Railway track equipped with perovskite solar cell

Abstract

To solve a problem in which conventional solar cells are made of hard silicon, such that a light-receiving surface is made of mechanically strong glass, and since this glass is hard, there is a risk that it is to break or crack due to mechanical forces such as vibrations caused by passing trains and paving stones that are sometimes kicked up by trains.SOLUTION: There is provided a railway track equipped with a perovskite solar cell which is installed between rails with one light-receiving surface facing the ground in a semi-cylindrical shape, and the light-receiving surface is covered with a plastic material. Furthermore, a power transmission line for the electricity generated by the solar cells is provided below the non-light-receiving surface of the solar cells. The power transmission line is also configured to be used for information and communications.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a railway line equipped with solar cells, and in particular to a train line equipped with solar cells whose light-receiving surfaces are shaped like the top surfaces of a kamaboko (fish-shaped tube) between the rails. [Background technology]

[0002] Compared to other modes of transportation, railways are highly energy-efficient and generally have a low environmental impact. Therefore, it is important for Japan as a nation to maintain railway operations, including local lines across the country. Meanwhile, the decline in regional railway ridership has long been a nationwide issue. The COVID-19 pandemic has particularly hit railway companies, leaving them with no financial resources to support unprofitable lines. Looking at the "operating ratio," which indicates the costs required to maintain railways in order to generate revenue, the highest ratio is found on the Kururi Line in Chiba Prefecture, between Kururi Station and Kazusa-Kameyama Station, where 15,546 yen is spent on maintaining the tracks and rolling stock to generate a 100 yen fare. This situation is a problem not only for JR but also for private railways, leading to the ongoing closure of many lines. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-311502 Summary of the Invention [Problem to be solved by the invention]

[0004] Previously, solar cells installed on railway tracks, particularly between the rails, have been used to generate electricity. The idea is to use the generated electricity to propel trains and meet other power demands, thereby promoting the use of green energy and improving the profitability of railway operations. However, conventional solar cells have been constructed with rigid silicon, and their light-receiving surfaces are made of mechanically strong glass. Because of the rigidity of this glass, they are susceptible to cracking and breakage due to vibrations from passing trains and mechanical forces from paving stones sometimes kicked up by trains. To minimize cracking and breakage, the cells must be protected by a relatively strong frame. Furthermore, while it is desirable to tilt the light-receiving surface relative to the ground to prevent dust and rainwater from accumulating on the surface, attempting to tilt two solar cells symmetrically on either side of the rails at the same apex makes it difficult to join the solar cells at this center, making them prone to dust and rainwater accumulation. This causes a problem in that dust accumulated in the central position can spread across the inclined surface of the solar cell. [Means for solving the problem]

[0005] Therefore, the present invention uses flexible, impact-resistant perovskite solar cells, and protects the light-receiving surface with a plastic material. The light-receiving surface of the perovskite solar cell is curved like the top surface of a kamaboko (fish cake) and installed between the railroad tracks. [Effects of the Invention]

[0006] By adopting the above-mentioned measures, the present invention has made it possible to reduce, compared to the prior art, the risk of the light-receiving surface of the solar cell being damaged by vibrations or mechanical forces caused by the passing of trains, etc. Also, it is effective to make the light-receiving surface non-parallel to the ground in order to exclude dust, rainwater, etc. from the light-receiving surface as much as possible, and in doing so, it is possible to eliminate structural steps on the light-receiving surface, especially in the center position between the rails, thereby enhancing the exclusion effect. [Brief explanation of the drawings]

[0007] [Figure 1] Conceptual diagram of the shape of the light receiving surface of the solar cell of the present invention [Figure 2] FIG. 10 is a diagram showing the layout of power transmission wiring according to a second embodiment. [Figure 3] A diagram showing the connection structure between one solar cell of the present invention and an adjacent solar cell, and also showing how the solar cell of the present invention is fixed to a railway line. [Figure 4] FIG. 1 is a diagram showing how the power generated by the solar cell of the present invention is transmitted via a feeder line used by a train. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <Embodiment 1: Mainly relates to claim 1> <Outline of Embodiment 1> This embodiment is a railway track equipped with a perovskite solar cell, which is a solar cell installed between rails and has a single light-receiving surface configured in a semi-cylindrical shape. <Configuration of Embodiment 1> <Embodiment 1: Description of the Configuration: Solar Cells Installed Between Rails>

