WO2021127712A1 - Héliostat - Google Patents

Héliostat Download PDF

Info

Publication number
WO2021127712A1
WO2021127712A1 PCT/ZA2020/050071 ZA2020050071W WO2021127712A1 WO 2021127712 A1 WO2021127712 A1 WO 2021127712A1 ZA 2020050071 W ZA2020050071 W ZA 2020050071W WO 2021127712 A1 WO2021127712 A1 WO 2021127712A1
Authority
WO
WIPO (PCT)
Prior art keywords
heliostat
flexible member
wind
tarp
reflective
Prior art date
Application number
PCT/ZA2020/050071
Other languages
English (en)
Inventor
Thomas Charles BAIN
Original Assignee
Bain Thomas Charles
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bain Thomas Charles filed Critical Bain Thomas Charles
Publication of WO2021127712A1 publication Critical patent/WO2021127712A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/82—Arrangements for concentrating solar-rays for solar heat collectors with reflectors characterised by the material or the construction of the reflector
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/80—Airborne solar heat collector modules, e.g. inflatable structures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/81—Arrangements for concentrating solar-rays for solar heat collectors with reflectors flexible
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S2023/83—Other shapes
    • F24S2023/832—Other shapes curved
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S2025/01—Special support components; Methods of use
    • F24S2025/017—Tensioning means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/71—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with parabolic reflective surfaces
    • F24S23/715—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with parabolic reflective surfaces flexible
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
    • F24S23/745—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces flexible
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y02E10/47—Mountings or tracking

Definitions

  • This invention relates to a heliostat.
  • a heliostat including: - a flexible member defining a plurality of nodes wherein at least a portion of a surface of the flexible member is reflective; a lifting means connected to the flexible member for lifting a portion of the flexible member to a height above a ground surface; tensioning members connected to the plurality of nodes defined by the flexible member at one end for allowing the flexible member to be tensioned when opposing ends of the tensioning members are connected to an anchoring surface; and an adjustment means for adjusting the tension of the tensioning members causing the reflective surface of the flexible member to change shape to allow sunlight hitting the reflective surface to be reflected towards a desired target surface.
  • the flexible member may include a plurality of reflective elements mounted thereon so as to define the reflective surface, preferably defining a plurality of reflective surfaces.
  • the flexible member may be in the form of a tarp.
  • the tarp may be manufactured from any suitable material which may be selected from the group including basalt fibre, basalt fibre mesh, nylon, PVC, and air-tight material.
  • the flexible member may have a generally parabolic shape for allowing sunlight to be reflected by the reflective elements towards and onto the target surface.
  • the material from which the flexible member may be manufactured may be embossed and/or joined to a stiff material member to reduce its flexibility.
  • the material from which the flexible member may be manufactured may be UV resistant.
  • the stiff material member may be manufactured from any suitable material, preferably being manufactured from glass fibre.
  • the flexible member may include a permeable portion for allowing wind to pass therethrough to reduce wind forces exerted on the flexible member and to prevent the build-up of suction pressures behind the flexible member.
  • the permeable portion of the flexible member may be reflective.
  • holes may be defined in the flexible member for allowing passage of air therethrough thereby allowing wind to pass through the flexible member and reduce wind forces exerted on the flexible member.
  • the flexible member may be in the form of a plurality of cables forming a support lattice which may connect the lifting means to the nodes located at the junctures between reflective elements.
  • the reflective element may be manufactured from a lightweight flexible material, preferably being manufactured from a plurality of laminated layers, which layers may include a reflective film layer manufactured from a reflective material, such as a metallic material for example.
  • the reflective element may be in the form of tensioned film.
  • the reflective element may be manufactured from a material having high thermal resistance, high thermal conductivity and/or a low thermal expansion co efficient.
  • the reflective element may be preformed into a shape and/or profile which may serve to compensate for the change in shape thereof as a result of being lifted by the lifting means in use. Holes may be defined in the reflective elements for reducing forces exerted thereon by wind and for reducing turbulence on the operatively rearward side of the flexible member.
  • the reflective elements may be arranged on the flexible member to be in close proximity to each other for maximising reflective surface area. Further, it is to be appreciated that smaller gaps between adjacent reflective elements minimises wind pressure differences between the different reflective elements.
  • Each reflective element may have a surface area in the range of 15m 2 to 40m 2 , preferably having a surface area in the region of 25m 2 . It is to be appreciated that the size and surface area of the reflective elements are dependent on a user’s requirements and may be larger if necessary, for example, the reflective elements could be 10m by 10m should a particular user require same. Further preferably, the reflective elements may have a width and length in the region of 5m.
  • a supporting structure may be provided for supporting the reflective elements on the flexible member.
  • the supporting structure may include a supporting member on which the reflective element may be mounted, and a supporting framework for supporting the supporting member, and with it, the reflective element, on the flexible member.
  • the supporting member may have a generally concave shape, preferably a slight concave shape, further preferably having a double parabolic shape, in order to maximize the amount of sunlight to be received and reflected by the reflective elements of the flexible member.
  • the supporting member may be in the form of a tensioned membrane.
  • the supporting structure may be in the form of an inflatable flexible member, such as a mattress or similar.
  • the supporting framework may include a plurality of supports which may be arranged in a grid-like manner.
  • the supports may be manufactured from layers of various suitable composite materials wherein the composite materials having a higher strength and/or density are utilised for supports located towards a periphery of the reflective element and wherein layers of lower strength and/or density are utilised for supports located generally centrally relative the reflective element, typically for reducing the overall weight of the supporting structure. Haunches may be defined in the supports for reducing stress concentrations therein.
  • the supports may be manufactured from any suitable lightweight synthetics, plastics or metallic material. Preferably, the supports may be manufactured from any one of the group including, but not limited to, polystyrene, expanded polystyrene, GeofoamTM, or titanium.
  • the supporting structure may further include foot members which may be shaped and/or configured to allow the supporting framework to rest on the flexible member.
  • the foot members may be located at substantially equal distances from a centre point of the reflective element for allowing the parabolic shape of the flexible member to be maintained in use.
  • the foot members may have a generally dome shape wherein a flat portion of the dome is attached to the supporting framework so as to ensure that contact points between foot members of a single reflective element and the flexible member are always the same distance to the centre point of the reflective element.
  • the size of the foot members may be varied to compensate for an imbalanced resultant moment caused by some foot members being placed closer to the centre point of the reflective element than others, to ensure that the parabolic shape of the flexible member is maintained to allow the sunlight to be reflected onto the target surface.
  • the foot members are connected to the supporting framework via spring members for allowing a constant force to be applied on the flexible member.
  • the foot members may be extendable, thereby capable of applying variable force as required to ensure that the reflective element is orientated as desired.
  • the position of the extendable foot members may be controlled via an actuator arrangement.
  • the actuator arrangement may be arranged in electrical communication with a sensor arrangement for sensing differences in wind forces acting on windward and leeward sides of the flexible member such that the actuator arrangement is activated under predetermined wind conditions.
  • the extendable foot members may be configured to compensate for elongation of the tension members in use so as to ensure that the reflective elements are maintained in the correct orientation.
  • the supporting framework may yet further include attachment means for allowing the supporting framework to be attached to the flexible member.
  • the attachment means may be shaped and/or configured to receive the foot members of the supporting framework therein for attaching the supporting framework to the flexible member via the foot members.
  • the attachment means may be in the form of any suitable fastener or joint such as a screw-thread fastener, adhesive, pin joint, ball joint, clasp, clip or the like, preferably being in the form of a plurality of clips.
  • the clips may be arranged between the supporting framework and the flexible member at locations proximal to the nodes for minimising displacement of the clips as a result of the flexible member flexing during windy conditions.
  • Spacer members may be provided between the reflective elements and the supporting members for allowing deformation of the supporting member which may have occurred over time to be corrected. It is to be appreciated that the spacer members allow the supporting framework to experience an increase in direct stress applied to the supporting framework as a result of allowing creep to occur overtime and, therefore the mass of the supporting framework may be decreased and/or the allowable wind loads increased.
