The present invention relates to solar energy collection apparatus and more particularly, to a concentrating type collector that uses a lens to concentrate the solar rays.
Solar energy collection devices are well established and may be categorised according to two types. Non-concentrating collectors receive the solar radiation directly, as parallel rays of radiation. Such devices typically comprise a solar panel, or array of photovoltaic cells that may be heated and configured to transmit and store the solar radiation.
A further type of solar collector is referred to as a concentrating type which reflects or refracts the radiation using lenses or minor assemblies so as to concentrate the rays onto a target as a more focused solar footprint.
WO 2009/134208 discloses a solar energy collector that utilises a lens to focus the solar radiation and is mounted via a cradle with a plurality of solar cells fixed to the cradle base to receive the light from the lens.
WO 2009/125334 discloses a solar energy generating device having a fixed orientation concentrator, in the form of a Fresnel lens of the new focus and linear solar collector mounted parallel to the focal point of the lens and configured to move in any direction perpendicular to the linear focus in order to attempt to obviate the need for additional orientating mechanisms for the lens.
WO 2005/057092 discloses a solar energy collection system in which a lens is used to focus the solar radiation onto a receiving body to convert the radiation into electrical and/or heat energy. A pivoting structure is provided to enable rotation of the target in the east/west direction in order to track the concentrated radiation transmitted through the lens.
US 2009/0272425 discloses a concentrating solar receiver that utilises a Fresnel lens to both reflect and refract solar radiation to a thermal cycle engine that coverts the solar energy to mechanical energy which in turn is converted to electrical energy. Movement of the solar receiver is controlled by a sun tracking sensor and actuation provided by a vertical and horizontal drive motor.
WO 2009/002168 discloses an array of rotatably mounted lenses for concentrating solar radiation onto collectors that are coupled to a heat transfer liquid. The liquid, when heated by the solar radiation may be guided through a heat exchanger to generate steam for electricity generation. The array of lenses is configured to rotate about two perpendicular axes to track the position of the sun throughout the day.
However, there is a continued need for apparatus that will efficiently harness the solar radiation throughout the day and year whilst being of a design sufficiently robust to withstand weathering by the elements whilst maximising the use of the incident radiation.
Accordingly, the inventors provide solar energy concentrating and support apparatus configured to harness and concentrate solar energy suitable for use in regions that frequently experience an abundance of sunlight and are exposed environments. The apparatus is also configured to withstand weathering by the elements without loss of energy conversion efficiency.
According to a first aspect of the present invention there is provided solar energy concentrating apparatus comprising: an array of lenses to receive and to concentrate solar radiation towards a plurality of targets; at least one lens support structure to moveably mount each lens of the array to receive the solar radiation; a first lateral movement mechanism to move the lenses in a first lateral direction relative to the targets; a second lateral movement mechanism to move the lenses in a second lateral direction relative to the targets; a third lateral movement mechanism to move the lenses in a direction up and down relative to the targets; a first rotational movement mechanism to rotate the lenses about a first axis extending substantially in the second lateral direction; and at least one drive means to drive the lens movement mechanisms.
Preferably, the apparatus further comprises a second rotational movement mechanism to rotate each lens about a second axis extending in the first lateral direction. The axes of rotation of the in the second rotational direction is substantially perpendicular to the axes of rotation of a lens in the first rotational direction.
Optionally, the lens support structure comprises a primary support having a circumferential or peripheral ring type frame to mount the lens, a support shaft extending centrally through the lens and support cables extending from the central shaft to the outer ring frame. Additionally, the lens support structure may further comprise a secondary support to mount the primary support, the secondary support comprising cables extending around the primary support. Preferably, the cables of the primary and secondary support are pre-stressed such that when placed under tension the cables are resistant to twisting, elongate extension and distortion due to incident mechanical forces.
Preferably, the array of lenses is arranged in rows of lenses to form a grid network of lenses with rows in the first lateral direction and rows in the second lateral direction.
Preferably, each lens of the array comprises a plurality of Fresnel lenses extending in at least two substantially parallel planes, one above the other so as to provide an air flow gap between the planes of the lenses. Additionally the lenses may be constructed from individual sections of Fresnel lenses according to a staggered or multi-planar configuration to provide airflow vents or ducts through the assembled lens to minimise the perpendicular force component of the incident wind when installed and in use. Fins or other air flow directing elements may also be attached to the lens to assist with deflecting or channelling air. Such fins may also be attached to other components of the apparatus.