[0009] The "solar cell installed between the rails" is a solar cell with a semi-cylindrical light-receiving surface that is installed between the two rails on which the train runs, and is configured so that its top is located lower than the top surface of the rails. However, if this does not interfere with the running of the train, the top of the solar cell may be configured to be higher than the top surface of the rails. <Embodiment 1: Description of the Configuration: Significance of Installation Between Rails>

[0010] The "significance of installing between the rails" is that the area between the rails of a railway track does not perform any particular function in train operation, and should be used for any useful purpose. Furthermore, standards are established for railway tracks, particularly for two rails, to ensure safe and comfortable train operation, and these standards are strictly adhered to. Therefore, when laying any structure over long distances, the shape and size of the solar cells to be installed can be made consistent, and the installation work is standardized and therefore easy, making this an excellent location. Railway tracks are generally laid over long distances, and are therefore an excellent resource in that they provide a fairly large amount of space for installing solar cells. <Embodiment 1: Description of the Structure: Perovskite Solar Cell>

[0011] A "perovskite solar cell" converts sunlight into electricity using a material with a crystalline structure called perovskite. Perovskite solar cells consist of a power-generating layer made of perovskite, flanked by layers for transporting electrons and holes. These layers are further layered with electrodes and sealing films. Flexible plastic sealing films can be used, particularly those with high UV resistance. Silicone-based plastic films are also suitable. Perovskite solar cells are characterized by their extremely thin, lightweight, flexible, and bendable power-generating layer. Therefore, their overall shape is highly flexible, and as mentioned above, solar cells with semi-cylindrical surfaces can be used to prevent dust and rainwater from accumulating on the light-receiving surface. Furthermore, they can be mass-produced at low cost using coating and printing techniques. Furthermore, they have the advantage of being able to generate electricity even under low light conditions, such as indoor lighting, making them suitable for use on cloudy or rainy days, and even from train track lighting. <Embodiment 1: Description of the Configuration: The light receiving surface is configured as a single semi-cylindrical light receiving surface>

[0012] Figure 1 is a conceptual diagram depicting a light-receiving surface configured in a kamaboko shape. The curvature of the kamaboko shape, the height from the installation surface to the top of the kamaboko, and the length between both ends of the kamaboko are essentially design factors. As an example, the length between both ends of the kamaboko is approximately 800 to 1000 mm, and the height from the installation surface to the top of the kamaboko is approximately 50 to 100 mm. The longitudinal length of the solar cell is also a design factor. However, when a single solar cell is secured to the ground only in the adjacent areas to other solar cells at both ends, as shown in Figure 3, a length of approximately 1 to 2 m is preferred to reduce the risk of mechanical damage caused by strong winds. Furthermore, when both ends of a single solar cell are secured to the ground relatively closely, the total length may be approximately 2 to 5 m. It is possible to configure the track so that no solar cells are installed in areas where the track curves, but in the case of gentle curves, it is also possible to configure the track so that relatively short solar cells of approximately 50 cm to 1 m are installed.

[0013] The reason for "configuring the solar panel so that one solar receiving surface is in a semi-cylindrical shape relative to the ground" is to minimize the adhesion or accumulation of materials that obstruct the entry of sunlight onto the solar receiving surface. It is also possible to make the solar receiving surface flat and tilt it relative to the ground, but in that case, the tilt direction must be optimized for each location depending on the direction of the track and the direction of the sunlight, making the installation of the solar panels more complicated. It is also possible to install solar panels on a roof, as in the prior art document. However, this would create grooves along the boundary between the two solar panels, and would require metal sheeting to prevent the grooves, which increases the risk of dust and dirt accumulating in the grooves and metal sheeting. Furthermore, the metal sheeting would not generate electricity from the solar panels, resulting in a loss of surface area.

