Gravity-Based Energy Storage Systems

Abstract

An energy storage system and method that allows for significantly larger capacity for a given capital cost in gravity-based energy storage in a single shaft, thereby improving the cost per unit energy for large-scale energy storage, while also allowing for continuous input and output of power over the entire range of the system's energy capacity at external connection points, includes a multi-weight storage system having at least two weights, two transport devices each having a transport device linkage that can be coupled to and separated from a respective weight, the transport devices transporting the weights along a predefined path that defines a vertical displacement and defines a respective path volume, and a second linkage path volume that does not overlap with the first path volume and is defined by an area through which the second linkage separated from the weights is advanced or passed along its respective predefined vertical path of travel.

Description

[Technical field]

[0001] The present invention relates generally to the field of energy storage, and more particularly to devices and systems for gravity-based energy storage using weights. [Background technology]

[0002] Gravity-based energy storage systems are increasingly being recognized as a method of energy storage and grid balancing that can be reliable, operate over a very long cycle life, and exhibit high efficiency. Large-scale pumped hydroelectric generation, which also relies on gravity, is well known, but in recent years, technological innovations in weights and shafts, particularly weight and cable systems, have used solid weights to improve energy storage and provide benefits in energy capacity, meeting the demands of regional and national grids, and improving response times.

[0003] For example, WO-A-2014 / 131806 and WO-A-2018 / 134620 describe the use of a winch and cable arrangement to raise and lower a weight within a shaft in order to temporarily store energy from an external power system and supply it to the external power system when required.

[0004] There are several systems in which multiple weights (multi-weights) are used in one shaft to increase the energy capacity and improve the economic efficiency (lower capital investment in shaft and land). For example, US-A-2015 / 0048622 describes numerous embodiments using multiple weights to provide enhanced capacity energy storage. Similarly, DE-A-4135440 shows a multi-weight configuration in a single shaft with external storage at the top and bottom. Such multi-weight and cable gravity-based energy storage systems suffer from a particular drawback, which is that while such systems have enhanced energy capacity, they are prone to power input or output interruptions while storing (or charging) and discharging the full energy capacity. The interruptions are a result of the existence of an end point for the vertical transport of each individual weight, the associated cable being separated and moved to connect to the subsequent weight, and the need to slow down the transport of the weight as it approaches the end of its travel distance.

[0005] To be economically advantageous and to receive or supply high quality power from or to an external power grid, energy storage systems advantageously provide large energy capacity and continuous input / output throughout that capacity.

[0006] The present inventors have discovered improvements in energy storage systems that address shortcomings of existing technology. Summary of the Invention [Problem to be solved by the invention]

[0007] There is a need to improve energy storage systems to provide higher quality energy storage in larger volumes with better cost efficiency using gravity based systems with cables and weights.

[0008] It is an object of the present invention to provide an energy storage system that is capable of receiving and / or supplying power at the full energy capacity of a multi-weight gravity-based energy storage system without interruption or disruption at the point of connection to the external grid. [Means for solving the problem]

[0009] According to the first aspect of the present invention, The first weight, The second weight, a first transport device, the first transport device comprising a first transport device coupling that is connectable to and disconnectable from the first weight and that mechanically couples the first weight to the first transport device, the first transport device being configured to transport the first weight along a first predefined path that defines a vertical displacement between a first upper position and a second lower position; a second transport device, the second transport device comprising a second transport device coupling that is connectable to and disconnectable from the second weight and that mechanically couples the second weight to the second transport device, the second transport device being configured to transport the second weight along a second predefined path that defines a vertical displacement between a first upper position and a second lower position; a first path volume defined by a first weight coupled to the first transport device coupling being advanced or passed along a first predefined path; a second path volume defined by a second weight coupled to the second transport device coupling being advanced or passed along a second predefined path, at least a portion of which overlaps with the first path volume; a second connector path volume defined by the second connector separated from the weight being advanced or passed between the upper position and the lower position along a respective predefined path; Including, The second connection passage volume does not overlap with the first passage volume; A multi-weight gravity-based energy storage system is provided.

[0010] In a second aspect of the present invention, there is provided a method of energy storage using the system defined above.

[0011] In a third aspect of the present invention, there is provided an energy storage method for continuously inputting and / or outputting power to a multi-weight gravity-based energy storage system across its entire energy capacity without interruption or discontinuity, the method comprising: providing a multi-weight gravity-based energy storage system as defined above; and operating the energy storage system to raise and lower successive weights in response to power input / output requests to the energy storage system, slowing down the rate at which the weights are raised and lowered as they approach the end of their path and commencing the movement of another weight to make up for the reduction in power input / output caused by a first weight slowing down and coming to a halt at the end of its path, such that the input / output from the energy storage system can provide the required power continuously for the time it takes to raise and lower at least two successive weights.

[0012] In a fourth aspect of the present invention, there is provided a method of storing energy in a multi-weight gravity-based energy storage system comprising at least two weights configured to be raised and lowered by a transport device along respective predefined paths and comprising a controller for controlling operation of the transport device and movement of the weights in response to a request for storing excess energy from an external system or discharging energy to an external system, the method comprising simultaneously moving the at least two weights along respective predefined paths to provide increased power input / output for a short period of time.

[0013] In a fifth aspect of the present invention, there is provided a control system for continuously charging or discharging energy in a multi-weight gravity-based energy storage system as defined above.

[0014] In a sixth aspect of the present invention, there is provided a winch and cable arrangement comprising a winch, a cable and a sheave arrangement at the lower end of the arrangement, the cable being configured to pass around two sheaves of the sheave arrangement to accommodate differences in speed control between the two winches.

[0015] In a seventh aspect of the present invention there is provided a suspended platform system for providing a suspended load-bearing platform for an energy storage system of claim 1 within a shaft, the system comprising a platform element, a plurality of suspension members which engage with the platform element and from which the platform element is suspended, and a fixing mechanism for fixing the suspension members in a raised position relative to the platform element. Effect of the Invention

