Adsorption enhanced compressed air energy storage

Abstract

A method of sorbent enhanced storage and release of compressed gas is disclosed. The method comprises the steps of providing a sorbent solid inside a pressurizable container; compressing a gas, preferably air, to provide a compressed gas. The method further comprises supplying the compressed gas to the sorbent in the pressurizable container and allowing the gas to be adsorbed onto the sorbent under pressure. The method further comprises storing the compressed gas in the pressurizable container and releasing the compressed gas and adsorbed gas from the pressurizable container to drive a mechanical device. An apparatus for storing and releasing compressed gas, a method of storing gas under pressure and a sorbent material composition are also disclosed.

Description

Technical Field

[0001] This invention generally relates to energy storage, such as storing electrical or pneumatic energy beyond immediate needs. For example, the storage preferably involves converting excess energy into potential energy in a pressurized gas and, as needed, converting the stored energy into alternative energy forms, such as electrical or pneumatic energy.

[0002] In a preferred embodiment, the storage preferably involves converting electrical energy into potential energy in a pressurized gas, and converting the stored energy back into electrical energy as needed. The present invention particularly relates to a system and method for storing electrical energy in the form of potential energy in a pressurized gas.

[0003] The invention may also relate to components and materials for such energy storage and release systems, such as advantageous storage media and storage media containers, release mechanisms, and energy conversion components.

[0004] The technologies discussed can be generally related to compressed air energy storage (CAES), and specifically to adsorption-enhanced CAES technology. Background Technology

[0005] Generators with a minimum output level (below which the unit cannot sustain operation), such as nuclear power plants, and generators with highly variable and unpredictable, intermittent output levels, such as wind, tidal, wave, and solar power, often generate more electricity than needed during off-peak hours and / or may provide insufficient electricity during peak hours. To utilize surplus or fluctuating electricity production, storage systems have been proposed to store electricity (in various forms) during periods of surplus generation or low off-peak demand (temporarily) for later release when demand is higher (i.e., electricity supply can be time-shifted through storage).

[0006] Effective energy storage can thus help reduce overall energy waste; and by acting as a buffer to reduce the unpredictability and intermittency of its output, it can promote the adoption of wind, solar, wave, or tidal energy systems as alternatives to traditional fossil fuel power generation. One goal is to achieve a flexible and reliable energy supply (mechanical, thermal, or electrical), despite the inherent unpredictability and intermittency of energy itself.

[0007] Unfortunately, current energy storage solutions are not well suited for grid-scale applications (electricity supply networks, such as the National Energy Grid) due to the use of unsustainable materials (e.g., limited material supply and limited recyclability of materials used in energy storage, such as batteries), short lifespans (e.g., less than 10,000 cycles), poor scalability (e.g., security risks or limited economies of scale for storage capacities exceeding 1 MWh), and geographical limitations (e.g., pumped hydro storage and compressed air storage).

[0008] Numerous attempts have been made to achieve sustainable energy storage solutions, encompassing chemical energy, gravitational potential energy, electrical potential energy, high-temperature thermal energy, latent heat, thermochemical heat, and kinetic energy. Examples have been reported in scientific and commercial literature. One known energy storage technology in this field is compressed air energy storage (CAES).

[0009] The empty space between particles in air and gas allows air or gas (hereinafter also referred to as "gas") to be compressed and confined in a pressurized container. This effectively stores potential energy (also called "energy potential") in the compressed gas, which is relative to the initial state of the gas or relative to ambient pressure (such as atmospheric pressure). This stored energy potential can be used as an energy buffer and decouples the pressurization of the gas from the subsequent conversion of the gas pressure into another form of energy to different points in time. For example, the energy potential at release can be used to generate electricity using an expander-generator, or to provide suitable fluid power, or any other type of mechanical power derived from the potential energy of the pressurized gas, for pneumatic tools such as paint spray nozzles, air guns, pneumatic actuators, vortex tubes (which can separate the pneumatic energy of compressed gas into hot and cold streams with different thermal energy levels), or any other pneumatic tool that can use air or gas streams as needed, such as wrenches, grinders, hammers, sanders, drills, nail guns / crack nail guns, ratchet, screwdrivers, actuators, etc.

[0010] CAES is an energy storage method that uses compressed air to store and release energy. In its preferred form, it can be implemented as a large-scale, grid-scale energy storage technology designed to balance power supply and demand, particularly in systems with significantly intermittent renewable energy sources such as wind and solar power. It can also be used on a smaller scale, for example, to provide electrical or fluid power, or any other type of mechanical power, to various devices at a factory site, or at the residential level.

