Gravity energy storage system

Abstract

Even when the masses of the multiple weights differ from each other, the power generated by the multiple weights is stabilized. [Solution] The gravity energy storage system 1 comprises a plurality of weights 50 with different masses and a control unit 70. The control unit 70 controls the movement of the weights 50, including their descent. The control unit 70 individually identifies the plurality of weights 50 and acquires information on the predicted fluctuations in power generation that will occur when the weights 50 are lowered, for each weight 50. The control unit 70 determines one or both of the following conditions: the number of weights 50 to be lowered simultaneously, and the interval between the start of descent of the plurality of weights 50, so as to suppress fluctuations in power generation that will occur when the plurality of weights 50 are lowered simultaneously. The control unit 70 controls the descent of the weights 50 so as to lower them based on the determined conditions.

Description

Technical Field

[0006] , , ,

[0005] , ,

[0001] The present invention relates to a gravity energy storage system that generates electricity by dropping a weight.

Background Art

[0002] For example, Patent Document 1 describes a conventional gravity energy storage system (referred to as an energy storage system in the same document). In the gravity energy storage system described in this document, it is described that electricity is generated by moving a weight (referred to as a block in the same document) from a high position to a low position (such as

[0005] in the same document).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the masses of a plurality of weights are not constant, the generated power by the plurality of weights may become unstable.

[0005] Therefore, an object of the present invention is to provide a gravity energy storage system that can stabilize the generated power by a plurality of weights even when the masses of the plurality of weights are different from each other.

Means for Solving the Problems

[0006] The gravity energy storage system comprises a plurality of weights with different masses and a control unit. The weights are used for gravity energy storage. The control unit controls the movement of the weights, including their descent. The control unit identifies the plurality of weights individually. The control unit obtains information on the expected fluctuations in generated power that will occur when the weights are lowered, for each weight. The control unit determines one or both of the following conditions: the number of weights to be lowered simultaneously, and the interval between the start of descent of the plurality of weights, so as to suppress fluctuations in generated power that would occur when the plurality of weights are lowered simultaneously. The control unit controls the descent of the weights so as to lower them based on the determined conditions. [Effects of the Invention]

[0007] The gravity energy storage system described above allows for the stabilization of the power generated by multiple weights, even when the masses of the weights differ from each other. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of gravity energy storage system 1. [Figure 2] Figure 1 is a top view of the gravity energy storage system 1 shown in Figure 1. [Figure 3] This figure shows the method for preparing the weight 50 shown in Figure 1. [Figure 4] Figure 3 shows a diagram illustrating the method of compressing the material used for the weight 50 shown in Figure 3. [Figure 5] Figure 1 shows a graph illustrating the schematic time-dependent changes in the descent velocity and generated power of the weight 50. [Figure 6] Figure 1 is a flowchart showing an example of the processing performed by the control unit 70. [Modes for carrying out the invention]

[0009] The gravity energy storage system 1 will be described with reference to Figures 1 to 6.

[0010] Gravity energy storage system 1 is a system (gravity energy storage device, gravity power plant) that performs gravity energy storage, as shown in Figure 1. Gravity energy storage system 1 stores and generates electricity using the potential energy (renewable energy) of the weight 50. For example, in gravity energy storage system 1, surplus electricity when electricity demand is relatively low (such as at night) is used to raise the weight 50 from the lower standby position 11 to the upper standby position 13 (storage electricity). Then, in gravity energy storage system 1, when electricity demand is relatively high (for example, during peak electricity demand in the daytime), the weight 50 is lowered from the upper standby position 13 to the lower standby position 11, thereby generating electricity (generating electricity).

[0011] The gravity energy storage system 1 may be installed in various locations. The whole or a part of the gravity energy storage system 1 may be installed on flat ground, for example, inside a building (for example, a warehouse type), or on a tower. The whole or a part of the gravity energy storage system 1 may be installed in a place with elevation differences, such as a mountain, or it may be installed underground. The gravity energy storage system 1 may be configured to allow the weight 50 to be raised and lowered vertically. The gravity energy storage system 1 may be configured to allow the weight 50 to be raised and lowered in a direction inclined with respect to the vertical, for example, the weight 50 may be configured to be raised and lowered along a mountain slope (for example, a gondola type, a cable car type, etc.). If the weight 50 contains radioactive waste, the gravity energy storage system 1 must be installed in a place where the radioactive waste can be properly managed. The above-mentioned "place where radioactive waste can be properly managed" is, for example, the site of a source of radioactive waste, and specifically, for example, the site of a nuclear facility (such as a nuclear power plant).

[0012] Specifically, for example, if gravity energy storage system 1 is warehouse-type, the power generation capacity is 25 MW, the power generation in 4 hours is 100 MWh, and the conversion efficiency is 85-90%. Note that these figures are merely examples and can vary (the same applies to the figures below).

[0013] This gravity energy storage system 1 comprises a lower standby position 11, an upper standby position 13, a lifting unit 20, a weight moving unit 30, a weight row 40, a reading device 60, and a control unit 70.

[0014] The lower standby position 11 is the position (deck, station) where the descended weight 50 (weight 50 before ascending) is placed. The upper standby position 13 is the position where the ascended weight 50 (weight 50 before descending) is placed. The height from the lower standby position 11 to the upper standby position 13 can be set in various ways. If the gravity energy storage system 1 is of the warehouse type, the height from the lower standby position 11 to the upper standby position 13 is, for example, 150m.

[0015] The lifting unit 20 is a device (lifting mechanism) for raising and lowering the weight 50. The lifting unit 20 raises and lowers the weight 50 between the lower standby position 11 and the upper standby position 13. Multiple lifting units 20 are provided (see Figure 2). The lifting unit 20 comprises an upward section 21 and a downward section 23. The structure of the lifting unit 20 can be set in various ways depending on the installation location of the gravity energy storage system 1. In the example shown in Figure 1, the lifting unit 20 comprises a frame 25a, a motor 25b, a wire 25c, and a weight holding section 25d.

[0016] The lifting unit 21 is a device (lifting device) that lifts the weight 50. The lifting unit 21 increases the potential energy of the weight 50 by lifting the weight 50 from the lower standby position 11 to the upper standby position 13. Multiple lifting units 21 are provided. Depending on the installation location of the gravity energy storage system 1, the lifting unit 21 may lift the weight 50 in the vertical direction, or it may lift the weight 50 in a direction inclined with respect to the vertical direction.

[0017] The lowering part 23 is a device (lowering device) for lowering the weight 50. The lowering part 23 lowers the weight 50 from the upper standby position 13 to the lower standby position 11. The lowering part 23 converts the potential energy of the weight 50 into electrical energy generated by the motor 25b (generator). A plurality of lowering parts 23 are provided. Depending on the installation location of the gravity energy storage system 1 and the like, the weight 50 may be lowered (dropped) in the vertical direction, or the weight 50 may be lowered in a direction inclined with respect to the vertical direction. The lowering part 23 and the raising part 21 may be provided individually or may be shared.

[0018] The frame 25a is a structure constituting the lifting part 20. The frame 25a supports the motor 25b. The frame 25a may support a pulley (not shown) around which the wire 25c is hung. In the example shown in FIG. 1, the frame 25a is arranged so as to connect the lower standby position 11 and the upper standby position 13. The frame 25a may guide the weight 50 or may guide the weight holding part 25d.

[0019] The motor 25b is an electric motor and a generator. When the raising part 21 and the lowering part 23 are provided individually, the motor 25b of the raising part 21 functions as an electric motor for raising the weight 50, and the motor 25b of the lowering part 23 functions as a generator for generating electricity by the lowering of the weight 50. When the raising part 21 and the lowering part 23 are shared, the motor 25b functions as both an electric motor and a generator (a generating electric motor). The motor 25b can be arranged at various positions depending on the installation location of the gravity energy storage system 1 and the like. In the example shown in FIG. 1, the motor 25b is arranged near the upper standby position 13 and is arranged at the upper part of the frame 25a. The motor 25b may be arranged near the lower standby position 11 or the like.

[0020] Wire 25c is connected to motor 25b. For example, wire 25c is connected to weight 50 via weight holding part 25d. The direction in which wire 25c extends may be changed by a pulley (not shown). In the example shown in FIG. 1, since gravity energy storage system 1 is configured to raise and lower weight 50 in the vertical direction, wire 25c is arranged to extend in the vertical direction. When gravity energy storage system 1 is configured to raise and lower weight 50 in a direction inclined with respect to the vertical direction, wire 25c is arranged to extend in a direction inclined with respect to the vertical direction.