  • the portion of the flexible member beneath the reflective element may be substantially impermeable to wind so as to prevent the supporting member from experiencing wind forces exerted thereon, which wind forces may cause a convex shape of the reflective element resulting in less sunlight being reflected on the target surface, as well as minimizing uneven bending of the attachment means.
  • the impermeable portion of the flexible member may serve to reduce stresses on the supporting structure, and further, may serve to reduce the likelihood of cyclic stress reversal and associated fatigue failure of the supporting structure.
  • the nodes may be located at the junctures between the plurality of reflective elements.
  • the nodes may be in the form of layers of material stacked on top of each other for strengthening thereof.
  • the layers of material may be manufactured from any suitable material which may have a desired degree of stiffness and flexibility.
  • the layers of material may have various thicknesses. It is to be appreciated that the thicker layers of material may act as stress relievers for the surrounding area of the flexible member which defines the node.
  • the layers may be formed from layers of circular material stacked on top of each other, preferably concentrically, so as to form a node of tapering thickness.
  • the node may taper in thickness away from a point at which the tensioning member is connected to the node for accommodating stress concentrations at the node as a result of being connected to the tensioning members. It is to be appreciated that accommodation of stress concentrations reduce the likelihood of tears or rips occurring in the flexible member.
  • a wind-tight fabric may overlay the flexible member on a operatively rearward side thereof.
  • the wind-tight fabric may be attached between nodes or tensioning members leading to the nodes for allowing wind forces to be diverted away from the supporting structure to the nodes or tensioning members.
  • the wind-tight fabric placed on the leeward or operatively rearward side of the flexible member serves to reduce wind forces on the operatively under side of the supporting structure, thereby reducing stresses, resonance and/or turbulence, and reducing the likelihood of cyclic stress reversal and associated fatigue failure of the supporting structure.
  • the wind tight fabric may include holes defined therein for permitting passage of wind at predetermined locations, thereby directing the wind away from the supporting structure. The holes may lead to generally cylindrical sleeves manufactured from wind tight fabric for allowing the wind to pass through the flexible member while minimising the wind forces exerted on the supporting structure.
  • the lifting means may be in the form of a balloon and/or blimp which may be filled with a gas, which gas is typically lighter than air so as to provide a degree of lift.
  • a plurality of balloons may be connected to the flexible member, preferably along a width thereof.
  • the plurality of balloons may be spaced apart a distance in the region of 7.5m for ensuring that balloons deflected by gusts of wind do not come into contact with adjacent balloons when flailing.
  • Balloons located towards peripheral regions of the flexible member may be smaller than the balloons located towards a generally central region of the flexible member so as to increase lifting forces of the balloons over the generally central region of the flexible member.
  • the peripherally located balloons may be partially filled with gas for reducing the lifting force thereof.
  • the gas may be in the form of any suitable gas with a density that is less than that of air or any suitable heated gas, preferably being hydrogen.
  • the balloons may be of any suitable geometric shape, preferably being shaped so as to minimise effects of wind thereon, preferably having a relatively low drag co-efficient. It is to be appreciated that the lower the drag co-efficient of the balloon, the smaller deflection occurs as a result of wind.
  • the balloons may have a generally elongate cylindrical shape, wherein an operatively lower end region of the balloon may have a generally cone shape.
  • the balloons may have a diameter in the range of 3m to 7m, preferably being in the region of 4.5m. It is to be appreciated that the size and volume of the balloons are dependent on a user’s requirements and may be larger if necessary.
  • Spacers may be provided for spacing adjacent balloons apart from each other thereby reducing the likelihood of the adjacent balloons rubbing against each other and wearing down the balloon material, in use. Typically, spacers may be provided when the balloons are of a size which does not permit sufficient spacing in order to prevent contact therebetween.
  • a single elongate balloon having a width which spans the width of the flexible member may be utilised for reducing the varying effects of wind forces on the flexible member.
  • the lifting means may further include buoyant aerofoils which may be fastened to the flexible member and/or the balloons for providing additional lift when wind speeds increase.
  • the aerofoils may be inflated with a gas which may be lighter than air, preferably being inflated with hydrogen.
  • a connector may be provided for connecting the lifting means to the flexible member.
  • the connector may be in the form of a cable or rope which may be fastened to the balloon at one end and which may be fastened to the flexible member at an opposite end.
  • the cable or rope may be connected to the flexible member via a ball joint connector.
  • An anchoring means may be provided for anchoring the balloons to the ground surface.
  • the anchoring means may be in the form of a cable, rope or the like.
  • the anchoring means may include a first set of cables extending from the balloon to the ground surface substantially beneath the balloon and a second set of cables extending at an angle from an operatively upper portion of the balloons to the anchoring surface.
  • the first set of cables may be connected to a motor and reel arrangement for allowing the balloons to be reeled in when necessary.
  • the second set of cables may serve to prevent the balloons from touching one another as a result of wind acting thereon.
  • the cables may be connected to the balloons in an alternating manner. It is to be appreciated that the spacers may be utilised in conjunction with the anchoring means to reduce the likelihood of frictional contact between the balloons in use.
  • the tensioning members may be connected to the plurality of nodes on either side of the flexible member.
  • the tensioning members are connected to and extend from the nodes on both sides of the flexible member.
  • the tensioning members may be in the form of any one of the group including a rope, cable, tether, basalt fibre and wire.
  • the tensioning members may be manufactured from any suitable material which has a low flexibility, high strength and/or a high density. It is to be appreciated that having a stronger tensioning member allows a smaller diameter to be utilised, thereby reducing the required size and weight of the reel.
  • the tensioning members may be in the form of steel cables which may have a thickness in the range of 3mm to 8mm, preferably being in the region of 6mm.
  • the adjustment means may include a motor and reel arrangement.
  • the adjustment means may include a plurality of motor and real arrangements for adjusting individual tensioning members attached to the plurality of nodes.
  • a motor of the motor and reel arrangement may be in the form of any suitable motor, preferably being in the form of a brushless motor. It is to be appreciated that a brushless motor is advantageous in that it requires relatively minimal maintenance.
  • the motor may be in the form of a stepper motor for allowing the tension of the tensioning members to be adjusted in desirable increments.
  • a reel of the motor and reel arrangement may be driven by the motor. The reel may be sized, shaped and/or configured to allow the tensioning members to be wound therearound.
  • the reel may include a guide formation, preferably in the form of a groove, for guiding a tensioning member while being wound around the reel so that the tensioning member is wound up uniformly. More particularly, a width of the groove may be slightly wider than a width of the tensioning members so as to ensure that during winding, each successive wind of the tensioning member is directly on top of the preceding wind, thereby preventing the tensioning members from winding adjacent one another on the reel. It is to be appreciated that ensuring uniform winding of the tensioning members improves accuracy when determining the number of windings of the tensioning members on the reel, which in turn facilitates the measurement of a reeling-in and/or releasing rate using a measuring device.
  • the measuring device may be in the form of any suitable measuring device for determining the number of revolutions that the reel has been reeled in and/or released as well as a current rotational position of the reel. It is to be appreciated that the number of revolutions may be used to determine an estimation of a length of the tensioning members that has been reeled in and/or released in order to determine an estimated current length of the tensioning members for determining the reeling-in and/or releasing rate of the reel.
  • the motor may be powered by any suitable powering means which may be selected from the group including photovoltaic cells, batteries, a fuel source, stored heated liquid sodium and electrical power.
  • the adjustment means may include a controller for controlling the motor and reel arrangements such that the flexible member is displaced via the tensioning members into an orientation, position and/or shape which ensures that sunlight is reflected to the target surface.
  • the controller may be arranged in communication with a position sensing arrangement for sensing a position of each node of the flexible member relative a reference point.
  • the position sensing arrangement may include a plurality of electromagnetic radiation emitters mounted on each node of the flexible member and a receiver mounted on a fixed surface remote from the flexible member.
  • the receiver may be connected to the controller such that when one of the emitters is displaced out of position, which may indicate that a node is incorrectly positioned, the controller causes the motor and reel arrangement associated with that particular node to activate thereby displacing the node until the signal from the emitter is received, which may indicate that the node is correctly positioned.
  • the controller may be arranged in communication with the extendable foot members for allowing control thereof in order to displace the relevant reflective elements into a correctly aligned position.
