Patent Application
20170191700
The present invention relates to the field of electricity generation, and more specifically to methods of electricity generation from renewable energy sources.
In one form, the present invention relates to systems harnessing thermal energy from the sun. In one particular aspect the invention is suitable for use as an apparatus and method for support for optical devices that direct and concentrate sunlight (and its corresponding thermal energy component) for use in electricity generation. It will be convenient to hereinafter describe the invention in relation to electricity generation, however it should be appreciated that the present invention is not limited to that use, only.
Throughout this specification the use of the word “inventor” in singular form may be taken as reference to one (singular) inventor or more than one (plural) inventor of the present invention.
It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. Moreover, the discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor's knowledge and experience, however, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein.
Methods of electricity generation from fossil fuels such as oil, gas and coal suffer from the drawback that these resources are finite. Further, the conversion to electricity of these types of raw materials is usually by combustion and this process results in by-products which may pollute. Moreover, such pollution is generally accepted as being linked to climate change. Therefore increased attention in recent years has been given to methods of generating electricity from renewable resources and this can be referred to as ‘clean tech’ or ‘clean energy’.
One method of generating electricity from renewable resources utilises the thermal energy component of solar radiation. These systems, as a first process, collect thermal energy then, as a second process, convert it into electricity. Since the subsequent process of converting the collected thermal energy into electricity requires relatively complex and expensive equipment, a desirable economical approach involves systems that collect incoming solar radiation from a large area and concentrate it as a first step before conversion to electricity in an efficient manner. The methodology described here of extracting thermal energy from the sun is referred to as Concentrating Solar Power (CSP) or Concentrating Solar Thermal (CST). The technologies involve use mirrors to concentrate (focus) the sun's light energy and convert it into heat that can be used, for example, to create steam to drive a turbine that generates electrical power.
Modern concentrating solar thermal electricity generation methods employ trough, dish and centralised tower architectures. These utilise systems of optical devices; usually mirrors, which reflect solar thermal energy from a large area to a small area where it is used to heat a medium termed a “heat transfer fluid”.
Trough systems generally use large, U-shaped (parabolic) reflectors (focusing mirrors) that have oil-filled pipes running along their centre, or focal point. The mirrored reflectors are tilted toward the sun, and focus sunlight on the pipes to heat the oil inside to as much as 400° C. The hot oil may then be used to boil water, which makes steam to run conventional steam turbines and generators.
Dish or engine systems use mirrored dishes about 10 times larger than a backyard satellite dish to focus and concentrate sunlight onto a receiver. The receiver is mounted at the focal point of the dish. To capture the maximum amount of solar energy, the dish and receiver assembly tracks the sun across the sky. In one exemplary system, the receiver is integrated into a high-efficiency “external” combustion engine. The engine has thin tubes containing hydrogen or helium gas that run along the outside of the engine's four piston cylinders and open into the cylinders. As concentrated sunlight falls on the receiver, it heats the gas in the tubes to very high temperatures, which causes hot gas to expand inside the cylinders. The expanding gas drives the pistons. The pistons turn a crankshaft, which drives an electric generator. The receiver, engine, and generator may comprise a single, integrated assembly mounted at the focus of the mirrored dish.
Centralised tower systems use many mechanically operated mirrors, termed heliostats that track the sun and focus its rays onto a thermal receiver. The thermal receiver may sit on top of a tall tower in which concentrated sunlight heats a fluid, such as molten salt, usually above 500° C. The hot fluid can be used immediately to make steam for electricity generation or stored for later use. Advantageously, molten salt retains heat efficiently, so it can be stored for days before being converted into electricity. That means electricity can be generated during periods of peak need, or on cloudy days or even several hours after sunset.
In centralised tower architecture systems, the main components include: a mirror array, a centralised tower with a thermal receiver, a heat transfer system, and a power block.
The mirror array includes software controlled hardware components working together to concentrate solar thermal energy upon the thermal receiver that is located atop the tower and contains the heat transfer fluid. Once heated, the heat transfer fluid is circulated to the power block where the thermal energy is converted to electricity.