[0016] The energy storage system of the present invention allows for significantly larger capacity for a given capital cost for gravity-based energy storage in a single shaft, resulting in improved cost per unit energy for large scale energy storage, while providing continuous input and output of power at external connection points over the entire range of the system's energy capacity. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a representation of one embodiment of an energy storage system of the present invention in a perspective view. [Diagram 2] FIG. 1 illustrates a side view of an energy storage system according to one embodiment of the present invention. [Diagram 3] FIG. 1 illustrates a representation of one embodiment of an energy storage system of the present invention in a perspective view, showing an arrangement of winches. [Figure 4] FIG. 1 illustrates a representation of one embodiment of an energy storage system of the present invention in a perspective view, showing a gantry storage configuration. [Diagram 5]FIG. 5A illustrates a front view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in a detached configuration. FIG. 5B illustrates a side view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in a detached configuration. FIG. 5C illustrates a cross-sectional view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in a detached configuration. FIG. 5D illustrates a front view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in an engaged configuration. FIG. 5E illustrates a side view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in an engaged configuration. FIG. 5F illustrates a cross-sectional view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in an engaged configuration. FIG. 5G illustrates a perspective view of a weight attachment / detachment mechanism of a transport device connection of an embodiment of a system of the invention in an engaged configuration. [Figure 6] FIG. 5B shows a cutaway perspective view of the transport device connector of FIGS. 5A-5G. [Figure 7] FIG. 7 shows a perspective view of the transport device interface of FIGS. 5 and 6, which is transparent to show the docking on the near side. [Figure 8-1] Figure 8A shows a series of steps in a side cutaway showing a system of one embodiment of the invention in use, Figure 8B shows a series of steps in a side cutaway showing a system of one embodiment of the invention in use, and Figure 8C shows a series of steps in a side cutaway showing a system of one embodiment of the invention in use. [Figure 8-2] Figure 8D shows a series of steps in a side cutaway showing a system of one embodiment of the invention in use. Figure 8E shows a series of steps in a side cutaway showing a system of one embodiment of the invention in use. [Figure 9] FIG. 13 is a perspective view of a hanging weight support system of a preferred embodiment of another aspect of the energy storage system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention relates to an energy storage system that is a multi-weight gravity-based energy storage system. The system comprises at least a first weight and a second weight, preferably a third weight and optionally further weights. The system comprises a first transport device configured to transport the first weight along a first predefined path defining a vertical displacement between a first upper position and a second lower position, and a second transport device configured to transport the second weight along a second predefined path defining a vertical displacement between the respective first upper position and the second lower position. The first transport device comprises a first transport device coupling that mechanically couples the first weight to the first transport device and that can be coupled to and separated from the first weight. The second transport device comprises a second transport device coupling that mechanically couples the second weight to the second transport device and that can be coupled to and separated from the second weight.

[0019] The first path volume is defined by a first weight coupled to a first transport device coupling being advanced or passed along a first predefined path. The second path volume is defined by a second weight coupled to a second transport device coupling being advanced or passed along a second predefined path. The second coupling path volume is defined by a second coupling separated from the weight being advanced or passed along the respective predefined path between an upper position and a lower position. Each of the path volumes can be considered as a two-dimensional area covered when the article (e.g., the first weight, the first transport device coupling, the second weight, the second transport device coupling, or a combination of the weight and the transport device coupling) is viewed along the longitudinal axis of the predefined path. In some cases, in preferred embodiments, each of the two-dimensional areas covered is a maximum cross-sectional area and / or the path volume can be considered as a maximum cross-sectional area advanced or passed along the respective predefined path.

[0020] In the systems of the present invention, at least a portion of the second pathway volume overlaps with the first pathway volume, and the second junction pathway volume does not overlap with the first pathway volume.

[0021] The first connector path volume is preferably defined by the first connector, preferably separated from the weight, being advanced or passed along a respective predefined path between the upper and lower positions, and the first connector path volume preferably does not overlap with the second path volume.

[0022] The system preferably comprises at least three weights, more preferably more than three weights, such as at least five weights, even more preferably at least ten weights, and optionally at least twenty, such as up to fifty weights. The appropriate number of weights can depend on the depth of the shaft, the size of the weights, and the desired energy capacity. In one embodiment, the system comprises between six and twenty weights. In another embodiment, the system comprises between fifteen and fifty weights.

[0023] Thus, preferably, the energy storage system further comprises a third weight and optionally further weights, and the first and / or second transport device can be coupled to each of the third weight and the optional further weight to ensure a respective mechanical coupling and can be configured to transport the third weight and the optional further weight along a third or further predefined path defining a vertical displacement between the first upper position and the second lower position. Each of the third and further path volumes is defined by an area in which the third and further weights coupled to each transport device coupling (first or second) are navigated or pass through the respective predefined path, and these path volumes preferably at least partially coincide with the first predefined path and / or the second predefined path. Preferably, each of the third or any further path volumes overlaps at least with the first path volume, and preferably with the second path volume. More preferably, all of the third and further path volumes at least partially overlap with the first path volume and the second path volume, and even more preferably with each other.

[0024] In particularly preferred embodiments, the first predefined path, the second predefined path and the third and further paths preferably overlap along at least 50% of their lengths, more preferably overlap along at least 70%, even more preferably overlap along at least 80%, or may be the same.

[0025] By providing that the second pathway volume and the first pathway volume (and optionally the third and optional further pathway volumes) at least partially overlap, a multi-weight gravitational energy storage system can be provided in a small shaft with multiple transport devices (e.g. winches) capable of simultaneously or sequentially raising and lowering successive weights with no or minimal interruption in energy storage or release operations, thereby reducing capital costs and the overall cost of energy storage.

[0026] The system of the present invention is particularly useful and preferably configured to provide a power input / output from the system at the required power continuously over the time period for raising and lowering at least two successive weights, preferably at least three successive weights, preferably all weights in the system. This is preferably achieved by a controller configured to cause the system to slow down the rate at which the weights are raised or lowered as the weights approach the end of their path and to initiate movement of another weight to make up for the reduced power input / output caused by the first weight slowing down and coming to a halt at the end of its path, such that the input / output from the system can be provided at the required power continuously over the time period for raising and lowering at least two successive weights.

[0027] Preferably, the first weight and the second weight cannot pass each other along their respective paths.

[0028] A weight path volume for each weight may be defined by that weight as it passes through a predefined path (e.g. the two dimensional area covered by that weight, or the area of ​​the weight as seen from the predefined path). Preferably the weight path volumes of the first weight and the second weight overlap, and preferably the weight path volumes of the third and further weights overlap with the path volume of the first weight, and preferably also overlap with the path volume of the second weight.

[0029] The medial swept weight area and medial swept path area of ​​each weight may be the area defined by the cross-section of the path volume at the medial portion of the path of the respective weight and the weight associated with the transport device connector. The medial portion of the path means a portion of the middle portion, typically the middle third (as opposed to the first third of the last third of the path).

[0030] Preferably, the medial passageway region of the second weight overlaps with the medial passageway region of the first weight. Preferably, the medial passageway region of any third and further weights overlaps with the medial passageway region of the first weight, and preferably also with the medial passageway region of the second weight, more preferably with the medial passageway region of each of the other weights.

[0031] Preferably, the medial passage area of ​​the first weight overlaps with the medial passage area of ​​the second weight (and preferably, independently, any third and further weights) by an amount of at least 50% of the medial passage area of ​​the second weight, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, and most preferably at least 95%.

[0032] Preferably, the medial passage weight region of the first weight overlaps with the medial passage weight region of the second weight (and preferably, independently, any third and further weights) in an amount of at least 50% of the medial passage weight region of the second weight or of any third or further weights, respectively, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, even more preferably at least 95%, even more preferably at least 98%, and optionally completely overlaps.

[0033] Preferably, the total inner passage area of ​​the first inner passage area plus the second inner passage area is, for example, at most 30% larger than the first inner passage area and / or the second inner passage area, preferably at most 20% larger, more preferably at most 15% larger, and optionally at most 10% larger. This is preferably true for the total inner passage area of ​​all weights.

[0034] Preferably, at least a portion of the second pathway volume overlaps with the first pathway volume by an amount of at least 20% of the first pathway volume, preferably at least 30%, more preferably at least 50%, and optionally at least 80%.

[0035] Preferably, the total volume of the first and second pathway volumes is, for example, no more than 30% larger than the first pathway volume, more preferably no more than 20% larger, due to the extent of overlap.

