WO2023187359A1

WO2023187359A1 - Energy harvesting apparatus, system and method of manufacture

Info

Publication number: WO2023187359A1
Application number: PCT/GB2023/050799
Authority: WO
Inventors: Karthikeyan Velayutham
Original assignee: Katrick Technologies Limited
Priority date: 2022-03-29
Filing date: 2023-03-28
Publication date: 2023-10-05
Also published as: TW202407213A; GB2617317B; GB2617317A; GB202204477D0

Abstract

An energy harvesting apparatus is disclosed. The energy harvesting apparatus comprises a central spindle, and one or more radial arms mechanically connected to the central spindle and extending radially from the central spindle. Each arm has one or more turbines mechanically connected to the arm. The central spindle, one or more radial arms and turbines are located within a duct. In use, rotation of the turbine drives rotation of the one or more radial arms, which drives rotation of the central spindle. The energy harvesting apparatus provides an alternative apparatus for generating renewable energy with numerous advantages. The apparatus harvests energy from a greater cross-sectional area, has minimal negative environmental impact and is suitable for numerous locations and applications.

Description

1 Enerqv Harvestinq

, System and Method of Manufacture

2

3 The present invention relates to an energy harvesting apparatus, system and method of

4 manufacture. In particular, the energy harvesting apparatus is suitable for harvesting

5 energy from a fluid flow, such as wind, to produce renewable energy.

6

7 Backqround to the Invention

8

9 A conventional horizontal-axis wind turbine known in the art typically comprises three0 blades. The wind turbine converts the kinetic energy of the wind into mechanical motion1 according to the principle of aerodynamic lift. In operation, the blades rotate and drive a2 generator which converts the mechanical motion into electricity. 3 4 Whilst wind turbines are widely used in the energy industry to offer a source of renewable5 energy, there are numerous disadvantages. Wind turbines can only operate within a6 narrow wind speed window. For example, if the wind speed is too high there is a risk of7 damaging the wind turbines. Conversely if the wind speed is too low, then there may not8 be enough aerodynamic lift to rotate the blades. 9 1 Commercial wind farms typically comprise large wind turbines which can be over 100 m

2 tall. Whilst large wind turbines are more efficient than smaller scale micro wind turbines,

3 the large wind turbines typically dominate the surrounding landscape and have a negative

4 aesthetic impact on the environment. There are further negative environmental

5 consequences as wind turbines can affect the surrounding wildlife. For example, the

6 blades of the wind turbines can kill birds.

7

8 In addition, such large wind turbines are not suitable to be located in urban landscapes, by

9 motorways and especially not near airports as they tend to produce a significant turbulent0 flow in the wake of the blades. 1 2 Summary of the Invention 3 4 It is an object of an aspect of the present invention to provide an energy harvesting5 apparatus that obviates or at least mitigates one or more of the aforesaid disadvantages of6 the energy harvesting apparatus known in the art. 7 8 According to a first aspect of the present invention there is provided an energy harvesting9 apparatus comprising a central spindle, one or more radial arms mechanically connected0 to the central spindle and extending radially from the central spindle, each arm having one1 or more turbines mechanically connected to the arm, 2 wherein, in use, rotation of the turbine drives rotation of the radial arm, which drives3 rotation of the central spindle, 4 and wherein the central spindle, radial arms and turbines are located within a duct. 5 6 The inventors have found that the energy harvesting apparatus captures a greater7 sweepable area (/.e., the cross-sectional area of a fluid flow that may contact a turbine)8 than conventional horizontal-axis wind turbines, and thus increases the efficiency of9 energy capturing. This is because the energy harvesting apparatus captures a larger0 portion of the fluid flow energy incident upon the apparatus. 1 2 Furthermore, given that the position of the turbine within the duct changes as the central3 spindle rotates, this advantageously compensates for variations in fluid flow across the4 cross-sectional area of the duct. 5 1 Additionally, by integrating the components of the energy harvesting apparatus into a duct,

2 the apparatus can be compact, is modular and can form part of a larger system. Not only

3 can the energy harvesting apparatus be discreetly integrated into the environment in the

4 form of walls, but it is also suitable for locations typically not considered for apparatus

5 known in the art, such as urban landscapes, motorways, airports and even under water

6 locations. Thus, the energy harvesting apparatus is not limited to remote areas (often

7 considered areas of natural beauty) and so there is no reason for a negative public

8 opinion.