[0021] Weight holding part 25d holds weight 50 with respect to wire 25c. Weight holding part 25d (and weight moving part 30 described later) is handling equipment for handling weight 50. Weight holding part 25d is attached to wire 25c. Weight holding part 25d is connected to motor 25b via wire 25c. For example, weight holding part 25d may hold weight 50 from below. Specifically, weight holding part 25d may include a basket (frame-shaped or container-shaped). Also, for example, weight holding part 25d may hold weight 50 from above. Specifically, weight holding part 25d may include a hook that is hung on suspension part 55d (described later) of weight 50, and may include a fastening device (such as a twist lock) for holding weight 50 from above.

[0022] Weight moving part 30 is a device (weight moving device, drive part) that changes the position of weight 50. Weight moving part 30 (and weight holding part 25d) is handling equipment for handling weight 50. Note that lifting part 20 is not included in weight moving part 30. Weight moving part 30 is provided at lower standby position 11 and upper standby position 13. For example, weight moving part 30 moves weight 50 from upper standby position 13 to lowering part 23. Weight moving part 30 moves weight​​​If the weights 50 do not form a weight row 40 (described later), the weight moving unit 30 may move the weight 50 selected by the control unit 70 as the weight 50 to be lowered from the upper standby position 13 to the lowering unit 23. If the weights 50 do not form a weight row 40, the weight moving unit 30 may move the weight 50 selected by the control unit 70 as the weight 50 to be raised from the lower standby position 11 to the uppering unit 21.

[0024] The weight moving unit 30 may move the weights 50 (move the entire weight row 40) without changing the order of the weights 50 within the weight row 40 (described later) if the weights 50 form a weight row 40. For example, the weight moving unit 30 may move a weight 50 that has been raised from the lower standby position 11 to the upper standby position 13 to a predetermined position (for example, the very back) in the weight row 40 at the upper standby position 13. Alternatively, the weight moving unit 30 may move a weight 50 that has been lowered from the upper standby position 13 to the lower standby position 11 to a predetermined position (for example, the very back) in the weight row 40 at the lower standby position 11. The weight moving unit 30 may also change the order of the weights 50 within the weight row 40 (see the order changing unit 31 described later). The weight moving unit 30 may also move a weight 50 to a weight row 40 different from the weight row 40 to which it belongs (for example, an adjacent weight row 40).

[0025] Specifically, the weight moving unit 30 may include a device that moves the weight 50 while supporting it from below. For example, the weight moving unit 30 may include a conveyor 30a. The conveyor 30a may be, for example, a roller conveyor or a belt conveyor. The weight moving unit 30 may include a trolley 30b. The weight moving unit 30 may be attached to the weight 50. For example, the weight moving unit 30 may include wheels 30c. The wheels 30c may be attached to the container 55 (see Figure 3) (for example, the bottom surface of the container 55), or to the weight 50 without a container 55 (for example, the bottom surface of the weight 50). The weight moving unit 30 may include a device that lifts and moves the weight 50 while supporting it from below. For example, the weight moving unit 30 may include a lifting device (for example, a forklift) not shown. The weight moving unit 30 may include a device that moves the weight 50 while supporting it from above. For example, the weight moving unit 30 may include a crane 30d for lifting and moving the weight 50. The weight moving unit 30 may also include a sequence changing unit 31.

[0026] The order changing unit 31 changes (rearranges) the order of the weights 50 within the weight row 40 when the weights 50 form a weight row 40 (see the description of the weight row 40 for details). For example, the order changing unit 31 may be equipped with a conveyor 30a, a trolley 30b, wheels 30c, or a crane 30d. The order changing unit 31 may change the order of the weights 50 after moving the weights 50 above the weight row 40 (for example, by lifting or hoisting them). As shown in Figure 2, the order changing unit 31 may change the order of the weights 50 after moving the weights 50 laterally from the weight row 40 (such as in a horizontal direction perpendicular to the direction in which the weight row 40 is arranged).

[0027] The weight row 40 is a row of multiple weights 50 (a row formed by arranging multiple weights 50). As shown in Figure 1, the weight row 40 may be located at the upper standby position 13 or at the lower standby position 11. In the example shown in Figure 1, the weight row 40 is a row of weights 50 arranged horizontally. The weight row 40 may also be a row of weights 50 arranged vertically (a stacked row), or a row of weights 50 arranged in a direction inclined with respect to the horizontal. The weight row 40 may be a row of weights 50 arranged in a straight line, a row of weights 50 arranged in a curve, or a row of weights 50 arranged in a meandering (back and forth) manner. As shown in Figure 2, multiple weight rows 40 are provided. By continuously (one after another, simultaneously) lowering multiple weights 50 from multiple weight rows 40, it becomes possible to obtain an appropriate (certain amount of) power generation (details will be described later).

[0028] Each of these weight rows 40 is provided for each lifting section 20. That is, one weight row 40 is provided for each lifting section 20. More specifically, one weight row 40 is provided for each lowering section 23, positioned at the upper standby position 13. As shown in Figure 1, one weight row 40 is provided for each raising section 21, positioned at the lower standby position 11.

[0029] The weight row 40 has a "front" to "back" order. When generating electricity with the gravity energy storage system 1, the weights closest to the descent section 23 (positions that are scheduled to be descended earlier) are designated as the "front" of the weight row 40. Conversely, the weights furthest from the descent section 23 (positions that are scheduled to be descended later) are designated as the "back" of the weight row 40. When storing energy with the gravity energy storage system 1, the weights closest to the ascent section 21 may be designated as the "front" of the weight row 40, and the weights furthest from the ascent section 21 may be designated as the "back" of the weight row 40. Here, the order changing unit 31 may change the order of the weights 50 within the weight row 40 from front to back. Specifically, the position of the weight 50 before the order change by the order changing unit 31 may be in front of the very back of the weight row 40, for example, it may be at the very front, or in a position between the very front and the very back (in the middle of the row). The position of the weight 50 after the order change by the order change unit 31 may be behind its position before the order change. For example, it may be at the very back of the weight row 40, or it may be at a position between the position before the move and the very back (in the middle of the row). The order change unit 31 may also change the order of the weights 50 within the weight row 40 from back to front. As shown in Figure 2, the weight row 40 comprises a waiting row 40a and a reserve row 40b.

[0030] The standby row 40a is a row of weights 50 that are lowered (activated) when the power generated by the gravity energy storage system 1 is above a predetermined value (under normal conditions).

[0031] The reserve column 40b is a weight column 40 for adjusting the power generated in the gravity energy storage system 1. The reserve column 40b is not normally operated (it is prepared), but is operated when it is necessary to temporarily increase the power generated. Specifically, the reserve column 40b is a weight column 40 that is lowered only when the power generated in the gravity energy storage system 1 is below a predetermined value. The number of standby columns 40a and reserve columns 40b can be set in various ways. For example, the majority of the weight columns 40 may be standby columns 40a and some may be reserve columns 40b. Specifically, for example, the ratio of the number of standby columns 40a to the number of reserve columns 40b may be 9:1 (the value of the ratio can be set in various ways).

[0032] As shown in Figure 1, the weight 50 is an object (heavy object) that stores potential energy in gravity energy storage in gravity energy storage system 1. The weight 50 is raised and lowered by the lifting unit 20. Multiple (many) weights 50 are provided. For example, if gravity energy storage system 1 is a warehouse type, more than 10,000 weights 50 (specifically about 12,600, etc.) are provided in the gravity energy storage system 1 as a whole (the number of weights 50 can be set in various ways). The weight 50 has a mass, size, and shape that can be handled by handling equipment for the weight 50 (for example, weight holding unit 25d, weight moving unit 30).

[0033] The mass of each of the weights 50 differs from that of the other weights 50. The difference in mass among the weights 50 may be, for example, 1 ton or more. As will be described later, the fluctuation in the generated power when the weights 50 are lowered is suppressed by the control unit 70, so the masses of the weights 50 may differ. Specifically, the mass of each weight 50 may be 20 tons, 25 tons, 30 tons, etc. (various masses can be set). For example, in the gravity energy storage system 1 as a whole, the mass of the weights 50 is approximately 25 tons × 12,600 = approximately 315,000 tons. Note that among the weights 50, there may be weights 50 with the same mass.

[0034] The size (dimensions) of the weight 50 may or may not be constant across multiple weights 50. There may be variations in the size of the multiple weights 50 (there may be variations in small and large sizes, and there may be multiple patterns).

[0035] The shape of the weight 50 is preferably constant (including approximately constant) for multiple weights 50, but does not have to be constant. There may be variations in the shape of the weight 50 (there may be weights 50 of various shapes). For example, the shape of the weight 50 may be cylindrical, polygonal prism (triangular prism, quadrilateral prism, etc.), or a shape close to these. In the example shown in Figure 3, the shape of the weight 50 is a quadrilateral prism, a rectangular parallelepiped, etc. The weight 50 may include a container 55, which will be described later. The weight 50 may not include a container 55, and may be a solid, integrally constructed object (for example, a concrete block, etc.).