[0014] When constructing the light-receiving surface of a solar cell as in the present invention, the same installation work can be performed regardless of the direction of the track and the direction of sunlight, regardless of the position of the track. Furthermore, as mentioned above, perovskite solar cells are flexible, so there is a possibility that they can be automated, like undersea cable-laying ships. In other words, it is conceivable to use a dedicated solar cell installation train to lay solar cells while traveling along the track. For example, when placing a rolled solar cell panel on the track, it can be curved like a kamaboko (semi-cylindrical rod). The solar cell rolled up into a roll does not need to be a single solar cell along its entire length; it is preferable that a cutting area be set in advance so that one solar cell is formed at each predetermined length, and that the cutting area be automatically cut with a cutter.

[0015] It is also preferable that the cut portion be provided with a lead terminal for extracting power. In some cases, the power from the solar cells is ultimately transferred to a medium-distance transmission line such as a feeder line, as shown in Figure 4. If the power transmission wiring for transferring power to the feeder line is placed below the solar cells as in the second embodiment described below, this power transmission wiring can also be prepared in a roll and placed in the track at the same time as the solar cells are placed. <Embodiment 1: Description of the Structure: Transparent Plastic Covering Solar Cell>

[0016] The "plastic that covers the solar cell" needs to be flexible and impact resistant, but UV resistance is especially important because the solar cell must be exposed to sunlight for long periods of time outdoors. UV resistance means that its transparency is less likely to deteriorate over time due to UV rays. In addition to the silicone-based transparent plastics mentioned above, the following plastics are also highly UV resistant. Polymethyl methacrylate (PMP): PMP, known by the trade name TPX®, is a plastic that exhibits high transmittance across the entire ultraviolet range. PMP also offers heat resistance, mold release properties, and chemical resistance, making it suitable for use in medical devices and optical components. Polyetherimide (PEI): Also known as ULTEM®, PEI is a high-performance thermoplastic polymer that can withstand high temperatures. PEI has high transmittance in the UVC region, making it suitable for use in laser processing and semiconductor manufacturing. Fluoropolymers: Fluoropolymers include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluorinated ethylene propylene (FEP). Fluoropolymers are highly resistant to ultraviolet light, chemically inert, and have excellent weather resistance. Fluoropolymers have been used in optical fibers and other applications. Silicone-based plastics: Silicone-based plastics are a type of plastic that has high UV transmittance and UV resistance. Examples of silicone-based plastics include fluorosilicone resins and silicone acrylate resins. These plastics have high transmittance even in the deep UV region, and are characterized by minimal cracking or color change due to UV degradation. They also have heat and chemical resistance, and have been used in optical components and medical devices. Silicone-based plastics exhibit excellent performance as plastics that have high UV transmittance and UV resistance. Specific products include Fluorosilicone Resin: Shin-Etsu Silicone Selection Guide. <Embodiment 1: Solar Cell Installation Structure on Railway Track>

[0017] Regarding the "solar cell installation structure on railway tracks," this can differ depending on whether the trackbed is gravel (ballast) or slab. A gravel trackbed is called a ballast trackbed (ballast track), while a slab trackbed is called a slab trackbed (slab track). The former track structure is a traditional track commonly seen on conventional lines, while the latter, slab track, is often seen on elevated tracks. A typical example is the Shinkansen track. When installing the solar cell of the present invention on the latter track, it is recommended to fix it relatively firmly to the track, assuming that the solar cell will be replaced as it deteriorates every 5 to 10 years. For example, a method is to drill a hole in the slab and install a female screw, and then fix it with a male screw through a hole in the margin of the plastic covering the solar cell that protrudes from the solar cell.

[0018] However, in the case of ballasted track, maintenance work on the ballast requires periodically lifting the track to add new gravel underneath or replacing all the gravel underneath with new gravel. To prepare for such situations, it is preferable to configure the solar cells so that they can be easily attached and detached from the track. However, making them detachable prevents the solar cells from becoming detached from the track due to vibrations caused by passing trains. Therefore, in the case of ballasted track, it is preferable to configure each solar cell and its adjacent solar cells so that they are fixed to a common plate-like structure at both ends of the width of the semi-cylindrical solar cell, as shown in Figure 3(b), and to press this plate down from above with two additional plates that extend from the underside of the rails.