[0011] A large buffer (i.e., capacity) is advantageous whether using a CAES system to power an expander-generator for electricity generation or to provide pressure energy for pneumatic tools. In the former (electric) example, a larger buffer can store more energy, which can then be converted into electricity as needed. In the latter example, a larger buffer increases the fluid capacitance in the pneumatic device and can meet higher peak demands while maintaining low peak power usage of the compressor. In the latter example, the storage can essentially be a highly efficient container for compressed gas, compressed from excess energy on the power grid.

[0012] In known CAES systems, increasing the buffer size means storing a larger mass of gas within the volume of a container (e.g., a gas cylinder or any type of gas canister). Traditionally, this is achieved by increasing the storage volume, increasing the storage pressure, and / or by changing the gas phase to a liquid state at significantly higher pressures or significantly lower temperatures. Storing gas as a liquid state allows for higher mass densities compared to the gaseous state. However, for many gases (e.g., nitrogen, oxygen, and carbon dioxide), this adds significant complexity due to their critical points being far removed from atmospheric conditions. For example, very high pressures or very low temperatures may be required, increasing the complexity and risks associated with the storage system. Alternatives to increasing the buffer size may require more space to accommodate a larger volume or more materials and complex handling to withstand higher pressure loads. These disadvantages limit the application of CAES systems and lead to larger pneumatic devices due to the increased size of the container tank. Furthermore, manufacturing gas containers capable of withstanding sufficiently high pressures and / or low temperatures and / or being properly designed is more expensive than manufacturing gas containers for medium pressures and / or temperatures. When designing such gas containers, the regulations that the gas container must comply with need to be considered. An example of such regulations is the European Parliament and Council Directive 2014 / 68 / EU, known as the "Pressure Equipment Directive." The higher the pressure, the greater the risk, and under such regulations, gas containers must meet more requirements, which in turn leads to higher design costs.

[0013] Adsorption (adsorption and desorption) surfaces can be used to increase the total mass density of gas stored in a given volume. In such methods, adsorbents (such as nanoporous materials) can be used to provide a pore framework that offers a (very) high surface area per volume and numerous adsorption sites. Within such a solid framework, in addition to the pressure energy stored by the storage container itself, intermolecular forces between gas molecules and the solid can be utilized. Therefore, a gas container with such a solid framework can store more air / gas than a gas container at the same pressure without a solid framework. In other words, including an adsorbent within the internal volume of a pressure vessel can help store a certain mass of gaseous material at a lower pressure, compared to a higher pressure would be required to store the same mass of gas in an internal volume without an adsorbent. Lower pressure means lower mechanical loads on the container walls while maintaining or allowing an increase in the mass of gas contained per unit volume. In turn, this approach can allow for reduced robustness of the storage container, such as the amount of material required, while still being able to store the same amount of gas. Similarly, this allows for storing more gas in the same storage container. Thus, greater buffering can be achieved without resorting to large volumes, extreme pressures, phase changes, or complex controls.

[0014] In principle, CAES systems can work with any compressible gas; however, in some cases, it is advantageous to use atmospheric air, primarily due to its availability rather than the need for specialized or expensive gases requiring special storage.

[0015] There are many types of adsorbent materials that have an affinity for air (such as nitrogen and oxygen), and attempts have been made to achieve adsorbent-enhanced CAES systems.

[0016] For example, porous zeolite materials (crystalline aluminosilicate minerals with a variety of unique porous structures) have been widely used and have found many applications in gas and air storage and selective gas filtration. Their high surface area and intricate channel networks are considered excellent candidates for gas adsorption and storage. Zeolites act as molecular sieves, selectively adsorbing molecules based on their size and polarity.

[0017] However, improvements to adsorption-enhanced CAES systems remain desirable. For example, it may be desirable to increase the capacity and / or efficiency of adsorption-enhanced CAES systems while maintaining or reducing pressure and / or temperature fluctuations involved in gas capture, storage, and release. For instance, the present invention may aim to reduce the buffer size in CAES systems by introducing improved techniques for adsorption-enhanced CAES. The present invention may also, or alternatively, seek to improve the adsorption properties of adsorption-enhanced CAES, for example, compared to current adsorption capacities.

[0018] US2013219892A1 discloses a compressed air energy storage module, including an integrated thermal energy storage and recovery device. It discloses a gas cylinder filled with particulate material that stores thermal energy and adsorbs air.

[0019] WO2015022633A1 discloses a vehicle that includes an adsorption storage for maintaining fuel reserves.