[0036] The weight 50 may contain various materials. For example, the weight 50 may contain concrete or metal. The weight 50 may contain materials that were used for purposes other than the weight 50 (recycled materials). The weight 50 may contain waste 50a, which will be described later. The weight 50 may also contain materials that are used solely to constitute the weight 50 (materials that are not recycled materials).

[0037] This weight 50 comprises, for example, waste 50a, bulk density improving material 53 (see Figure 4), container 55, contents 57, and identifier 59.

[0038] Waste 50a may include general waste, industrial waste, or radioactive waste. Waste 50a may include materials generated from dismantled facilities (dismantling waste), for example, dismantling waste generated from nuclear facilities (such as nuclear power plants). Waste 50a may include materials generated from dismantled buildings (such as concrete), or equipment and piping used in dismantled facilities (such as metal). Waste 50a may also include clearance materials 51 generated from nuclear facilities. Clearance materials 51 include clearance materials 51a and clearance target materials 51b.

[0039] Clearance material 51a is waste 50a generated at a nuclear facility that has been confirmed to have radioactivity below a specified clearance level. Clearance material 51a is material that has undergone the clearance process described later (in its post-clearance state). Clearance material 51a can be reused or disposed of in the same way as general waste (unlike radioactive waste). The above "clearance level" (clearance standard) is a standard for radioactivity concentration and is set for each type of radioactive material (nuclide). For example, clearance levels are stipulated by law. Specifically, for example, the clearance level is the standard stipulated in Article 2 of the current "Rules concerning confirmation, etc., that the radioactivity concentration of radioactive materials contained in materials and other objects used in factories, etc., does not require measures to prevent damage from radiation (Nuclear Regulation Authority Rule No. 16 of 2020)".

[0040] Clearance items 51b are waste 50a generated at nuclear facilities that have not been confirmed to have radioactivity below the clearance level. Clearance items 51b are radioactive waste. Clearance items 51b include items for which the clearance process described later has not been completed (items before clearance). Clearance items 51b also include items whose radioactivity currently exceeds the clearance level, but which are expected to fall below the clearance level in the future. For example, clearance items 51b include items whose contamination is mainly due to radionuclides with relatively short half-lives, and which are expected to decay and decrease in radioactivity over a specified period, eventually falling below the clearance level.

[0041] (Regarding decommissioning waste from nuclear facilities) This section explains waste 50a generated when a nuclear facility (e.g., a nuclear power plant) is dismantled. When a nuclear facility is dismantled, waste 50a (dismantling waste) is generated. More than 90% of the dismantling waste is treated as non-radioactive waste 50a (NR). NR includes, for example, parts of the dismantling waste that were not in direct contact with the reactor cooling system, and parts that are considered to be free from the effects of radioactive activation. In addition, a few percent of the dismantling waste becomes clearance material 51b. More specifically, dismantling waste that does not fall under NR but has an extremely low level of radioactive contamination or activation, and whose impact on human health is negligible, and therefore does not need to be treated as radioactive material, is classified as clearance material 51b. For example, when one nuclear reactor is dismantled, the amount of clearance material 51b generated can amount to tens of thousands of tons.

[0042] (Regarding clearance processing) Once clearance treatment is performed on clearance material 51b and it is confirmed that its radioactivity is below the clearance level, this clearance material 51b can be treated as clearance material 51a. This clearance treatment takes time. Specifically, for clearance treatment, the properties of clearance material 51b, the level of contamination, and the pre-planned radioactivity measurement method must be described in the clearance approval application form, and this application form must be submitted to the Nuclear Regulation Authority and approved by the Nuclear Regulation Authority. After this approval (clearance approval) is obtained, radioactivity measurements of clearance material 51b must be carried out according to the prescribed procedures and methods, and the measurement results must be described in the clearance confirmation application form and submitted to the Nuclear Regulation Authority. Then, clearance material 51b whose radioactivity measurement results are confirmed to be below the clearance level can be treated as clearance material 51a. These processes take time.

[0043] In the following explanation, the material of the weight 50 is not limited to clearance material, etc. 51.

[0044] (Bulk density improvement material 53) The weight 50 preferably contains bulk density-enhancing material 53, as shown in Figure 4. The bulk density-enhancing material 53 is a material that has been modified to have an increased bulk density. The above "bulk density" refers to the mass per unit volume, including the gaps between the materials that make up the weight 50. When the weight 50 contains bulk density-enhancing material 53, even if the size of the weight 50 is the same, the mass of the weight 50 increases, improving the function of the weight 50 (improving the power generation). As a result, the weight 50 can easily secure a certain amount of mass above a predetermined value, which is necessary to obtain an appropriate amount of power generation. In particular, when the material of the weight 50 includes waste 50a, the bulk density tends to be lower (it tends to be hollow inside) compared to a weight 50 made of solid material (for example, a solid concrete block). For this reason, it is preferable that the waste 50a that makes up the weight 50 is bulk density-enhancing material 53. Furthermore, the bulk density-enhancing material 53 does not necessarily have to contain waste 50a.

[0045] The bulk density-enhancing material 53 may be contained in a container 55 (described later), or it may not be contained in a container 55 (the bulk density-enhancing material 53 may be used as a weight 50 as is). The bulk density-enhancing material 53 may be contained in a container 55 for transport or storage, etc. Furthermore, the bulk density-enhancing material 53 contained in a container 55 for transport or storage, etc. may be contained in a container 55 that is larger than the container 55 for transport or storage, etc.

[0046] The bulk density improving material 53 may include a material obtained by melting the material that will be used for the weight 50 and then solidifying the melted material (molten solidified material). The bulk density improving material 53 may also include a material obtained by crushing the material that will be used for the weight 50 and then solidifying the crushed material (crushed solidified material), or it may include a material obtained by crushing the material and then packing it into a container 55 without solidifying it. The bulk density improving material 53 may also include compressed material 53a.

[0047] The compressed material 53a is a material that has been compressed (volume reduced) from the material that will be used to make the weight 50. The compressed material 53a is obtained by compressing the material that will be used to make the weight 50, for example, using a compression device A11. Compression processing (processing) is a simpler process than crushing and melting, and can improve the bulk density of the weight 50. As a result, when the weight 50 contains the compressed material 53a, the manufacturing cost of the weight 50 can be reduced compared to when the weight 50 contains the bulk density-enhancing material 53 but does not contain the compressed material 53a.

[0048] The compressed material 53a is formed, for example, as follows: [Compression Example 1] The compressed material 53a may include a compression container 53a1, or it may not include a compression container 53a1. [Compression Example 1a] For example, the material to be used for the weight 50 (e.g., waste 50a) is placed in a compression container 53a1. The compressed material 53a may then be formed by compressing the compression container 53a1 and the material placed in the compression container 53a1 with the compression device A11. [Compression Example 1b] The material to be used for the weight 50 (e.g., waste 50a) may be compressed without being placed in a compression container 53a1 (as is) to form the compressed material 53a. [Compression Example 2] The material for the weight 50 (object to be compressed) before being compressed by the compression device A11 may be compressed in various directions. For example, the object to be compressed may be compressed in only one direction, or it may be compressed in multiple directions. [Compression Example 2a] For example, if the shape of the object to be compressed is cylindrical, the object may be compressed in one or both of the axial and radial directions. [Compression Example 2b] For example, if the object to be compressed is a rectangular parallelepiped, the object may be compressed in only one direction, in two directions, or in three directions.

[0049] The compression container 53a1 is a container that holds the object to be compressed (a container for compression and volume reduction). The compression container 53a1 is also the container 55 described later. The shape and material of the compression container 53a1 can be set in various ways. For example, the compression container 53a1 may be cylindrical, or it may be a can, specifically a drum. For example, the compression container 53a1 may be a rectangular parallelepiped (for example, a box).

[0050] Container 55 contains (arranges together) the materials (contents 57) that will be used to make the weights 50. Container 55 is configured to accommodate contents 57 of varying shapes and sizes. Container 55 has a size and shape that can be handled by the handling equipment (e.g., weight holder 25d, weight moving part 30) that handles the weights 50 shown in Figure 1. Preferably, the shape and size of the container 55 shown in Figure 3 are standardized (including nearly standardized) across multiple containers 55 (weights 50). In this case, the handling equipment can easily handle the container 55 (handling can be simplified). The specific structure of the container 55 can be set in various ways. In the example shown in Figure 3, the container 55 comprises a container body 55a, a lid 55b, a contents holder 55c, and a suspension part 55d. Container 55 may also be equipped with wheels 30c (see Figure 1, see the description of the weight moving part 30 above).