9 0 Furthermore, having a duct further enhances the power generation of the energy 1 harvesting apparatus compared to an equivalent apparatus that is absent a duct. 2 However, one possible disadvantage of using a duct is that turbulence is increased. That3 being said, the inventors have surprisingly found that by having the one or more radial4 arms rotate about the central axis S of the central spindle, turbulence within the duct can5 be reduced. Therefore, the combination of the two features (i.e. a duct and rotation about6 the central spindle) advantageously increases power generation without the turbulence7 issues typically associated therewith. 8 9 Preferably, the central spindle has a central axis S. Preferably, each arm has a central0 axis R. Preferably, in use, rotation of the turbine drives rotation of the one or more radial1 arms about its central axis R and about the central axis S of the central spindle, which2 drives rotation of the central spindle. 3 4 Preferably, the apparatus comprises a plurality of radial arms. Preferably, one or more of5 the radial arms have a plurality of turbines. Both features advantageously further increase6 the efficiency of energy capturing. 7 8 Preferably, the central spindle is located centrally within the duct. 9 0 Preferably, the connection between the turbine(s) and the radial arm(s), and/or the1 connection between the radial arm(s) and the central spindle, comprises a gear 2 arrangement. 1 Preferably, one or more of the turbines comprises one or more blades mounted about a

2 turbine rotation axis. More preferably, one or more of the turbines comprises a plurality of

3 blades. Yet more preferably, all the turbines comprise a plurality of blades.

4

5 Optionally, one or more of the blades are foils. In these embodiments, preferably all the

6 blades are foils.

7

8 Optionally, the central spindle is parallel to the rotation axes of the turbines. Alternatively,

9 the central spindle is perpendicular to the rotation axes of the turbines. 0 1 Preferably, the radial arms extend from the central spindle to the perimeter of the duct.2 This advantageously increases the cross-sectional area in which the apparatus can3 capture energy from the fluid flow. 4 5 Optionally, the radial arms are offset from one another along the central spindle. 6 7 Optionally, at least two radial arms are positioned in the same plane perpendicular to the8 central spindle. 9 0 Optionally, the radial arms are distributed along the length of the central spindle. 1 2 In alternative embodiments, there may be provided an energy harvesting apparatus3 comprising one or more flaps. The one or more flaps may be located at an inlet opening of4 the duct. Alternatively, or additionally, the one or more flaps may be located at a trailing5 edge of the blades of the turbines. The flaps may induce turbulent fluid flow. 6 7 In alternative embodiments, there may be provided an energy harvesting apparatus8 comprising a mesh across an inlet opening and/or an outlet opening of the duct. The9 mesh advantageously induces turbulent fluid flow (by disrupting the fluid flow) and/or acts0 as a barrier protecting the components of the energy harvesting apparatus (e.g., the1 turbines). 2 3 In alternative embodiments, there may be provided an energy harvesting apparatus4 comprising flow restrictors located within the duct. The flow restrictions may narrow (or5 widen) the cross-sectional shape of the passageway through the duct and may act as a 1 bottle neck increasing the velocity of the fluid flow. The flow restrictors may disrupt the

2 fluid flow to create turbulent fluid flow. According to the Venturi effect, this restriction

3 results in a reduction of fluid pressure in the narrow region of the duct. This increases the

4 energy captured and further enhances the operation and efficiency of the energy

5 harvesting apparatus.

6

7 Preferably, the energy harvesting apparatus further comprises at least one generator

8 mechanically connected to the central spindle, employed to convert movement of the one

9 or more turbines (via movement of the central spindle) into electricity. 0 1 The energy harvesting apparatus may comprise a single generator. Alternatively, the2 energy harvesting apparatus may comprise a plurality of generators, each generator3 independently generating electricity. Preferably, each of the radial arms in a particular4 plane perpendicular to the central spindle may connect to a single generator. 5 6 The one or more generators may be any suitable generator known in the art, for example,7 a conventional electric generator. 8 9 In alternative embodiments, there may be provided an energy harvesting apparatus0 comprising a lens. The lens is suitable for focusing solar radiation and inducing 1 convection air flow. This feature is particularly suited to a wind energy harvesting 2 apparatus; in other words, an apparatus not submerged under water. The lens may take3 the form of a conventional optical lens. The lens may be orientated to focus solar radiation4 in the region of an outlet opening of the duct. Consequently, the fluid at the outlet opening5 is hotter than the fluid at the inlet opening. In other words, the lens creates a thermal6 gradient between the inlet opening and outlet opening of the duct. This thermal gradient7 induces a convection fluid flow, increasing the velocity and kinetic energy of the fluid flow8 through the duct. Thus, the lens enhances the output of the energy harvesting apparatus9 as it increases the amount of electricity generated. It will be appreciated that the energy0 harvesting apparatus may comprise multiple lenses all orientated towards the outlet1 opening of the duct. 2 3 In alternative embodiments, there may be provided an energy harvesting apparatus4 comprising a layer of noise insulation. When the energy harvesting apparatus takes the 1 form of a panel suitable for use on a high-rise building, in addition to the panel generating

2 electricity, the noise insulation would provide sound proofing for the building.

