Artificial air storage for compressed air storage

Abstract

Compressed air storage system, DLS system, comprising:an air storage assembly (20) formed from one or more conduits (11) for storing compressed air, each of which is a tubular element (21i) comprising a composite material.

Description

FIELD OF THE INVENTIONThe present invention relates to an artificial air storage device for use in a compressed air storage device (DLS) as a solution, more particularly to a ring-shaped artificial air storage device based on glass / carbon fibers (for example, a composite material) for use in a DLS (for example, an adiabatic DLS).BACKGROUNDIn the field of compressed air storage (DLS) systems, a particularly important influencing factor for the effectiveness and longevity of the storage solution is the design and the material of the air storage containers. These systems have conventionally used tubes arranged in parallel as grids, a decision for this design being common, but involving several challenges inherent in themselves. The parallel arrangement of tubes requires a complex design of end closures and concrete parts to maintain structural integrity and to resist enormous pressure at the ends of the tubes when the compressed air is stored. This increases the complexity of construction and maintenance and results in high costs.In the conventional construction, moreover, the space requirement is often very high, which gives restrictions where few areas are available or areas are expensive. The spatial constraints and rigid structural design in parallel grid shapes compromise the adaptability of DLS systems to various geographic and infrastructural circumstances. This rigid construction limits the broad applicability of DLS technologies and they are limited to areas where such an arrangement can be accommodated without enormous cost or logistic difficulties.In addition to the structural requirements imposed by the shape of parallel grids, the selection of material for these tubes will significantly affect the overall performance of DLS systems. Because of its initially favourable costs and mechanical strength, steel has previously been the material in the manufacture of compressed air storage containers. However, steel pipes have several difficult aspects, such as corrosion or cost. When laid in the ground or under harsh environmental conditions, steel reacts with moisture and other elements causing corrosion which impairs the integrity of the storage system. Due to this loss of quality, frequent inspection, repair and replacement measures may be necessary, as a result of which the long-term operating costs increase and the effects on the environment increase. The fact that temperature changes affect steel also entails difficulties. In response to temperature changes, steel expands and contracts, which can result in a weakened structure and possible defects. This sensitivity not only gives rise to safety concerns, but also additional requirements for construction and maintenance in order to mitigate temperature-related effects. Moreover, more importantly, when steel is used for pipes to store compressed air at a very high pressure, the diameter of the pipe that can be used is limited, thereby further reducing the volume of compressed air that can be stored on a particular area of the plant.With a novel construction and material selection for air stores, the invention described in this utility application addresses these issues. This invention dispenses with the conventional parallel grid and steel design shape and thus provides a more efficient, durable and more compact solution for DLS systems.SUMMARYIn this invention, in the field of compressed air storage systems, an innovative construction is introduced which focuses on a structure using, as a parallel grid of storage tubes, one or more rings, unlike the conventional one. The overall construction is greatly simplified with this annular structure and reduces the complexity associated with high end pressure in conventional systems. The circuit arrangement also provides flexibility in the requirements of installation and space requirements. With this construction, space can be used more efficiently and can be adapted to various environmental conditions and geographical conditions, thereby making DLS systems more applicable.In addition to the innovative structural design, this invention proposes the use of modern composite materials, in particular with glass and carbon fibers, for the production of the storage rings. These materials have a better ratio of strength to weight compared to conventional steel, whereby the resistance of the system to negative environmental influences such as corrosion and temperature fluctuations is substantially improved. Moreover, with these materials, tubes with a larger diameter and consequently a larger storage capacity can be designed.Embodiments provide a compressed air storage, DLS, system comprising: an air storage assembly formed from one or more conduits for storing compressed air, each of which is a tubular member comprising a composite material.In one embodiment, the DLS system includes an air compression and release control mechanism.In one embodiment, the DLS system includes at least two joined piping and the tubular members are modular.In one embodiment, the composite material comprises carbon fibers and / or glass fibers and a resin matrix, which may be a thermosetting polymer matrix of polyester or epoxy resin.In one embodiment, the composite fibers are oriented in the circumferential direction of the tubular member.In one embodiment, the diameter of the tubular member is greater than 3.5 meters.In one embodiment, the tubular members are connected via one or more angled connectors at a bending angle.In one embodiment, the air storage assembly is in the form of a substantially closed loop or a closed circuit, wherein the substantially closed loop or the closed circuit may substantially have the form of a ring, a doughnut, an oval, or a racetrack. The substantially closed loop air storage assembly may also include a plurality of concentric substantially closed loops.In one embodiment, the air storage assembly is laid in the ground.In one embodiment, the DLS system is an adiabatic DLS system.The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings and from the claims.BRIEF DESCRIPTION OF THE DRAWINGSFig. 