Preferably, the first lateral movement mechanism comprises cables extending in the first (east-west) direction and pulley wheels and/or spools and stanchions positioned at the end of each row of lenses in the first (east-west) direction, the stanchions coupled to one of the cables in the east-west direction such that when the drive means is actuated the stanchions pivot in the east-west direction and the lenses move laterally in the first (east-west) direction. Also preferred is that the second lateral movement mechanism comprises cables extending in the second (north-south) direction and pulley wheels and/or spools and stanchions positioned at the end of each row of lenses in the second (north-south) direction, the stanchions coupled to one of the cables in the second (north-south) direction such that when the drive means is actuated the stanchions pivot in the second (north-south) direction and the lenses move laterally in the second (north-south) direction. Also preferred is that the third lateral movement mechanism comprises cables and pulley wheels and/or spools. Also preferred is that the first rotational movement mechanism comprises cables and pulley wheels and/or spools.
The present apparatus is configured to orientate the lenses continuously towards the stationary targets or target such that the focal point of the lenses and the concentrated solar radiation is always directed to the same region. This avoids consideration of means to move the targets to receive the concentrated solar radiation. Also, the size of the target bodies may be minimised to reduce the footprint of the apparatus by always concentrating the solar radiation to the same region via movement of the lenses in the three lateral coordinates (x, y and z) and one or two rotational axis.
Preferably, the second rotational movement mechanism comprises cables extending substantially in the second (north-south) direction and pulley wheels and/or spools.
The present apparatus may comprise any suitable means to provide lateral actuation of the lenses in the x, y and z coordinates and rotational movement in the two axes, as will be appreciated by those skilled in the art. Accordingly, the drive for the movement mechanisms may also comprise standard components including electric, electromagnetic, solar or other fuel driven motors. Where the present invention is implemented with cables the drive means for the first, second and third lateral movement mechanisms and the first and second rotational movement mechanisms may comprise a motorised winch, pulley wheel or spool to shorten and lengthen each of the respective cables. Reference within this specification to ‘cable’ includes all manner of relatively thin member including specifically a cord, flex, lead, wire, chain, rope and the like. Preferably, the cables comprise wound steel cables including specifically stainless steel cables that may be coated to improve resistance to weathering and corrosion.
As will be appreciated, any support structure may be used to suspend the lenses above the ground and the respective targets. Such suspension systems may comprise entirely rigid structures including for example interconnected steel girders to form a three dimensional frame structure. Alternatively or in addition, the lens support structure may comprise a catenary or other moveable suspension mechanism.
Preferably, the lens support structure comprises a crane block mounted between the lenses in the second (north-south) direction, the crane block being connected to the cables of the first, second and third lateral movement mechanisms to translate movement imparted by the drive means to move the lenses of the array. The crane block may comprise one or a plurality of motors to drive one or a plurality of pulley wheels or spools to drive indirectly rotation of the lens about at least one axis. Preferably, the crane block is connected to the support structure and in particular the secondary support structure that mounts the primary support structure via at least one shaft, each lens configured to rotate about each respective shaft in the first (east-west) direction.
According to a second aspect of the present invention there is provided a method of concentrating solar radiation comprising: receiving and concentrating solar radiation towards of a plurality of targets using an array of lenses; supporting the array of lenses using a moveable support structure; moving the array of lenses in a first lateral direction relative to the targets using a first lateral movement mechanism; moving the array of lenses in a second lateral direction relative to the targets using a second lateral movement mechanism; moving the lenses in a direction up and down relative to the targets using a third lateral movement mechanism; rotating the lenses about a first axis extending substantially in the second lateral direction using a first rotational movement mechanism; and driving the movement mechanisms to move the lenses in the lateral and rotational directions.
According to a third aspect of the present invention there is provided solar energy collection apparatus comprising: solar energy concentrating apparatus as described herein; a conduit network to contain a gas phase working fluid and allow the fluid to flow in contact with the targets such that the working fluid is heated by the targets.
Preferably, the collection apparatus further comprises a heat storage device connected in fluid communication to the targets by the conduit network to receive the heated working fluid, the storage device comprising a heat storage material to store the heat energy received from the working fluid. Optionally, the conduit network comprises metal, ceramic and/or clay based piping. Optionally, the material of the storage device comprises a natural mineral such as stone or rock. Alternatively the storage material may comprise a synthetic aggregate such as concrete and the like.
