covers an opening 106 of optionally between 0 .25sqm and 2 .5sqm and may optionally be of circular cross-section with an optional flared opening to improve the chances of obtaining laminar flow of seawater through tubes 109, to which the openings 106 are connected . A further pair of side doors 108" is located further back in the hull 102 : one side door 108" in the port side and one side door 108" in the starboard side . A further tube 109" extends from each side door to a joint opening 161 in corresponding tubes 109. An optional valve 160 is located in at the joint opening to allow seawater to flow through either tube 109 or tube 109" or both tube 109 and tube 109" and on into tube section 109" ' and into electric generator apparatus 121 .

The marine vessel 101 may further comprise a directional control system (not shown) comprising a computer for controlling adjustment of the rudder, with a directional feedback system for compensating for any effect caused by the flow of seawater through the opening and the flow tunnel, whilst the marine vessel, such as a ship is underway .

The marine vessel 101 may further comprise a stability control system (not shown) comprising a computer for adjusting stability control surfaces around the marine vessel, such as a ship, with a stability feedback system for any effect caused by the flow of seawater through the opening and the flow tunnel whilst underway or at anchor .

Referring to Figure 9A and 9B each side door 108" may be openable to form a scoop 108" ' to facilitate diversion of flow of seawater through the opening 106" into the tube 109" . The side door 108" may be closable so that the door is planar with the hull 102 .

The flow of seawater through impellers (not shown) rotates a rotor 129 of electric generator 133 to produce electricity turning kinetic energy in the flow of seawater into electrical energy . The produced electric current flows through wires 136' to charge and store energy in battery bank 136. The battery bank 136 is connected to and powers a desalination plant 163 and a green hydrogen producing plant 164 . Seawater flows from the electric generator apparatus 121 through conduit 118 to a stern of the vessel and through a stern opening 148 in the hull 102 in the stern end 104 . The stern opening 148 may be arranged above or below the waterline and may be arranged behind or in front of the propellers (not shown) of the marine vessel 101 or to one side of , above or below the propellers . The stern opening 148 may be arranged to exit the marine vehicle within any wake produced by the marine vehicle . The stern opening 148 may be provided with a hinged flap (not shown) other selectively opening and closing door (not shown) or may simply be a permanent opening .

It is envisaged that the green hydrogen producing plant 164 will incorporate an electrolysis stage using electrodes .

It is envisaged that in other embodiments of the invention, the arrangement of impellers shown in the figures may be replaced with any similar adapted arrangements used in rotary positive displacement pumps , such as a gear pump, screw pump, rotary vane pump or downhole pump used in the oil well drilling industry . Thus the axis of the rotor may be in-line with the direction of flow of seawater through the conduit .

It is envisaged that the door 8 may be slideable along the exterior of the hull to open and close . Alternatively, it is envisaged that the door 8 is hinged, such that the door selectively closes to be substantially planar with the outer surface of the hull and an open position within the hull and may open to a substantially perpendicular position within the tube 9 . It is envisaged the door 8 may be provided with metal-to-metal seals or plastics material seals to facilitate a hard-wearing water-tight seal between the door 8 and the opening 6 in the hull . The main functions of the door are : to reduce or inhibit flow of water through the apparatus 1 ; to minimise hull skin friction when the apparatus is not in use, such as when it is not desired to generate electricity using the apparatus ; and to provide a water tight seal . It should be noted that if there is a water leak between the hull and the tub 9, it will not cause a major problem, as water would simply be contained by the valve 10 .

It is also envisaged that the opening in the hull may be provided with a flared opening to improve the chances laminar flow to be maintained in the seawater flowing through the tube 9 and conduits 12 , 18 .

Claims

1 . A marine vessel having a hull (2 , 102 ) and a hull interior, the marine vessel further comprising a flow tunnel ( 9, 109) arranged in the hull interior providing a seawater flow path ( 9' 109' ) , the flow tunnel having an inlet ( 6, 106) penetrating the hull under the waterline (7 ) , an outlet penetrating the hull and an impeller (28) arranged in the seawater flow path, the impeller rotating a rotor (29) of an electrical generator apparatus (21 , 22 , 23) for producing electricity from rotation of the impeller .