3

4 Preferably, the energy harvesting apparatus is a wind energy harvesting apparatus. In

5 these embodiments, the fluid flow is wind. The one or more foils comprise one or more

6 aerofoils.

7

8 Alternatively, or additionally, the energy harvesting apparatus is a water flow energy

9 harvesting apparatus. In these embodiments, the fluid flow is a water flow. The one or0 more foils comprise one or more hydrofoils. 1 2 One or more of the turbines may be a horizontal-axis wind turbine. Alternatively, or3 additionally, one or more of the turbines may be a vertical-axis wind turbine, such as a4 Darrieus wind turbine. 5 6 According to a second aspect of the present invention there is provided an energy 7 harvesting system comprising two or more energy harvesting apparatus in accordance8 with the first aspect of the present invention. 9 0 Preferably, the two or more energy harvesting apparatus are stacked side-by-side and/or1 upon each other. 2 3 The energy harvesting apparatus or energy harvesting system may take the form of a wall,4 a fence, panel(s) for a structure or building or even a component within a structure. The5 energy harvesting apparatus or energy harvesting system may be located in regions of6 high fluid flow, and particularly high turbulent fluid flow. 7 8 As an example, for a wind energy harvesting apparatus or system where the fluid of the9 fluid flow is air, high turbulent air flow could be found near a motorway, an airport or even0 on a high-rise building. 1 2 As another example, for a liquid flow energy harvesting apparatus or system where the3 fluid of the fluid flow is, for example water, high turbulent water flow could be found at a4 tidal barrier, a tidal estuary, a dam, river flood defences, bridge supports or even within 1 water transport pipes. It will be appreciated that a liquid flow energy harvesting apparatus

2 or system would be submerged under water.

3

4 Embodiments of the second aspect of the invention may comprise features to implement

5 the preferred or optional features of the first aspect of the invention or vice versa.

6

7 According to a third aspect of the present invention there is provided a use of an energy

8 harvesting apparatus in accordance with the first aspect of the present invention, or an

9 energy harvesting system in accordance with the second aspect of the present invention,0 for generating electrical energy. 1 2 Embodiments of the third aspect of the invention may comprise features to implement the3 preferred or optional features of the first and/or second aspects of the invention or vice4 versa. 5 6 According to a fourth aspect of the present invention there is provided a method of7 manufacturing an energy harvesting apparatus comprising: 8 providing a duct; and 9 providing a central spindle located within the duct, the central spindle comprising one or0 more radial arms mechanically connected to the central spindle and extending radially1 from the central spindle, each arm having one or more turbines mechanically connected to2 the arm, 3 wherein, in use, rotation of the turbine drives rotation of the radial arm, which drives4 rotation of the central spindle. 5 6 Preferably, the method of manufacturing an energy harvesting apparatus further 7 comprises providing a generator, the generator being mechanically connected to the8 central spindle and employed to convert movement of the one or more turbines into9 electricity. 0 1 In alternative methodologies, there may be provided a method which further comprises2 characterising an air flow. Characterising the fluid flow may comprise characterising the3 mean fluid flow speed, fluid flow speed distribution, turbulence, fluid flow shear profile,4 distribution of fluid flow direction and long-term temporal fluid flow variations. 5 1 In alternative methodologies, there may be provided a method which further comprises

2 determining the optimum parameters of the fluid energy harvesting apparatus for use with

3 the fluid flow. Determining the optimum parameters of the energy harvesting apparatus

4 may comprise determining one or more of: the dimensions of the fluid energy harvesting

5 apparatus; the dimension and shape of the duct, the shape and structure of the blades; the

6 relative positioning of two or more turbines within the duct; and the arrangement and

7 configuration of the generator.

8

9 Embodiments of the fourth aspect of the invention may comprise features to implement the0 preferred or optional features of the first, second and/or third aspects of the invention or1 vice versa. 2 3 According to a fifth aspect of the present invention there is provided an energy harvesting4 apparatus comprising a central spindle having a central axis S, one or more radial arms5 mechanically connected to the central spindle and extending radially from the central6 spindle, each arm having a central axis R and having one or more turbines mechanically7 connected to the arm, 8 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms about9 its central axis R and about the central axis S of the central spindle, which drives rotation0 of the central spindle, 1 and wherein the central spindle, one or more radial arms and turbines are located within a2 duct. 3 4 Embodiments of the fifth aspect of the invention may comprise features to implement the5 preferred or optional features of the first, second, third and/or fourth aspects of the6 invention or vice versa. 7 8 According to a sixth aspect of the present invention there is provided a method of 9 manufacturing an energy harvesting apparatus comprising: 0 providing a duct; and 1 providing a central spindle located within the duct, the central spindle having a central axis2 S and comprising one or more radial arms mechanically connected to the central spindle3 and extending radially from the central spindle, each arm having a central axis R and4 having one or more turbines mechanically connected to the arm, 1 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms about

2 its central axis R and about the central axis S of the central spindle, which drives rotation

3 of the central spindle.