[0051] The container body 55a is the main body portion (lower container) of the container 55. The container body 55a holds the contents 57. For example, the container body 55a may be box-shaped with an opening, or cylindrical with a bottom and an opening.

[0052] The lid portion 55b is the lid (upper lid portion) of the container 55. The lid portion 55b closes the opening of the container body portion 55a. For example, the lid portion 55b seals the inside of the container 55. The lid portion 55b does not have to seal the inside of the container 55. There may be a gap between the container body portion 55a and the lid portion 55b.

[0053] The contents-holding section 55c prevents the contents 57 from moving relative to the container body 55a within the container body 55a. For example, the contents-holding section 55c may be equipped with one or more partition plates, or it may be equipped with fasteners to secure the contents 57.

[0054] The lifting portion 55d is for lifting the container 55 (lifting device, fitting). The lifting portion 55d is for attaching the lifting device (hook, rope, etc.) of a device for lifting the weight 50 (for example, a crane 30d (see Figure 1), a transport device A13 (see Figure 3), etc.). The lifting portion 55d may be provided on the container body portion 55a, and in the example shown in Figure 3, it is provided on the upper end of the container body portion 55a. The lifting portion 55d may also be provided on the lid portion 55b. The lifting portion 55d may be a lifting ring (annular member), a U-shaped member, etc. Note that if the container 55 is moved while supported from below, the container 55 does not need to be equipped with a lifting portion 55d.

[0055] The contents 57 are the objects contained in the container 55. The contents 57 may or may not contain waste 50a, for example. The contents 57 may contain bulk density improving material 53 (see Figure 4) or compressed material 53a (see Figure 4). The compressed material 53a of the contents 57 may or may not contain a compression container 53a1 (see Figure 4). The contents 57 may or may not contain concrete or metal. Concrete has a lower density than metal. Therefore, when trying to unify (match) the mass of multiple weights 50 as much as possible, the larger the container 55 needs to be, the more concrete the contents 57 contain compared to the metal contained in the contents 57. For example, if all or most of the contents 57 are concrete (or if the weights 50 are concrete blocks without a container 55), the larger the container 55 needs to be compared to the case where all or most of the contents 57 are metal. Note that it is not necessary to unify the mass of multiple weights 50.

[0056] If the contents 57 include clearance items 51b, the container 55 is configured to suppress the diffusion of radioactive material from within the container 55 and the effects of radiation on the surrounding area. In this case, the spread of contamination by radioactive material is suppressed, and the exposure of workers around the container 55 is suppressed. For example, the container 55 is sealed to suppress the diffusion of radioactive material from within the container 55. The material and thickness of the container 55 are also configured to suppress the effects of radiation on the surrounding area. The contents 57 may include a main contents 57a and a filler 57b.

[0057] The main containment 57a is the portion of the containment 57 other than the packing material 57b. For example, the main containment 57a includes waste 50a, etc.

[0058] The packing material 57b prevents the contents 57 (main contents 57a) from moving relative to the container body 55a within the container body 55a. The packing material 57b may be in powder form, granular form, or a solidified form of powder or granular material. The packing material 57b may be waste material 50a or a material other than waste material 50a (for example, cement). The contents 57 do not necessarily have to contain the packing material 57b. For example, if the main contents 57a is used as a weight 50 and then reused for a different purpose than the weight 50, the work and processing of removing the packing material 57b from the main contents 57a is time-consuming. Therefore, in cases where the main contents 57a is reused, it may be preferable not to use the packing material 57b.

[0059] The identifier 59 is for the purpose of individually identifying the weights 50. The identifier 59 is provided on the weights 50. The identifier 59 is, for example, an identification code or an identification tag. The identifier 59 may be something from which information can be read from visual information (images), and specifically may include one or more of the following: barcodes, two-dimensional barcodes, letters, symbols, and markers. The identifier 59 may be a nameplate engraved with a barcode, letters, etc. The identifier 59 may be something from which information can be read from radio waves, and specifically may be an RFID (Radio Frequency Identification) tag. The identifier 59 may be attached to the weights 50 or embedded in the weights 50.

[0060] As shown in Figure 1, the reading device 60 is a device that reads (scans) the information of the identifier 59. The reading device 60 may be a contact type that reads the information of the identifier 59 by making contact with the identifier 59, or a non-contact type that reads the information of the identifier 59 without making contact with the identifier 59.

[0061] The reading device 60 and identifier 59 are for individually identifying the weights 50. The reading device 60 and identifier 59 are used to determine the position of the weights 50. For example, if the weights 50 form a weight row 40, the reading device 60 and identifier 59 may be used to determine which weight row 40 and in what order each weight 50 is positioned. For example, the reading device 60 and identifier 59 may be used to obtain information on the power generated when the weights 50 are lowered.

[0062] The reader 60 may read the identifier 59 before the weight 50 is used for gravity energy storage in the gravity energy storage system 1 (as described later). The reader 60 reads the identifier 59 when the weight 50 is being used for gravity energy storage in the gravity energy storage system 1. For example, the reader 60 may be positioned at a location where the weight 50 passes, or it may be positioned near the location where the weight 50 passes. Specifically, for example, the reader 60 may be configured to automatically read the identifier 59 when the weight 50 passes near the reader 60.

[0063] The reading device 60 may be able to read the identifier 59 of the weight 50 located at the upper standby position 13, or it may be able to read the identifier 59 of the weight 50 located at the lower standby position 11. The reading device 60 may be able to read the identifier 59 of the weight 50 located at the lifting section 20, or it may be able to read the identifier 59 of the weight 50 located at the rising section 21, or it may be able to read the identifier 59 of the weight 50 located at the lowering section 23. When the weights 50 form a weight row 40, the reading device 60 may be able to read the identifier 59 of the weight 50 that is about to be lined up in the weight row 40, or it may be able to read the identifier 59 of the weights 50 that are lined up in the weight row 40.

[0064] It is preferable that the reading device 60 reads the identifier 59 of the weight 50 before the weight 50 descends in the descent section 23. In this case, the information of the weight 50 associated with the identifier 59 (described later) can be used to predict the output power assuming the weight 50 is lowered, and to adjust (rearrange) the order of the weights in the weight row 40.

[0065] When the weights 50 form a weight row 40, it is preferable for the reading device 60 to read the identifier 59 of the weight 50 at a position where the order of the weights 50 (the position of the weight 50 in the weight row 40) can be reliably determined. In this case, the information of the weight 50 associated with the identifier 59 can be used to adjust (rearrange) the descent order of the weights 50 in the weight row 40 (described later). Specifically, for example, it is conceivable that weights 50 may be added or removed at the lower waiting position 11. In this case, it is preferable for the reading device 60 to read the identifier 59 at a position other than the location where the weights 50 are added or removed (e.g., the lower waiting position 11) and before the weights 50 descend. In this case, it is preferable for the reading device 60 to read the identifier 59 of the weight 50 at a position other than the location where the weights 50 are added or removed (e.g., the lower waiting position 11) and before the weight 50 is lined up at the very back of the weight row 40 (e.g., when it is about to be lined up).

[0066] For example, in the example shown in Figure 1, the reading device 60 can read the identifier 59 of the weight 50 at the upper standby position 13 before the weight 50 is placed at the very back of the weight row 40. In this example, the reading device 60 can read the identifier 59 at a position closer to the lifting unit 21 than the position at the very back of the weight row 40 at the upper standby position 13, and at a position near the lifting unit 21. The reading device 60 may also be able to read the identifier 59 of the weight 50 that is being lifted by the lifting unit 21, or it may be able to read the identifier 59 of the weight 50 just before it is lifted by the lifting unit 21.

[0067] The control unit 70 is a computer that performs signal input / output, calculations (processing), and information storage. The functions of the control unit 70 are realized by the execution of a program stored in the control unit 70's memory unit by the calculation unit of the control unit 70. The control unit 70 may be connected to other devices by wireless communication or by wired communication. The control unit 70 may be distributed and arranged in multiple parts (it may constitute a distributed system). For example, information is input to the control unit 70 from the reading device 60. For example, the control unit 70 outputs a command (signal) to the weight moving unit 30 to operate the lifting unit 20 and the weight moving unit 30. Focusing on the functions of the control unit 70, the control unit 70 comprises an identification management unit 71 and a weight moving control unit 73.

[0068] The identification management unit 71 (identification management system) identifies (manages) multiple weights 50 individually (details will be described later).