[0019] The plate-like object is preferably made of a non-conductor to prevent an electrical short circuit between the two rails. Furthermore, the plate-like object is preferably firmly fixed to the rail, preferably by welding. This is to prevent the fixed position of the plate-like object relative to the rail from shifting due to vibrations caused by passing trains. When the solar cells are removed from the track for track maintenance, the solar cells are detached from the plate-like object connecting the adjacent solar cells. It is preferable that the plate-like object has a certain degree of flexibility, so it is preferably made of a weather-resistant plastic material. The solar cells and the plastic plate-like object are preferably joined using a relatively flexible adhesive.

[0020] <Embodiment 1: During railway construction>

[0021] The solar cells of this embodiment are perovskite solar cells, and so are flexible, and when carrying out construction, maintenance, or inspection of railway tracks, they can be rolled up in the short direction to reduce the curvature of the semi-cylindrical shape and be concentrated so as not to get in the way of work. In this case, the wiring for power transmission can also be rolled up together. <Effects of Embodiment 1>

[0022] By adopting the above-mentioned measures, in this embodiment, the risk of the light-receiving surface of the solar cell being damaged by vibrations or mechanical forces caused by the passing of a train, etc., can be reduced compared to conventional cases. Also, it is effective to make the light-receiving surface non-parallel to the ground in order to exclude dust, rainwater, etc. from the light-receiving surface as much as possible, and in doing so, it is possible to eliminate structural steps on the light-receiving surface, particularly at the center position between the rails, thereby increasing the exclusion effect. <Embodiment 2: Mainly relating to claim 2>

[0023] <Outline of Embodiment 2>

[0024] As shown in Figure 2, this embodiment is a railway track based on embodiment 1, in which a transmission line for power generated by the solar cells is arranged below the non-light-receiving surface of the solar cells. That is, this invention is a railway track having solar cells installed between the rails, in which one unit of solar cell arranged between the rails consists of a single perovskite solar cell, the light-receiving surface of which is configured in a semi-cylindrical shape, and in which a transmission line for power generated by the perovskite solar cells is arranged in the space between the underside of the curved plate-shaped solar cell that defines the semi-cylindrical light-receiving surface and the paving stones or road surface of the track. <Configuration of Second Embodiment> <Embodiment 2: Underside of non-light-receiving surface>

[0025] The reason for the phrase "below the non-light-receiving surface" is that the solar cells of the present invention are arranged with their light-receiving surfaces curved in a semi-cylindrical shape, and therefore there is space on the non-light-receiving surface side, which is the back side of the light-receiving surface, created by curving the flat solar cells. The underside of the solar cell panel is also convenient for physically protecting the power transmission lines. For this reason, in embodiment 2, the electricity generated by the solar cells is arranged below the non-light-receiving surface of the solar cells. In addition to the power transmission lines, signal lines for transmitting signals for train traffic management can also be arranged below the non-light-receiving surface.

[0026] In addition, Figure 2(a) shows the power transmission wiring placed on a sleeper, ballast, or slab below the non-receiving surface. In this case, there is no need to fix it to the resting surface, it is enough to simply place the wiring. Figure 2(b) shows the power transmission wiring suspended from a power transmission wiring suspension part that hangs from the non-receiving surface, and is not in contact with the underside. If the track uses ballast, i.e. gravel, the gravel is moved when the ballast is replaced or the rail height is adjusted, and there is a risk that the wiring will be damaged by these operations, so the wiring is left floating. <Embodiment 2: Power transmission line>

[0027] In order to transmit the electricity generated by solar cells, an appropriate transmission cable must be used. The amount of electricity generated by a solar cell varies depending on the area and performance of the solar cell. Generally, the amount of electricity generated by a solar cell per square meter is around 100W to 300W, so if 10 solar cells laid on a railway line are connected in parallel and transmitted over a distance of 1km, an electric cable with an allowable current of around 20A to 30A will suffice. Suitable electric cables include vinyl insulated wire, vinyl insulated vinyl sheath cable, and cross-linked polyethylene insulated sheath cable. Since the cable is below the light-receiving surface, there is less direct sunlight and the insulating material is less likely to deteriorate due to ultraviolet rays.