2 . A marine vessel as claimed in Claim 1 , wherein a selectively openable door (8 , 108) is arranged to cover the inlet opening in the hull .

3 . A marine vessel as claimed in Claim 1 or 2 , wherein the flow tunnel is provided with a valve (10) to selectively open and close the seawater flow path .

4 . A marine vessel as claimed in Claim 3 , wherein the valve is a shut-off valve and a drain point (18 ' ) is provided in said flow tunnel, said shut-off valve may be activated to close to inhibit ingress of seawater into said flow tunnel, so that the flow tunnel can be evacuated of water through said drain point .

5 . A marine vessel as claimed in any preceding claim, wherein the inlet opening is arranged in a bow end (103) of the hull .

6. A marine vessel as claimed in any preceding claim, wherein the inlet opening may be arranged to have at least a portion of the opening perpendicular to the flow natural flow of seawater when the marine vessel is underway sufficient to allow a continuous uninterrupted flow into the flow tunnel .

7 . A marine vessel as claimed in any preceding claim, wherein the opening is planar with the portion of the hull .

8 . A marine vessel as claimed in any preceding claim, further comprising a debris control apparatus (13 ) in the seawater flow path .

9. A marine vessel as claimed in any preceding claim, further comprising a battery bank (36, 136) to store electric energy produced by the electric generator apparatus .

10 . A marine vessel as claimed in any preceding claim, the electric generator apparatus further comprising a second impellor on said rotor .

11 . A marine vessel as claimed in any preceding claim, further comprising at least one further electric generator apparatus (22 , 23) in the flow tunnel .

12 . A marine vessel as claimed in Claim 11 , wherein the at least one further electric generator apparatus is in series with the electric generator apparatus .

13 . A marine vessel as claimed in any preceding claim, further comprising a side inlet opening (106" ) distant to the inlet opening .

14 . A marine vessel as claimed in Claim 13 , wherein the side inlet opening is arranged in a side of the hull .

15 . A marine vessel as claimed in Claim 13 , further comprising a directional control system comprising a computer for controlling adjustment of the rudder, with a directional feedback system for compensating for any effect caused by the flow of seawater through the opening and the flow tunnel .

16. A marine vessel as claimed in Claim 13 , further comprising a stability control system comprising a computer for adjusting stability control surfaces around the ship, with a stability feedback system for any effect caused by the flow of seawater through the opening and the flow tunnel .

17 . A marine vessel as claimed in Claim 13 , 14 or 15, wherein the side inlet comprises a scoop for facilitating flow of seawater into the tube (109" ) .

18 . A marine vessel as claimed in any preceding claim, wherein the outlet opening is located in a stern wall of the hull .

19. A marine vessel as claimed in any preceding claim, further comprising an electrolysis apparatus for producing hydrogen from clean water, the power for the electrolysis apparatus provided by the electrical generator apparatus .

20 . A marine vessel as claimed in any preceding claim, wherein further comprising a desalination plant , power for the desalination plant provided by the electrical generator apparatus .

21 . An apparatus for capturing energy from a marine vessel, the apparatus comprising a flow tunnel ( 9, 109) arrangeable in a hull interior of a marine vessel, the flow tunnel for providing a seawater flow path, the flow tunnel having : an inlet ( 6, 106) and an inlet valve (10) ; an outlet (48 , 148) and an outlet valve (46) ; a drain point (18 ' ) ; and an impeller (28) arranged in the seawater flow path, the impeller rotating a rotor (29) of an electrical generator apparatus (21 , 22 , 23) for producing electricity from rotation of the impeller .

22 . An apparatus for capturing energy from flowing water, the apparatus comprising a flow tunnel, the flow tunnel for providing a water flow path, the flow tunnel having : an inlet and an inlet valve; an outlet and an outlet valve; and an impeller arranged in the water flow path, the impeller rotating a rotor of an electrical generator apparatus for producing electricity from rotation of the impeller .