[0036] The multi-weight gravity-based energy storage system preferably comprises a plurality of weights movable between respective first upper and second lower positions, the first upper and second lower positions defining a respective vertical displacement of each weight, the respective vertical displacements of each weight may be the same or may be different depending on how the weights are stored in the upper and lower positions.

[0037] The predefined path according to the present invention may be, for example, vertical or at an angle to the vertical. For example, the weight may be moved between its upper and lower positions by a dolly & rail arrangement or, in the case of an angled path to the vertical, by suspending and lowering the weight along a vertical path using a winch & cable arrangement. Preferably, the predefined path is a vertical path that corresponds directly to the vertical displacement between the upper and lower positions of the weight. By vertical displacement is meant the vertical distance between a first upper position and a second lower position. Preferably, the first predefined path and the second predefined path each define a vertical path between a respective first upper position and a second lower position. Preferably, each predefined path defines a vertical path between a respective first upper position and a second lower position.

[0038] Preferably, the energy storage system comprises a shaft, at least part of the path of which is followed by a first predefined path and a second predefined path, more preferably also optionally third and further predefined paths.

[0039] The shaft can be formed in a tower erected above ground, or in a shaft or hole dug into the ground, or partially in a tower above ground and in a shaft in the ground. Optionally, the shaft can be formed against a surface, for example a cliff face or an external surface of a tall structure, depending on which embodiment is followed, and the shaft cover can preferably be made against such a surface. Preferably, the shaft is a closed shaft. The shaft can be closed, for example, by a shaft wall dug into the ground, preferably lined, or by a tower cover, or by a cover formed on the (cliff or structure) surface, or by a combination of these. Preferably, the shaft is formed in the ground. The underground shaft used in the system can be dug specifically for the system, or can be converted from an existing shaft (for example a gallery).

[0040] The shafts used in any of the storage systems of the preferred embodiments of the present invention may be of any suitable depth, for example 10m or more, 50m or more, but preferably in the range of 100m to 4000m. For example, relatively shallow shafts may be provided having a depth of up to 500m, for example 100m to 350m. Alternatively, relatively deep shafts may be provided, preferably having a depth of more than 500m, preferably more than 1000m, such as 1250m to 3000m.

[0041] The shaft may have any suitable width (or range of cross sections) provided it is capable of accommodating the pathway volume of the weight. Preferably the width is in the range 1.5m to 20m, preferably 3m or more, more preferably 5m to 15m, more preferably up to about 10m.

[0042] In one implementation of the system of the invention, the system can be deployed in an existing shaft or a modified existing shaft. Such shafts are around 300m to 5000m deep and preferably have a diameter of 3m to 10m. For example, existing shafts (e.g. existing coal shafts) may have a depth of 300m to 1200m and preferably have a diameter of 5m to 7m. Alternatively (e.g. in closed metal mine shafts in the UK) the depth may be 50m to 750m and preferably have a diameter of 2.5m to 6m, preferably 3m to 5m (mostly square or rectangular shafts, e.g. 3m x 5m). In yet another option, for example in existing heavy metal / anhydrite mines in the UK, the shafts may be up to 1200m deep and have a circular shaft diameter of 5m to 8m. In yet another option, very deep shafts (e.g. existing gold / corrugated metal shafts such as those in South Africa) may have depths of, for example, 1500m to 3000m and preferably diameters of 5m to 9m.

[0043] In another implementation, a new shaft may be excavated for the system. In one such embodiment, the new shaft may be 30m to 120m deep and is preferably excavated using traditional caisson construction techniques. Such shafts may typically be 6m to 25m in diameter, generally circular in cross section, and preferably lined with concrete. In another such embodiment, the shaft may be 100m to 350m deep and is preferably excavated using automated shaft drilling techniques. Preferably, these shafts are generally circular in cross section and have a diameter of 6m to 18m in diameter. Again, the shafts are preferably lined with concrete. In a further such embodiment, the shaft may be 100m to 700m deep and is preferably formed by reverse circulation (e.g. head drilling) into hard rock. Preferably, the shafts are generally circular in cross section and have a diameter of 3m to 8m. Preferably, the shafts are lined with concrete by slipform construction techniques.

[0044] Generally speaking, new shafts drilled for the system will have a diameter in the range 4m to 10m and a depth of 50m to 750m, preferably a diameter of 6m to 10m and a depth of 50 to 250. For new shafts drilled into hard rock, the diameter will preferably be in the range 4m to 6m and the depth will be 400m to 700m.

[0045] The shaft preferably has a cross-sectional area which is no more than 75% larger than the total area of ​​the combined inner passage areas of the first and second weights (to which their respective transport device connections are connected), and this cross-sectional area is preferably no more than 75% larger than the total area of ​​the combined inner passage areas of any third and further weights, preferably no more than 50% larger, optionally in the range 5% to 30% larger, optionally 10% or more, for example up to 20% larger.

[0046] Optionally, each of the first and second weights, and optionally any third or further weights, may be coupled to either the first and second transport device hookups, or may be coupled to either the first and second transport device hookups, respectively. In a preferred embodiment, each weight is configured to be engageable only with either the first and second transport device hookups by providing the weight with only one pair of opposing coupling docks.

[0047] The first and second transport devices may be any suitable configuration or mechanism for transporting the first and second weights along their respective paths.

[0048] Preferably, the first transport device comprises a winch & cable (or chain, preferably cable) arrangement and the second transport device also comprises a winch & cable arrangement, preferably separate from the first winch & cable arrangement, the first and second winch & cable arrangements comprising one or more transport device couplings (coupling members arranged on or in relation to the cable arrangement) for coupling and decoupling the respective weights.

[0049] Preferably, each winch and cable arrangement comprises at least one winch located at or associated with the opening of the shaft or at the upper edge of the shaft. A cable can be preferably wound up and down by the at least one winch to raise and lower a weight via a link associated with the cable.

[0050] The winch and cable arrangement may include an arrangement of sheaves or pulleys to configure the arrangement as desired and as would be understood by one skilled in the art.

[0051] Preferably, each winch and cable arrangement comprises at least two winches, one located on each opposing side of the shaft entrance, each opposing winch cooperating with at least one coupling member for connecting and disconnecting the cable to and from the weight.

[0052] More preferably, each winch and cable arrangement comprises two opposing winch pairs arranged on opposite sides of the entrance to the shaft, each opposing winch pair cooperating with the cable arrangement and at least one connecting member for coupling to and decoupling from the weight.

[0053] Preferably, each winch and cable arrangement is positioned near the top of the shaft in an orthogonal arrangement relative to the other winch and cable arrangement.

[0054] Preferably, each transport device connection comprises a connection member cooperating with a respective connection dock of the weight.

[0055] In one embodiment, the connecting member is adjustable between a first configuration, in which it is coupled with the weight, e.g. the coupling dock of the weight, and a second configuration, in which it is separated. Preferably, when separated from the weight, the connecting member can be raised and lowered by a winch & cable without colliding with the weight in the shaft (e.g. because it is located on the side of the shaft). In a preferred embodiment, the connecting member in the first configuration has a protruding member, e.g. in the form of a sliding plate, which is extendable from the side of the main part of the connecting member via one or more extending arms or actuators, preferably moving laterally from the main part. When connected to the coupling dock of the weight, the protruding member can be actuated to cause the connecting member to assume the first configuration, whereby the protruding member enters a recess formed in the side of the weight. Preferably, if the protruding member is in the form of a sliding plate or otherwise has an upwardly facing element, the recess has an upwardly facing slot, such that when the connecting member is lifted, the upwardly facing element of the protruding member (e.g. the upper end of the sliding plate) engages with the slot of the recess to couple with the connecting member of the weight. The connecting member can be separated by reversing the process. Preferably, it can be activated and deactivated via a hydraulic actuator, but alternatively it can be activated and deactivated by an electric or other actuator.