  • the adjustment means may be configured to compensate for elongation of the tensioning members in use.
  • the adjustment means may be configured to adjust the tension of the tensioning members according to a position of the sun, preferably for allowing the reflective elements to be orientated to reflect sunlight to the target surface.
  • the adjustment means may be arranged in communication with a light sensor, preferably a light intensity sensor for sensing in which direction the sun is shining.
  • a clutch and/or brake system may be provided for applying a braking force on the motor and reel arrangement to stop reeling in or out of the tensioning members.
  • the clutch and/or brake system may include an actuating means for actuating the clutch and/or brake system.
  • the actuation means may be in the form of a solenoid.
  • a stabilising means may be provided for stabilising the reel of the motor and reel arrangement when torque is applied thereto by the motor.
  • the stabilising means may be attached to the reel for counteracting a moment created by a torque of the motor.
  • the stabilising means may be in the form of a rotating counterweight which may be attached to the reel at an angle substantially perpendicular to the motor. It is to be appreciated that the stabilising means ensures that the motor and reel arrangement is stable on a single axis when the torque of the motor is counteracted by the tension of the stabilising means.
  • the stabilising means may be in the form of cables, preferably pretensioned cables, which may be attached to the reel at an angle perpendicular to the motor at one end, and to the ground surface at an opposing end.
  • the cables may be attached to the ground surface at an acute angle.
  • a motor anchoring member may be provided for anchoring the motor to the ground surface.
  • a plurality of motor anchoring members may be provided for anchoring the motor to the ground surface.
  • the motor anchoring member may be in the form of a cable which is attached to the motor.
  • the motor anchoring member may be attached to the motor via a cylindrical member for allowing the torque of the motor to be counteracted.
  • the motor anchoring member may be secured to a support member of a windbreak system.
  • the support member may be in the form of a pole.
  • the motor anchoring member may be anchored to the ground surface by a body of high mass, preferably a bag filled with sand and/or any other suitable material.
  • the member of high mass may be in the form of any one of the group including a concrete block, sand bag or rock.
  • the target surface may be in the form of a heat receiving collection device for a power generation system.
  • the target surface may be in the form of a radiation concentration device for concentrating radiation onto a photovoltaic system which is more efficient at higher fluxes, preferably onto a concentration photovoltaic system which is capable of withstanding a solar concentration ratio in excess of 1 :1000, thereby reducing the quantity of solar absorption material required to generate a particular quantity of energy.
  • the target surface may be in the form of a solar furnace.
  • Wind force counteracting members may be provided for counteracting wind forces exerted on the flexible member.
  • the counteracting members may be in the form of cables, ropes or the like.
  • the wind counteracting members may be attached to the flexible member for counteracting forces exerted on the flexible member by the wind.
  • Damping means may be provided for damping and reducing resonance experienced by the reflective element, supporting structure or flexible member as a result of wind.
  • damping means may be in the form of damper which may be connected to any one or more of the connecting points between the supporting structure and the flexible member, between the nodes and the tensioning members, and between the tensioning members and the adjustment means.
  • additional dampers or shock absorbers may be arranged between the lifting means and the flexible member for reducing shock experienced by the flexible member resulting from sudden changes in wind speed.
  • a windbreak system may be provided for reducing the effects of wind on the flexible member, tensioning members and/or lifting means in use.
  • the windbreak system may be in the form of any suitable windbreak system.
  • the windbreak system may surround the flexible member, tensioning members and lifting means for protecting against forces exerted thereon by the wind.
  • the windbreak system may have a height in the range of 2m to 6m, preferably being in the region of 3m.
  • the windbreak system may include support members and panels extending between the support members.
  • the support members may be in the form of vertical poles secured to the ground surface and for supporting the panels in a substantially vertical position relative to the ground surface.
  • the support members may be secured to the ground surface by way of cables and/or ropes extending from the support members.
  • the windbreak system may be located on a crest of a hill surrounding the flexible member, tensioning members and/or lifting means. It is to be appreciated that the hill may be in the form of an earthwork or Geofill® mound.
  • a retraction system may be provided for retracting the flexible member into a retracted stowage condition when wind speeds exceed a predetermined maximum.
  • the predetermined maximum wind speed may be in the region of 10m/s.
  • the predetermined maximum may be monitored on an hourly basis, preferably being calculated using an average hourly wind speed and typically excludes gusts of wind.
  • the retraction system may include a displacement arrangement for displacing the flexible member such that it folds and/or stacks on top of itself, preferably in a generally concertina fashion, while being displaced into the retracted stowage condition.
  • the displacement arrangement may be configured to displace the flexible member such that it is in lay flat abutment with the ground surface, typically in an emergency situation where wind speeds would destroy the flexible member or supporting structure.
  • the displacement arrangement may include a plurality of cables which may extend between the nodes of the flexible member and a plurality of motor and reel arrangements for allowing the cables to be reeled in in a predetermined order so as to facilitate folding of the flexible member.
  • a wind prediction system may be provided for predicting a magnitude and direction of wind acting on the flexible member, lifting means and/or tensioning members.
  • the wind prediction system may be in the form of any suitable wind prediction system.
  • the wind prediction system may be in the form of a floating member, preferably a balloon and/or blimp, which may be connected to an anchoring means, preferably a rope.
  • the anchoring means forms an angle with the ground surface which angle may be used to determine the magnitude and direction of the wind acting on the floating member.
  • a measuring device may further be provided for measuring said angle. It is to be appreciated that the measuring device may be attached to the ground surface, preferably the measuring device may be attached to a metal plate which rests on a concrete slab which covers a portion of the ground surface.
  • the wind prediction system may be in the form of a LIDAR.
  • a radar system may be utilised to determine and/or predict wind speeds.
  • the radar system may be configured to utilise the doppler effect to determine wind speeds. It is to be appreciated that when bursts and/or gusts of wind are detected, the flexible member and with it, the plurality of reflective elements, may be retracted into the retracted stowage condition.
  • the wind prediction system may be arranged in communication with the retraction system for allowing the flexible member to be retracted before winds reach excessive speeds.
  • a processing unit may be arranged in communication, preferably wireless communication, with the measuring device for processing the information measured by the measuring device to determine the magnitude and direction of the wind.
  • the processing unit may be in the form of any suitable processing unit, preferably a computer.
  • the processing unit may also be in communication with sensors on the plurality of nodes for processing information determined by the sensors to determine the position of each of the nodes relative to the target surface.
  • a sunlight reflection system which includes a plurality of heliostats as hereinbefore described which may be arranged to form corridors to direct wind between the heliostats.
  • the heliostats which may be arranged on the periphery of the sunlight reflection system acts as shields from excessive wind for the other heliostats and thus need to be configured to be stronger and/or shielded by higher windbreak systems.
  • a secondary heliostat may be provided which may be configured to receive and reflect sunlight from the plurality of heliostats on to the target surface.
  • the secondary heliostat may have any suitable shape, preferably a linear parabolic trough shape or a semi-circular parabolic trough shape.
  • a slope of the linear parabolic or semi-circular trough shape may decrease in magnitude the further a point on it is located from a centre point thereof for allowing sunlight reflected by the heliostats onto the secondary heliostat to be reflected onto the target surface.
  • the secondary heliostat may have a semi-circular shape.
  • the secondary heliostat may be sized, shaped and/or configured to compensate for potential misalignments present in any one or more of the plurality of heliostats from which sunlight is reflected.
  • the secondary heliostat may be elevated, preferably being positioned at an angle relative the plurality of heliostats from which sunlight is reflected, for allowing a sunlight from a plurality of heliostats placed in next to each other, typically in rows, to be received by the secondary heliostat.
  • the plurality of heliostats may be placed on slope so that heliostats placed in front of others do not obstruct the sunlight from the heliostats placed further back, and prevent the sunlight from reaching the secondary heliostat.
  • a cooling system may be provided for cooling the secondary heliostat in use. It is to be appreciated that the heliostat according to the present invention may be configured to be used in any system which requires heat such as hydrogen production and desalination of water and sea water.