[0069] The weight movement control unit 73 controls the movement of the weight 50. The weight movement control unit 73 controls the descent of the weight 50. The weight movement control unit 73 may also control the ascent of the weight 50. Specifically, the weight movement control unit 73 controls the operation of the lifting unit 20. The weight movement control unit 73 may also control the position of the weight 50. Specifically, the weight movement control unit 73 controls the operation of the weight movement unit 30. The weight movement control unit 73 determines how to operate the weight movement unit 30 and controls the movement of the weight 50 based on the determined information (details will be described later).

[0070] (Specific example of preparing weight 50) Referring mainly to Figure 3, an example of a method for preparing the weight 50 when waste material 50a is used as the weight 50 will be explained.

[0071] For example, the decommissioning of a nuclear facility (e.g., decommissioning a nuclear power plant) generates waste 50a. Clearance material 51b is extracted from the waste 50a. Clearance processing (measurement and evaluation of radioactivity) is performed on the clearance material 51b, and clearance material 51a is selected from the clearance material 51b. If a weight 50 containing clearance material 51b is used as the weight 50 of the gravity energy storage system 1 (see Figure 1), the identification management unit 71 acquires and stores the radioactivity data (described later) of the clearance material 51b.

[0072] As shown in Figure 4, the waste 50a is subjected to a process that increases its bulk density (e.g., compression), thereby becoming a bulk-density-enhanced material 53 (e.g., compressed material 53a). Specifically, for example, the waste 50a is placed in a compression container 53a1. Then, the compression device A11 compresses the waste 50a and the compression container 53a1.

[0073] As shown in Figure 3, waste 50a and the like are contained in the container 55 as contents 57. Specifically, for example, the contents 57 are contained in the container body 55a. Then, the lid 55b is attached to the container body 55a, closing the opening of the container body 55a. For example, the inside of the container 55 is sealed.

[0074] The container 55 and its contents 57 (weight 50) are moved by a transport device A13 (e.g., a crane). For example, the container 55 and its contents 57 are placed on a loading station A17. The loading station A17 is, for example, located within the site where the gravity energy storage system 1 (see Figure 1) is installed (within the gravity energy storage plant). Subsequently, the container 55 and its contents 57 are used as weight 50.

[0075] (Identification management) The reading device 60 reads the identifier 59 of each weight 50 (specifically, the weight 50 before it is used for gravity energy storage). The identification management unit 71 stores (manages) the information of the identifier 59 read by the reading device 60 and the information of the weight 50 for each weight 50, associating them together. Details of the information of the weight 50 managed by the identification management unit 71 are as follows, for example.

[0076] The information about weight 50 includes information about the mass of weight 50. The mass of weight 50 is measured by mass measuring device A15. Mass measuring device A15 may be provided, for example, on the transport device A13, or it may be provided separately from the transport device A13.

[0077] The information about the weight 50 may include information about the energy generated when the weight 50 is lowered. The information about the weight 50 may also include information about the power generated when the weight 50 is lowered, and may also include information about fluctuations (time-dependent changes) in the power generated (see Figure 5).

[0078] If the weight 50 contains clearance items 51 (either or both of clearance items 51a and / or clearance target items 51b), the information of the weight 50 may include information that ensures the traceability of the clearance items 51. For example, the information of the weight 50 may include information about the source of the clearance items 51. Specifically, the information about the source of the clearance items 51 may include information about the nuclear facility (e.g., name), information about the unit (equipment, facility, etc.) (e.g., name), or information about the location (part) where it was generated. For example, if the clearance items 51 are contained in a container 55, the information of the weight 50 may include information about when the clearance items 51 were contained in the container 55 (e.g., date and time).

[0079] If the weight 50 includes clearance items 51, the information of the weight 50 may include information indicating the status of the clearance items 51. The information indicating the status of the clearance items 51 may include, for example, one or more of the following: whether it is awaiting radioactive decay, awaiting clearance processing (verification), and whether clearance has been confirmed (whether it is clearance item 51a).

[0080] If the weight 50 includes clearance items 51a, the information on the weight 50 may include information (e.g., a number) on the confirmation certificate issued at the time of clearance processing (inspection).

[0081] If the weight 50 contains the object to be cleared 51b, the information on the weight 50 may include radioactivity data. The radioactivity data may include, for example, information on the radioactivity concentration of each nuclide measured and evaluated for the object to be cleared 51b. The radioactivity data may also include information on the estimated storage period required before falling below the clearance level. In this case, the radioactivity decay status of the object to be cleared 51b can be managed. In this case, the timing of releasing the weight 50 containing the object to be cleared 51b for clearance processing (measurement and evaluation of radioactivity concentration) (stopping its use as the weight 50 of the gravity energy storage system 1 (see Figure 1)) can be determined (predicted).

[0082] Furthermore, the information about the weight 50 may include various other types of information besides those mentioned above. For example, the information about the weight 50 may include information about the shape of the weight 50, information about the dimensions of the weight 50, and information about the material of the material from which the weight 50 is made (concrete, metal, etc.).

[0083] (Example of operation of gravity energy storage system 1) The gravity energy storage system 1 shown in Figure 1 is configured to operate, for example, as follows. Here, we will describe the case where the weights 50 form a weight row 40.

[0084] The gravity energy storage system 1 uses surplus power during periods of relatively low power demand (such as at night) to increase the potential energy of the weights 50. Specifically, the weights 50 are raised from the lower standby position 11 to the upper standby position 13. More specifically, the weights 50 placed in the lower standby position 11 are moved by the weight moving unit 30 to the lifting unit 21, sequentially from the front of the weight row 40 (basically from the front). The weights 50 that have moved to the lifting unit 21 are held by the weight holding unit 25d of the lifting unit 21 and raised by the motor 25b. The weights 50 that have been raised to the lifting unit 21 are released from the weight holding unit 25d of the lifting unit 21 and moved by the weight moving unit 30 to the upper standby position 13, forming the weight row 40. These weights 50 are placed at the very back of the weight row 40. The reading device 60 reads the identifier 59 of the weights 50. For example, the reading device 60 reads the identifier 59 of the weight 50 that has been raised by the lifting unit 21 and is about to be placed in the weight row 40.

[0085] The gravity energy storage system 1 generates electricity when electricity demand is relatively high (for example, during peak daytime electricity demand). Specifically, the weight 50 is lowered from the upper standby position 13 to the lower standby position 11. More specifically, the weight 50, which is positioned at the upper standby position 13, is moved by the weight moving unit 30 to the position of the lowering unit 23, starting from the front of the weight row 40 (basically from the front). The weight 50 that has moved to the position of the lowering unit 23 is held by the weight holding unit 25d of the lowering unit 23 and lowered. At this time, the motor 25b of the lowering unit 23 is rotated, causing the motor 25b to generate electricity.

[0086] (Characteristics of fluctuations in generated power) Figure 5 shows a schematic graph of the change in the descent speed of the weight 50 from the start of its descent to its stop, and a graph of the change in the generated power over time (fluctuation characteristics). The change in the generated power over time from the start of the descent of the weight 50 to its stop, as shown in Figure 1, is predetermined mainly by the mass of the weight 50 and the specifications of the descent unit 23 (such as the specifications of the motor 25b). The generated power depends on the rotational speed of the motor 25b and on the descent speed of the weight 50. The descent speed of the weight 50 depends on the mass of the weight 50. The descent speed of the weight 50 increases from an initial velocity of 0 until it reaches a constant speed where the tension (resistance) of the wire 25c and the gravity of the weight 50 are balanced (see Figure 5). The generated power gradually increases from the start of the descent of the weight 50, and when the descent speed of the weight 50 becomes constant, the generated power also becomes constant (see Figure 5). If the weight 50 were to reach the bottom of the descent section 23 (e.g., the floor) while maintaining the constant speed described above, one or both of the weight 50 and the descent section 23 would be damaged. Therefore, as the weight 50 approaches the height of the lower standby position 11 (e.g., the floor), a brake is applied to the descent of the weight 50, and the speed of the weight 50 is gradually reduced (see Figure 5). At the beginning of the braking process, the generated power is greater than the power generated when the weight 50 descends at the "constant speed" described above (see Figure 5). Then, as the weight 50 approaches the bottom of the descent section 23 (as the speed of the weight 50 approaches 0), the generated power gradually decreases (see Figure 5). Thus, the change in generated power over time (variability characteristics) when the weight 50 is descended is predetermined by the mass of the weight 50, etc.