According to the fourth aspect of the present invention there is provided apparatus for converting solar energy to electrical energy comprising: solar energy concentrating apparatus as described herein; solar energy collection apparatus as described herein; a heat exchanger connected in fluid communication with the conduit network to receive the heated working fluid and to transfer the received heat energy; a turbine coupled to a heat exchanger; an electric generator coupled to the turbine to generate electricity.
According to a fifth aspect of the present invention there is provided a method of supplying electricity generated by the apparatus as described herein to an electricity network and to a method of delivering the electricity via the network to a plurality of users.
According to a sixth aspect of the present invention there is provided solar energy concentrating apparatus having a lens support structure comprising: an annular or polygonal frame configured to surround a concentrating lens at an outer perimeter region of the lens; a plurality of radial spokes mounted at the frame and extending from the frame to a mount positioned substantially centrally relative to the annular frame and the radial spokes.
According to a seventh aspect of the present invention there is provided solar energy concentrating apparatus having a support frame to mount a concentrating lens, the lens comprising: at least one first lens plate extending in a first plane; at least one second lens plate extending in a second plane, the second lens plate being spatially separated from the first lens plate in a direction perpendicular to the planes to provide a gap between the first and second lens plates.
According to an eighth aspect of the present invention there is provided solar energy concentrating apparatus to support a concentrating lens, the apparatus comprising: a plurality of elongate support members comprising one or a plurality of cables extending between a first mount and a second mount; wherein a separation distance between the members in a direction perpendicular to the direction between the first and second mounts increases away from each of the first and second mounts to reach a maximum separation region: wherein a concentrating lens mounted substantially at the maximum separation region and is suspended between the first and second mounts by the support members.
According to a ninth aspect of the present invention there is provided solar energy concentrating apparatus to mount at least one concentrating lens to direct concentrated solar radiation from the lens onto a target, the apparatus comprising: a moveable stanchion mounted at a first end by a pivoting or moveable joint to allow a second end of the stanchion to move laterally in x, y and z coordinates relative to the first end; at least one lens connecting member extending between a region towards the second end of the stanchion and a region close to or at lens such that movement of the second end of the stanchion is translated to provide a corresponding movement of the lens.
According to a tenth aspect of the present invention there is provided solar energy concentrating apparatus to move at least one concentrating lens to direct the concentrated solar radiation from the lens onto a target, the apparatus comprising: a suspension system configured to suspend at least one lens above the ground, at least part of the suspension system extending above the lens relative to the ground; a crane mechanism positioned so as to raise and lower the lens relative to the suspension system.
According to an eleventh aspect of the present invention there is provided solar energy concentrating apparatus to move at least one concentrating lens to direct concentrated solar radiation from the lens onto a target, the apparatus comprising: a lens support structure to mount a lens moveably relative to a target; a first elongate track mounted above the ground and extending in a first direction; a second elongate track mounted above the ground and extending in a second direction transverse or perpendicular to the first direction; wherein the lens, via the support structure, is capable of movement laterally in the first direction along the first track and in the second direction along the second track such that movement of the lens along the first and second tracks is configured to orientate the lens to direct concentrated solar radiation from the lens onto the target.
According to a twelfth aspect of the present invention there is provided solar energy concentrating apparatus to move at least one concentrating lens to direct concentrated solar radiation from the lens to a target, the apparatus comprising: a suspension system configured to suspend at least one lens above the ground; the suspension system comprising: a plurality of columns upstanding from the ground; a beam or catenary system mounted upon the columns and capable of suspending the lens above the ground.
A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:
Referring to
The primary support 111 is mounted within secondary support 100 that also comprises a plurality of tensioned, pre-stressed cables 102 that extend radially outward from common point A to extend over two annular rings or polygonal frame 108 that extend around primary support 111. Cables 102 extend over each rigid polygonal or annular frame 108 and then converge to a second common point A aligned axially with the first common point A. Primary support 111 is mounted at secondary support 100 via a rotatable shaft 400 with one end of shaft 400 rotatably connected to the lens 106 and a second end 401 rigidly connected to secondary support 100. Accordingly, lens 106 is cable of rotation about axis 103. Shaft 400 and lens 106 are held in position via suitable cables 104 as described further with reference to
Cables 102 and 110 may comprise separate cables or may comprise respective single cables that are wound around the respective frames and mounts to create the seemingly multi-cable construction.