Mirror array hardware comprises devices termed heliostats, which ordinarily include an optical element (this may be a mirror or lens for example) mounted upon a drive mechanism capable of angling and moving the optical element, these components are mounted upon a support apparatus. To achieve high levels of concentration, numerous heliostats are utilised in a single mirror array. Modern centralised tower solar thermal mirror arrays may deploy hundreds or even thousands of heliostats.
Modern heliostat control software includes sun tracking functionality, the ability to re-calibrate the targeting accuracy of the heliostat, and the ability to compensate for axial misalignment of the drive mechanism that may occur over time due to environmental factors such as ground movement.
Under software control, the heliostat drive mechanism is capable of controlling the orientation of the optical element in order to direct incoming solar thermal energy to the thermal receiver throughout the day taking into account the apparent movement of the sun across the sky.
The need for tracking accuracy, consistency and reliability necessarily result in the drive mechanism being a relatively expensive, accurate device manufactured to high engineering tolerances.
The drive mechanism acts as an intermediary, between the support apparatus and the optical element, and it controls the orientation of the optical element by “pushing back” against the support apparatus in order to move the optical device relative to the ground upon which the support apparatus is located.
An apparatus for heliostat support necessarily offers the drive mechanism and therefore the optical element stability against incoming axial (up/down), lateral (north/south/east/west) and torsional (clockwise/counter-clockwise) forces, thus ensuring the reflected thermal energy absorbed by the heat transfer fluid is maximised. The ability of the apparatus for heliostat support to provide stability to the drive mechanism and optical element is of key importance to the efficiency of the overall power generation system, since a lack of stability will likely result in sun tracking inaccuracy, and this leads to reduced overall system efficiency and reduced electrical output of plant operation.
Incoming forces which act upon the heliostat and which the support apparatus must resist in order to provide the stability necessary for accurate sun tracking (i.e. ensuring the reflected image of the sun remains on the thermal receiver) are primarily of an environmental nature and the most commonly experienced of these is wind. In order to maximise reflected sunlight, the optical element surface area is maximised, however this maximised surface area for reflection also means there is a maximised surface area in relation to wind.
Since a heliostat support apparatus is necessarily located outdoors, and the possible sizes (dictating wind effect) of the optical elements may vary, the levels of incoming environmental forces due to wind that must be resisted by the support apparatus also vary widely. Light winds in the vicinity of 0 km/h to 15 km/h are experienced on a daily basis. However extreme winds, exceeding 100 km/h for example, are also known to occur.
Incoming environmental forces, such as wind, act to move the optical element but not the ground or the support apparatus. The effect is that the drive mechanism, between the optical element and the support apparatus, must overcome these wind forces in order to continue to re-orientate the optical device and track the moving sun. However the drive mechanism is a mechanical device with inherent limits and incoming wind forces above the capabilities of the drive mechanism's inherent limits may result in a tracking error or permanent damage to the drive mechanism.
The high number of heliostats used in a mirror array means that the cost of the mirror array including mechanical and electrical hardware; the mirrors, drive mechanisms and support apparatus, and their associated power supply systems, are a highly significant factor in the economics of a centralised tower architecture for electricity generation plants.
Current solutions to the problems of providing support to heliostats are generally complex assemblies consisting of many individual components. The heliostat support depicted in
Alternative approaches to the problem of providing support to a heliostat, such as that outlined in US patent application US20100024802, to Van Der Westhuyzen, comprise a support for a heliostat drive being provided by a “fixed pedestal”. Van Der Westhuyzen mainly deals with the apparatus that orients the optical element (essentially a drive mechanism) however the fixed pedestal upon which the drive mechanism equivalent is mounted is defined as a pole inserted into the ground.
Another solution is set out by Gauche in PCT application WO2013027131A1, wherein the problem of providing a support apparatus for a heliostat is answered by the provision of a tripod like component having feet that are rested upon the ground, the components being interconnected. The interconnected arrangement may further include use of pegs, at the three extremities, which serve to anchor the feet to the ground.
Power supply arrangements for known heliostat systems generally take the form of insulated cables located below ground level. The cables, which form both sides of the power supply circuit, are therefore costly to install, requiring trenches.