1 is a simplified view of a grid structure for the prior art memory. Fig. 2 is a simplified view of a ring structure for the memory according to an embodiment of the invention. FIG. 3 is a simplified view of a pipe section for the reservoir according to an embodiment of the invention.DETAILED DESCRIPTION OF THE EMBODIMENTSThe embodiments will now be described in detail below with reference to the accompanying drawings. However, the disclosure may not be limited to the embodiment in which the spirit of the disclosure is set forth, and by adding, changing, deleting, and the like another embodiment that is within the scope of the gist of another previous disclosure or the present disclosure may be easily proposed.The terms used in this application have been chosen to include currently valid, widely used general terms. In certain cases, a term may be one that has been arbitrarily set by the applicant. In such cases, the meaning of the term is defined in the relevant portion of the detailed description. Thus, the terms used in the description section are not to be defined simply by the description of the terms, but are to be defined based on both the meaning of the terms and the general description of the present disclosure.Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that throughout the drawings, the same reference numerals are used to designate the same or similar elements.In renewable energies, development takes place at a speed never present. After this increase, there is a desire in particular to reduce the carbon dioxide output. Serving as corner pillars of this energy turn are solar energy, wind energy, water power and geothermal energy. In contrast to conventional fossil fuels, these renewable energy carriers promising an almost inexplicable energy supply with a substantially smaller ecological footprint. Throughout the world, countries are investing intensively in these technologies.Solar energy, for example, can be used via solar cells that convert sunlight directly into electrical current. Wind energy can likewise be generated via wind turbines, which convert kinetic wind energy into electrical current. Finally, when water power is applied, running water is used for power generation. These energy carriers individually and collectively have the potential to substantially reduce our fossil fuel dependence.However, the incorporation of some renewable energy carriers into existing energy networks presents considerable challenges, primarily because they are not available continuously and nonpredictably. Thus, in particular, solar and wind energy are strongly dependent on weather conditions, time of day or season. Solar panels, for example, can only generate electric power when the sun is looking, and their performance is affected by factors such as sun vaulting and angles. Wind is needed to operate wind turbines and its efficiency depends on the wind speed and the constant availability of wind. These fluctuations can lead to deviations between the energy supply and the demand. For example, the generation of solar energy is highest during the course of the day, which may not correspond to peak load times, especially in the evening.This fluctuation is not only day related, but also a matter of season. In many areas, resources in the area of solar and wind energy fluctuate considerably between the seasons, as a result of which the reliable availability of these energy carriers is influenced. For example, in some areas in winter months, less sun may appear or wind speed may be lower at certain times a year. The integration of renewable energy carriers into the power grid becomes even more complicated due to the seasonal fluctuations, since planning safety is necessary here both for periods with excesses and with undersupply.One solution to this challenge is in energy storage technologies that can store the surplus energy generated from renewable energy carriers during high output times and then consume when low is generated or demand is high. The storage of energy has therefore become very important for constant and reliable energy supply when using energy from renewable energy carriers.One of the most common forms of energy storage is battery technology, in particular lithium ion batteries. These batteries are becoming increasingly used in both private and commercial installations for the use of renewable energy carriers. They store excess energy generated during production peaks, at solar energy for example noon, and they provide it during times when little energy is generated, for example at night. This not only allows a more uniform supply of electrical energy to be achieved, but also reduces the dependence on conventional additional energy sources, for example generators operated with fossil fuels. However, there are some disadvantages when batteries are used for energy storage. First of all, the high initial costs are a considerable obstacle, since the expenses required for battery storage systems, in particular for industrial applications, can be considerable. Second, there are ecological concerns associated with the manufacture and disposal of batteries. The recovery of raw materials such as lithium and cobalt, which are required for battery production, is often associated with high energy consumption and can destroy the environment. Moreover, battery recycling and disposal of old batteries continue