Referring to
According to the present embodiment, a plurality of circumferentially extending tie cables 509 extend between each of the spoke cables 507 and are mounted upon respective plate mounts 508 positioned radially from centre 109 to the outer circumferential support 500. According to further specific embodiments, the lens support structure comprising outer frame 500, central mount 510 and radial spokes 507 does not comprise the connecting tie cables 509.
Referring to
Referring to
Referring to
Referring for
Referring to
Referring to
Referring to
A region 2008 of each lens is ‘cut-away’ or is devoid of lens plates 506 and support 500 such that the body of lens 106 does not interfere or contact the drive belts 2000, 2003, 1901 when each lens 106 is rotated 1905 about axis 103 as illustrated in
According to the further embodiment described with reference to
Crane block 300 also provides a means to mount a lateral displacement cable 3007. Crane blocks 300, positioned at end or terminating positions of a series (row) of interconnected lens supports 100, also mount a lateral displacement cable 3201 extending in the north-south axis as illustrated in
As will be appreciated, each winch assembly 3102 may be controlled electronically so as to automate diurnal and annular lateral movement of the lenses 106 specific to a particular geographical location and the relative sun motion to ensure that the solar radiation 3107 concentrated by each lens 106 is focused towards each respective stationary target 3100 and that the intensity of the radiation incident at target 3100 is not diminished or any reduction minimised by appropriate lens movement. The present apparatus is configured to orientate the lenses continuously throughout the day and year to concentrate and focus the solar radiation towards a single region (target 3100). That is, the focal position of the lenses does not change in the lateral east-west and north-south direction, nor does it change in the vertical direction. Accordingly, the target area may be relatively small and no consideration needs to be given to coordinated movement of the target in response to movement of the lenses and/or sun position.
As will be appreciated, the present apparatus is configured for manual and automated electronic control of the various drive components so as to provide computer and electronic control and actuation of the lateral east-west, north-south displacement; the vertical displacement 2604 and the annular and diurnal rotational movement of each lens assembly 106. Individual electronic control may be provided for each type of lateral and rotational drive means. Alternatively, a common electronic control may be provided to regulate all mechanical components. Moreover, actuation sensors (not shown) may also be provided and positioned at regions of the apparatus to monitor the imparted motion to the various components. Such movement sensing may then be coupled to the electronic control to provide diagnostic assessment, performance monitoring and automatic correction in the event of any undesired movement. For example, auto-correction via the electronic control may be required to compensate for unwanted movement due to wind forces incident at the apparatus. In addition to motion sensors, the apparatus may further comprise thermal, humidity, wind speed, air pressure, UV and other solar radiation sensors (not shown) to provide data to the electronic control which may then initiate instruction and control of the mechanical components in response. In particular, diode sensors (for example, four sensors) may be positioned at the region of the target to determine if the concentrated solar radiation form the lens is appropriately directed towards the target for optimum performance and to receive the maximum amount of solar radiation. As will be appreciated, the electronic control is network-configured to provide geographically remote monitoring, control and information/data exchange. The drive motors required to drive translational (horizontal and vertical) and rotational movement may be powered by suitable photovoltaic cells and/or conventional electrical motors.
Accordingly, each lens 106 is capable of movement through approximately 140° (diurnal rotation) in order to track the daily movement of the sun. A second diurnal (translational) motion in an east-west direction along diurnal beam 2703 further compensates for the movement of the sun during the day to ensure a maximum concentration of solar radiation 3107 at stationary target 3100. Vertical movement of the lens 106 is also required during this diurnal translation and rotational motion and this is achieved via cable 301 and associated cranes or winches 2600 described with reference to
A first annual (translational) movement of lenses 106 occurs via annual rail 2705. A second annual (rotational) motion optionally also occurs via rotation of each lens 106 about pivot axis 103. This rotation is provided through approximately 50° and corresponds to the latitude alignment of the lens when initially installed at a particular geographical location. An alternative arrangement may simply involve an initial manual angular adjustment of each lens 106 so as to correctly align for the geographical latitude when the apparatus is initially installed. According to this further embodiment, the focal position of the lenses may be adjusted manually or automatically to compensate for the annual solar motion to ensure sufficient concentrated solar radiation 3107 is incident at targets 3100. However, and as will be appreciated, rotation of the lens about two axis is beneficial to minimise the force component perpendicular to the plane of the lens created by the incident wind. The second rotational motion therefore may be optionally employed to minimise the force on the apparatus due to the wind and reduce any possible damage or unwanted movement of the apparatus.