It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems.
In one aspect the present invention provides apparatus for supporting a heliostat comprising; a rigid, elongate vertical member, the vertical member comprising a first end region and a second end region, the first end region operatively connected to a heliostat drive mechanism via a drive mechanism connection means, the second end region adapted for being driven into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat, and, at least one stabilising structure, wherein the at least one stabilising structure comprises a rigid interconnection between a first vertical member of a heliostat support and a second vertical member of another heliostat support.
Preferably, the vertical member comprises naturally occurring materials or fibres, comprising one or a combination of: timber; metallic materials comprising steel and aluminium; synthetic materials comprising plastics. Most preferably, the vertical member comprises an electric resistance welded hollow mild steel pipe having a circular cross-sectional shape.
Preferably, a nominal bore dimension of the vertical member is about 50 millimetres.
Preferably, the vertical member second end region has a length greater than about 300 millimetres.
Preferably, the at least one stabilising structure comprises an anti-torsion member comprising a rigid, elongate member comprising a first end region and a second end region, the first end region having operable interconnection to a first heliostat drive mechanism support vertical member, the second end region having operable interconnection to a second heliostat drive mechanism support vertical member.
Preferably, the anti-torsion member comprises naturally occurring materials or fibres, comprising one or a combination of: timber; metallic materials comprising steel and aluminium; synthetic materials comprising plastics.
Preferably, the anti-torsion member comprises an electric resistance welded hollow mild steel pipe having a circular cross-sectional shape.
Preferably, the nominal bore dimension of the anti-torsion member is about 25 millimetres.
Preferably, the anti-torsion member operable interconnection means includes at least one plate.
Preferably, the operable interconnection means comprises two opposed plates adapted to clamp the vertical member.
Preferably, the plates achieve the clamping effect by use of at least one laterally orientated fastener system.
Preferably, the at least one plate comprises a mild steel body having a ridged shape.
Preferably, the at least one plate has a thickness of about 4 millimetres.
In another aspect the present invention provides apparatus for supporting a heliostat comprising; a rigid, elongate vertical member, the vertical member comprising a first end region and a second end region, the first end region operatively connected to a heliostat drive mechanism via a drive mechanism connection means, the second end region adapted for being driven into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat, and, the drive mechanism connection means is adapted to isolate the drive mechanism from torsional forces between the drive mechanism and the vertical member above a pre-determined threshold.
Preferably, the isolation from torsional forces is achieved by frictional means. Preferably, the drive mechanism connection means includes at least one plate.
Preferably, the drive mechanism connection means comprises three opposed plates adapted to clamp the drive mechanism and the vertical member.
Preferably, the plates achieve the clamping effect by use of at least one laterally orientated fastener system.
Preferably, the at least one plate comprises an arrangement of two mild steel external plates and an aluminium intermediate plate. Preferably, the mild steel external plates comprise a ridged shape. Preferably, the mild steel external plates have a thickness of about 4 millimetres. Preferably, the aluminium intermediate plate comprises a scalloped profile. Preferably, the aluminium intermediate plate has a minimum thickness of about 4 millimetres.
In another aspect the present invention provides apparatus for supporting a heliostat comprising; a rigid, elongate vertical member, the vertical member comprising a first end region and a second end region, the first end region operatively connected to a heliostat drive mechanism via a drive mechanism connection means, the second end region adapted for being driven into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat, at least one stabilising structure, wherein the at least one stabilising structure comprises a rigid interconnection between a first vertical member of a heliostat support and a second vertical member of another heliostat support, wherein at least the vertical member and the at least one stabilising structure are adapted to form a portion of the heliostat drive mechanism power supply circuit.
Preferably, the portion of the heliostat drive mechanism power supply circuit formed is the current return path.
In yet another aspect the present invention provides a method for supporting a heliostat comprising the steps of: operatively connecting a first end region of a rigid, elongate vertical member to a heliostat drive mechanism via a drive mechanism connection means; driving a second end region of the rigid, elongate vertical member into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat, and, stabilising with at least one stabilising structure comprising a rigid interconnection between a first vertical member of a heliostat support and a second vertical member of another heliostat support.