4

5 Embodiments of the sixth aspect of the invention may comprise features to implement the

6 preferred or optional features of the first, second, third, fourth and/or fifth aspects of the

7 invention or vice versa.

8

9 According to a seventh aspect of the present invention there is provided an energy0 harvesting apparatus comprising a central spindle having a central axis S, one or more1 radial arms mechanically connected to the central spindle and extending radially from the2 central spindle, each arm having a central axis R and having one or more turbines3 mechanically connected to the arm, 4 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms about5 its central axis R and about the central axis S of the central spindle, which drives rotation6 of the central spindle. 7 8 Embodiments of the seventh aspect of the invention may comprise features to implement9 the preferred or optional features of the first, second, third, fourth, fifth and/or sixth aspects0 of the invention or vice versa. 1 2 According to an eighth aspect of the present invention there is provided a method of3 manufacturing an energy harvesting apparatus comprising: 4 providing a central spindle, the central spindle having a central axis S and comprising one5 or more radial arms mechanically connected to the central spindle and extending radially6 from the central spindle, each arm having a central axis R and having one or more7 turbines mechanically connected to the arm, 8 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms about9 its central axis R and about the central axis S of the central spindle, which drives rotation0 of the central spindle. 1 2 Embodiments of the eighth aspect of the invention may comprise features to implement3 the preferred or optional features of the first, second, third, fourth, fifth, sixth and/or4 seventh aspects of the invention or vice versa. 5 1 Brief of Drawinas

2

3 There will now be described, by way of example only, various embodiments of the

4 invention with reference to the drawings, of which:

5

6 Figure 1 presents a perspective view of a central spindle and a radial arm having a turbine

7 in accordance with an embodiment of the present invention;

8

9 Figure 2 presents a perspective view of a central spindle and a radial arm having two0 turbines in accordance with an alternative embodiment of the present invention; 1 2 Figure 3 presents a perspective view of a central spindle and two radial arms each having3 two turbines in accordance with an alternative embodiment of the present invention;4 5 Figure 4 presents a perspective view of an energy harvesting apparatus in accordance6 with an alternative embodiment of the present invention; 7 8 Figure 5 presents a schematic cross-sectional view of an energy harvesting apparatus in9 accordance with an alternative embodiment of the present invention; 0 1 Figure 6 presents a perspective view of a central spindle and a radial arm having a turbine2 in accordance with an alternative embodiment of the present invention; 3 4 Figure 7 presents a perspective view of a central spindle and a radial arm having two5 turbines in accordance with an alternative embodiment of the present invention; 6 7 Figure 8 presents a perspective view of a central spindle and two radial arms each having8 two turbines in accordance with an alternative embodiment of the present invention;9 0 Figure 9 presents a perspective view of an energy harvesting apparatus in accordance1 with an alternative embodiment of the present invention; 2 3 Figure 10 presents a schematic cross-sectional view of an energy harvesting apparatus in4 accordance with an alternative embodiment of the present invention; 5 1 Figure 11 presents a schematic cross-sectional view of the distribution of radial arms along

2 the length of the central spindle in accordance with an embodiment of the present

3 invention; and

4

5 Figure 12 presents a schematic cross-sectional view of the distribution of radial arms along

6 the length of the central spindle in accordance with an alternative embodiment of the

7 present invention.

8

9 In the description which follows, like parts are marked throughout the specification and0 drawings with the same reference numerals. The drawings are not necessarily to scale1 and the proportions of certain parts have been exaggerated to better illustrate details and2 features of embodiments of the invention. 3 4 Detailed Description of the Preferred Embodiments 5 6 An explanation of the present invention will now be described with reference to Figures 17 to 12. 8 9 Enerov Harvestino

0 1 Figure 1 depicts part of an energy harvesting apparatus 1 a. More specifically, the energy2 harvesting apparatus 1a is suitable for harvesting energy from a fluid flow such as wind,3 tidal flows, or river flows. 4 5 The energy harvesting apparatus 1 a comprises a central spindle 2 having a central axis S6 and a generator 3 mechanically connected to the central spindle 2. The generator 3 is7 centred about the central spindle 2. Also mechanically connected to the central spindle 28 is a radial arm 4, positioned at the opposite end of the central spindle 2 to that which is9 connected to the generator 3. The radial arm 4 extends radially from the central spindle 2. 0 The radial arm 4 is mechanically connected to the central spindle 2 through a first gear1 arrangement 5. The radial arm 4 has a central axis R and comprises a turbine 6 2 mechanically connected to the radial arm 4. The turbine 6 is mechanically connected to3 the radial arm 4 through a second gear arrangement 7, at the opposite end of the radial4 arm 4 to that which is connected to the central spindle 2. The turbine 6 comprises three5 foils 8 radially extending from a turbine rotation axis 9. 1