[0056] The energy storage system of the present invention is particularly useful for storing excess energy from an external grid, or for supplying and discharging the stored energy as needed to an external grid or to an external demand, typically an external power grid such as a regional or national power grid.

[0057] Preferably, the energy storage system includes an input connection and an output connection to an external system (eg, an external power system), which may be a single point of connection.

[0058] Preferably, the energy storage system comprises a motor for driving a transport device, which may preferably be a winch & cable configuration, for lifting the weight or weights along the path from a lower position to an upper (stored energy) position, thereby allowing the system to be charged. Preferably, the energy storage system comprises a generator for generating electricity for export to an external power system from an energy output resulting from lowering the weight or weights from an upper position to a lower position, thereby allowing the system to be discharged. Preferably, the generator is coupled to a winch of the winch & cable configuration. Optionally, the motor and generator are one configured device coupled to the winch or winches.

[0059] Preferably, the system includes a controller (e.g., a processor and software configured to control the system) that controls the operation of the transport device and the movement of the weight in response to a request to store energy from an external system or discharge energy to an external system.

[0060] Preferably, the controller or control system is configured to detect or receive a signal related to demand from an external system (e.g., a power grid) and initiate the lifting or lowering of the weight and / or at the same time adjust the speed at which the weight is lifted or lowered to exactly match the demand (or requirement) of the external system. The controller or control system should therefore be in signal communication with the external system (e.g., a power grid), be configured to react to external system signals and, in a preferred embodiment, have a motor for driving the winch.

[0061] Preferably, the controller or control system is configured to detect when the weight approaches the end of a predefined path, e.g., the bottom of the shaft, near the bottom of the shaft near the previous weight, or near the top of the shaft, so that the system can be configured to slow the rate at which the weight is raised or lowered as it approaches the end of its path, and to automatically initiate the movement of another weight to smoothly replace the reduction in power input / output caused by the first weight slowing down and stopping at the end of its path. Thus, a continuous level of input / output from the system in the external connection can be provided. Optionally, the controller or control system can be preprogrammed to match the movement of the second weight when the first weight is slowed down as it approaches the top or bottom of the predefined path, and / or is configured to respond to sensor signals, such as sensors on the transport device (e.g., winch) related to the speed of cable movement and sensors in the shaft detecting the location and speed of the weights.

[0062] The controller is preferably configured to control movement of the linking members from the raised position to the lowered position and vice versa to gather additional weights for continuing the input / output by raising or lowering a third or subsequent weight. The controller is preferably configured to raise or lower such unattached linking members to reach the top or bottom of the predefined path in a time sufficient to engage the additional weights.

[0063] Preferably, the energy storage system has a fully charged configuration (i.e., maximum energy stored) with all weights raised to their upper positions, and a fully discharged configuration (i.e., minimum energy stored) with all weights lowered to their lower positions.

[0064] The weights may be stored at or associated with the upper and lower locations by any suitable means. For example, the weights may be stored at the bottom of the shaft in the respective pathway volumes (e.g., stacked on top of each other) and / or stored at the top of the shaft (e.g., one weight held under another by some retaining mechanism that still allows, for example, cables to pass through). The weights may be stored in an upper storage space associated with the upper locations, outside the respective pathway volumes or at or near the top of the shaft, and / or in a lower storage space associated with the lower locations, outside the respective pathway volumes or at or near the bottom of the shaft.

[0065] According to a preferred embodiment, in a fully discharged configuration, the first weight can be located at the bottom of the shaft in a first path volume when separated from its respective transport device, the second weight can be located above the first weight at the bottom of the shaft in a second path volume when separated from its respective transport device, and any third or further weights can be located or stacked above their respective previous weights at the bottom of the shaft in their respective path volumes. Thus, in this case the path volume of each weight is different (depending on how the weights are stored at the top of the shaft), and each successively lowered weight has a smaller path volume (assuming a common upper position for these weights outside the shaft) and a smaller energy storage capacity (assuming these weights are of the same mass).

[0066] In another embodiment, in a fully discharged configuration, the separated first weight may be stored in a bottom storage space associated with the shaft outside the first pathway volume, and the separated second and any third or further weights are preferably stored in storage spaces associated with the shaft outside the respective pathway volumes. Any suitable bottom storage space can be used, but preferably a bottom storage conveyor is provided to transport each of the first weight and preferably the second weight and any third or further weights from their respective lowered positions to the storage spaces outside the respective pathway volumes. The storage conveyor may take any suitable form, for example a track with a movable platform thereon, a conveyor belt, or a carousel that rotates a number of storage spaces through the shaft to expose a further unused storage space at the bottom of the shaft for receiving the next weight by lowering the weight into the unused storage space at the bottom of the shaft and then rotating into the storage space.

[0067] According to one embodiment, in a fully charged configuration, a first weight detached from its respective transport device is stored in its upper position within the first path volume, a second weight, when detached from its respective transport device, is positioned vertically adjacent to the first weight in its upper position within the second path volume, and any third or further weights are positioned adjacent to their respective immediately preceding weights in their respective upper positions within the respective path volumes, which may be within the shaft or within a vertical path volume above the opening of the shaft.

[0068] According to another embodiment, in a fully charged configuration, the first weights separated from their respective transport devices are stored in an upper storage space outside the first path volume, the second weights separated from their respective transport devices are stored in an upper storage space outside the second path volume, and any third or further weights are stored in an upper storage space outside the respective path volumes. Preferably, an upper storage conveyor is provided to transport each of the first weights and preferably the second weight and any third or further weights from their respective upper locations to the storage spaces outside the respective path volumes. The upper storage conveyor may comprise any suitable means, such as a gantry crane & matrix type storage arrangement, and / or a carousel.

[0069] In one embodiment of the invention, the weights are positioned and stacked at the bottom of the shaft in a discharged configuration, the bottom being effectively provided by a suspended platform suspended at a position above the actual bottom of the shaft, as will be described in more detail below in further aspects of the invention.

[0070] The weight may be of any suitable mass, depending for example on the total energy storage required (taking into account the vertical displacement provided by the system).

[0071] Preferably the second weight and preferably the third and any further weights have a mass within 30% of the mass of the first weight, preferably within 20%, more preferably within 10%, even more preferably within 5%, most preferably within 1%, and ideally the same mass as the first weight.

[0072] In one embodiment, the first weight has a mass in the range of 25 tons to 1000 tons, preferably in the range of 50 tons to 500 tons. The weights are scaled according to the particular application that can be effectively handled by the system. The weights are preferably of similar mass to each other, or identical mass. A typical weight designed to provide a large energy capacity in a suitable shaft may be, for example, 250 tons to 750 tons, such as approximately 500 tons.