to remain difficult and pose issues to long term environmental impact. Finally, batteries have a limited life characterized by a limited number of charge-enable cycles. Their efficiency and capacity decrease over time, which ultimately requires replacement, thereby increasing battery storage related costs and resource usage overall.A further option is storage via pumped storage water power plants, in particular in industrial applications. During the production of excess energy, water is pumped to a higher level, which can then flow down again through turbines if necessary, as a result of which electrical current is generated. This method is particularly effective for storing large amounts of energy over longer periods of time and can contribute across the network to the compensation of supply and demand. However, suitable geographical conditions and considerable infrastructure expenses are required for this.A very promising approach is adiabatic compressed air storage devices (ADLs), which represent a significant advance in the field of energy storage in order in particular to be able to more effectively deal with the fluctuation of renewable energy carriers. This technology addresses a significant challenge in the energy sector: how can large amounts of energy be stored efficiently both efficiently and in an environmentally friendly manner?In conventional DLS systems, electric power, which is frequently generated from renewable energy carriers at times or times where much is produced, is used to compress air. This compressed air can be stored in underground stores such as caverns or exhausted natural gas deposits. As the demand for electric power increases, this compressed air is released, heated (typically by combustion of natural gas) and used to drive turbines to generate electric power. Particularly ineffective in this process is the heat loss in the air compression phase to be compensated for with the adiabatic DLS system.The advantage of adiabatic DLS is that they can absorb and store the heat generated during the compression of air. In the adiabatic process, the air heats up very strongly when compressed using excess electric energy. In the adiabatic system, this heat is not dissipated but rather absorbed using a thermal energy storage system which generally comprises materials having a high heat storage capacity, such as water or salt melts.Once this heat is stored, it can be recovered later in the discharge cycle. If there is a need for electrical energy, the compressed air is released from the reservoir. However, unlike conventional DLSs, where natural gas is often used to re-heat the air, the adiabatic system utilizes the stored heat energy. This preheated air is then used to operate a turbine which produces electrical energy. This process offers several advantages. First, the overall energy efficiency of the system is significantly improved. By absorbing and recovering the heat from the compression phase, less additional energy has to be introduced in the discharge phase in the adiabatic DLS. Thus, more electrical energy is generated per unit of stored air, thereby increasing the effectiveness of the system as an energy storage solution. Moreover, adiabatic DLS are more environmentally friendly compared to conventional DLS systems. Because no fossil fuels or much less thereof are needed to re-heat the air, less greenhouse gas emissions are produced that are associated with the generation of electric current at peak load times. This property is well suited for world-wide turning towards more sustainable and renewable energy carriers.Moreover, adiabatic DLS systems are geographically less constrained than some other forms of energy storage such as pumped storage hydroelectric power plants. Although suitable subterranean formations must be provided for storing air, their availability is greater than that of the particular topographical features required to be met in stored pumped storage. Adiabatic DLS are flexible in scalability. The technology can be scaled up to allow for the storage requirements of larger energy networks, making it a convenient option for its broad application in various geographic and industrial contexts.Despite these advantages, however, certain challenges are encountered in the development and implementation of adiabatic DLS technology. A major challenge is the costs associated with the development and construction of these systems, particularly the costs and space required for the construction and installation of the storage portion which must be able to store a large amount of compressed air over numerous cycles. In other words, there are challenges to handling sufficient size for storage and to provide structures that can withstand high pressures important for this technology to be usable on an industrial scale.Conventionally, the storage structures used in this type of DLS system are made from tubing and connectors which may be uniaxial or biaxial. In uniaxial connectors, axial thrust is not transmitted from one piece of tubing to the next, and the tubing is thus not reinforced to absorb such force. Biaxial connectors, on the other hand, are designed to take all the pressure from one piece of tubing to the next, and the tubing is reinforced to take up the force. However, biaxial systems are much more expensive than uniaxial tubing and connectors.Storage tank systems conventionally consist of pipe segments joined and joined together in the form of a grid having the shape of a structure with parallel pieces as shown in Fig. 1. In this figure, a storage tank system 10 is shown with X joined pipe segments 11 having a length L and oriented parallel to each other in the form of a grid. In the example shown in FIG. 1, there are four joined piping segments. Each of these segments may itself consist of one or more pipe sections joined together in the axial direction. Since