2 In operation, a fluid flow 10 flows past the foils 8 inducing aerodynamic or hydrodynamic

3 forces. This force causes rotation of the foils 8, which rotates about the turbine rotation

4 axis 9. Through the second gear arrangement 7, rotation of the turbine 6 causes rotation

5 of the radial arm 4 about its central axis R. Through the first gear arrangement 5, rotation

6 of the radial arm 4 causes rotation of the central spindle 2 about its central axis S. Thus,

7 rotation of the turbine 6 drives rotation of the radial arm 4 about its central axis R and

8 about the central axis S of the central spindle 2. The generator 3 converts movement of

9 the central spindle 2 into electricity. 0 1 It will be appreciated the fluid flow 10 could take the form of a gas flow or a liquid flow.2 The foils 8 take the form of one or more aerofoils or one or more hydrofoils depending on3 whether the fluid flow 10 is a gas flow or a liquid flow. 4 5 The turbine 6 comprises three foils 8, but it will be appreciated that the turbine 6 may6 comprise any suitable number of foils 8. Additionally, it will be appreciated that the exact7 shape and dimensions of the foils 8 is not critical to the invention and thus can be any8 suitable shape and dimension. 9 0 Figure 2 depicts part of an energy harvesting apparatus 1b. This energy harvesting1 apparatus 1 b comprises all the features of the energy harvesting apparatus 1 a depicted in2 Figure 1 . In addition, the energy harvesting apparatus 1 b comprises a further turbine 113 on the radial arm 4, such that the radial arm 4 comprises two turbines 6,11 . The second4 turbine 11 is mechanically connected to the radial arm 4 at a position between the first5 turbine 6 and the first gear arrangement 5. The energy harvesting apparatus 1 b depicted6 in Figure 2 advantageously captures energy from the fluid flow 10 over a greater cross-7 sectional area than the energy harvesting apparatus 1a depicted in Figure 1 . 8 9 Figure 3 depicts part of an energy harvesting apparatus 1c. This energy harvesting0 apparatus 1c comprises all the features of the energy harvesting apparatus 1b depicted in1 Figure 2. In addition, the energy harvesting apparatus 1c comprises a second radial arm2 12 on the central spindle 2, such that the central spindle 2 comprises two radial arms 4,12,3 each comprising two turbines 6,11 . The second radial arm 12 is mechanically connected4 to the central spindle 2 at a position between the first radial arm 4 and the generator 3.5 The energy harvesting apparatus 1c in Figure 3 advantageously captures energy from the 1 fluid flow 10 over an even greater cross-sectional area than the energy harvesting

2 apparatus 1 b depicted in Figure 2.

3

4 Figure 4 depicts an energy harvesting apparatus 1d. This energy harvesting apparatus 1d

5 comprises all the features of the energy harvesting apparatus 1c depicted in Figure 3. In

6 addition, the energy harvesting apparatus further comprises an additional radial arm 13

7 and an additional turbine 14 on each arm, such that each radial arm 4,12,13 comprises

8 three turbines 6,11 ,14. The central spindle 2, radial arms 4,12,13 and turbines 6,11 ,14 are

9 located within a duct 15. The central spindle 2 is located centrally within the duct 15, with0 each radial arm 4,12,13 extending to the internal perimeter of the duct 15. 1 Advantageously, the duct 15 acts to channel the fluid flow 10 through the energy 2 harvesting apparatus 1d. 3 4 As can be seen in Figure 4, the duct 15 has a substantially circular cross-sectional shape. 5 However, it will be appreciated that the duct 15 may have any suitable cross-sectional6 shape. 7 8 Figure 5 depicts an energy harvesting apparatus 1e having a duct 15. Within the duct is a9 central spindle 2 and a generator 3 mechanically connected to the central spindle 2. The0 central spindle 2 comprises four radial arms 4,12,13,16, each comprising a turbine 6. The1 radial arms 4,12,13,16 are radially offset from one another around the central spindle 2.2 Additionally, the radial arms 4,12,13,16 are distributed along the length of the central3 spindle 2. 4 5 In operation, the fluid flow 10 enters the duct 15 through the inlet opening 17, flows past6 the foils 8 inducing aerodynamic or hydrodynamic forces and then exits the duct 157 through the outlet opening 18. This force causes rotation of the foils 8, which rotates8 about the turbine rotation axis 9. Through the second gear arrangement 7, rotation of the9 turbine 6 causes rotation of the radial arm 4 about its central axis R. Through the first gear0 arrangement (not shown), rotation of the radial arm 4 causes rotation of the central spindle1 2 about its central axis S. Thus, rotation of the turbine 6 drives rotation of the radial arm 42 about its central axis R and about the central axis S of the central spindle 2. The 3 generator 3 converts rotational movement of the central spindle 2 into electricity. 4 5 Alternative Energy Harvesting Apparatus 1