[0087] (Simultaneous descent of multiple weights 50) For the gravity energy storage system 1 to generate power continuously, it is necessary to continuously (one after the other) lower the multiple weights 50 shown in Figure 2. In order to suppress fluctuations in the total power generated by the multiple descending weights 50 (also called total power generated), (to make it as uniform as possible), the next weight 50 must start descending at the latest when the previous weight 50 begins to decelerate. For this reason, multiple weights 50 must be descending simultaneously. For example, if only one weight 50 descends in one descent section 23, then multiple weights 50 must be descending in multiple descent sections 23 simultaneously. Also, for example, if the gravity energy storage system 1 is of the gondola type, multiple weights 50 may descend simultaneously in one descent section 23. Note that while multiple weights 50 must be descending simultaneously, the start of the descent of multiple weights 50 does not need to be simultaneous. However, the start of the descent of multiple weights 50 may be simultaneous.

[0088] As shown in the example in Figure 5, the increase in power generation during the descent of the weight 50 (shape of the graph) and the decrease in power generation during the deceleration of the weight 50 (shape of the graph) do not necessarily cancel each other out. Therefore, ideally, it is desirable to suppress fluctuations in total power generation by starting the descent of the weight 50, as shown in Figure 2, one after another at short intervals (time intervals).

[0089] If all the weights 50 have equal mass, the output fluctuation of the total generated power can be suppressed by keeping the interval between the start of the descent of the weights 50 constant (keeping the number of weights 50 descending simultaneously constant). On the other hand, in this embodiment, the masses of the weights 50 differ from one another (there is variation). Therefore, if the interval between the start of the descent of the weights 50 is kept constant, the total generated power will fluctuate (change over time). Specifically, when a light weight 50 is descended, the total generated power decreases, and when a heavy weight 50 is descended, the total generated power increases.

[0090] (Power fluctuation suppression control) Therefore, the control unit 70 (more specifically, the weight movement control unit 73) shown in Figure 1 determines the conditions for the descent of the weights 50 (also called descent conditions) (for example, timing) in such a way as to suppress fluctuations in the power generated (total power generated) when multiple weights 50 are lowered simultaneously. Specifically, the control unit 70 performs the following processing. The control unit 70 will be described below with reference to Figure 1.

[0091] The control unit 70 acquires information (fluctuation characteristics) (see Figure 5) on the predicted fluctuations in generated power that will occur when each weight 50 (specifically, one weight 50) is lowered. The control unit 70 may calculate (predict) the information on the fluctuation characteristics of generated power, or it may acquire it from outside the control unit 70. The calculation of information by the control unit 70 is included in the "acquisition" of information by the control unit 70.

[0092] The control unit 70 determines (in detail, searches, modifies (adjusts), and determines) the conditions for lowering the weights 50 in a manner that suppresses fluctuations in the total generated power. The conditions for lowering determined by the control unit 70 may include the number of weights 50 to be lowered simultaneously (also called the number of weights lowered). The conditions for lowering determined by the control unit 70 may also include the interval between the start of lowering of multiple weights 50 (also called the lowering interval). The conditions for lowering determined by the control unit 70 may also include the order in which the weights 50 are lowered (also called the lowering order). For example, if the weights 50 form a weight row 40, the conditions for lowering determined by the control unit 70 may include the order of the weights 50 in the weight row 40.

[0093] When the control unit 70 increases the output power, it may increase the number of weights being lowered, shorten the lowering interval (which may result in an increase in the number of weights being lowered), or select a weight with a larger mass 50 to be lowered. For example, if the weights 50 form a weight row 40, the control unit 70 may, in order to increase the output power, place the weights 50 with a smaller mass further back in the weight row 40 than the frontmost weight, or place the weights 50 with a larger mass at the front of the weight row 40. When the control unit 70 decreases the output power, it may reduce the number of weights being lowered, lengthen the lowering interval (which may result in a decrease in the number of weights being lowered), or select a weight with a smaller mass 50 to be lowered. For example, if the weights 50 form a weight row 40, the control unit 70 may, in order to decrease the output power, place the weights 50 with a larger mass further back in the weight row 40 than the frontmost weight, or place the weights 50 with a smaller mass at the front of the weight row 40.

[0094] The control unit 70 controls the lowering unit 23 to lower the weight 50 according to the determined lowering conditions. Specifically, the control unit 70 controls the lowering unit 23 to lower the weight 50 based on the determined number of lowering units and lowering interval. The control unit 70 may also control the weight moving unit 30 to lower the weight 50 in the determined lowering order.

[0095] (Further specific examples of power fluctuation suppression control) A specific example of the power fluctuation suppression control process by the control unit 70 will be explained with reference to the flowchart shown in Figure 6. Unless otherwise specified, the process will be explained in order. Note that the order of the process can be changed in various ways. Also, as mentioned above, the control unit 70 will be explained with reference to Figure 1, and each step (S11 to S25) shown in Figure 6 will be explained with reference to Figure 6.

[0096] In step S11, the control unit 70 obtains the initial value of the number of descending units, the initial value of the descent interval, and the current descent order. The initial value of the number of descending units and the initial value of the descent interval are set in the control unit 70 in advance (before the prediction of total power generation).

[0097] In step S12, the control unit 70 predicts the total power generation. Specifically, the control unit 70 predicts (calculates) the change in total power generation over time, assuming that the weights 50 are lowered in the current descent order with initial values ​​for the number of weights and the descent interval.

[0098] In steps S21 to S25, the control unit 70 adjusts the number of descending elements, the descent interval, and the descent order so that the fluctuation amount of the total generated power is within an acceptable range. In this example, the control unit 70 searches for conditions for the number of descending elements and the descent interval that keep the fluctuation amount of the total generated power within an acceptable range by adjusting one or both of the number of descending elements and the descent interval.

[0099] For example, if the predicted value of the fluctuation in total power generation exceeds the acceptable range (total power generation becomes too large), the control unit 70 may reduce the number of descents from the "initial value of the number of descents" until the predicted value of the fluctuation in total power generation falls within the acceptable range (further specific examples will be described later). Also, for example, if the predicted value of the fluctuation in total power generation exceeds the acceptable range, the control unit 70 may lengthen the descent interval from the "initial value of the descent interval" until the predicted value of the fluctuation in total power generation falls within the acceptable range (further specific examples will be described later).

[0100] For example, if the predicted value of the fluctuation in total generated power falls below the acceptable range (total generated power becomes too small), the control unit 70 may increase the number of descents from the "initial value of the number of descents" until the predicted value of the fluctuation in total generated power falls within the acceptable range (further specific examples will be described later). Also, for example, if the predicted value of the fluctuation in total generated power falls below the acceptable range, the control unit 70 may shorten the descent interval from the "initial value of the descent interval" until the predicted value of the fluctuation in total generated power falls within the acceptable range (further specific examples will be described later).

[0101] Then, if the control unit 70 adjusts (changes) the number of descending units and the descent interval, but the amount of fluctuation in the total generated power does not fall within an acceptable range (if YES is found in step S22), it adjusts the descent order (step S25). Further specific examples of these processes will be explained below.

[0102] In step S21, the control unit 70 determines whether the predicted value of the fluctuation amount of total power generation is within an acceptable range. More specifically, the control unit 70 determines whether the fluctuation amount of total power generation within a predetermined period (e.g., several tens of seconds) is within an acceptable range. The above "predetermined period" and "acceptable range" are set in advance in the control unit 70 (before the determination in step S21). If the predicted fluctuation amount of total power generation is not within an acceptable range (if NO in step S21), the control unit 70 performs the process in step S22. If the predicted fluctuation amount of total power generation is within an acceptable range (if YES in step S21), the current descent conditions are determined as the conditions for actually lowering the weight 50 (step S21y). The control unit 70 controls the descent unit 23 to lower the weight 50 according to the determined descent conditions. After that, the control unit 70 finishes the current series of processes (proceeds to "end") and starts the next series of processes (returns to "start").

[0103] In step S22, the control unit 70 determines whether the fluctuation in total generated power cannot be kept within an acceptable range by adjusting only the number of descending particles and the descent interval. Specifically, the control unit 70 determines whether the adjusted number of descending particles and the descent interval (described later in step S23) have reached the limit of the adjustable range (there is no more room for adjustment). The limit is set in advance in the control unit 70. If the number of descending particles and the descent interval have reached the limit (if YES in step S22), the fluctuation in total generated power cannot be kept within an acceptable range by adjusting only the number of descending particles and the descent interval. In this case, the control unit 70 performs the process in step S25. If the number of descending particles and the descent interval have not reached the limit (if there is room for adjustment of the number of descending particles and the descent interval, if NO in step S22), the control unit 70 performs the process in step S23.