[0073] In one example, the energy storage system includes a vertical shaft in which the winch and cable arrangement described above is located to raise and lower a number of weights by storing and releasing the stored energy, and is utilized in a shaft created for this purpose. The dimensions selected for the newly drilled shaft may depend on several geological and commercial factors. In one example, a newly drilled shaft of approximately circular cross section may be excavated with an inner diameter of 10 m and a depth of 200 m. The system may include a number of weights, approximately 550 tons per weight. If 26 weights are incorporated into the energy storage system and stored (stacked on top of each other) at their lowest point in the shaft when discharged and stored outside the shaft when fully charged, the system may provide a deliverable energy storage capacity of 6.6 MWh, assuming a power generation efficiency of 94%. Similar energy ratings may also be achieved with a larger number of smaller, lower mass weights.

[0074] In another aspect of the invention, a suspended platform system is provided for providing a suspended load-bearing platform, the system comprising a platform element, a plurality of suspension members which engage the platform element and from which the platform element is suspended, and a securing mechanism for securing the suspension members in an elevated position relative to the platform element.

[0075] The suspended platform system is preferably suitable for placement within a vertical shaft, with the platform elements providing a load-bearing platform upon which weights may be placed in the gravity-based energy storage system defined above. The suspended platform should be sized to fit within the shaft, with the suspension members having a length that allows the platform elements to be suspended within the shaft at a distance above the actual bottom of the shaft.

[0076] Preferably, the suspended platform system can be installed at the top of an existing shaft, which helps to eliminate the need for quarrying below the shaft and can also help to eliminate the need for workers to descend the shaft for installation operations.

[0077] This aspect of the suspended platform system may also have the advantage that it can be used in existing shafts that have adverse characteristics such as abandoned machinery, water, etc. in their lowest regions. Using this platform approach, the energy storage system defined above can also be operated without being affected by these characteristics.

[0078] In another embodiment, a sealing mechanism can be installed on the side or underneath the suspended platform to separate the portion of the shaft being utilized from the volume below the platform, which can be beneficial in situations where the lower portion contains gases that are dangerous to people, equipment and the environment, such as methane, which is present in coal mines.

[0079] The platform element may be any platform suitable for supporting a weight for use in the energy storage system defined above. The platform element may be, for example, a frame element having engagement members for receiving the weight or support members for supporting the weight, or may be a grid-like arrangement. In one embodiment, the platform element is a planar rigid member, preferably a solid support member.

[0080] The suspension members may be any suitable members capable of suspending a platform element from an elevated position within the shaft, such as the top of the shaft. Preferably a plurality of suspension members are provided, for example at least three, more preferably four, or optionally five or six or more. The suspension members are preferably elongate members which are engaged with, or preferably attached or mounted to, the platform element which may be suspended from it within the shaft, and which are secured by a securing mechanism, preferably at or near the surface.

[0081] The suspension members may optionally be rigid members, such as rods, or are preferably flexible members, such as cables.

[0082] Preferably, the suspension members are capable of extending into the shaft and therefore have a length dependent on the depth to which it is desired to place the platform elements, for example the suspension members may have a length up to 500m, such as 50m or more, preferably between 100m and 1000m, more preferably between 200m and 400m.

[0083] The suspension members may be engaged with the platform element by any suitable means. For example, the suspension members (e.g. in the case of cables) may engage with receiving grooves located on the bottom surface of the platform element, or may engage via sheaves located on the bottom surface of the platform element, so that two opposing suspension members may be formed by one cable extending from the top of the shaft down the shaft to engage the bottom surface of the platform element and support the shaft up to the top. However, the suspension members are preferably affixed or otherwise rigidly engaged to connection points on the bottom surface of the platform element, or on the peripheral edge of the platform element, or on the top surface of the periphery of the platform element.

[0084] Optionally, where the suspension member is a cable, the suspension member may be provided with a tension member that can be adjusted to shorten the length of the cable to maintain a desired horizontal orientation of the platform element.

[0085] Optionally, the suspension member, when used with the energy storage system defined above, may act as a guide for raising and lowering the weight in the shaft. The weight may be mounted with rollers or skids to engage the cable for this purpose. The rollers or skids may include shock absorbing means.

[0086] The fixing mechanism may be any suitable means for fixing the suspension members and enabling them to suspend the platform element within the shaft. In one embodiment, the fixing mechanism comprises one or more anchors associated with each suspension member. For example, the fixing mechanism may include at least one ground engaging anchor, such as a threaded anchor that is screwed into the ground to which the suspension members can be attached. For example, if the suspension members are cables, each cable may be fixed by at least one ground engaging anchor in the ground adjacent to the shaft opening, for example several meters away (e.g. 5 meters to 10 meters, or up to 20 meters from the shaft opening, e.g. the edge of the shaft opening). In this embodiment, a sheave may further be provided that is arranged in relation to the shaft opening or the edge of the shaft through which the fixed cable can extend down the shaft.

[0087] In another preferred embodiment, the fixing mechanism may comprise a load-distributing anchor support member, preferably positioned around the shaft opening on the ground and having or defining an opening (smaller, or larger or the same size as the shaft opening) above the shaft opening. The anchor support member may optionally be a frame member. Preferably, the anchor support member is a flat member, more preferably a plate-like member, for example a plate of steel or other metal, or a plate of reinforced concrete (e.g. concrete reinforced with wire mesh). Such an anchor support member may simply be placed on the ground above the shaft opening or around the shaft opening, or the anchor support member itself may be fixed to the ground, for example at the edge around the shaft opening. The lateral extent of the anchor support member may be any suitable amount, but may typically be between 5m and 25m in total, preferably between 10m and 20m. Optionally, there may be a skirt member extending from the anchor support member, typically extending from the edge of an opening formed in the anchor support member, preferably extending downwardly to effectively line the top of the shaft over which the anchor support member is located. For example, the skirt may extend up to 15m into the shaft, for example 3m to 10m. The skirt may be made of any suitable material, but is preferably made of a rigid material and more preferably of similar construction to the anchor support member, for example a steel tubular skirt, or a reinforced concrete skirt.

[0088] The suspension members according to this general embodiment may be affixed or fixed to the anchor support member, for example by fastening to mounting means on the top surface of the anchor support member, or by engaging a peripheral edge of the anchor support member (and a sheave is provided at the edge of an opening in or defined by the anchor support member), or by mounting or affixing to the edge of an opening in or defined by the anchor support member, if a skirt of the anchor support member is present.

[0089] Optionally, laterally projecting members may be provided that engage the shaft walls to stabilize the platform elements or suspension members and / or to allow some load bearing support by the shaft walls of the system. The laterally projecting members may take any suitable form. Preferably, the laterally projecting members are rigid and optionally deployable from a retracted position (to facilitate installation) to a deployed position (engaging with the shaft walls). The laterally projecting members may be, for example, folding and extending hydraulic members, or threaded members, or a combination thereof.

[0090] The laterally projecting members may be configured to abut against the wall of the shaft or may be configured to be affixed to the wall of the shaft.

[0091] Preferably, the laterally protruding members are positioned relative to the platform element, for example, the laterally protruding members are positioned below or mounted to a bottom surface of the platform element, hi one embodiment, the laterally protruding members are configured to protrude from a lateral end of the platform element.