2 Figure 6 depicts part of an energy harvesting apparatus 1f which is analogous to the part

3 of an energy harvesting apparatus 1 a depicted in Figure 1 . Figure 7 depicts part of an

4 energy harvesting apparatus 1g which is analogous to the part of an energy harvesting

5 apparatus 1 b depicted in Figure 2. Figure 8 depicts part of an energy harvesting

6 apparatus 1 h which is analogous to the part of an energy harvesting apparatus 1c

7 depicted in Figure 3. Figure 9 depicts an energy harvesting apparatus 1 i which is

8 analogous to the energy harvesting apparatus 1d depicted in Figure 4. Figure 10 depicts

9 an energy harvesting apparatus 1j which is analogous to the energy harvesting apparatus0 1e depicted in Figure 5. 1 2 The difference between the embodiments depicted in Figures 6 to 10 compared to the3 embodiments depicted in Figures 1 to 5 is that vertical-axis wind turbines with a blade 194 are employed. Each turbine 6,11 ,14 comprises three blades 19, but it will be appreciated5 that each turbine may comprise any suitable number of blades 19. Additionally, it will be6 appreciated that the exact shape and dimensions of the blades 19 is not critical to the7 invention and thus can be any suitable shape and dimension. 8 9 Additionally, the embodiments depicted in Figures 6 to 10 are absent of a second gear0 arrangement. Instead, the blades 19 of the turbine 6,11 ,14 are positioned around the1 radial arm 4,12,13,16, such that rotation of the turbine 6,11 ,14 directly causes rotation of2 the radial arm 4,12,13,16 about its central axis R. Thus, in these embodiments, the3 turbine rotation axis 9 should be construed to be along the radial arm 4,12,13,16 and in4 particular its central axis R. 5 6 In alternative embodiments, there may be provided an energy harvesting apparatus7 comprising one or more flaps. The one or more flaps may be located at an inlet opening of8 the duct. Alternatively, or additionally, the one or more flaps may be located at a trailing9 edge of the blades of the turbines. The flaps may induce turbulent fluid flow. 0 1 In alternative embodiments, there may be provided an energy harvesting apparatus2 comprising a mesh across an inlet opening and/or an outlet opening of the duct. The3 mesh advantageously induces turbulent fluid flow (by disrupting the fluid flow) and/or acts4 as a barrier protecting the components of the energy harvesting apparatus (e.g., the5 turbines). 1

2 In alternative embodiments, there may be provided an energy harvesting apparatus

3 comprising flow restrictors located within the duct. The flow restrictions may narrow (or

4 widen) the cross-sectional shape of the passageway through the duct and may act as a

5 bottle neck increasing the velocity of the fluid flow. The flow restrictors may disrupt the

6 fluid flow to create turbulent fluid flow. According to the Venturi effect, this restriction

7 results in a reduction of fluid pressure in the narrow region of the duct. This increases the

8 energy captured and further enhances the operation and efficiency of the energy

9 harvesting apparatus. 0 1 In alternative embodiments, there may be provided an energy harvesting apparatus2 comprising a lens. The lens is suitable for focusing solar radiation and inducing 3 convection air flow. This feature is particularly suited to a wind energy harvesting 4 apparatus; in other words, an apparatus not submerged under water. The lens may take5 the form of a conventional optical lens. The lens may be orientated to focus solar radiation6 in the region of an outlet opening of the duct. Consequently, the fluid at the outlet opening7 is hotter than the fluid at the inlet opening. In other words, the lens creates a thermal8 gradient between the inlet opening and outlet opening of the duct. This thermal gradient9 induces a convection fluid flow, increasing the velocity and kinetic energy of the fluid flow0 through the duct. Thus, the lens enhances the output of the energy harvesting apparatus1 as it increases the amount of electricity generated. It will be appreciated that the energy2 harvesting apparatus may comprise multiple lenses all orientated towards the outlet3 opening of the duct. 4 5 In alternative embodiments, there may be provided an energy harvesting apparatus6 comprising a layer of noise insulation. When the energy harvesting apparatus takes the7 form of a panel suitable for use on a high-rise building, in addition to the panel generating8 electricity, the noise insulation would provide sound proofing for the building. 9 0 Distribution of Radial Arms 1 2 Figure 11 depicts one exemplary arrangement of the radial arms 4 along the length of the3 central spindle 2. In this arrangement, the radial arms 4 are offset from one another along4 the central spindle 2, such that no two radial arms are directly opposing. 5 1 Figure 12 depicts an alternative exemplary arrangement of the radial arms 4 along the