pressure is applied to the ends of such tank sections 11, the ends must be reinforced or secured with reinforced / longitudinally force-fit end closures. In view of the high pressures prevailing in a compressed air storage system required in a DLS installation, Y concrete blocks 12, which are concrete abutment blocks, may be formed around the end closures of each of the joined pipe segments 11. These heavy concrete blocks provide a counterforce to the pressure exerted on the end closures of the joined pipe segments 11. These concrete blocks 11 make the construction somewhat more complex, especially since the interface between the pipe material and the concrete must be taken into account. Not only is there considerable extra costs incurred when used in an underground / underground storage system, but also more volume is needed near the plant in the ground which is not used directly for the storage of compressed air. It will be appreciated that these storage structures are not optimal in that heavy and expensive fittings must be used due to the enormous pressures created at the ends of the joined pipe segments, thereby reducing the volume actually used for underground storage.One solution proposed in the present invention is to arrange the assembly of the joined pipe segments or the air storage arrangement 20 comprising the pipe 21 in such a way that their ends are practically omitted, which would otherwise have to be provided with end closures. This is achieved by joining the pipe sections 21 i(see FIG. 3 ) at an angle (or the so-called bending angle α) so as to form a closed circuit of pipes ( 21). This closed piping circuit may have approximately the shape of a ring, a doughnut, an oval, or a race track, as shown in FIG. 2. In this figure, three joined pipe segments 11 or 21i are shown, which are formed into three rings arranged one after another in a radial direction. Figure 2 shows a three ring embodiment, however the invention may be embodied with a single ring or any plurality of X rings. The higher the number of rings, the greater the surface area of the disk that forms the largest ring and the greater the volume of compressed air that the storage tank system can accommodate in one and the same type of pipe. In the annular design of the construction, no end closures are required and thus no use of concrete blocks 12 for reinforcing these ends, where high compressive forces concentrate. In this embodiment, the thrust force is distributed over a plurality of connectors, for example a plurality of angled connectors. By selecting the angle at the connectors, a lower pressure can be calculated at each connector in such a way that from a sufficient laying depth and under certain conditions of the floor surrounding the pipeline, the compressive force or shear force is distributed in such a way that no reinforcement made of concrete such as thrust bearings or abutment blocks is required any longer or no stone bed is required any longer.In the following Tables 1 and 2, comparisons between parallel-piece embodiments and embodiments according to the present invention using a closed loop of annular piping are shown.Taking as an example a pipeline DN3500 with a storage capacity of 300,000 m 3 over a total pipe length of 33 km, eight different variants of the grid structure were investigated, in which the pieces lie parallel, as is shown in FIG. 1. As shown in Table 1 below, the number of pieces must be selected so that the number of concrete blocks Y is matched with the length L of the area in which the storage tank is to be installed. In variant 1 with two parallel pieces, the smallest number of concrete blocks is required at the ends of the pipe pieces. In this variant, however, an area having a length of more than 16 km is required. In variant 8, with the same volume, the length of the used area is less than 4 km, but with the great disadvantage that 18 concrete blocks must be laid for the counter pressure. Table 1 Table 112416,523611,03488,345106,656125,567144,778164,189183,7Using the parameters of the pipeline DN3500 with a volume of 300,000 m 3 three variants can be similarly examined in the construction according to the inventive embodiment of FIG. 2. In these three variants, the use of concrete blocks or pressure bearings for the counterpressure can be dispensed with. The space required for the storage tank system is also considerably smaller, since the land distance required for laying amounts to between 3.5 and 2.2 km depending on the variant (from 3 to 5 pieces). Table 2 Table 21303,50,42402,70,53502, 20, 7Usually, compressed air storage containers installed in the ground have been constructed from steel. However, the use of steel for tubular storage containers for storing compressed air has several disadvantages, especially when installed in the ground. One issue is corrosion because steel tends to corrode, especially when installed in the ground, which may have different moisture levels and a different chemical composition. This corrosion may weaken the structural integrity of the storage container, possibly leading to failure. The risk of corrosion and other forms of degradation may also require periodic maintenance and inspection, which increases operating costs and results in longer downtime. Another potential difficulty is that steel undergoes temperature changes, thereby expanding and contracting. This is particularly serious in underground storage where considerable temperature fluctuations can occur, potentially leading to structural loads. Moreover, steel is more expensive than composite solutions.Furthermore, the weight of steel makes transport and installation more demanding and expensive, in particular in the case of large-scale storage systems. Even with maintenance, steel storage containers have a limited service life due to unavoidable wear, which can represent a substantial disadvantage. In