  • FIG. 1 to 3 are three-dimensional schematics showing a generally front, rear and side view of a heliostat in accordance with the present invention
  • Figure 4 is an enlarged three-dimensional view showing a flexible member of the heliostat
  • Figure 5 is three-dimensional partially cut-away view showing a reflective element mounted on the flexible member
  • Figures 6 and 7 are three-dimensional partially cut-away views of the flexible member showing foot members resting thereon;
  • Figures 8 and 9 are three-dimensional views showing the supporting structure resting on the flexible member via foot members;
  • Figure 10 is a three-dimensional view showing the supporting structure resting on the flexible member via the foot members and a wind-tight fabric beneath the flexible member;
  • Figure 11 is a three-dimensional schematic showing a buoyant aerofoil fastened to a balloon
  • Figures 12 and 13 are three-dimensional schematics showing a motor and reel arrangement with different stabilising means, respectively;
  • Figure 14 is a three-dimensional close-up view showing a portion of the windbreak system
  • Figure 15 is a sectioned side view showing the high mass member;
  • Figure 16 is a two-dimensional schematic showing a side view of the flexible member;
  • Figure 17 is a three-dimensional schematic of the flexible member while being retracted into a retracted stowage condition
  • Figure 18 is a three-dimensional schematic of the flexible member nearing the retracted stowage condition
  • Figure 19 is a three-dimensional schematic showing a wind prediction system
  • Figure 20 is a three-dimensional schematic showing a sunlight reflection system in accordance with a second aspect of the present invention
  • Figures 21 and 22 are three-dimensional schematics showing a secondary heliostat having two different shapes, respectively;
  • Figure 23 is a three-dimensional schematic showing the sunlight reflection system
  • Figure 24 is a schematic showing a path of the nodes as the flexible member is retracted towards the retracted stowage condition
  • Figure 25a is a schematic showing the nodes of the flexible member is as the tensioning members are retracted
  • Figure 25b is a schematic showing the secondary verifying method
  • Figure 26a is a schematic showing the method for calculating the optimal position of the vertical centre nodes
  • Figure 26b is a schematic showing the method for calculating the optimal position of the remainder of the nodes.
  • Figure 27 is a schematic showing the method for calculating the current and desired position of the nodes.
  • reference numeral 10 refers generally to a heliostat.
  • the heliostat 10 includes a flexible member in the form of a tarp 12 defining a plurality of nodes 14 between a plurality of reflective elements 16 mounted on the tarp 14, the reflective elements 16 defining a plurality of reflective surfaces 18, a lifting means in the form of balloons 20 connected to the tarp 12 for lifting a portion of the tarp 12 to a height above a ground surface 22, tensioning members in the form of steel cables 24 connected to the plurality of nodes 14 at one end of the tarp 12 for allowing the tarp 12 to be tensioned when opposing ends of the cables 24 are connected to an anchoring surface 26, and an adjustment means in the form of a plurality of motor and reel arrangements 28 for adjusting the tension of the cables 24 causing the reflective surface of the tarp 12 to change shape to allow sunlight 30 hitting the reflective surfaces 18 of the reflective elements 16 to be reflected towards a desired target surface 32.
  • the tarp 12 is manufactured from any suitable material which is selected from the group including basalt fibre, basalt fibre mesh, nylon, PVC, and air-tight material.
  • the tarp 12 has a generally parabolic shape for allowing sunlight to be reflected by the reflective elements 16 towards and onto the target surface 32.
  • the material from which the tarp 12 is manufactured is embossed or joined to a stiff material member (not shown) to reduce its flexibility.
  • the material from which the tarp 12 is manufactured is UV resistant.
  • the stiff material member (not shown) is manufactured from any suitable material, typically being manufactured from glass fibre.
  • the tarp 12 includes a permeable portion 34 for allowing wind to pass therethrough to reduce wind forces exerted on the tarp 12 and to prevent the build-up of suction pressures behind the tarp 12, typically the leeward side or operatively rearward side thereof.
  • the permeable portion 34 of the tarp 12 can be reflective.
  • holes can be defined in the tarp 12 for allowing passage of air therethrough thereby allowing wind to pass through the tarp 12 and reduce wind forces exerted on the tarp 12.
  • the tarp 12 is in the form of a plurality of cables (not shown) forming a support lattice (not shown) which connects the balloons 20 to the nodes 14 located at the junctures between reflective elements 16.
  • the reflective element 16 is manufactured from a lightweight flexible material, typically being manufactured from a plurality of laminated layers (not shown), which layers include a reflective film layer (not shown) manufactured from a reflective material, such as a metallic material for example.
  • the reflective element 16 is in the form of tensioned film (not shown).
  • the reflective element 16 is manufactured from a material having high thermal resistance, high thermal conductivity and a low thermal expansion co-efficient.
  • the reflective element 16 is preformed into a shape and profile which serves to compensate for the change in shape thereof as a result of being lifted by the balloons 20 in use.
  • holes can be defined in the reflective elements 16 for reducing forces exerted thereon by wind and for reducing turbulence on the or operatively rearward side of the tarp 12.
  • the reflective elements 16 are arranged on the tarp 12 to be in close proximity to each other for maximising reflective surface area. Further, it is to be appreciated that smaller gaps between adjacent reflective elements 16 minimises wind pressure differences between the different reflective elements 16.
  • Each reflective element 16 has a surface area in the range of 15m 2 to 40m 2 , typically having a surface area in the region of 25m 2 .
  • the size and surface area of the reflective elements are dependent on a user’s requirements and may be larger if necessary, for example, the reflective elements could be 10m by 10m should a particular user require same.
  • the reflective elements 16 have a width and length in the region of 5m. It is to be appreciated that reflective elements 16 of smaller width and length lead to an exponential decrease in a mass of the supporting framework and required size of the balloons 20 which in turn results in a proportional decrease in a size of the motor and reel arrangement 28, and a mass of the steel cables 24 resulting in a reduction of the overall cost of the heliostat 10.
  • a supporting structure 36 is provided for supporting the reflective elements 16 on the tarp 12.
  • the supporting structure 36 includes a supporting member 38 on which the reflective element 16 is mounted, and a supporting framework 40 for supporting the supporting member 38, and with it, the reflective element 16, on the tarp 12.
  • the supporting member 38 has a generally concave shape, typically a slight concave shape, further typically having a double parabolic shape, in order to maximize the amount of sunlight to be received and reflected by the reflective elements 16 of the tarp 12.
  • the supporting member 38 is in the form of a tensioned membrane.
  • the supporting structure can be in the form of an inflatable flexible member, such as a mattress or similar.
  • the supporting framework 40 includes a plurality of supports 42 which is arranged in a grid-like manner.
  • the supports 42 are manufactured from layers of various suitable composite materials wherein the composite materials having a higher strength and density are utilised for supports 42.1 located towards a periphery of the reflective element 16 and wherein layers of lower strength and density are utilised for supports 42.2 located generally centrally relative the reflective element 16, typically for reducing the overall weight of the supporting structure 36. Haunches (not shown) are defined in the supports 42 for reducing stress concentrations therein.
  • the supports 42 are manufactured from any suitable lightweight synthetics, plastics or metallic material. Typically, the supports 42 are manufactured from any of the group including, but not limited to, polystyrene, expanded polystyrene, GeofoamTM, or titanium.
  • the supports 42 of the supporting framework 40 include supports 42.3 arranged in a cross-shape and additional supports 42.4 arranged in a square-shape to strengthen the supports 42.3
  • the supporting structure 36 further includes foot members 44 which are shaped and configured to allow the supporting framework 40 to rest on the tarp 12.
  • the foot members 44 are located at substantially equal distances from a centre point of the reflective element 16 for allowing the parabolic shape of the tarp 12 to be maintained in use.
  • the foot members 44 have a generally dome shape wherein a flat portion of the dome is attached to the supporting framework 40 so as to ensure that contact points between foot members 44 of a single reflective element 16 and the tarp 12 are always the same distance to the centre point of the reflective element 16.
  • the size of the foot members 44 can be varied to compensate for an imbalanced resultant moment caused by some foot members 44 being placed closer to the centre point of the reflective element 16 than others, to ensure that the parabolic shape of the tarp 12 is maintained to allow the sunlight 30 to be reflected onto the target surface 32.