2 length of the central spindle 2. In this arrangement, two radial arms are positioned

3 opposite one another in the same plane perpendicular to the central spindle (plane A), and

4 a further two radial arms are positioned opposite one another in a different plane

5 perpendicular to the central spindle (plane B). In some embodiments, the radial arms in

6 plane A are connected to a first generator (not shown) and the radial arms in plane B are

7 connected to a second generator (not shown), the two generators independently

8 generating electricity.

9 0 In a yet further exemplary arrangement, the distribution of radial arms may be a 1 combination of Figure 11 and Figure 12, in that there is at least one plane perpendicular to2 the central spindle having at least two radial arms, while at least one other radial arm has3 no directly opposing arm. 4 5 Method of Manufacturing an Energy Harvesting Apparatus 6 7 A method of manufacturing an energy harvesting apparatus 1 comprises providing a duct8 15; and providing a central spindle 2 located within the duct 15, the central spindle 29 having a central axis S and comprising one or more radial arms 4 mechanically connected0 to the central spindle 2 and extending radially from the central spindle 2, each arm 41 having a central axis R and having one or more turbines 6 mechanically connected to the2 arm 4. In use, rotation of the turbine 6 drives rotation of the one or more radial arms 43 about its central axis R and about the central axis S of the central spindle 2, which in turn4 drives rotation of the central spindle 2 about its central axis S. 5 6 In alternative methodologies, there may be provided a method which further comprises7 characterising an air flow. Characterising the fluid flow may comprise characterising the8 mean fluid flow speed, fluid flow speed distribution, turbulence, fluid flow shear profile,9 distribution of fluid flow direction and long-term temporal fluid flow variations. 0 1 In alternative methodologies, there may be provided a method which further comprises2 determining the optimum parameters of the fluid energy harvesting apparatus for use with3 the fluid flow. Determining the optimum parameters of the energy harvesting apparatus4 may comprise determining one or more of: the dimensions of the fluid energy harvesting5 apparatus; the dimension and shape of the duct, the shape and structure of the blades; the 1 relative positioning of two or more turbines within the duct; and the arrangement and

2 configuration of the generator.

3

4 As discussed previously, the energy harvesting apparatus 1 has numerous advantages.

5 The energy harvesting apparatus 1 captures a greater sweepable area (i.e. , the cross-

6 sectional area of a fluid flow 10 that may contact a turbine 6) than conventional horizontal¬

7 axis wind turbines, and thus increases the efficiency of energy capturing. This is because

8 the energy harvesting apparatus 1 captures a larger portion of the fluid flow 10 energy

9 incident upon the apparatus 1 . 0 1 Furthermore, given that the position of the turbine 6 within the duct 15 changes as the2 central spindle 2 rotates, this advantageously compensates for variations in fluid flow 103 across the cross-sectional area of the duct 15. 4 5 Additionally, by integrating the components of the energy harvesting apparatus 1 into a6 duct 15, the apparatus 1 can be compact, is modular and can form part of a larger system. 7 The duct 15 also provides physical protection for the components housed therein e.g., the8 turbines 6. Not only can the energy harvesting apparatus 1 be discreetly integrated into9 the environment in the form of walls, but it is also suitable for locations typically not0 considered for apparatus known in the art, such as urban landscapes, motorways, airports1 and even under water locations. Thus, the energy harvesting apparatus 1 is not limited to2 remote areas (often considered areas of natural beauty) and so there is no reason for a3 negative public opinion. 4 5 The energy harvesting apparatus 1 can be optimised accordingly to the characteristics of6 the fluid flow 10 such that the apparatus 1 is suitable for a broad range of applications.7 8 An energy harvesting apparatus is disclosed. The energy harvesting apparatus comprises9 a central spindle, and one or more radial arms mechanically connected to the central0 spindle and extending radially from the central spindle. Each arm has one or more 1 turbines mechanically connected to the arm. The central spindle, one or more radial arms2 and turbines are located within a duct. In use, rotation of the turbine drives rotation of the3 one or more radial arms, which drives rotation of the central spindle. The energy 4 harvesting apparatus provides an alternative apparatus for generating renewable energy5 with numerous advantages. The apparatus harvests energy from a greater cross-sectional 1 area, has minimal negative environmental impact and is suitable for numerous locations

2 and applications.