[0020] US2010133280A1 discloses a gas pressure vessel including a frame component comprising at least one porous metal-organic framework, the metal-organic framework comprising at least one bidentate organic compound coordinated with at least one metal ion. Summary of the Invention

[0021] To address the shortcomings of the prior art discussed above, a method for storing and releasing an adsorbent-enhanced compressed gas is proposed according to a first aspect of this disclosure. The method includes the steps of: providing an adsorbent solid (frame) inside a pressurizable container; and compressing, preferably, an air gas, to provide the compressed gas. The method further includes supplying the compressed gas to the adsorbent in the pressurizable container and causing the gas to adsorb onto the adsorbent under pressure. The method also includes storing the compressed gas in the pressurizable container and releasing the compressed gas and the adsorbed gas from the pressurizable container to drive a mechanical device. The mechanical device may be driven by the released gas to ultimately convert the potential energy of the pressurized gas into electrical, thermal, or mechanical energy (e.g., pneumatic or kinetic energy), hydrodynamic, or any other type of mechanical power, or any other form of energy conversion known in the field of compressed air energy storage (CAES) technology.

[0022] In an embodiment, preferably, the gas contained in the pressurized container is non-flammable and unsuitable for use as fuel. In a more preferred embodiment, the gas is suitable for driving pneumatic tools in a non-combustible manner.

[0023] In one embodiment of the above aspects, the adsorbent comprises a metal-organic framework.

[0024] In another embodiment of the above aspects, the metal-organic framework comprises a metal-organic framework (MOF) selected from Al-Fum (aluminum fumarate), HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from aluminum fumarate, HKUST-1, and / or MOF-177, and most preferably comprises aluminum fumarate.

[0025] In another embodiment of the above aspects, the metal-organic framework has an air adsorption capacity such that, in a pressure range of 5-100 bar, preferably 5-30 bar, and in a temperature range of 5-85°C, preferably 15-30°C, the density of adsorbed air is at least about twice the density of free air at the same ambient pressure and volume.

[0026] In another embodiment of the above aspects, the metal-organic framework has a water absorption of less than 0.25 g / g at a temperature of 5-85°C and a relative humidity of less than 25%; preferably, it has a water absorption of less than 0.05 g / g at a temperature of 5-85°C and a relative humidity of less than 25%.

[0027] In another embodiment of the above aspects, the gas is cooled using a cooler, heat exchanger, intercooler and / or precooler before being supplied to the adsorbent.

[0028] In another embodiment of the above aspects, the metal-organic framework has a pore volume / porosity of at least 0.4-2.5 cm3 / g, preferably 0.6-1.5 cm3 / g, and more preferably 0.8-1.3 cm3 / g.

[0029] In another embodiment of the above aspects, the metal-organic framework has a surface area of ​​at least 700 m² / g, more preferably at least 2000 m² / g, and even more preferably at least 3000 m² / g.

[0030] In another embodiment of the above aspects, the adsorbent comprises aluminum fumarate and / or aluminum particles, and / or a combination of different MOFs.

[0031] In another embodiment of the above aspects, the adsorbent comprises particles, powder, barrels, and / or granules.

[0032] In another embodiment of the above aspects, the adsorbent in particulate form comprises a thermally conductive binder, preferably wherein the binder has a higher thermal conductivity than the adsorbent.

[0033] In another embodiment of the above aspects, the thermally conductive adhesive comprises aluminum, graphene, and / or carbon nanotubes.

[0034] In another embodiment of the above aspects, supplying gas to the adsorbent includes supplying gas at a pressure of 5-100 bar.

[0035] In another embodiment of the above aspects, releasing the adsorbed gas to the mechanical device includes releasing the adsorbed gas at a pressure of 2 bar or higher.

[0036] In another embodiment of the above aspects, the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube, or an expansion valve.

[0037] In another embodiment of the above aspects, releasing the adsorbed gas to the mechanical device includes desorbing the adsorbed gas from the adsorbent.

[0038] In another embodiment of the above aspects, the desorption of gas from the adsorbent includes thermal desorption, such as by temperature fluctuations or electromagnetic radiation, and / or mechanical desorption, i.e. by mechanical disturbance, such as by applying pressure waves using air or other gases, by pressure fluctuations, and / or by ultrasonic technology.

[0039] In another embodiment of the foregoing, the gas comprises one of nitrogen, oxygen, carbon dioxide, air, and / or mixtures thereof.

[0040] To address any drawbacks of the prior art, a second aspect of this disclosure provides an apparatus for storing and releasing compressed gas, comprising: a compressor for compressing gas (preferably air), a storage unit in gas communication with the compressor, the storage unit including a pressurizable container having an internal volume containing an adsorbent for adsorbing the compressed gas, and a mechanical device in gas communication with the storage unit, the mechanical device being arranged to receive released compressed gas from the storage unit and thereby generate mechanical energy.