[0092] Optionally, the suspension members are provided with reinforcing or support members at predefined locations on the length of the suspension members. Preferably, the reinforcing or support members are interconnected to define a circumferential support frame, preferably having openings to allow movement of weights (as defined in the energy storage system above). Optionally, the circumferential support frame is provided with laterally projecting members, which enable the circumferential support frame to engage with the wall of the shaft in which the system is located to stabilize the circumferential support from the suspension members and indeed the suspension members, and optionally the circumferential support frame can extend to the wall of the shaft, which allows the wall to provide load support to the system via the circumferential support frame. The laterally projecting members can be as defined above individually.

[0093] When a platform element is placed in a shaft, it preferably has a lateral dimension (excluding protruding members) that is between 50% and 95% of the corresponding cross-sectional dimension of the shaft in which it is placed.

[0094] The suspended platform system, as a preferred embodiment, can preferably be integrated into the energy storage system previously described.

[0095] The invention will now be described in more detail, without limitation, with reference to the accompanying drawings, in which: FIG.

[0096] In Fig. 1, the energy storage arrangement 1 is shown with a first weight 3 in a lower rest position 17 at the bottom 15 of a shaft 19 and a second weight 5 in an intermediate position between its respective lower rest position at the bottom 15 and a first upper position (not shown) at or near the top of the shaft 19. A first cable set 7 including first opposing cables 21 and 23 is shown with a first coupling member 25 for engagement with a first coupling dock 27 of the first weight 3 but removed from the first coupling dock 27. As shown, the coupling member 25 may be lowered by the cable 7 (and associated winch, not shown) towards the first weight 3 to engage it as part of a charging cycle (or energy storage cycle) and the winch (not shown) may be controlled to lift the first weight 3, or the coupling member 25 may be lifted by the cable 7 past the second weight 5 towards the top of the shaft 19 to engage a third weight (not shown) as part of a discharging cycle. The second weight 5 is suspended within the shaft 19 in a position between the bottom 15 and the top (not shown) by a second cable set 13 consisting of second opposing cables 29 and 31 via a second linkage 33. The second weight 5 is about to be or is being lifted by a winch (not shown) associated with the second cable set 13 during a charge cycle, or is being lowered to the bottom 15 during a discharge cycle. In either charging or discharging, the unused cable set 7 and linkage 25 must pass the other (e.g. second) weight 5 and linkage 33 arrangement unhindered. Thus, by the time the second weight 5 comes to rest or is stacked on the first weight 3 at the bottom of the shaft 19, the first linkage 25 can be lifted by the first cable set 7, for example by a winch (not shown), to engage a third weight (not shown) and is ready to be lowered by the first cable set 7. This configuration and method allows for continuous discharge (or, alternatively, charging) without the interruption that is characteristic of known multi-weight, single shaft gravity-based energy storage systems.Assuming a discharge cycle in which a second weight 5 is lowered by the second set of cables 13, the second weight 5 is stacked on top of the first weight 3 at the bottom 15 of the shaft 19. A third weight (not shown), which is removed from the top of the shaft 19 by returning the first set of cables 7, is lowered and stacked on top of the second weight 5 at the bottom 15 of the shaft 19. Each successive weight stored in a stack at the bottom 15 of the shaft 19 has a shorter vertical movement than the previous weight, and the release of stored energy with the lowering of each weight is less than that of the previous one.

[0097] The first weight 3 and the second weight 5 (and subsequent weights) are of similar magnitude.

[0098] The winch preferably operates faster when raising or lowering an unused linkage (e.g. 25) than a linkage (e.g. 33) attached to a weight (e.g. second weight 5), so that in the time it takes for the second weight 5 to be lowered from the top of the shaft 19 to the bottom 15, the first linkage 25 can be detached from the first weight 3, return to the top of the shaft 19 and engage the next (third) weight (not shown) to begin its descent. The same should happen for successive weights, thus avoiding any interruptions in power input / output.

[0099] 2 shows a side cross-sectional view of the energy storage arrangement 1 with the second weight 5 being lowered by the second winch arrangement 35 and the first linkage member 25 being raised by the first winch arrangement 37 for attachment to a third weight (not shown) so that the discharge cycle can continue uninterrupted. The unused linkage member 25 is arranged to pass unhindered past the descending second weight 5. The winch arrangements 35, 37 are typically located in a surface surrounding the upper end of the shaft 19.

[0100] FIG. 3 shows a preferred embodiment of the energy storage system 1 in a cutaway view of the top of the shaft 19, with a second weight 5 being shown being lowered by a second winch arrangement 35. The second winch arrangement 35 comprises opposing cable pairs 29 and 31, on which a second linkage member 33 is disposed which engages the second weight 5. The cable pairs 29 and 31 are lowered or raised by winch pairs 39 and 41, respectively. The winch pairs 39 and 41 are disposed opposite each other on either side of the shaft edge 43 on the ground (not shown). The winch pairs 45 and 47 of the first winch arrangement 37 are perpendicular to the winch pairs 39 and 41 and disposed opposite each other on either side of the shaft edge 43. Each winch pair 39, 41, 45, and 47 winches a respective cable 29, 31, 21, and 23. Cables 29, 31, 21 and 23 are connected at one end to one of winches 39, 41, 45 and 47 and are looped around connecting members 33 and 25. This ensures that variations in the winding speed of each pair of winches can be adjusted by adjusting the connecting members on the cables.

[0101] FIG. 4 shows an energy storage arrangement 1 in a cutaway perspective view according to one embodiment of the invention. The energy storage arrangement 1 includes a shaft 19 through which a weight can be raised and lowered between the top and bottom 15 of the shaft 19. Two opposing winch pairs 39 and 41 operate to lower (via cables 29, 31 and linkage 33) a second weight 5 towards the bottom 15 of the shaft 19 (not shown here), while opposing winch pairs 45 and 47 operate to lift a first linkage 25 from the bottom 15 of the shaft 19, releasing it from a first weight 3 that was most recently lowered (shown in other figures). The first linkage 25 is then lifted back up to the top of the shaft 19 for engagement with a third weight 49 that is stored in a storage area 53 outside the shaft 19 beside the winch at the top of the shaft 19 together with a trailing weight 51. An overhead crane 55 is provided for hoisting the third and subsequent weights 49 and 51 out of and into the shaft 19 through the upper end. A gantry arrangement 57 is provided along which the overhead crane 55 moves to engage the third weight 49 by engagement between a crane coupling 59 of the crane 55 and a corresponding weight coupling (not shown) on the upper surface 61 of the third weight 49 (and subsequent weight 51). The third weight 49 is lifted by the crane 55, carried up the shaft 19 and lowered into the shaft 19 between the winches 39, 41, 45 and 47 until it reaches the upper end of the shaft 19 and is ready to engage the first coupling member 25. Once the coupling member 25 is engaged, the crane coupling 59 can be removed from the upper surface 61 of the third weight 49 and the third weight 49 is lowered towards the bottom 15 (not shown).

[0102] 5A-5G show the coupling member 25 in a configuration detached from the first weight 3 (FIGS. 5A-5C) and engaged with the first weight 3 (FIGS. 5D-5G).