The present lens and supporting structure assembly is specifically designed to withstand wind forces generated from wind speeds of up to approximately 20 mph. The use of cables is particularly advantageous as, when placed under tension and according to the present structural arrangement, provide a very robust lens support assembly whilst minimising the surface area against which the wind force is incident. Therefore, a reasonable proportion of the wind may pass through the lens assembly as described referring to
To compensate for thermal expansion when exposed to large temperature variation, that will be experienced when the present apparatus is positioned for use in a hot daytime but cold night time environment, such as a desert and the like, all or most cables used in the present apparatus are tensioned or pre-stressed, to for example, 138 MPa, found to maintain the required tension for an approximate 60° C. temperature change.
According to a specific implementation, each lens 106 comprising the plurality of individual Fresnel lenses 506 is assembled according to conventional construction methods. Each lens 106 may be 7 to 10 metres in diameter. Such a lens 106 is configured for use with a target 3100 with a 30 cm to 50 cm diameter target window where, for example, the target comprises a 60 cm diameter pipe (not shown) to accommodate a heat transfer fluid forming part of a network or system associated with a heat store, turbine and/or heat exchanger as described with reference to International patent application no. PCT/GB2010/050536, which is hereby incorporated by reference. This is however summarised with reference to
Referring to
Referring to
Additionally, to reduce the loading forces at regions of the apparatus when the columns 3500 are pivoted from position B to position C, crane 3503 may be configured to displace laterally from position A to position B coincidentally.
This lateral movement of crane 3501 ensures suspension cable 301 remains vertical or near vertical during diurnal movement of the lens 106 to track the position of the sun 3800 and ensure solar radiation 3107 is continuously focused towards target 3100 during daylight hours.
Referring to
As will be appreciated, the lens assemblies 106 and associated components 111, 100 and 300 may be suspended or supported by any suitable mechanism capable of enabling each lens 106 to move laterally in the east-west (x) and north-south (y) directions, a perpendicular vertical (z) direction and diurnal rotation through 140° and annual rotation through approximately 50°. The support and suspension system must also be configured to allow the through-flow of air in order to withstand wind sheer forces incident on the apparatus.
Suitable mechanical actuation apparatus for the lens assemblies 106 may comprise rack and pinion mechanisms, chains, belts, cables, actuation rams (including pneumatic, hydraulic and other fluid operated rams and pistons), servo controlled mechanisms, concertina assemblies, telescopic actuators, rail and wheel assemblies, catenaries and suspension cable systems, magnetic and electromagnetic rotational and translational movement components and the like.
Referring to
The heat storage device 4401 is connected in fluid communication with the targets 3100 by the conduit network 4400 which is configured to receive the heated working fluid. The storage device 4401 comprises a heat storage material 4406 (optionally stone or a natural mineral but also including synthetic aggregate) to store the heat energy received from the working fluid. Typically, each target 3100 comprises a heat transfer body positioned in the flow path of the working fluid as it flows through the target 3100. Thermal insulation (not shown) is also provided around the targets 3100 and fluid network 4400, and heat store 4401, to ensure minimum energy loss through conduction. Suitable valves 4408 and working fluid circulation fans 4407 control the flow of the working fluid around the network 4400. The working fluid heated by lenses 106 is coupled to the working fluid within the heat exchanger network 4403 which is in turn fed to the turbine 4404. An electricity generator 4405 is then coupled and powered by turbine 4404. According to further embodiments, an intermediate heat exchanger may be positioned between conduit network 4400 and heat store 4401 such that the working fluid within heat store 4401 is different to that that flows through each target 3100. Additionally, an embodiment of the present invention may not comprise the heat store 4401 and may simply comprise a plurality of heat exchangers 4402 in fluid communication with a working fluid that flows through, around or in thermal contact with targets 3100.
The present apparatus is suitable to create a grid network or array of moveable lenses 106 positioned above respective targets 3100 and installed at geographical locations with high solar radiation and available land space. The present apparatus is typically ground mounted. However, further embodiments may comprise additional floatation devices or water submerged pylons and support structures to enable the present apparatus to be geographically located over water and in particular the sea.
Number | Date | Country | Kind |
---|---|---|---|
1001012.2 | Jan 2010 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/GB2011/050101 | 1/21/2011 | WO | 00 | 8/6/2012 |