[0041] In one embodiment of the second aspect, the gas from the compressor is cooled by an intercooler or aftercooler before entering the storage unit, and the heat extracted therefrom is stored in the thermal energy storage unit.

[0042] In another embodiment of the second aspect, the storage unit comprises a metal can or a polymer (e.g., aramid), preferably having an external reinforcement (e.g., carbon fiber), and a metal can with substantially straight walls, such as a cuboid can or a cylindrical can.

[0043] In another embodiment of the second aspect, the storage unit further includes means for heat exchange, an intermediate heater, heat tracing lines and / or a preheater.

[0044] In another embodiment of the second aspect, the heat exchange apparatus is arranged to circulate a cold fluid or a hot fluid as heat is charged in and released, respectively.

[0045] In another embodiment of the second aspect, the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube or an expansion valve.

[0046] In another embodiment of the second aspect, the device further includes a thermal energy storage unit for storing thermal energy.

[0047] In another embodiment of the second aspect, the heat exchanger, intermediate heater, and / or preheater use heat extracted from thermal energy storage.

[0048] In another embodiment of the second aspect, the device is arranged to use excess electrical and / or thermal energy to drive the compressor and / or add heat to the thermal energy storage unit.

[0049] In another embodiment of the second aspect, the device is arranged to release compressed gas from a storage tank filled with adsorbent and extract heat from a thermal energy storage unit to convert it into mechanical energy, and may further convert it to deliver electrical and / or thermal energy to an external load.

[0050] To address any drawbacks of the prior art, a third aspect of this disclosure provides a method for storing a gas under pressure, comprising the steps of: compressing the gas, preferably to 5-100 bar; supplying the compressed gas to a sealable container in which an adsorbent material is provided; and causing the compressed gas to adsorb onto the adsorbent.

[0051] In one embodiment of the third aspect, the method further includes at least one of the following steps: storing the gas for a limited period of time; and / or releasing the adsorbed gas to drive a turbine to generate electricity.

[0052] In another embodiment of the third aspect, the compressed gas in the sealable container is heated using a heat exchanger, intermediate heater, and / or preheater provided before or inside the storage unit.

[0053] To address any shortcomings of the prior art, a third aspect of this disclosure provides an adsorbent material composition comprising: a metal-organic framework (MOF) adsorbent and a thermally conductive material.

[0054] In one embodiment of the third aspect, the MOF is selected from Al-Fum (aluminum fumarate), HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from aluminum fumarate, HKUST-1, and / or MOF-177, and most preferably contains aluminum fumarate.

[0055] In another embodiment of the third aspect, the thermally conductive material is a binder material that has a higher thermal conductivity than MOF and binds the particles of MOF material together.

[0056] In another embodiment of the third aspect, the adsorbent material is provided in particulate form, comprising an MOF adsorbent and a thermally conductive binder.

[0057] In another embodiment of the third aspect, the MOF is mixed or blended with a solid material having higher thermal conductivity.

[0058] In another embodiment of the third aspect, the thermally conductive material comprises aluminum. Attached Figure Description

[0059] The embodiments will now be described by way of example only with reference to the accompanying schematic diagrams, in which corresponding reference numerals denote corresponding parts, wherein:

[0060] Figure 1 The apparatus and method for storing and releasing compressed air are shown;

[0061] Figure 2 The water absorption properties of aluminum fumarate and zeolite-13X were demonstrated;

[0062] Figure 3 The water absorption and dehydration properties of aluminum fumarate and zeolite-13X were demonstrated;

[0063] Figure 4 The pore size distribution of aluminum fumarate is shown. Detailed Implementation

[0064] Certain embodiments will be described in more detail below. However, it should be understood that these embodiments should not be construed as limiting the scope of this disclosure.

[0065] CAES (Cyber-Based Energy Storage) comprises energy storage and release steps. Storing surplus electricity can be advantageous during periods of overproduction (e.g., when (renewable) energy generation exceeds demand). The stored surplus energy can then be released when electricity demand increases or (renewable) energy generation decreases. While many energy storage and release methods exist, the most significant advantage of CAES systems is their potential for large-scale and long-term energy storage. CAES is particularly well-suited for providing grid-scale energy storage solutions.

[0066] CAES can also be designed for small-scale energy storage, such as home-scale energy storage.

[0067] In its simplest form, energy storage in a CAES system involves using surplus electrical energy to drive a compressor that compresses air. This compressed air is then stored in a container, underground cavern, depleted natural gas field, or a specially constructed above-ground container. After storage, the compressed air can be released and used to drive mechanical units that convert the generated mechanical energy back into electrical energy.