  • the foot members 44 are connected to the supporting framework 40 via spring members 46 for allowing a constant force to be applied on the tarp 12.
  • the foot members 44 can be extendable, thereby capable of applying variable force as required to ensure that the reflective element 16 is orientated as desired.
  • the position of the extendable foot members (not shown) are controlled via an actuator arrangement (not shown).
  • the actuator arrangement (not shown) is arranged in electrical communication with a sensor arrangement (not shown) for sensing differences in wind forces acting on windward and leeward sides of the tarp 12 such that the actuator arrangement (not shown) is activated under predetermined wind conditions.
  • the extendable foot members (not shown) are configured to compensate for elongation of the steel cables 24 in use so as to ensure that the reflective elements 16 are maintained in the correct orientation.
  • the supporting framework 40 yet further includes attachment means (not shown) for allowing the supporting framework 40 to be attached to the tarp 12.
  • the attachment means (not shown) is shaped and configured to receive the foot members 44 of the supporting framework 40 therein for attaching the supporting framework 40 to the tarp 12 via the foot members 44.
  • the attachment means (not shown) is in the form of any suitable fastener or joint such as a screw-thread fastener, adhesive, pin joint, ball joint, clasp, clip or the like, typically being in the form of a plurality of clips (not shown).
  • the clips are arranged between the supporting framework 40 and the tarp 12 at locations proximal to the nodes 14 for minimising displacement of the clips (not shown) as a result of the tarp 12 flexing during windy conditions.
  • Spacer members are provided between the reflective elements 16 and the supporting members 38 for allowing deformation of the supporting member 38 which has occurred over time to be corrected. It is to be appreciated that the spacer members (not shown) allow the supporting framework 40 to experience an increase in direct stress applied to the supporting framework 40 as a result of allowing creep to occur overtime and, therefore the mass of the supporting framework 40 is decreased and the allowable wind loads increased.
  • the portion 35 of the tarp 12 beneath the reflective element 16 is substantially impermeable to wind so as to prevent the supporting member 38 from experiencing wind forces exerted thereon, which wind forces may cause a convex shape of the reflective element 16 resulting in less sunlight being reflected on the target surface, as well as minimizing uneven bending of the attachment means (not shown).
  • the impermeable portion of the flexible member serves to reduce stresses on the supporting structure 36, and further, serves to reduce the likelihood of cyclic stress reversal and associated fatigue failure of the supporting structure 36.
  • the nodes 14 are located at the junctures between the plurality of reflective elements 16.
  • the nodes 14 are in the form of layers of material stacked on top of each other for strengthening thereof.
  • the layers of material are manufactured from any suitable material which has a desired degree of stiffness and flexibility.
  • the layers of material have various thicknesses. It is to be appreciated that the thicker layers of material act as stress relievers for the surrounding area of the tarp 12 which defines the node 14.
  • the layers are formed from layers of circular material stacked on top of each other, typically concentrically, so as to form a node of tapering thickness.
  • the node 14 tapers in thickness away from a point at which the tensioning member is connected to the node 14 for accommodating stress concentrations at the node 14 as a result of being connected to the steel cables 24. It is to be appreciated that accommodation of stress concentrations reduce the likelihood of tears or rips occurring in the tarp 12.
  • a wind-tight fabric 47 overlays the tarp 12 on an operatively rearward side thereof. The wind-tight fabric 47 is attached between steel cables 24 leading to the nodes 14 for allowing wind forces to be diverted away from the supporting structure 36 to the steel cables 24.
  • the wind- tight fabric 47 placed on the leeward side or operatively rearward side of the tarp 12 serves to reduce wind forces on the operatively under side of the supporting structure 36, thereby reducing stresses, resonance and/or turbulence, and reducing the likelihood of cyclic stress reversal and associated fatigue failure of the supporting structure 36.
  • the wind tight fabric 47 includes holes (not shown) defined therein for permitting passage of wind at predetermined locations, thereby directing the wind away from the supporting structure 36.
  • the holes (not shown) lead to generally cylindrical sleeves (not shown) manufactured from wind tight fabric for allowing the wind to pass through the tarp 12 while minimising the wind forces exerted on the supporting structure 36.
  • the balloons 20 are filled with a gas, which gas is typically lighter than air so as to provide a degree of lift.
  • a plurality of balloons 20 are connected to the tarp 12, typically along a width thereof.
  • the balloons 20 are spaced apart a distance in the region of 7.5m for ensuring that balloons 20 deflected by gusts of wind do not come into contact with adjacent balloons 20 when flailing.
  • Balloons 20.1 located towards peripheral regions of the tarp 12 are smaller than the balloons 20.2 located towards a generally central region of the tarp 12 so as to increase lifting forces of the balloons 20 over the generally central region of the tarp 12.
  • the peripherally located balloons 20.1 are partially filled with gas for reducing the lifting force thereof.
  • the peripherally located balloons 20.1 need to apply a smaller lifting force to the tarp 12 than the centrally located balloons 20.2 so that the generally central region of the tarp 12 remains taught.
  • the gas is in the form of any suitable gas with a density that is less than that of air or any suitable heated gas, typically being hydrogen.
  • the balloons 20 are of any suitable geometric shape, typically being shaped so as to minimise effects of wind thereon, typically having a relatively low drag co-efficient. It is to be appreciated that the lower the drag co-efficient of the balloon 20, the smaller deflection occurs as a result of wind.
  • the balloons 20 have a generally elongate cylindrical shape, wherein an operatively lower end region of the balloon 20 has a generally cone shape.
  • the balloons 20 have a diameter in the range of 3m to 7m, typically being in the region of 4.5m. It is to be appreciated that the size and volume of the balloons 20 are dependent on a user’s requirements and may be larger if necessary.
  • spacers are provided for spacing adjacent balloons 20 apart from each other thereby reducing the likelihood of the adjacent balloons 20 rubbing against each other and wearing down the balloon material, in use.
  • spacers are provided when the balloons 20 are of a size which does not permit sufficient spacing in order to prevent contact therebetween.
  • a single elongate balloon (not shown) having a width which spans the width of the tarp 12 is utilised for reducing the varying effects of wind forces on the tarp 12. It is to be appreciated that having more than one balloon 20 is advantageous in that if one balloon 20 fails catastrophically the tarp 12 is still lifted, the balloon 20 can easily be replaced, and more than one balloon 20 will assist the tarp 12 to be retracted with ease. It is to be appreciated further that an uplift force exerted by the balloons 16 on the tarp 12 is at least 1.5 times greater that the weight of the tarp 12 in order for the tarp 12 to maintain a desired shape.
  • Buoyant aerofoils 21 are provided which are fastened to the balloons 20 for providing additional lift when wind speeds increase.
  • the aerofoils 21 are inflated with a gas which is lighter than air, typically being inflated with hydrogen.
  • a connector 48 is provided for connecting the balloons 20 to the tarp 12.
  • the connector 48 is in the form of a cable which is fastened to the balloon 20 at one end and which is fastened to the tarp 12 at an opposite end.
  • the cable 48 is connected to the tarp 12 via a ball joint connector (not shown).
  • the anchoring means includes a first set of cables 50 extending from the balloons 20 to the ground surface 22 substantially beneath the balloon 20 and a second set of cables 51 extending at an angle from an operatively upper portion of the balloons to the anchoring surface 26.
  • the first set of cables 50 are connected to a motor and reel arrangement (not shown) for allowing the balloons 20 to be reeled in when necessary.
  • the second set of cables 51 serve to prevent the balloons 20 from touching one another as a result of wind acting thereon. It is to be appreciated that an operatively upper surface of the balloons 20 can be retracted to be level with the ground surface 22 utilising the first set of cables 50. It is to be appreciated that the spacers (not shown) can be utilised in conjunction with the second set of cables 51 to reduce the likelihood of frictional contact between the balloons 20 in use.
  • the steel cables 24 are connected to the plurality of nodes 14 on either side of the tarp 12. Typically, the steel cables 24 are connected to and extend from the nodes on both sides of the tarp 12.