In still another aspect, the present invention provides a method for supporting a heliostat comprising the steps of: operatively connecting a first end region of a rigid, elongate vertical member to a heliostat drive mechanism via a drive mechanism connection means; driving a second end region of the rigid, elongate vertical member into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat, and, isolating the drive mechanism from torsional forces between the drive mechanism and the vertical member above a pre-determined threshold.
In still yet another aspect the present invention provides a method for operating a heliostat comprising the steps of: operatively connecting a first end region of a rigid, elongate vertical member to a heliostat drive mechanism via a drive mechanism connection means; driving a second end region of the rigid, elongate vertical member into frictional contact with the ground to provide resistance to environmental forces impacting the heliostat; stabilising with at least one stabilising structure comprising a rigid interconnection between a first vertical member of a heliostat support and a second vertical member of another heliostat support, and, adapting the vertical member and the at least one stabilising structure to form a portion of the heliostat drive mechanism power supply circuit.
Preferably the step above of driving the second end region of the rigid, elongate vertical member into frictional contact with the ground is achieved by driving equipment.
Preferably, the step above of driving the second end region of the rigid, elongate vertical member into frictional contact with the ground is achieved without use of concrete.
Preferably, the step above of affixing the at least one anti-torsion member is achieved by a fastener system.
Preferably the method of affixing the heliostat drive mechanism is achieved by a fastener system.
In some embodiments described herein there is provided apparatus for supporting a heliostat, including; a rigid, elongate vertical member, the vertical member including a first end region and a second end region, the first end region including a heliostat drive mechanism connection means, the second end region located in the ground.
In other embodiments described herein there is provided apparatus for supporting a heliostat, including a rigid, elongate vertical member, the vertical member including a first end region and a second end region, the first end region including a heliostat drive mechanism connection means, the second end region located in the ground, the vertical member further including operable interconnection to at least one anti-torsion member, wherein the at least one anti-torsion member is a rigid, elongate member including a first end region and a second end region, the first end region having operable interconnection to a first heliostat drive mechanism support vertical member, the second end region having operable interconnection to a second heliostat drive mechanism support vertical member.
In yet other embodiments described herein there is provided a method for supporting a heliostat including the steps of: providing a rigid, elongate vertical member, the vertical member including a first end region and a second end region, the first end region including a heliostat drive mechanism connection means, locating the second end region in the ground, and affixing a heliostat drive mechanism via the heliostat drive mechanism connection means.
In yet other embodiments described herein there is provided a method for supporting a heliostat including the steps of: providing a rigid, elongate vertical member, the vertical member including a first end region and a second end region, the first end region including a heliostat drive mechanism connection means, the vertical member further including an anti-torsion member operable interconnection, locating the second end region in the ground, and providing a rigid elongate anti-torsion member, and affixing the anti-torsion member via the anti-torsion member operable interconnection, and affixing the anti-torsion member to the vertical member of a second support for a heliostat, and affixing a heliostat drive mechanism via the heliostat drive mechanism connection means.
Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.
In essence, embodiments of the present invention stem from the realisation by the inventor that current methods and apparatus for heliostat support may be optimised in order to offer stability in relation to regular incoming environmental forces whilst also isolating the drive mechanism from otherwise damaging environmental forces.
In essence, embodiments of the present invention stem from the realisation, by the inventor, that current methods and apparatus for heliostat support may be simplified whilst simultaneously offering improved levels of stability.
Further embodiments of the present invention stem from the realisation, by the inventor, that current methods and apparatus for heliostat support may be optimised in order to offer necessary levels of stability in relation to normal incoming environmental forces whilst also isolating the heliostat drive mechanism from otherwise damaging incoming environmental forces.
Further embodiments of the present invention stem from the realisation, by the inventor, that current methods and apparatus for heliostat support may be improved by integration of power supply functionality with the support apparatus structural components.
Advantages provided by the present invention centre around simplification and cost reduction flowing from:
Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the relevant art from this detailed description.
Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:
In an embodiment of the present invention, as shown in
The vertical member 20 is of a rigid, elongate nature and may be constructed from a suitable material known to those skilled in the relevant art, including but not limited to; naturally occurring materials or fibres, including timber, metallic materials including steel and aluminium, or synthetic materials including plastics.
In a preferred embodiment of the present invention the vertical member 20 is constructed from electric resistance welded hollow mild steel pipe having a circular cross-sectional shape and a nominal bore dimension of about 50 millimetres.
The depth of penetration of the second end region 40 into the ground 70 is determined in each site location experimentally according to the geotechnical characteristics of the ground in that specific location. For example, in regions where the ground 70 is of a softer composition (having sandy, or clay like characteristics for example) the second end region 40 may be penetrated more deeply in order to achieve the necessary ground reaction. This is in contrast to harder, rockier type ground conditions which require relatively shallower penetration of the end region 40 to achieve the necessary ground reaction.
In general the length of the vertical member 20 and the depth of penetration into the ground 70 would exceed about 300 millimetres.
In a preferred embodiment of the present invention, the length of the vertical member 20 is about 3000 millimetres and the second end region 40 located in the ground 70 is about 2200 millimetres in length.
Advantageously the vertical member 20 is a low cost item and requires little fabrication, other than cutting to the required length. Various cross sectional profiles of the vertical member such as square, star etc are envisaged for offering an anti-torsional resistance and are encompassed in the scope of the present invention.
Embodiments of the present invention may include stabilising structures. These may include earth engaging configurations comprising one or a combination of protrusions or indentations. In one example a stabilising structure is provided in the form of an anti-torsion member 80. The anti-torsion member offers resistance to torsional forces that may be applied to the support apparatus from environmental conditions, such as wind for example. An anti-torsion member 80 may take the form of one or more projections rigidly affixed to the vertical member 20 and having size, shape and number suitable to the ground conditions at the site location.
In another embodiment a stabilising structure is provided by way of a rigid interconnection between a first vertical member of a heliostat support and a second vertical member of another heliostat support. In a preferred embodiment of the present invention, as shown in
In a preferred embodiment, the elongate stabilising member 90 is constructed from electric resistance welded hollow mild steel pipe having a circular cross-sectional shape and a nominal bore dimension of about 25 millimetres.
In a preferred embodiment of the present invention, the length of the elongate anti-torsion member 90 is about 2400 to 2500 and preferably 2486 millimetres.
Advantageously, the elongate anti-torsion member 90 is a low cost item and requires little fabrication, other than cutting to the required length.
Preferred embodiments encompass use of vertical members having characteristics further adapted according to their position within the mirror array. The vertical member 20 may be of a greater diameter or penetrated to a greater depth when located at the extremities of the mirror array as these locations encounter higher short term environmental forces, for example, wind loading.
Operable interconnection 111 between the first end region 100 or second end region 110 of the elongate anti-torsion member 90 may include a system of plates that may be permanently connected via suitable techniques known to those skilled in the relevant art such as welding, riveting and swaging for example.
In a preferred embodiment of the present invention, the operable interconnection, shown generally as 111, in
The opposed plates 120 may be constructed from a suitable material known to those skilled in the relevant art, including but not limited to; naturally occurring materials or fibres including timber, metallic materials including steel and aluminium, or synthetic materials including plastics.
In a preferred embodiment of the present invention the opposed plates 120 are constructed from stamped approximately 4 millimetre thick mild steel having a ridged shape that maximises strength and contact area with the vertical member 20 and elongate anti-torsion member 90.
Embodiments of the present invention as shown in
In preferred embodiments, the drive mechanism connection means 50 is adapted to isolate the heliostat drive mechanism 60 from torsional forces that may arise between the drive mechanism 60 and the vertical member 20 (from environmental conditions, for example) that may otherwise damage the internal components of the drive mechanism 60.
Isolation of damaging torsional forces (note that the actual magnitude of torsional force at which damage occurs to the drive mechanism is determined by the design of the drive mechanism) is achieved in preferred embodiments of the present invention by frictional means.