[0103] In Figs. 5A-5C, the connecting member 25 suspended from the cable 21 can pass the weight 3 freely without colliding with the weight 3. The connecting member 25 includes a main part 63 to which the cable 21 is attached and a sliding plate 65 arranged on the inner surface (weight side) of the main part 63 and cooperating therewith. When the connecting member 25 is aligned with the weight 3, and in particular with a recess-shaped connecting dock 27 in the weight 3, the sliding plate 65 can be moved laterally from the main part 63 into the recess 67 of the connecting dock 27. The connecting member 25 is then lifted up, and an upper part of the sliding plate 65 engages with a slot 69 in an upper part of the recess 67, thereby locking the connecting member 25 to the connecting dock 27.

[0104] 5C, 5F and the cross-sectional view of FIG. 6, the sliding plate 65 is provided with six hydraulic actuators 77 which extend through bushes 79 formed in the main part 63 and serve to control the movement of the sliding plate 65 away from / back to the main part 63 and to cooperatively engage and hold the sliding plate 65 in the recesses 67 and slots 69. The lower end of the sliding plate 65 is provided with lateral wings 73 which cooperate with lateral slots 75 associated with the recesses 67 to inhibit rotation of the coupling member 25 when the coupling member 25 is engaged with the docking dock 27.

[0105] To release the connecting member 25 from the weight 3, the connecting member 25 is lowered below the weight 3, thereby removing the sliding plate 65 from the slot 69 (and the side wings 73 from the lateral slots 75), and the hydraulic actuator 77 is then actuated to pull the sliding plate 65 into contact with the main part 63, in which position the connecting member 25 can be safely raised or lowered below the weight 3 without further contact.

[0106] 7 shows a perspective view of the weight 3 through which one of the connecting docks 27 for receiving the sliding plate 65 is seen. As can be seen, when the sliding plate 65 is placed in the recess of the connecting dock 27 and the connecting member 25 is lifted, the upper end of the sliding plate 65 fits into the slot 69, and at the same time, the side wings 73 of the sliding plate 65 engage with the lateral slots 75 of the connecting dock 27. The abutment surface 81 of each lateral slot 75 serves to abut the lateral wings 73 and also to counteract a possible rotational movement of the connecting member 25 due to the position of the sliding plate 65 being offset from the stationary center of gravity of the connecting member 25 suspended from the cable 21 and the sliding plate 65 engaging with the weight 3 when the connecting member 25 is engaged and lifting the weight.

[0107] The operation of the multi-weight gravity-based energy storage arrangement 1 is shown in Figures 8A-8E. The energy storage arrangement 1 is configured with a controller (not shown) for controlling the movement of the weights 3, 5, 49, 51 between raised and lowered positions in the shaft 19 to store energy (by lifting the weights) or release energy (by lowering the weights) according to the demand of an external system, typically a power grid. The system is charged by converting power from the power grid by motors in response to signals from the controller to drive winches 39, 41, 45, 47 (shown in the previous figures) to lift the weights 3, 5, 49, 51 from a relatively low position to a relatively high position, typically one after the other, or two weights may be lifted simultaneously for a short period of time if high power is required for a short period of time. When a demand for power is detected or requested from an external system such as a power grid, the controller sends a signal to the winches 39, 41, 45, 47 to lower the weights 3, 5, 49, 51 from a raised (charged) position to a lowered (discharged) position, and the release of gravitational potential energy is converted into electricity by the generators and exported to the external system. Again, the lowering of the weights 3, 5, 49, 51 is typically done in sequence for continuous, uninterrupted power output, although they may be lowered two at a time to satisfy short-term high demands for power.

[0108] In FIG. 8A, configuration 1 shows a shaft 19, around the upper end of which are arranged opposing winch pairs 39 and 41 of one winch arrangement, and opposing winch pairs 45 and 47 of a second winch arrangement. A weight 3 is resting at the bottom 15 of the shaft 19, which has just been lowered by opposing cable pairs 29 and 31 attached to the weight 3 via a first coupling member 25 associated with the winch pair 39 and 41 and which engages with a corresponding coupling dock 27 on one side of the weight 3. A weight 5 is located at the upper end of the shaft 19, which engages with a second coupling member 33 at the coupling docks 27 at the front and rear of the weight 5. The weight is suspended from the cable pairs 21 and 23 (shown in the previous figures) associated with the winch pairs 45 and 47. The weight 5 is ready to be lowered. A third weight 49 and a further weight 51 are stored in an above-ground storage area 53 outside to the side of the shaft 19. A gantry arrangement 57 with an overhead crane 55 is provided for transporting the weights 49,51 between an above ground storage area 57 and a position where they engage the coupling members 25,33 at the upper end of the shaft 19 as required.

[0109] Upon receiving a signal from the controller (not shown) requesting an extension of power output to the external system, the winch pair 45 and 47 lowers the weight 5 down the shaft 19 as shown in FIG. 8B. At the same time, the winch pair 39 and 41 are signaled to lift the cable pair 29 and 31 and the first link member 25 which has been released from the weight 3. The cable pair 29 and 31 are lifted to the top of the shaft and connected with the third weight 49, and are lifted at a faster rate than they are lowering the weight 5 so that the weight 5 begins to descend before it reaches its rest position. Also at the same time, the controller (not shown) signals the crane 55 which engages the third weight 49 via the crane coupling 59 and the top of the weight 49 to hoist the weight 49 and transport it by the gantry 57 to a position above the shaft 19 ready for use. The weight 49 is then lowered by crane 55 through a gap between opposing winch pairs 39, 41, 45, 47 sufficient for the weight 49 to travel, and is held at the top of the shaft 19 immediately below the winch 45, engaged (via a coupling dock 27 on one side of the weight 49) with the most recently raised first coupling member 25, which can be released by the crane coupling 59 once firmly engaged. This process should all be completed while the weight 5 is being lowered so that when the second weight 5 reaches its lower rest position (shown in FIG. 8C ) stacked on top of the first weight 3 at the bottom 15 of the shaft 19, the third weight 49 can begin to be lowered, thereby allowing continuous, uninterrupted power output from the arrangement 1.

[0110] As shown in Figure 8D, as the third weight 49 is lowered, the second linking member 33 and cable pairs 21 and 23 are raised at a faster rate by the winch pairs 45 and 47 to encounter and engage a further weight 51 engaged by the crane 55 via the crane hitch 59 for transport by the gantry 57 to the top of the shaft 19. Again, the raised linking member 33 is able to pass the descending weight 49 without collision so that it can be positioned at the top of the shaft 19 engaged with the weight 51 via the hitch dock 27 and ready for release by the crane 55 so that it can be lowered to release further energy to an external system once the third weight 49 has reached its lower rest position where it is stacked on top of the second weight 5 at the bottom 15 of the shaft 19.

[0111] Thus, configuration 1 provides significantly increased energy capacity with a smaller and more cost effective lifting means for a given shaft 19 by utilising multiple weights 3, 5, 49, 51, and the use of two weight / cable arrangements can provide continuous energy input from / output to the external system without interruption across the full energy capacity of configuration 1.

[0112] 9 shows a suspended platform system 83 for placement in a shaft (not shown) for raising and lowering a weight 85 for use in the energy storage system described in more detail above, according to one embodiment of the invention. The platform element 87 is suspended (typically in the shaft) by ten cable suspension members 89 that extend around the periphery of the platform element 87 and are affixed to peripherally arranged brackets 91 that are affixed to the bottom surface of the platform element 87. The cable suspension members 89 may be attached at their opposing ends to an anchor support member 93 in the form of a spreader plate for placement above the shaft (not shown) on the ground, with an opening 95 that should generally coincide with the opening of the shaft (not shown). The edge 97 around the opening 95 may be provided with a number of fixtures or brackets 99 to which the cable suspension members can be secured. The weight 85 may be placed on the top surface 101 of the platform element 87 in the discharged configuration of the energy storage system.