[0104] In step S23, the control unit 70 adjusts either the number of descents or the descent interval, or both. For example, if the predicted value of the fluctuation amount of total generated power exceeds the allowable range (total generated power becomes too large), the control unit 70 may decrease the number of descents by one, or lengthen the descent interval by a predetermined interval. The above "predetermined interval" is set in advance by the control unit 70 (before adjusting the descent interval). Also, for example, if the predicted value of the fluctuation amount of total generated power falls below the allowable range (total generated power becomes too small), the control unit 70 may increase the number of descents by one, or shorten the descent interval by a predetermined interval. After step S23, the control unit 70 performs the processing in step S25.

[0105] In step S24, the control unit 70 adjusts the number of weights to be lowered if it determines that it is impossible to keep the fluctuation of the total generated power within an acceptable range by adjusting only the number of weights to be lowered and the interval between weights to be lowered (if the result in step S22 is YES). For example, if it is assumed that the weights 50 are lowered in the current order, and multiple weights 50 of small (or large) mass are lowered simultaneously (concentrated) in the multiple lowering units 23 shown in Figure 2, then the result in step S22 is YES. In this case, the control unit 70 determines the order in which the weights will be lowered so that the fluctuation of the total generated power is within an acceptable range. The control unit 70 then controls the weight moving unit 30 so that the weights 50 are lowered in the determined order. For example, if the weights 50 form a weight row 40, the control unit 70 changes (rearranges) the order of the weights 50 in the weight row 40.

[0106] Specifically, the control unit 70 determines which weight 50 is located in which position (for example, in which order of which weight row 40) based on the information of the identifier 59 (see Figure 1). The control unit 70 also obtains information about the weight 50 associated with the identifier 59 (for example, information such as mass and generated power). Based on the position of the weight 50 and information such as the mass of the weight 50, the control unit 70 determines the order in which the weights 50 are lowered so that the fluctuation in total generated power remains within an acceptable range. Specifically, for example, if the heaviest weights 50 are concentrated at the front of multiple weight rows 40, the control unit 70 may move one or more of the heaviest weights 50 to a position behind the front of the weight row 40 (for example, to the very back). If the lightest weights 50 are concentrated at the front of multiple weight rows 40, the control unit 70 may move one or more of the lightest weights 50 to a position behind the front of the weight row 40 (for example, to the very back). Even if the weights 50 do not form a weight row 40, the control unit 70 adjusts the descent order of the weights 50 so that the fluctuation amount of the total generated power is within an acceptable range.

[0107] In step S25, the control unit 70 predicts the total power generation. Specifically, the control unit 70 predicts (calculates) the change in total power generation over time, assuming that the weight 50 is lowered under the lowering conditions after adjustment (steps S23, S24). Then, the control unit 70 determines whether the predicted fluctuation in total power generation is within an acceptable range (returning to step S21).

[0108] (Addition and replacement of weight 50 containing waste 50a) As shown in Figure 3, the weight 50 may contain waste 50a. In order to operate the gravity energy storage system 1 (see Figure 1), a large amount of weight 50 is required. Therefore, the amount of waste 50a may be insufficient during the initial operation of the gravity energy storage system 1. In this case, during the initial operation of the gravity energy storage system 1, weight 50 that does not contain waste 50a (for example, concrete blocks) may be used, and weight 50 containing waste 50a may be added as waste 50a is generated. Alternatively, as waste 50a is generated, weight 50 that does not contain waste 50a may be replaced with weight 50 that contains waste 50a.

[0109] (Challenges and effects of clearance object 51a) Currently, the reuse of clearance items 51a (through clearance systems, etc.) is not yet well-established in society. Therefore, until clearance systems and similar measures are fully established in society, the reuse of clearance items 51a may be limited to within the power industry or for exhibitions aimed at promoting understanding. If the operator of gravity energy storage system 1 (gravity energy storage plant) is a power generation company (a company within the power industry), it is easier to reuse clearance items 51a (suitable for limited reuse within the power industry) regardless of whether clearance systems are fully established in society.

[0110] As the decommissioning of nuclear power plants increases, a large amount of clearance material 51a is generated. Consideration is being given to reusing this large amount of clearance material 51a in the form of radioactive waste disposal containers and building materials. However, the demand for disposal containers and building materials may be insufficient compared to the large amount of clearance material 51a generated. For example, a 25MW (100MWh in 4 hours) gravity energy storage system 1 (see Figure 1) requires approximately 315,000 tons of ballast 50. Therefore, by utilizing clearance material 51a as ballast 50 in gravity energy storage system 1, a reliable reuse destination for clearance material 51a can be secured.

[0111] When reusing clearance materials 51a, special management may be required to ensure traceability. However, if clearance materials 51a are used as weights 50, a large quantity of clearance materials 51a can be consolidated into a single gravity energy storage system 1 (see Figure 1) (energy storage station). Therefore, traceable management of clearance materials 51a becomes easier.

[0112] A storage location is needed for the clearance material 51a while awaiting the decision on its reuse destination and its transportation to the reuse destination. However, if the clearance material 51a is used as the counterweight 50 of the gravity energy storage system 1, the gravity energy storage system 1 (power plant) can function as a storage location for the clearance material 51a. Therefore, the storage location for the clearance material 51a that was previously required becomes unnecessary.

[0113] (Challenges and effects of clearance target object 51b) Under the clearance system, the clearance process (procedures such as approval applications, and measurement and evaluation of radioactivity) takes time. Furthermore, clearance items 51b, before being approved as clearance items 51a, must be handled as radioactive materials. Additionally, clearance items 51b require storage space. For example, a large storage area is needed for clearance items 51b for extended periods, such as while waiting for approval procedures during clearance and while waiting for radioactivity decay. However, if clearance items 51b are used as weights 50, the gravity energy storage system 1 can function as a storage location for clearance items 51b. Therefore, the previously required storage space for clearance items 51b becomes unnecessary.

[0114] (Calculation of radioactive decay) If the weight 50 includes the object to be cleared 51b, it is preferable for the control unit 70 (specifically, the identification management unit 71) to manage the radioactivity decay status of the object to be cleared 51b. Specifically, it is preferable for the control unit 70 to manage information indicating the radioactivity decay status of the object to be cleared 51b over time for each weight 50 that includes the object to be cleared 51b. For example, the control unit 70 calculates (predicts) the radioactivity decay status over time for each weight 50 from the radioactivity data of the object to be cleared 51b. For example, the control unit 70 may manage the remaining time until the radioactivity concentration of the object to be cleared 51b falls below the clearance level for each weight 50. The control unit 70 may also manage the relationship between radioactivity concentration and time for each weight 50. The control unit 70 may also manage the radioactivity concentration for each nuclide.

[0115] The control unit 70 manages the radioactivity decay status of the clearance object 51b, allowing the weight 50 containing the clearance object 51b to be released (removed and moved) from the gravity energy storage system 1 at an appropriate time for radioactivity measurement and evaluation. Specifically, the clearance object 51b can be released at the time when it is estimated that the radioactivity has decayed to below the clearance level (i.e., it is in a clearanceable state). For example, the control unit 70 distinguishes and manages weights 50 that are estimated to be in a clearanceable state and weights 50 that are estimated not to be in a clearanceable state. For example, when the radioactivity decays to below the clearance level, the control unit 70 may change the information indicating the status of the weight 50 from "waiting for radioactivity decay" to "waiting for clearance verification."

[0116] (effect) The effects of the gravity energy storage system 1 shown in Figure 1 are as follows:

[0117] (Effects of the first invention) [Configuration 1] The gravity energy storage system 1 comprises a plurality of weights 50 with different masses and a control unit 70. The weights 50 are used for gravity energy storage. The control unit 70 controls the movement of the weights 50, including their descent. The gravity energy storage system 1 comprises the following [Configuration 1-1].

[0118] [Configuration 1-1] The control unit 70 individually identifies the multiple weights 50. The control unit 70 acquires information on the predicted fluctuations in power generation that will occur when the weights 50 are lowered, for each weight 50. The control unit 70 determines one or both of the following conditions (lowering conditions): the number of weights 50 to be lowered simultaneously (number of weights to be lowered), and the interval between the start of lowering of the multiple weights 50 (lowering interval). The control unit 70 controls the lowering of the weights 50 so as to lower them based on the determined conditions (lowering conditions).

[0119] The above [Configuration 1-1] provides the following effect. In the gravity energy storage system 1, the masses of the multiple weights 50 are different from each other. Therefore, for example, if the number of weights 50 that are lowered simultaneously is kept constant, and the interval between the start of descent of the multiple weights 50 is kept constant, the power generated by the multiple weights 50 in the gravity energy storage system 1 (total power generated) will fluctuate greatly (become unstable). Therefore, the gravity energy storage system 1 is equipped with the above [Configuration 1-1]. Thus, one or both of the conditions (descent conditions) of the number of weights 50 that are lowered simultaneously (number of weights lowered) and the interval between the start of descent of the multiple weights 50 (descent interval) become conditions that suppress fluctuations in the total power generated. Therefore, the gravity energy storage system 1 can stabilize the power generated by the multiple weights 50 (total power generated) even when the masses of the multiple weights 50 are different from each other.