3

4 Throughout the specification, unless the context demands otherwise, the terms “comprise”

5 or “include”, or variations such as “comprises” or “comprising”, “includes” or “including” will

6 be understood to imply the inclusion of a stated integer or group of integers, but not the

7 exclusion of any other integer or group of integers. Furthermore, unless the context clearly

8 demands otherwise, the term “or” will be interpreted as being inclusive not exclusive.

9 0 The foregoing description of the invention has been presented for purposes of illustration1 and description and is not intended to be exhaustive or to limit the invention to the precise2 form disclosed. The described embodiments were chosen and described in order to best3 explain the principles of the invention and its practical application to thereby enable others4 skilled in the art to best utilise the invention in various embodiments and with various5 modifications as are suited to the particular use contemplated. Therefore, further 6 modifications or improvements may be incorporated without departing from the scope of7 the invention as defined by the appended claims.

Claims

1 Claims

2

3 1 . An energy harvesting apparatus comprising a central spindle having a central axis S,

4 one or more radial arms mechanically connected to the central spindle and extending

5 radially from the central spindle, each arm having a central axis R and having one or

6 more turbines mechanically connected to the arm,

7 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms

8 about its central axis R and about the central axis S of the central spindle, which drives

9 rotation of the central spindle, 0 and wherein the central spindle, one or more radial arms and turbines are located1 within a duct. 2 3 2. The energy harvesting apparatus as claimed in claim 1 , wherein the apparatus4 comprises a plurality of radial arms. 5 6 3. The energy harvesting apparatus as claimed in claim 1 or claim 2, wherein one or7 more of the radial arms comprise a plurality of turbines. 8 9 4. The energy harvesting apparatus as claimed in any of the preceding claims, wherein0 the central spindle is located centrally within the duct. 1 2 5. The energy harvesting apparatus as claimed in any of the preceding claims, wherein3 the connection between the turbine and the radial arms, and/or the connection4 between the radial arms and the central spindle, comprises a gear arrangement. 5 6 6. The energy harvesting apparatus as claimed in any of the preceding claims, wherein7 one or more of the turbines comprises one or more blades mounted about a turbine8 rotation axis. 9 0 7. The energy harvesting apparatus as claimed in claim 6, wherein one or more of the1 blades are foils. 2 3 8. The energy harvesting apparatus as claimed in claim 6 or claim 7, wherein the central4 spindle is parallel to a rotation axes of the turbines. 5

1 9. The energy harvesting apparatus as claimed in claim 6 or claim 7, wherein the central

2 spindle is perpendicular to a rotation axes of the turbines.

3

4 10. The energy harvesting apparatus as claimed in any of the preceding claims, wherein

5 the radial arms extend from the central spindle to the perimeter of the duct.

6

7 11 . The energy harvesting apparatus as claimed in any of the preceding claims, wherein

8 the radial arms are radially offset from one another around the central spindle.

9 0 12. The energy harvesting apparatus as claimed in any of the preceding claims, wherein at1 least two radial arms are positioned in the same plane perpendicular to the central2 spindle. 3 4 13. The energy harvesting apparatus as claimed in any of the preceding claims, wherein5 the radial arms are distributed along the length of the central spindle. 6 7 14. The energy harvesting apparatus as claimed in any of the preceding claims, further8 comprising at least one generator mechanically connected to the central spindle,9 employed to convert movement of the one or more turbines into electricity. 0 1 15. An energy harvesting system comprising two or more energy harvesting apparatus as2 claimed in any of the preceding claims. 3 4 16. Use of an energy harvesting apparatus as claimed in any one of claims 1 to 14 or an5 energy harvesting system according to claim 15 for generating electrical energy. 6 7 17. A method of manufacturing an energy harvesting apparatus comprising: 8 providing a duct; and 9 providing a central spindle located within the duct, the central spindle having a central0 axis S and comprising one or more radial arms mechanically connected to the central1 spindle and extending radially from the central spindle, each arm having a central axis2 R and having one or more turbines mechanically connected to the arm, 3 wherein, in use, rotation of the turbine drives rotation of the one or more radial arms4 about its central axis R and about the central axis S of the central spindle, which drives5 rotation of the central spindle. 1

2 18. The method of manufacturing an energy harvesting apparatus as claimed in claim 17,

3 further comprising providing a generator, the generator being mechanically connected

4 to the central spindle and employed to convert movement of the one or more turbines

5 into electricity.

6

7 19. The method of manufacturing an energy harvesting apparatus as claimed in claim 17

8 or claim 18, further comprising characterising a fluid flow.

9 0 20. The method of manufacturing an energy harvesting apparatus as claimed in claim 19,1 further comprising determining the optimum parameters of the energy harvesting2 apparatus for use with the fluid flow.