  • the steel cables 24 are in the form of any one of the group including a rope, cable, tether, basalt fibre and wire. It is to be appreciated that having a stronger tensioning member allows a smaller diameter to be utilised, thereby reducing the required size and weight of the reel.
  • the steel cables 24 have a thickness in the range of 3mm to 8mm, typically being in the region of 6mm.
  • the motor and reel arrangements 28 are configured to adjust the tension in the individual steel cables 24 attached to the plurality of nodes 14.
  • a motor 28.1 of the motor and reel arrangement 28 is in the form of any suitable motor, typically being in the form of a brushless motor. It is to be appreciated that a brushless motor is advantageous in that it requires relatively minimal maintenance.
  • the motor 28.1 is in the form of a stepper motor for allowing the tension of the steel cables 24 to be adjusted in desirable increments.
  • a reel 28.2 of the motor and reel arrangement 28 is driven by the motor 28.1.
  • the reel 28.2 is sized, shaped and configured to allow the steel cables 24 to be wound therearound.
  • the reel 28.2 includes a guide formation (not shown), typically in the form of a groove (not shown), for guiding a steel cable 24 while being wound around the reel 28.2 so that the steel cable 24 is wound up uniformly. More particularly, a width of the groove (not shown) is slightly wider than a width of the steel cable 24 so as to ensure that during winding, each successive wind of the steel cable 24 is directly on top of the preceding wind, thereby preventing the steel cables 24 from winding adjacent one another on the reel 28.1.
  • the measuring device (not shown) is in the form of any suitable measuring device for determining the number of revolutions that the reel 28.1 has been reeled in and/or released as well as a current rotational position of the reel 28.1. It is to be appreciated that the number of revolutions is used to determine an estimation of a length of the steel cable 24 that has been reeled in and/or released in order to determine an estimated current length of the tensioning members for determining the reeling-in and/or releasing rate of the reel 28.1.
  • the motor 28.2 is powered by any suitable powering means (not shown) which is selected from the group including photovoltaic cells, batteries, a fuel source, stored heated liquid sodium and electrical power.
  • the motor and reel arrangement 28 includes a controller (not shown) for controlling the motors 28.2 thereof such that the tarp 12 is displaced via the steel cables 24 into an orientation, position or shape which ensures that sunlight 30 is reflected to the target surface 32.
  • the controller (not shown) is arranged in communication with a position sensing arrangement (not shown) for sensing a position of each node 14 of the tarp 12 relative a reference point (not shown).
  • the position sensing arrangement includes a plurality of electromagnetic radiation emitters (not shown) mounted on each node 14 of the tarp 12 and a receiver (not shown) mounted on a fixed surface (not shown) remote from the tarp 12.
  • the receiver (not shown) is connected to the controller (not shown) such that when one of the emitters (not shown) is displaced out of position, which may indicate that a node 14 is incorrectly positioned, the controller (not shown) causes the motor and reel arrangement 28 associated with that particular node 14 to activate thereby displacing the node 14 until the signal from the emitter (not shown) is received, which may indicate that the node 14 is correctly positioned.
  • the controller (not shown) is arranged in communication with the extendable foot members (not shown) for allowing control thereof in order to displace the relevant reflective elements 16 into a correctly aligned position.
  • the motor and reel arrangement 28 is configured to compensate for elongation of the steel cables 24 in use.
  • the motor and reel arrangement 28 is configured to adjust the tension of the steel cables 24 according to a position of the sun, typically for allowing the reflective elements 16 to be orientated to reflect sunlight 30 to the target surface 32. More particularly, the motor and reel arrangement 28 is arranged in communication with a light sensor, typically a light intensity sensor (not shown) for sensing in which direction the sun is shining.
  • a light sensor typically a light intensity sensor (not shown) for sensing in which direction the sun is shining.
  • a brake system (not shown) is provided for applying a braking force on the motor and reel arrangement 28 to stop reeling in or out of the steel cables 24.
  • the brake system includes an actuating means (not shown) for actuating the brake system (not shown).
  • the actuation means (not shown) is in the form of a solenoid (not shown).
  • a stabilising means is provided for stabilising the reel 28.1 when torque forces are applied thereto by the motor 28.2.
  • the stabilising means is attached to the reel 28.2 for counteracting a moment created by a torque of the motor.
  • the stabilising means is in the form of a rotating counterweight 52 which is attached to the reel 28.1 at an angle substantially perpendicular to the motor 28.2. It is to be appreciated that the stabilising means ensures that the motor and reel arrangement 28 is stable on a single axis when the torque of the motor 28.2 is counteracted by the tension of the stabilising means.
  • the stabilising means is in the form of cables 54, typically pretensioned cables 54, which are attached to the reel 28.1 at an angle substantially perpendicular to the motor 28.2 at one end, and to the ground surface 22 at an opposing end.
  • the cables 54 are attached to the ground surface 22 at an acute angle.
  • a motor anchoring member typically in the form of a cable 56, is provided for anchoring the motor 28.2 to the ground surface 22.
  • a plurality of anchoring members 56 are typically provided for anchoring the plurality of motors 28.2 to the ground surface 22.
  • the motor anchoring member 56 is attached to the motor 28.2 via a cylindrical member 58 for allowing the torque of the motor 28.2 to be counteracted.
  • the motor anchoring member 56 is secured to a support member of a windbreak system 64.
  • the support member is in the form of a pole 66.
  • the motor anchoring member 56 is anchored to the ground surface 22 by a body 60 of high mass, typically a bag filled with sand and/or any other suitable material.
  • the member of high mass 60 is in the form of any one of the group including a concrete block, sand bag or rock.
  • the target surface 32 is in the form of a heat receiving collection device for a power generation system.
  • the target surface 32 is in the form of a radiation concentration device (not shown) for concentrating radiation on to a photovoltaic system which is more efficient at higher fluxes, typically onto a concentration photovoltaic system which is capable of withstanding a solar concentration ratio in excess of 1:1000, thereby reducing the quantity of solar absorption material required to generate a particular quantity of energy.
  • the target surface 32 is in the form of a solar furnace (not shown).
  • wind force counteracting members in the form of cables 62 are provided for counteracting wind forces exerted on the tarp 12.
  • the cables 62 are attached to the tarp 12 for counteracting forces exerted on the tarp 12 by the wind. It is to be appreciated that the cables 62 form the smallest possible angle to the ground surface 22 so as to minimise the effects on the lifting force of the balloons 20 on the tarp 12, as shown in Figure 16.
  • Damping means (not shown) is provided for damping and reducing resonance experienced by the reflective element 16, supporting structure 36 or tarp 12 as a result of wind.
  • the damping means can be as a result of a thickness of the cables 24 wherein a sufficient thickness of the cable 24 reduces an amplitude of the resonance of the reflective element 16 and reduces the resonance of the reflective element 16 by counteracting with its own natural resonance.
  • the damping means is in the form of reactive voltage control (not shown) for evening out torque variation of the motor 28.2 caused by the resonance of the reflective element 16.
  • damping means are in the form of dampers (not shown) which are connected to any one or more of the connecting points between the supporting structure 36 and the tarp 12, between the nodes 14 and the steel cables 24, and between the steel cables 24 and the motor and reel arrangements 28.
  • additional dampers or shock absorbers are arranged between the ballOons 20 and the tarp 12 for reducing shock experienced by the tarp 12 resulting from sudden changes in wind speed.
  • a windbreak system 64 is provided for reducing the effects of wind on the tarp 12, steel cables 24 and balloons 20 in use.
  • the windbreak system 64 is in the form of any suitable windbreak system.
  • the windbreak system 64 surrounds the tarp 12, steel cables 24 and balloons 20 for protecting against forces exerted thereon by the wind.
  • the windbreak system 64 has a height in the range of 2m to 6m, typically being in the region of 3m.
  • the windbreak system 64 includes support members in the form of poles 66 and panels 68 extending between the poles 66.
  • the poles 66 are secured to the ground surface 22 for supporting the panels 68 in a substantially vertical position relative to the ground surface 22.
  • the poles 66 are secured to the ground surface 22 by way of cables 70 extending from the poles 66.