[0028] <Embodiment 2: Use of generated power as a premise>

[0029] The electricity generated by the solar cells installed on the railway line of the present invention may be used for a variety of purposes, including the following:

[0030] (1) It is used as driving energy for trains running on the tracks.

[0031] (2) Used in operation control systems. A "train traffic control system" (commonly known as PTC: Programmed Traffic Control) is a computer system used in railway train traffic management that centralizes and controls the Centralized Traffic Control (CTC), Automatic Route Control (PRC), traffic rescheduling system, and passenger information system based on a planned timetable. It has been introduced primarily in high-density train service areas in metropolitan areas and on high-speed railways such as the Shinkansen, in order to improve the efficiency of train traffic management and passenger service. PTC systems are used on Japan's Shinkansen and conventional railways. These facilities must function effectively even in the event of a large-scale disaster such as the Great East Japan Earthquake, but in the past, there was a risk that these functions would stop working due to power outages caused by power plant shutdowns. By disconnecting from the public power grid and enabling independent power procurement, as in the present invention, it becomes possible to prepare for emergencies.

[0032] (3) Used for railway ancillary facilities.

[0033] Examples of "railway ancillary equipment" include the following, and the electricity used by these can be generated by the track equipment of the present invention. Electric railway equipment: Equipment such as overhead lines and third rails that supply power to trains. Signal equipment: Equipment such as signals that indicate the route and stopping of trains, signals at railroad crossings, automatic train control (ATC) and automatic train stop (ATS). Electric lighting and power equipment: Station and track lighting, automatic ticket gates, platform doors, elevators, escalators, and other equipment. Information and communication systems: Facilities such as station and train announcements, electronic bulletin boards, radio and telephone systems, disaster prevention systems, surveillance cameras, and traffic management systems. Power generation facilities: Facilities such as thermal power plants and hydroelectric power plants that railway companies use to generate their own electricity. These can be used as backup power in the event that in-house power generation becomes unavailable. Substation equipment: Facilities such as substations and transmission lines that transform the electricity received from the power company for use by railways. Similarly, in the event of a disruption in the normal external power supply, it can be used to control substation equipment, investigate the cause of a failure, and obtain information on the current status of the substation equipment. Switch: A mechanism for branching railway tracks. Used for single-wing switches, double-wing switches, inner switches, outer switches, etc.

[0034] (4) Used by factories and facilities along railway lines

[0035] The electricity generated by the railway track of this invention could be used not only for internal consumption within the railway, but also for factories and facilities along the railway line. The owner of the railway track of this invention could increase sales and generate revenue by allowing external parties to use the electricity generated by this invention. This could potentially enable the railway transportation business to continue based on this revenue, particularly on lines where railway operating revenue is lower than actual operating costs. Furthermore, keeping the selling price of electricity low could help revitalize industries along the railway line. This could increase the number of railway users, potentially helping to revive the local economy through a positive spiral.

[0036] To supply such external power, it is necessary to install multiple substations along the line as needed and supply power from those substations to the external power source. However, when the line is long, weather conditions vary from place to place, resulting in a difference in the amount of power available between sunny and less sunny areas. This means that an imbalance between planned supply and demand may occur. In such cases, a system to adjust the imbalance is required. It is preferable for the system to constantly monitor the relationship between supply and demand in each region and include a distribution control system that distributes power from areas with excess supply to areas with excess demand. In particular, since multiple substations are installed along the electrified line, the power generated by the line of the present invention can be first supplied to a substation, then supplied to the overhead lines under the control of the distribution control system. Another substation then receives the power from the overhead lines and supplies it to the external power source. This allows the imbalance to be adjusted.

[0037] (5) Household consumption along the railway line The electricity generated by the railway line of this invention can be used for domestic consumption in homes along the railway line. In particular, in depopulated areas such as Hokkaido, Tohoku, and Kyushu, the cost of maintaining and managing the public power supply network is so high that the cost of supplying electricity exceeds the profits. In such areas, the efficiency of the power supply can be improved by eliminating the public power network and supplying electricity generated by the railway line of this invention.