[0068] As previously mentioned, including an adsorbent in the storage volume of a compressed container or gas tank increases the available buffer space in the container used to store compressed air; that is, the mass of gas contained in a given volume at a given temperature and pressure can be increased compared to a volume without an adsorbent. To maximize the effect of adsorption in compressed air storage, it is preferable to optimize the intermolecular interactions between the compressed air (adsorbate) and the adsorbent (adsorbent). To achieve this, the adsorbent preferably has a high affinity for compressed air (which is mainly composed of nitrogen and oxygen).

[0069] It has been recognized that zeolites used in CAES systems are known to effectively adsorb nitrogen and oxygen, and are generally effective. However, it has been recognized that the lifetime of zeolites in repeated adsorption and desorption cycles in atmospheric air may be limited, as is their ability to desorb gases under mild temperature conditions.

[0070] Through research, and without being bound by theory, it has been recognized that the adsorption sites in known zeolites may preferentially adsorb water (vapor) rather than nitrogen and oxygen, and that desorption of water from the zeolite surface requires a high energy input to heat the zeolite to remove moisture.

[0071] In this way, it has been recognized that a drawback of current CAES systems using zeolite adsorbents is their limited lifespan, or the high energy requirements for zeolite readjustment. As mentioned above, the moisture absorption-release of zeolite is believed to significantly impact its overall performance. Zeolites typically have a high affinity for water, even at low pressures, causing water vapor present in atmospheric air to preferentially occupy adsorption sites at ambient pressures and block sites available for air adsorption. This may be particularly concerning for practically usable CAES systems using atmospheric air as the compressible gas, as atmospheric air typically contains at least some humidity. While this concern can be addressed by drying the air to a low humidity level before compression, such a step would be energy-intensive and therefore detrimental to efficiency. Similarly, using specialized purified gases can address this issue, but it is generally not (cost-effective) efficient.

[0072] This problem can be partially mitigated by pressure fluctuation desorption, which optimizes the desorption process by controlling the pressure. However, very low pressures are required to remove water from the occupied sites. This often poses a problem, considering that the air stored in a CAES system should ultimately be released at the minimum permissible pressure (e.g., for conversion to mechanical energy using an expander or pneumatic motor). Alternatively, temperature fluctuation desorption can be used, which optimizes the desorption process by controlling the temperature. However, this also often poses a problem, as the temperature required for complete dehydration of common zeolites can be as high as 200°C. This, in turn, leads to increased energy consumption and reduced storage and release efficiency.

[0073] To maximize adsorption in CAES, the gas selectivity of the adsorbent is preferably suited to the gas used as the storage gas. However, contaminants may exhibit a higher affinity for the adsorbent, causing them to fill the pores, which are then no longer usable for adsorbing the target gas (nitrogen and oxygen). This is not necessarily a problem, as long as the contaminants can contribute to the energy conversion after desorption. However, if these contaminants are not (completely) desorbed after storage, the pores they occupy will remain occupied in subsequent cycles. This further reduces the adsorption capacity of the adsorbent after each cycle, which is undesirable. Therefore, it is necessary to mitigate the interaction between the adsorbent and any possible contaminants: all adsorbed substances should preferably also be readily desorbable.

[0074] The high affinity between compressed air and the adsorbent implies that this interaction preferably has a high heat of adsorption, which is an indicator of the strength of their interaction. In characterizing materials, this is represented by analyzing the isothermal heat of adsorption obtained at different temperatures. Furthermore, to improve the reversible adsorption process, adsorption should involve only physisorption. This means utilizing weaker intermolecular interactions that are more easily reversed, rather than stronger covalent or ionic bonds. Therefore, the main phenomenon leading to a high isothermal heat of adsorption is the combination of highly attractive van der Waals forces between the gas and solid. High van der Waals forces minimize the external force required to fill the adsorbent pores with gas, resulting in higher adsorption capacity at lower gas storage pressures. For adsorbent materials, a high isothermal heat of adsorption is preferred.

[0075] However, similar to the condensation / evaporation equilibrium of liquid levels, the equilibrium point of adsorption is always determined by the balance between adsorption and desorption. This means that high adsorption is associated with low desorption. Therefore, when adsorption or desorption is desired, the operating conditions are preferably changed to shift the equilibrium point to the desired location. In cases where compressed air storage ultimately converts into mechanical energy, desorption conditions can advantageously occur at mild pressure levels. For example, if desorption requires vacuum pressure (e.g., below ambient atmospheric pressure), the gas is less suitable for CAES because it requires repressurization, which contradicts the goal of providing an efficient energy buffer.