[0120] (Effects of the second invention) [Configuration 2] The gravity energy storage system 1 of [Configuration 1] described above comprises the following [Configuration 2-1].

[0121] [Configuration 2-1] The control unit 70 determines the order in which the weights 50 are lowered (lowering order) in such an order that it suppresses fluctuations in the power generated (total power generated) when multiple weights 50 are lowered simultaneously. The control unit 70 changes the position of the weights 50 so that they are lowered in the determined order.

[0122] As described in [Configuration 2-1] above, the order in which the weights 50 descend (descension order) is such that fluctuations in the total generated power are suppressed. Therefore, the gravity energy storage system 1 can stabilize the generated power (total generated power) produced by the multiple weights 50, even when the masses of the multiple weights 50 are different from each other.

[0123] (Effects of the third invention) [Configuration 3] The gravity energy storage system 1 of [Configuration 1] described above comprises the following [Configuration 3-1].

[0124] [Configuration 3-1] As shown in Figure 3, the weight 50 includes either or both of the clearance material 51a and the material to be cleared 51b. The clearance material 51a is waste 50a generated at a nuclear facility that has been confirmed to have radioactivity below a predetermined clearance level. The material to be cleared 51b is waste 50a generated at a nuclear facility that has not been confirmed to have radioactivity below a clearance level.

[0125] As described in [Configuration 3-1] above, one or both of the clearance materials 51a and clearance target materials 51b generated at the nuclear facility can be utilized (reused) as weights 50.

[0126] (Effects of the fourth invention) [Configuration 4] The gravity energy storage system 1 described in [Configuration 3] above comprises the following [Configuration 4-1].

[0127] [Configuration 4-1] The weight 50 includes the object to be cleared 51b.

[0128] The above [Configuration 4-1] provides the following benefits: The clearance process performed on the object to be cleared 51b (details above) takes time. Therefore, a storage location for the object to be cleared 51b may be required during the clearance process. Also, if the radioactivity of the object to be cleared 51b exceeds the clearance level, a storage location for the object to be cleared 51b may be required while waiting for the radioactivity to decay. On the other hand, in the above [Configuration 4-1], the gravity energy storage system 1 (see Figure 1) can function as a storage location for the object to be cleared 51b. Therefore, there is no need to secure a separate storage location for the object to be cleared 51b from the gravity energy storage system 1.

[0129] (Effects of the fifth invention) [Configuration 5] The gravity energy storage system 1 described in [Configuration 4] above comprises the following [Configuration 5-1].

[0130] [Configuration 5-1] The control unit 70 manages information indicating the rate of radioactivity decay of the clearance target object 51b over time for each weight 50 that includes the clearance target object 51b.

[0131] The above configuration [5-1] allows for control over the timing of radioactivity measurement and evaluation during clearance processing. For example, the weight 50 containing the clearance object 51b can be removed (taken out and moved) from the gravity energy storage system 1 at an appropriate time for radioactivity measurement and evaluation.

[0132] (Effects of the sixth invention) [Configuration 6] Any one of the above configurations [Configuration 1] to [Configuration 5] gravity energy storage system 1 comprises the following configuration 6-1.

[0133] [Configuration 6-1] The weight 50 comprises a container 55 and contents 57 contained in the container 55.

[0134] As described in [Configuration 6-1] above, objects of various shapes (contents 57) can be placed in the container 55 and used as weights 50. For example, if the container 55 is of a specific size and shape, handling of the weights 50 by equipment (handling equipment) becomes easier.

[0135] (Effects of the seventh invention) [Configuration 7] Any one of the above [Configuration 1] to [Configuration 6] gravity energy storage system 1 comprises the following [Configuration 7-1].

[0136] [Configuration 7-1] As shown in Figure 4, the weight 50 includes a material for the weight 50 that has an improved bulk density (bulk density improved material 53).

[0137] As described in [Configuration 7-1] above, even if the space for placing the weight 50 is the same, the mass of the weight 50 can be increased, and the power generated can be increased.

[0138] (Effects of the 8th Invention) [Configuration 8] The gravity energy storage system 1 described in [Configuration 7] above comprises the following [Configuration 8-1].

[0139] [Configuration 8-1] The weight 50 includes a material that has been compressed to improve its bulk density (compressed material 53a).

[0140] As described in [Configuration 8-1] above, the bulk density of the material used for the weight 50 can be increased with a simpler process compared to methods other than compression (e.g., melting and solidification, crushing, etc.). As a result, the cost of manufacturing the weight 50 can be reduced.

[0141] (modified version) The above embodiments (including variations within the embodiments (hereinafter the same)) may be modified in various ways. For example, the number of components in the above embodiments may be changed, and some components may not be provided. For example, the arrangement of components may be changed. For example, the fixing or connection of components may be direct or indirect. For example, the inclusion relationships of components may be changed in various ways. For example, a component described as a subordinate component included in a higher-level component may not be included in this higher-level component, but may be included in other components. For example, what was described as multiple distinct elements may be treated as a single element. For example, what was described as a single element may be divided into multiple distinct elements. For example, each component may have only a part of each characteristic (function, arrangement, shape, operation, etc.).

[0142] For example, the order of the steps in the flowchart shown in Figure 6 may be changed, and some steps may be omitted. For example, various types of information (values, ranges, etc.) may be pre-set in the control unit 70, or they may be set by being read into the control unit 70 from an external storage device. For example, the control unit 70 may perform substantially the same processing as the processing (calculation, determination, etc.) of the above embodiment. For example, the processing procedure and the information used in the processing can be changed in various ways. Specifically, the control unit 70 may perform processing using information that can be converted into the various types of information used in the above embodiment. The processing performed by the control unit 70 may be combined in various ways.

[0143] The gravity energy storage system 1 is configured to perform each of the operations described above. A gravity energy storage program may be set to cause the control unit 70 (computer) to execute the processes that cause each of the operations described above. A gravity energy storage method may be performed to carry out each of the operations described above. Each of the operations described above may be referred to as a "step" in the program and method described above. For example, the adjustment of the number of descending units by the control unit 70 (step S23 in Figure 6) may be referred to as the "number of descending units adjustment step". [Explanation of Symbols]

[0144] 1. Gravity Energy Storage System 50 weights 70 Control Unit 51a Clearance items 51b Clearance items 55 Container 57 Containment 53. Materials with improved bulk density (materials in a state where bulk density has been increased) 53a Compressed material (a material whose bulk density has been increased by compression)

Claims

1. Used for gravitational energy storage, it consists of multiple weights with different masses, A control unit that controls the movement including the descent of the weight, Equipped with, The control unit, Multiple weights are identified individually, Information on the predicted fluctuations in power generation that occur when the aforementioned weight is lowered is acquired for each of the aforementioned weights. Determine one or both of the following conditions to suppress fluctuations in power generation that occur when multiple weights are lowered simultaneously: the number of weights to be lowered simultaneously, and the interval between the start of descent of the multiple weights. The descent of the weight is controlled so as to lower the weight based on the determined conditions. Gravity energy storage system.

2. A gravity energy storage system according to claim 1, The control unit, The order in which the weights are lowered is determined in such a way that fluctuations in the generated power that occur when multiple weights are lowered simultaneously are suppressed. The position of the weights is changed so that the weights are lowered in the determined order. Gravity energy storage system.

3. A gravity energy storage system according to claim 1, The aforementioned weight includes either or both of the clearance object and the object to be cleared. The aforementioned clearance material is waste generated at a nuclear facility, which has been confirmed to have radioactivity below a predetermined clearance level. The aforementioned clearance targets are waste generated at nuclear facilities that have not been confirmed to have radioactivity below the aforementioned clearance level. Gravity energy storage system.

4. A gravity energy storage system according to claim 3, The aforementioned weight includes the object to be cleared, Gravity energy storage system.

5. A gravity energy storage system according to claim 4, The control unit, Information indicating the rate of radioactivity decay over time for the object to be cleared is managed for each weight that includes the object to be cleared. Gravity energy storage system.

6. A gravity energy storage system according to claim 1, The aforementioned weight is Container and The contents contained in the aforementioned container, Equipped with, Gravity energy storage system.

7. A gravity energy storage system according to claim 1, The aforementioned weight includes a material for the weight that has been modified to have improved bulk density. Gravity energy storage system.

8. A gravity energy storage system according to claim 7, The aforementioned weight includes a material that has been compressed to improve its bulk density. Gravity energy storage system.

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