the underground installation of steel storage containers, moreover, care must be taken to determine whether the ground is suitable. If the storage system is made of steel, factors such as soil composition, stability and possible soil movements may have a greater effect on its safety and longevity. Since it is relatively inexpensive, the choice is frequently made of steel, but higher long-term costs for maintenance, corrosion protection and possible replacement measures can be obtained. Moreover, some types of soils might have problems of permeability and fattening, which may impair the integrity and performance of the storage system. The whole of these factors shows well how complex the use of steel in tubular storage containers for storing compressed air is and what possible disadvantages exist, especially when these storage containers are installed in the ground.Another difficulty with the use of steel is that the diameter of the pipe to be used for the accumulator could be limited. In the case of use of a DLS plant and taking into account the pressure of the compressed air which has to be achieved, it is difficult to achieve a tube diameter in the case of steel of more than 2.5 metres, as a result of which the volume which is stored in such a plant is limited.To overcome these difficulties, the present invention proposes the use of a tube made of a composite material, in particular a glass fibre or carbon fibre composite material.Figure 3 illustrates a tube 21i having the dimensions length D, radius R and thickness T. The tube may be slightly bent at an angle α to allow it to more easily join other tubes and thus achieve the curved closed construction discussed above. The use of a composite material for this tube offers the possibility of combining the unique properties of composite materials, thus creating a construction which is not only robust, but also efficient and versatile. The diameter of the tube (i.e. twice the radius R and the thickness T) can be, for example, greater than the maximum 2.5 metres when steel is used. The diameter of the tube may be greater than 3.5 meters or even greater than 5.5 meters.The materials used predominantly for the tube can be a reinforcement made of glass fibers and a polymer matrix, for example a matrix made of a thermosetting polymer, generally polyester or an epoxy resin, could be used. Glass fibers can be selected for their exceptional tensile strength and stiffness, whereas the polymer matrix joins these fibers, ensuring that stresses are properly conducted throughout the construction. In the manufacture of the tube, the fibers may be preferentially oriented in a circumferential direction (or ring direction) to resist the stress in the ring caused by the internal pressure. Thus, in a configuration such as the design as a doughnut, the floor in the environment resists most of the compressive stresses in the longitudinal direction, thus reducing the longitudinal stresses acting in the pipeline.The objective of the polymer matrix in this composite material is mainly fulfilled by polyester or epoxy resin, which are selected for their high adhesion, high chemical resistance and durability. This resin is a thermosetting polymer, thus it undergoes a curing process in which it is heated, thus creating a cured rigid matrix in which the glass fibers are securely encapsulated.The composite tube provides several advantages in terms of performance. With the high ratio of strength to weight, it can withstand high stresses without requiring too much weight, a major factor in many technical applications. Its corrosion resistance is another important advantage, especially in environments where contact with moisture or chemicals is important. Moreover, the composite material provides excellent thermal insulation and thus protects the contents of the pipe from external temperature fluctuations.

Claims

A compressed air storage system, DLS, system comprising: an air storage assembly (20) formed of one or more pipes (11) for storing compressed air, each of which is a tubular member (21i) comprising a composite material.The DLS system of claim 1, comprising an air compression and release control mechanism.The DLS system according to any one of the preceding claims, comprising at least two pipelines joined together.The DLS system of claim 3, wherein the tubular members (21i) are modular.The DLS system of any preceding claim, wherein the composite material comprises carbon fibers and / or glass fibers.The DLS system of any preceding claim, wherein the composite comprises a resin matrix.The DLS system of claim 6, wherein the resin matrix is a thermosetting polymer matrix of polyester or epoxy resin.The DLS system according to any one of claims 5 to 7, wherein the fibers are oriented in the circumferential direction of the tubular member (21i).The DLS system according to any of the preceding claims, wherein the diameter (D) of the tubular element (21i) is greater than 3.5 metres.The DLS system according to any one of the preceding claims 3 to 9, wherein the tubular elements (21i) are joined together at a bending angle (α) via one or more angled connectors.The DLS system of any preceding claim, wherein the air storage assembly (20) is in the form of a substantially closed loop or closed loop (21).The DLS system of claim 11, wherein the substantially closed loop or circuit (21) is substantially in the shape of a ring, a doughnut, an oval, or a racetrack.The DLS system of claim 11 or 12, wherein the air storage assembly (20) in the form of a substantially closed loop (21) comprises a plurality of concentric substantially closed loops.The DLS system of any preceding claim, wherein the air storage assembly (20) is installed in the ground.The DLS system of any preceding claim, wherein the DLS system is an adiabatic DLS system.

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