[0076] The equilibrium point of adsorption is influenced by molecular statistics. There are X pores on the solid available for adsorption, and Y gas molecules that might fit into the pores. To increase the chances of gas molecule adsorption, the number of possible interactions between the gas and the solid can be increased. This can be achieved by increasing the pressure. Furthermore, high molecular vibrations can make adsorption more difficult because they can overcome van der Waals forces. This means that lower temperatures (and generally lower system vibrations) will also facilitate easier adsorption. For desorption, the opposite conditions are preferred: low pressure and high temperature.

[0077] However, these conditions only affect the steady-state conditions of the CAES. Preferably, the addition of adsorbent does not affect the ability to charge or vent the gas storage at any desired mass flow rate. This means that adsorption kinetics also need to be considered. This can be improved using more extreme pressure and temperature fluctuations, but this is not always desirable because they may require additional complexity or energy input to achieve.

[0078] By employing temperature variations during the charging (adsorption) and de-energizing (desorption) phases, the adsorption process can be optimized to achieve a better balance between adsorption capacity and desorption energy requirements. Typically, lower temperatures are required during adsorption, and higher temperatures are required during desorption. Heating and cooling of the contents of the storage unit can be achieved by utilizing thermal energy storage in parallel with compressed air storage. The heat source required for this temperature rise can be recovered from the heat of compression, which aligns with the desired temperature fluctuations (i.e., cooling for adsorption and heating for desorption). This can be achieved by utilizing thermal energy storage in parallel with gas storage.

[0079] However, the second law of thermodynamics ensures that the temperature achievable before expansion cannot exceed the temperature generated during compression (without involving any external heat source). This problem can be solved by: (i) using adiabatic compression with the fewest possible stages to generate the highest possible heat of compression. This maximizes the usable energy value of the thermal energy storage; or (ii) using quasi-isothermal compression or multi-stage compression with multiple stages and intercoolers and / or aftercoolers. In practice, option (ii) seems most realistic because many compressors are limited in their ability to generate high temperatures to avoid damaging their sealing materials and lubricants. However, for energy storage applications (such as CAES), option (i) is more advantageous because it can take advantage of the high energy density of the thermal energy storage material at elevated temperatures, as well as the faster response resulting from the higher desorption rate caused by more extreme temperature fluctuations.

[0080] Temperature fluctuations can be achieved by heating the gas, the adsorbent, or both using a heat exchanger. This can be done upstream of the gas storage tank or inside the tank. The time required for either of these elements to reach the desired temperature depends on the heat transfer coefficient of the heat exchanger and the thermal conductivity of the adsorbent material.

[0081] A higher heat transfer coefficient can typically be achieved by increasing the heat transfer contact area and / or by utilizing some form of mass flow (such as a fan or agitator) next to that area.

[0082] Alternatively, the heat transfer coefficient of the adsorbent material can be increased. One way to improve the overall heat transfer rate inside a gas storage tank is to mix, blend, or combine the adsorbent material with a (more) thermally conductive material. For example, the adsorbent material can be combined with a binder material having higher thermal conductivity. For example, this material can be provided in particulate form of adsorbent and thermally conductive binder. That is, the binder has a higher thermal conductivity heat transfer coefficient than the adsorbent material.

[0083] Alternatively, the adsorbent can be mixed with different solid materials that have high thermal conductivity. For example, aluminum (or other highly thermally conductive and generally inert materials) particles or debris can be dispersed in the adsorbent material.

[0084] A heat exchanger (e.g., with coils or parallel pipes, finned or unfinned) may also be provided in the gas storage tank, and temperature fluctuations can be applied by a hot fluid flowing through the heat exchanger. This heat exchanger can be used to capture the sensible heat released during gas adsorption and / or to provide sensible heat for gas desorption.

[0085] One way to apply temperature fluctuations before compressed air is stored in the storage unit is to use a cooler after the air is compressed. This cooler is arranged to cool the gas before it enters the gas storage tank containing the adsorbent. In this way, the cooler will also indirectly cool the adsorbent, and the overall temperature of the storage unit will reach approximately the weighted average of the compressed air temperature and the adsorbent temperature.

[0086] Similarly, finding the optimal pressure fluctuation mechanism can significantly improve the efficiency of adsorption-enhanced CAES. It allows for effective control of the adsorption and desorption processes, ensuring a proper balance between adsorption capacity and the energy required for desorption. Pressure fluctuations can be achieved by compressing the gas at a higher pressure before storage and then expanding it at a lower pressure after storage. However, as mentioned earlier, this can result in energy consumption per unit mass of gas exceeding the energy recoverable during post-storage energy conversion. The compressed pressure must at least reach the storage pressure. The storage pressure in the adsorption-enhanced gas storage container should be the pressure that maximizes the mass of gas stored within that container. This can only be achieved within a pressure range where the equivalent gas density (i.e., the sum of adsorbed and non-adsorbed molecules per unit storage volume) is higher than the gas density in the same container without adsorbent. Otherwise, the additional storage capacity introduced by the adsorbent cannot overcome the additional volume it occupies, making the addition counterproductive.