  • the windbreak system 64 is located on a crest of a hill surrounding the tarp 12, steel cables 24 and balloons 20. It is to be appreciated that the hill can be in the form of an earthwork or
  • a retraction system 72 is provided for retracting the tarp 12 into a retracted stowage condition when wind speeds exceed a predetermined maximum.
  • the predetermined maximum wind speed is in the region of 10m/s.
  • the predetermined maximum is monitored on an hourly basis, typically being calculated using an average hourly wind speed and typically excludes gusts of wind.
  • the retraction system 72 includes a displacement arrangement (not shown) for displacing the tarp 12 such that it folds and stacks on top of itself, typically in a generally concertina fashion, while being displaced into the retracted stowage condition.
  • the displacement arrangement can be configured to displace the flexible member such that it is in lay flat abutment with the ground surface, typically in an emergency situation where wind speeds would destroy the flexible member or supporting structure.
  • the displacement arrangement (not shown) includes a plurality of cables which extend between the nodes 14 of the tarp 12 and a plurality of motor and reel arrangements (not shown) for allowing the cables to be reeled in in a predetermined order so as to facilitate folding of the tarp 12.
  • the cables are typically the first set of cables 50 of the anchoring means.
  • a wind prediction system 78 is provided for predicting a magnitude and direction of wind acting on the tarp 12, balloons 20 and steel cables 24.
  • the wind prediction system 78 is in the form of any suitable wind prediction system.
  • the wind prediction system 78 is in the form of a floating member, typically a balloon or blimp 80, which is connected to an anchoring means, typically a rope 82. It is to be appreciated that the rope 82 forms an angle with the ground surface 22, which angle is used to determine the magnitude and direction of the wind acting on the balloon or blimp 80.
  • a measuring device (not shown) is provided for measuring said angle.
  • the measuring device is attached to the ground surface 22, typically the measuring device (not shown) is attached to a metal plate (not shown) which rests on a concrete slab (not shown) which covers a portion of the ground surface 22.
  • the wind prediction system 78 is in the form of a LIDAR (not shown).
  • a radar system (not shown) is utilised to determine or predict wind speeds.
  • the radar system (not shown) is configured to utilise the doppler effect to determine wind speeds. It is to be appreciated that when bursts and/or gusts of wind are detected, the tarp 12 and with it, the plurality of reflective elements 16, is retracted into the retracted stowage condition.
  • the wind prediction system 78 is arranged in communication with the retraction system 72 for allowing the tarp 12 to be retracted before winds reach excessive speeds. It is to be appreciated that the further the wind prediction system is placed from the tarp 12, the more time the tarp 12 has to retract into the retracted condition which is advantageous in that less powerful motors are needed displace the tarp 12.
  • a processing unit 84 is arranged in communication, typically wireless communication, with the measuring device (not shown) for processing the information measured by the measuring device (not shown) to determine the magnitude and direction of the wind.
  • the processing unit 84 is in the form of any suitable processing unit, typically a computer.
  • the processing unit 84 is in communication with sensors (not shown) on the plurality of nodes 14 for processing information determined by the sensors (not shown) to determine the position of each of the nodes 14 relative to the target surface 32.
  • FIG. 20 to 23 depicts a sunlight reflection system 86 which includes a plurality of heliostats 10 as hereinbefore described which are arranged to form corridors to direct wind between the heliostats 10. It is to be appreciated that the heliostats 10 which are arranged on the periphery of the sunlight reflection system 86 act as shields from excessive wind for the other heliostats 10 and thus need to be configured to be stronger or shielded by higher windbreak systems.
  • a secondary heliostat 88 is provided which is configured to receive and reflect sunlight from the plurality of heliostats 10 on to the target surface 32.
  • the secondary heliostat 88 has any suitable shape, typically a linear parabolic trough shape as shown in Figure 21 or a semi-circular parabolic trough shape as shown in Figure 22.
  • a slope of the linear parabolic or semi-circular trough shape typically decreases in magnitude the further a point on it is located from a centre point thereof for allowing sunlight 30 reflected by the heliostats 10 onto the secondary heliostat 88 to be reflected onto the target surface 32.
  • the secondary heliostat 88 has a semi-circular shape.
  • the secondary heliostat 88 is sized, shaped and configured to compensate for potential misalignments present in any one or more of the plurality of heliostats 10 from which sunlight 30 is reflected.
  • the secondary heliostat 88 can be elevated, typically being positioned at an angle relative the heliostats 10 from which sunlight is reflected, for allowing a sunlight from a plurality of heliostats 10 placed in next to each other, typically in rows, to be received by the secondary heliostat 88.
  • the heliostats 10 can be placed on slope so that heliostats 10 placed in front of others do not obstruct the sunlight from the heliostats 10 placed further back, and prevent the sunlight from reaching the secondary heliostat 88.
  • a cooling system is provided for cooling the secondary heliostat 88 in use.
  • the rate of reeling in or release of all the cables 24 relative to each other is proportional to their corresponding node’s 15 distance from the current position of the nodes 15, to the position of the nodes 205 at an incremental distance 203 to the distance 204 at which the tarp 12 is vertical, so that the tarp 12 maintains its shape.
  • This incremental distance 203 is chosen as small enough so that the opposing motors acting on the node 15, are synchronized.
  • the position of each node 15 is checked periodically within an adequate time frame and the rate of reeling in or release of the motor and reel arrangement 28 is adjusted accordingly to make up the incremental distance 203 within the calculated time frame, so that the motors don’t pull against each other excessively or allow too much slack on the cables 24.
  • node positions are checked by the secondary verifying method described further below, for each node 15 and if they are out of tolerance by a specified amount, the positions are calculated by the second verifying method and the calculated position is taken as the correct position for that specific node.
  • the motor that is reeling in must be delayed by a small predetermined fraction of time so that it does not excessively tension against the opposing motors that are releasing, and as a result cause excessive stress in the motors and gearing of the opposing pairs of motors.
  • the position 205 of the node 174 the motor will tension against each other so that no positioning error accumulates.
  • the second stage is accomplished by the cables 24 retracting the tarp 12 to a position as shown most clearly in Figure 18. All the cables 13,20,56 retract simultaneously to lower the tarp 12 into the retracted condition. As the tarp 12 lowers, the weight of the tarp 12 serves to keep it in a zig zag formation as shown in Figure 17. A tension force in the tarp 12 provided by the balloons 20 will also aid in keeping the tarp 12 from sagging under its own weight during the initial period of stage two. As the tarp 12 lowers, more weight is transferred onto the cables 24 by the tarp 12 as the nodes 14 are lowered. Cables 48 keep the tarp 12 in position against a wind force (not shown).
  • a path 100 of the node 14 progresses from the vertical position 14a of the tarp 12 to an arbitrary partially retracted position 14b of the tarp 12 to a fully retracted position 14c of the tarp 12.
  • the points on this trajectory 100 are pre-calculated and the rate of reeling in or release of the motor 24 and reel 26 is calculated.
  • the rate of reeling in or release of all the cables 24 relative to each other is proportional to their corresponding node’s 15 distance from the current position of the nodes 15, to the position of the nodes 15 according to the precalculated position on the path 100.
  • the current position of the nodes is calculated by the secondary verifying method which is as follows, and as depicted in Figure 25b: -
  • chords “a”, “b”, ⁇ ” and “k” are known from the measuring device measurement.
  • each node 14 is checked periodically within an adequate time frame and the rate of retraction or release of the motor 28.2 and reel 28.1 adjusted accordingly so that the motors 28.2 don’t pull against each other excessively or stress the tarp 12 or conversely allow too much slack on the cables 24.
  • the motors 28.2 that are retracting must delay engaging by a small predetermined fraction of time so that they do not excessively tension against the opposing motors that are releasing and thus cause excessive stress in the motors.
  • the motors 28.2 will tension against each other so that no positioning error accumulates.
  • the top of the balloons 20 are pulled down when the tarp 12 is retracted so that they lie close to the ground surface 22 so that the whole of the balloons 20 are below the top of the windbreak system 64 in the retracted condition. This will serve to minimize wind forces from extreme wind conditions on the balloons 20.
  • the cables 54 will each have a motor and reel (not shown) which will serve to pull the top of the balloons 20 close to the ground surface 22.