Preferably, the connection means, shown generally as 50 in
Frictional effects arising between the surfaces of the drive mechanism 60, the plates 140, 150, 160 and the first end region 30 of the vertical member 20 serve to resist low level incoming environmental torsional forces between the drive mechanism 60 and the vertical member 20.
The degree of tightening of the fasteners 170 influences or controls the degree of frictional effect between the surfaces of the drive mechanism 60 and the plates 140 and 150 on one hand and the degree of frictional effect between the surfaces of the plates 150 and 160 and the first end region 30 of the vertical member 20 on the other hand. The frictional resistance may thus be adjusted to oppose incoming environmental torsional forces at levels that do not damage the drive mechanism, whilst allowing for slip when subjected to incoming environmental torsional forces that would damage the drive mechanism 60. In this way the connection means 50 serves to isolate the drive mechanism 60 from damage due to external environmental factors when torsional forces reach a predetermined threshold.
For example the fasteners 170 would generally be tightened sufficiently to result in a slip threshold that correlated to a magnitude of torque above that imparted upon the optical element by wind in the vicinity of 0 km/h to 40 km/h, but below the magnitude of torque that would result in damage to the drive mechanism 60. In practice this arrangement advantageously provides the resistance necessary to assure accurate tracking in normal operating conditions, whilst protecting the relatively expensive drive mechanism 60 from damage in extreme conditions.
Advantageously, in addition to protection from environmental forces such as high winds, the connection means 50 serves to protect the drive mechanism 60 from damage from other possible causes such as forces imparted from livestock, vehicles or even other heliostats or heliostat components for example that may interact with optical elements over the life of the system.
The opposed plates 140, 150, 160 are constructed from a suitable material known to those skilled in the relevant art, including but not limited to; naturally occurring material or fibres including timber, metallic materials including steel and aluminium, or synthetic materials including plastics.
In a preferred embodiment of the present invention the external opposed plates 140 and 160 are economically constructed from stamped approximately 4 millimetre thick mild steel having a ridged shape that maximises strength and contact area with the drive mechanism 60 and the vertical member 20. The intermediate opposed plate 150 is cost effectively constructed from extruded aluminium having a scalloped shape that maximises contact area with the drive mechanism 60 and the vertical member 20.
In embodiments of the present invention, the support apparatus is adapted to optimise drive mechanism power supply arrangements. As illustrated in
This aspect of the present invention offers benefits both in terms of reduction in materials and improvements in installation process. Primarily, the need for cables and cable connectors is significantly reduced, since the function of the cables and connectors of the current return path is performed by the apparatus components themselves.
Embodiments of the present invention comprise structures that offer reduction in cost during the support apparatus' installation phase.
The vertical member 20 may be easily carried by a single person (avoiding the need for cranes), and may be readily located in the ground without the need for pre-digging of a hole and employment of customary forms of site installation, using for example concrete. This obviates the need for earthworks, and reduces the cost of materials used in installation. Avoidance of the need to wait for concrete to cure reduces installation time and lowers installation costs.
In preferred embodiments, the step of locating the vertical member 20 in the ground 70 may for example be achieved through use of driving equipment.
As shown in
The elongate anti-torsion member 90 is readily carried by a single person and the opposed plates 120 that affix the anti-torsion member 90 may be rapidly attached via fasteners 130 utilising basic tools such as spanners and torque wrenches, that are highly portable and do not require electricity supply, thus reducing the cost of installation of the support apparatus.
Likewise, the opposed plate arrangement of the heliostat drive mechanism connection means (140, 150, 160) may be rapidly attached via the fasteners 170, offering similar cost reduction benefits.
Furthermore, the installation of the power supply system's current source path is greatly simplified in the present invention, because the insulated cable of the current source path is elevated and easily accessible. In comparison to prior art approaches, where the power supply materials are located underground, the ongoing maintenance of the power supply circuit of the present invention is achieved cost effectively due to its easily inspected configuration.
While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.
As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive.
Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures.
“Comprises/comprising” and “includes/including” when used in this specification are taken to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, ‘includes’, ‘including’ and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014901108 | Mar 2014 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AU2015/000189 | 3/30/2015 | WO | 00 |