[0087] Another property that can be optimized to improve adsorption kinetics and influence gas / solid interactions is the shape of the adsorbent (surface area and / or pore volume) and the size of the gas molecules. For faster kinetics, gas molecules ideally need to be able to easily pass through the material's framework and reach the pores, and the pore size should ideally be very close to the size of the gas molecules so that they can fit optimally inside, and van der Waals forces can attract molecules from multiple angles.

[0088] Besides temperature and pressure fluctuations, other measures can be used to increase molecular vibrations with macroscopic forces (e.g., collisions with other molecules, pressure waves, or electromagnetic perturbations). These forces can be tuned for the combination of adsorbent and adsorbed gas. In the case of collisions with other molecules, they preferably do not displace molecules “knocked out” from occupied sites. Therefore, the possibility of adsorption should be minimized in this case. In the case of pressure waves and electromagnetic perturbations, their amplitude and frequency can be tuned to the adsorbed gas molecules. For example, perturbing them at the resonant frequency of the gas molecules may be most advantageous.

[0089] Forced collisions with other molecules can be achieved by injecting pressurized gas into a gas storage tank, effectively knocking the adsorbed molecules out of their adsorption sites. The more molecules adsorbed, the greater the chance of collisions, thus amplifying the perturbation effect. Ideally, the pressurized gas is identical to the adsorbed gas, eliminating the need for separation and allowing storage in a secondary gas storage container.

[0090] Figure 1 A device 100 for storing and releasing compressed air is shown. As input, device 100 may include an air supply source 101. Air supply source 101 primarily comprises oxygen and nitrogen and may be supplied from atmospheric air or an external air tank. Air supply source 101 may also include filters, such as chemical filters, particulate filters, HEPA filters, coalescing filters, activated carbon filters, adsorption filters, electrostatic filters, and / or filters using ultraviolet light. The air may be (partially) dried to reduce or remove water vapor; that is, there may be steps to reduce the air humidity to a desired level.

[0091] The device 100 also includes a compressor 102 arranged to convert mechanical energy into compressed air 104. The compressor 102 receives an air supply source 101 and compresses it into compressed air 104. The compressor 102 may be driven by (excess) electricity. The compressor 102 can be of any type, such as a reciprocating compressor (e.g., a piston compressor), a rotary screw compressor, a scroll compressor, a centrifugal compressor, an axial compressor, a diaphragm compressor, and / or a vane compressor. After compression by the compressor 102, the compressed air 104 preferably has a pressure at which the air density remains less than or equal to the equivalent density of the air in the storage unit 105 containing the adsorbent at equilibrium. Preferably, this pressure ranges from 5 to 100 bar, more preferably between 5 and 30 bar. All pressures described herein are absolute pressures, meaning pressure relative to zero pressure in a vacuum, airless space.

[0092] Compressed air 104 can be stored in storage unit 105. Storage unit 105 is arranged to store compressed air 104 by encapsulating it in a container, such as a sealable container, canister, metal canister, inflatable polymer (e.g., aramid with carbon fiber external reinforcement), a metal canister with substantially straight walls, such as a cuboid or cylindrical canister, an underground cavern, a depleted natural gas field, and / or any other container capable of withstanding the pressure exerted by the compressed air 104. Storing, supplying, and / or adsorbing compressed air into storage unit 105 may also include controlling pressure and / or temperature to maintain a certain level or curve.

[0093] Storage unit 105 may also be arranged to store adsorbent 125. Device 100 includes adsorbent 125 arranged for adsorbing compressed air. Adsorbent 125 may comprise nanoporous materials, zeolites (e.g., zeolite 13X), activated carbon, silica (aero)gels, carbon nanotubes, porous polymers, preferably metal-organic frameworks (MOFs), such as Al-Fum (aluminum fumarate), HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66. In addition to their affinity for air, the aforementioned MOFs are particularly well-suited as adsorbents in CAES systems employing moist gases (e.g., atmospheric air) because they address one or more of the following issues: (i) other gaseous compounds (e.g., water vapor) compete with nitrogen or oxygen for adsorption sites at low pressures (making desorption difficult due to pressure fluctuations) or high temperatures (making desorption difficult due to temperature fluctuations), i.e., selective affinity for air becomes important; (ii) the large-scale production of adsorbents depends on the availability of their components (e.g., ligands) and synthetic routes that provide high yields at low cost; and (iii) the lack of stability of adsorbents under high mechanical and thermal stress. The aforementioned MOFs address one or more of these constraints and are excellent air adsorbents. For example, compared to zeolites, known MOFs (e.g., aluminum fumarate) are less prone to saturation by water molecules at lower pressures and desorb water molecules at relatively faster rates at lower temperatures.