[0038] Furthermore, if laying power lines from a substation is too costly, it is possible to install a charger at the substation and configure it so that it can charge storage batteries used in homes. Furthermore, it is conceivable to create a system that uses drones or other devices to periodically deliver these storage batteries to elderly households in depopulated areas. Solving the power supply problem in this way could slow the rate of depopulation, or conversely, trigger a population increase. The solution to the supply-demand balance problem is the same as in (4).

[0039] <Embodiment 2: Mechanism for transmitting generated power>

[0040] Figure 4 is a conceptual diagram of the present invention, using a feeder as an intermediate facility to transmit power generated on the track to a destination. Approximately 10 to 100 solar cells within the track are considered as one unit, and the generated electricity is preferably supplied to a DC-DC converter via a parallel connection. Generally speaking, whether a parallel or series connection is preferable when transmitting electricity generated by multiple solar panels to a converter depends on the specifications of the converter used, the number of solar panels, their installation location, wiring distance, and power generation capacity. Parallel connection allows the power generation capacity of the solar panels to be added together, while series connection allows the voltage of the solar panels to be added together. A combination of the two is also possible.

[0041] However, in a parallel connection, if the panels' power generation capacities differ, the overall power generation may be limited by the panel with the lower power generation capacity, and in a series connection, if the panels' voltages differ, the overall power generation may be limited by the panel with the lower voltage. Therefore, it is important to select the optimal connection method, taking into consideration the specifications of the converter used, the number of solar panels, installation location, wiring distance, power generation capacity, etc. However, in the case of solar cells installed within railway tracks, such as the present invention, it is thought that there will often not be a large difference in the amount of sunlight between solar panels on a scale of 10 to 100 panels, and therefore the difference in power generation between solar panels will not be that great, and therefore parallel connection is preferable.

[0042] As shown in Figure 4, the DC / DC converter boosts the voltage to a certain range and supplies it to the feeder line, where it is transmitted to the railway substation, which is then used as a power supply base for external use. When this electricity is used to power trains, it is converted to the optimum voltage for powering the train at the substation and returned to the electric power line.

[0043] <Embodiment 2: Use of power storage equipment>

[0044] The electricity generated by the solar panels can be stored in storage facilities installed in train substations and used by discharging it at night, on cloudy days, or when it rains. On non-electrified lines, where there are no substations, it is conceivable to install storage facilities at intervals of about 2 to 5 km.

[0045] <Effects of Embodiment 2>

[0046] By adopting this embodiment, the power generated on the railway line can be used safely and reliably for various purposes. <Embodiment 3: Mainly relating to claim 3>

[0047] <Outline of Embodiment 3>

[0048] In this embodiment, the power transmission line for the power generated by the solar cell is also used for information communication. <Configuration of Third Embodiment>

[0049] The information communication in this embodiment may be used to transmit the results of detection by weather detectors installed along railway tracks, control signals for railway ancillary equipment such as signals, etc. In particular, it may be used to assign identification numbers to a large number of solar cells of the present invention and transmit the operating status of each solar cell to a solar cell management server, etc.

[0050] Furthermore, it may be used to send control signals from a solar cell management server to the solar cells. When solar cells are connected in parallel to a certain unit to collect electricity, a unit control unit may be provided for controlling the power from the solar cells belonging to that unit on a unit basis. In this case, control commands to this unit control unit are sent from the solar cell management server, but may be sent via this transmission line. Furthermore, when using the transmission line for information communication, the transmission line must be connected over a long distance, so a power communication separation unit must be provided to separate power and communication at the connection part between each unit. <Effects of Embodiment 3>

[0051] According to this embodiment, the added value of the power transmission wiring can be increased by using the power transmission wiring for communication as well.

Claims

1. A railway line equipped with perovskite solar cells, which are installed between the rails so that one light-receiving surface faces the ground in a semi-cylindrical shape, and the light-receiving surface is covered with a plastic material.

2. A line equipped with perovskite solar cells according to claim 1, further comprising a power transmission line for transmitting the power generated by the solar cells below the non-light-receiving surface of the solar cells.

3. The line equipped with perovskite solar cells according to claim 2, wherein the power transmission line is also used for information communication.

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