  • the tarp 12 is stored in a substantially flat retracted condition as illustrated in Figure 17 to prevent the tarp 12 from collecting dust, being damaged by hail and the like.
  • the motor 28.2 and reel 28.1 will maintain in tension on the respective cables 24 to keep the tarp 12 in the retracted condition.
  • the tarp 12 In the retracted condition the tarp 12 is protected from the wind by an excavation hole (not shown), the hill (not shown) and the windbreak system 64.
  • the tarp 12 also presents a significantly reduced surface area to the wind.
  • the computer 84 calculates the specific, unique position of each node 15, 174 to reflect the incoming sun’s radiation to the centre point of the target 5 as follows:
  • a sun positioning determining device 172 determines the incoming direction vector 178 of the sunlight 30.
  • the position of the bottom middle node 173 is fixed and its co-ordinates are known from the method as described below and depicted in Figure 26a.
  • the co-ordinates of the top middle node 15, 174 and the remaining nodes 15,174 between the top middle node 15, 174 and the bottom middle node 173 are then calculated as follows: -
  • the perpendicular vector 177 to the face of the bottom middle node 173 so that it reflects the incoming sunrays 178 onto the centre of the target 5.
  • the perpendicular vector 177 to the face of the tarp 12 at the bottom middle node 173 is determined as the bisecting vector 177 which bisects the angle of the vector of the incoming sun’s rays 178 and the vector 183 between the position of the bottom middle node 173 and the target 5.
  • This direction vector 179 is the vector perpendicular to the bisecting vector 177 in the plane of the said bisecting vector 177 and the vector 183 between the position of the bottom middle node 173 and the target 5.
  • the perpendicular vector 184 to the face of the approximate position of the node 180 so that it reflects the incoming sunrays 178 onto the centre of the target 5.
  • the perpendicular vector 184 to the face of the tarp 12 at the approximate position of the node 180 is determined as the bisecting vector 184 which bisects the angle of the vector of the incoming sun’s rays 178 and the vector 185 between the position of the approximate position of the node 180 and the target 5.
  • An imaginary sphere manifold 186 is described by a rotational vector 187 which is of length of the said distance 183 and originates at the bottom middle node 173.
  • the co-ordinates of the node 174 are the point at which the bisecting vector 184 is tangent to the sphere manifold 186.
  • the co-ordinates of the remaining nodes of the tarp 12 are then determined as follows and as depicted in Figure 26b: Define a co-ordinate system with the direction vector 179 to the uppermost middle node as an axis, the bisecting vector 177 as another axis and a third axis which we will name the z-axis. Determine the unit direction 181 vector of the direction vector 179. Determine the unit vector 181 B to the approximate position of the node 180 using the x-axis and y-axis components of the node 174 projected onto the defined co-ordinate system.
  • the perpendicular vector 184 to the face of the approximate position of the node 180 so that it reflects the incoming sunrays 178 onto the centre of the target 5.
  • the perpendicular vector 184 to the face of the tarp 12 at the approximate position of the node 180 is determined as the bisecting vector 184 which bisects the angle of the vector of the incoming sun’s rays 178 and the vector 185 between the position of the approximate position of the node 180 and the target 5.
  • An imaginary sphere manifold 186 is described by a rotational vector 187 which is of length of the said distance 178 and originates at the bottom middle node 173.
  • the co-ordinates of the node 174 are the point at which a parallel vector 184B to the bisecting vector 184 is tangent to the sphere manifold 186.
  • the co-ordinates of the fixture point 188 of the cable 24 are known as they would have been determined after construction.
  • the scalar of the vector 189 between each of the nodes 15 and its corresponding fixture point 188 is then calculated.
  • a solar powered light transmitter 175B transmits light radiation of a specific or non-specific frequency. This light radiation is received by 3 cameras 180B of which the position of each camera 180B is known.
  • a reference node such as the bottom middle node 173, which may emit a unique radiation frequency, can be used as reference to enable the computer to determine the identity of the other nodes 15.
  • the photographs which are taken by the cameras 180B are transmitted to the central computer 170 which then for every node 15 determines the angles of inclination of the line joining each camera 180B to the node.
  • each node 15 is then determined by means of trilateration. It subsequently calculates a displacement vector 175 from the node 15 position to the correct position of the node 174 as shown in fig 11B.
  • the central computer 170 communicates to the PLC or logic system of the motors 28.2 which are connected, as mentioned previously, to each node 15 by means of cables 24 the amount by which the said motors 28.2 must slack or engage, that is reel in or reel out, to enable the node 15 and thus the surrounding tarp 12 to be in the correct position.
  • the rate of retraction or release of opposing motors 24 to a node 15 relative to each other is proportional to their corresponding node’s 15 distance from the current position of the nodes 15 to the correct position of the nodes 174.
  • the motors 24 that are retracting must delay engaging by a small predetermined fraction of time so that they do not excessively tension against the opposing motors 28.2 that are releasing and thus cause excessive stress in the motors 28.2 and gearing of the opposing pairs of motors 28.2.
  • the lag of the retracting motors 28.2 may be slightly more than the probable maximum error in the distance to be moved by the node 15.
  • the motors 28.2 will tension against each other so that no positioning error accumulates.
  • a suitable time interval will be chosen for the re-determination of the current node 15 positions and recalculation of the correct position of the nodes 174. If the said positioning determination method as shown in Figure 27 for one or more node 15 is out of tolerance according to the following secondary verifying method by a specified amount then the said secondary verifying method is to be adopted for positioning of those node.
  • heliostat 10 can be configured to be used in any system which requires heat such as hydrogen production and desalination of water and sea water.
  • the inventor believes that the heliostat 10 in accordance with the present invention is advantageous in that it is very cost effective to manufacture as a result of the heliostat 10 requiring less material to be manufactured and that the heliostat 10 will result in a much cheaper production process cost for the production of chemicals and materials especially the processes which are largely dependent on heat.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

L'invention concerne un héliostat (10) incluant un organe flexible définissant une pluralité de nœuds (14) entre une pluralité d'éléments réfléchissants (16) montés sur la bâche (12), un moyen de levage (20) relié à la bâche (12) et destiné à soulever une partie de la bâche (12) à une certaine hauteur au-dessus d'une surface du sol (22), des organes de tension (24) reliés à la pluralité de nœuds (14) à une extrémité de la bâche (12) et destinés à permettre de tendre la bâche (12) lorsque des extrémités en vis-à-vis des câbles (24) sont reliées à une surface d'ancrage (26), et un moyen de réglage (28) destiné à régler la tension des organes de tension (24) si bien que la surface réfléchissante de la bâche (12) change de forme pour permettre que la lumière du soleil (30) frappant les surfaces réfléchissantes (18) des éléments réfléchissants (16) soit réfléchie vers une surface cible (32) désirée.
PCT/ZA2020/050071 2019-12-20 2020-12-21 Héliostat WO2021127712A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA201908513 2019-12-20
ZA2019/08513 2019-12-20

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WO2021127712A1 true WO2021127712A1 (fr) 2021-06-24

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Application Number Title Priority Date Filing Date
PCT/ZA2020/050071 WO2021127712A1 (fr) 2019-12-20 2020-12-21 Héliostat

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WO (1) WO2021127712A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2754114A1 (de) * 1977-12-05 1979-06-07 Wolfgang Dr Hille Sonnenkraftwerk
EP0312075A1 (fr) * 1987-10-15 1989-04-19 Helmut Dr.-Ing. Menke Fourniture d'énergie solaire à hautes altitudes
JP2002320345A (ja) * 2001-04-20 2002-10-31 Kawasaki Heavy Ind Ltd 浮体および該浮体によるエネルギー吸収システム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2754114A1 (de) * 1977-12-05 1979-06-07 Wolfgang Dr Hille Sonnenkraftwerk
EP0312075A1 (fr) * 1987-10-15 1989-04-19 Helmut Dr.-Ing. Menke Fourniture d'énergie solaire à hautes altitudes
JP2002320345A (ja) * 2001-04-20 2002-10-31 Kawasaki Heavy Ind Ltd 浮体および該浮体によるエネルギー吸収システム

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