[0113] The present invention has been described with respect to preferred embodiments, but it will be appreciated that variations and modifications can be made by those skilled in the art without departing from the scope of the invention.

Claims

1. The first weight (3), A second weight (5); a first transport device configured to couple and separate from the first weight (3), the first transport device comprising a first transport device coupling (25) for mechanically coupling the first weight (3) to the first transport device, the first transport device configured to transport the first weight along a first predefined path defining a vertical displacement between a first upper position and a second lower position; a second transport device configured to couple and separate from the second weight (5), the second transport device including a second transport device coupling (33) that mechanically couples the second weight (5) to the second transport device, the second transport device configured to transport the second weight (5) along a second predefined path that defines a vertical displacement between a first upper position and a second lower position; a first path volume defined by an area through which the first weight (3) coupled to the first transport device coupling (25) is advanced or passed along the first predefined path; a second path volume defined by an area through which the second weight coupled to the second transport device coupling portion (33) is advanced or passed along the second predefined path, at least a portion of the second path volume overlapping the first path volume; a second connector path volume defined by an area through which the second connector (33), separated from any weight, is advanced or passed between the upper and lower positions along respective predefined paths; Including, At least a portion of the second pathway volume overlaps with the first pathway volume, and the second junction pathway volume does not overlap with the first pathway volume. A multi-weight gravity-based energy storage system (1).

2. 2. The energy storage system (1) of claim 1, wherein the at least a portion of the volume of the second path overlaps the volume of the first path by an amount of at least 30% of the volume of the first path.

3. 2. The energy storage system (1) of claim 1, wherein the first predefined path and the second predefined path each define a vertical path between the respective first upper location and second lower location, and wherein the first predefined path and the second predefined path follow the path of a shaft (19) in the earth, the shaft (19) having a depth of between 100 m and 4000 m.

4. 2. The energy storage system (1) of claim 1, wherein the first transport device and the second transport device each comprise a winch-and-cable arrangement.

5. 5. The energy storage system (1) of claim 4, wherein the first transport device comprises a first winch and cable arrangement and the second transport device comprises a second winch and cable arrangement separate from the first winch and cable arrangement, each of the winch and cable arrangements comprising one or more transport device couplings (25, 33) for coupling and decoupling a respective weight (3, 5).

6. 6. The energy storage system (1) of claim 5, wherein each of the winch and cable arrangements comprises two opposing winch pairs (35, 37) arranged on opposite sides of the shaft entrance (43), each of the opposing winch pairs (35, 37) cooperating with a cable arrangement (7, 13) and at least one transport device connection (25, 33).

7. a first connector path volume defined by an area through which the first connector (25) separated from the weight (3) is advanced or passed between the upper position and the lower position along a respective predefined path; Further comprising: The first junction passage volume does not overlap with the second passage volume.

7. An energy storage system according to any one of claims 1 to 6.

8. 7. The energy storage system (1) according to any one of claims 1 to 6, further comprising a third weight (49) and one or more further weights (51), wherein the first and / or the second transport device is capable of being coupled to each of the third weight (49) and the one or more further weights (51) to ensure a respective mechanical coupling and configured to transport the third weight (49) and the one or more further weights (51) along a third path or further predefined paths defining a vertical displacement between a first upper position and a second lower position.

9. 7. The energy storage system (1) of any one of claims 1 to 6, having a fully charged configuration in which all of the weights (3, 5, 49, 51) are raised to their respective upper positions and a fully discharged configuration in which all of the weights (3, 5, 49, 51) are lowered to their respective lower positions.

10. In the fully discharged configuration, the first weight (3) is located at the bottom (15) of the shaft in the first path volume when separated from the respective transport device, the second weight (5) is located above the first weight (3) at the bottom (15) of the shaft (19) in the second path volume when separated from the respective transport device, and the third weight (49, 51) is located or stacked on top of the respective previous weight at the bottom of the shaft in the respective path volume, or the separated first weight (3) is stored in a bottom storage space associated with the shaft (19) outside the first path volume, and the separated second and third weights (5, 49, 51) are stored in storage spaces associated with the shafts outside the respective path volumes, 10. The energy storage system (1) of claim 9, wherein in a fully charged configuration, the first weight (3) separated from the respective transport device is stored in its upper position within the first path volume, the second weight (5) when separated from the respective transport device is disposed in its upper position within the second path volume adjacent to the first weight, and the third weight (49, 51) is disposed in its upper position adjacent to the respective immediately preceding weight within the respective path volume, or the first weight (3) separated from the respective transport device is stored in an upper storage space (53) outside the first path volume by an upper storage conveyor including a gantry (57) or a carousel, the second weight (5) separated from the respective transport device is stored in an upper storage space outside the second path volume, and the third weight (49, 51) is stored in the upper storage space (53) outside the respective path volume.

11. An energy storage system as claimed in any one of claims 1 to 10, comprising input and output connections and a motor and / or generator.

12. a control device for controlling the operation of the first transport device and the second transport device and the movement of the weight (3, 5, 49, 51) in response to a request for storing surplus energy from an external system or discharging energy to the external system; 12. The energy storage system (1) according to any one of claims 1 to 11, wherein the control device is configured to cause the system (1) to slow down the speed of raising and lowering the weights (3, 5, 49, 51) as the weights (3, 5, 49, 51) approach the end of their path and to start the movement of another weight to compensate for the reduction in power input / output caused by the first weight slowing down and coming to a stop at the end of its path, so that the input / output from the system (1) can be provided at the required power continuously for the time it takes to raise and lower at least two successive weights (3, 5, 49, 51).

13. 1. A method of storing energy in a multi-weight, gravity-based energy storage system (1) for continuously inputting and / or outputting power to the system (1) across its entire energy capacity without interruption or discontinuity, the method comprising providing a multi-weight, gravity-based energy storage system (1) as defined in claim 1 and raising and lowering successive weights (3, 5, 49, 51) in response to power input / output demands on the system (1).

14. 14. The method of claim 13, further comprising operating the energy storage system to slow down the rate at which the weights (3, 5, 49, 51) are raised or lowered as the weights (3, 5, 49, 51) approach the end of their path and to initiate the movement of another weight to compensate for the reduction in power input / output caused by the first weight slowing down and stopping at the end of its path, so that the input / output from the system can be continuously provided at the required power for the duration of raising or lowering at least two successive weights (3, 5, 49, 51).

15. 15. The method according to claim 13 or 14, further comprising simultaneously moving the at least two weights (3, 5, 49, 51) along respective predefined paths to provide increased power input / output.

16. 1. A suspended platform system (83) for providing a suspended load-bearing platform (101) for an energy storage system (1) as defined in claim 1 within a shaft (19), comprising: a platform element (87), a plurality of suspension members (89) which engage with said platform element (87) and from which said platform element (87) is suspended, and a fixing mechanism (93) for fixing said suspension members (89) in an elevated position relative to said platform element (87).

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