[0094] Compared to zeolites, further advantages of using MOFs (such as Al-Fum) include: i) low cost associated with the use of potentially renewable dicarboxylic acid linkers and abundant metal cations (e.g., aluminum); ii) good water, mechanical, and thermal stability; iii) environmentally friendly synthetic routes involving only water and simple aluminum salts, with chemical linkers available from renewable biomass; iv) large-scale production with a record space-time yield of 3,600 kg / m³ / day; and v) large pore volume (0.65 cm³ / g) and surface area (1100 m² / g). Al-Fum, in particular, exhibits excellent tunability in properties such as porosity, surface area, and thermal conductivity. This combination of qualities, along with its excellent affinity for nitrogen (a major component of air), makes MOFs, especially Al-Fum, ideally suited for air adsorption in compressed air energy storage systems.

[0095] Adsorbent 125 may comprise powder, cartridges, and / or granules. Granules are understood to be adsorbent blocks or flakes with a maximum space size of no more than 3 cm, preferably 2 cm, most preferably 3 cm, and greater than at least 50 micrometers, such that the adsorbent is blocked by a compressed air filter. Alternatively, adsorbent 125 may comprise such a form with a thermally conductive binder. When Al-Fum is used as the adsorbent, adsorbent 125 may comprise a mixture of aluminum fumarate and aluminum, and / or a combination of different MOFs. When MOF is used as the adsorbent, adsorbent 125 preferably has an air adsorption capacity such that, in a pressure range of 5-100 bar (preferably 5-30 bar) and a temperature range of 5-85°C (preferably 15-30°C), the density of adsorbed air is at least twice greater than the density of free air at the same pressure. The adsorbent should also have a low water absorption capacity at low pressure (less than 30 cm³ at a maximum of 5 bar). 3 / g), and high water desorption kinetics (complete desorption time less than 20 minutes at 40% relative humidity and 65°C). Storage unit 105 is also arranged to store adsorbed air, i.e. compressed air that has been adsorbed by adsorbent 125.

[0096] The temperatures of the compressed air 104 and adsorbent 125 inside the storage unit 105 can be controlled by an internal heat exchanger 106, which may include coils or parallel tubes (finned or unfinned) for exchanging heat between the contents of the storage unit 105 and the hot fluid inside the heat exchanger 106. The heat exchanger 106 or any other heat exchange device is arranged to circulate either a cold or hot fluid as heat is charged and released, respectively.

[0097] The contents of storage unit 105 can be stored indefinitely, or until energy output is required, which can be in the form of mechanical energy or further converted into electrical energy. If energy output is required, the adsorbed air inside storage unit 105 can be desorbed, and / or compressed air 107 can be released from storage unit 105. Releasing, de-supplying, and / or desorbing compressed air from storage unit 105 may also include controlling pressure and / or temperature to maintain a certain level or curve. The released compressed air 107 preferably has a pressure of at least 2 bar.

[0098] The device 100 may also include a heat exchanger 108 arranged to control the temperature of the compressed air 109. Once controlled by the heat exchanger 108, the compressed air 109 preferably has a temperature of approximately room temperature (10-30°C).

[0099] The device 100 may also include a mechanical device 110 arranged to convert compressed air into mechanical energy. The mechanical device 110 may include a pneumatic motor, a turbine, an expander, a thermodynamic converter (e.g., a vortex tube), an expansion valve, and / or any other pneumatic actuator capable of converting compressed air into mechanical energy.

[0100] As previously described, storing, supplying, and / or adsorbing compressed air into and from storage unit 105, as well as releasing, de-supplying, and / or de-adsorbing compressed air from storage unit 105, may also include controlling pressure (through mechanical disturbances that generate pressure waves by using air or other gases, through pressure fluctuations, and / or through ultrasound) and / or temperature (through temperature fluctuations or electromagnetic radiation) to maintain a certain level or curve.

[0101] Pressure control can be achieved using sonication, which involves manipulating particles within storage unit 105 using ultrasound. While it may not directly and uniformly control pressure, it can influence the movement and distribution of particles or fluid, thereby locally affecting pressure. This can create pressure waves that facilitate the release, desiccation, and / or desorption of compressed air from storage unit 105. To achieve this, storage unit 105 may also include means for transmitting ultrasound, such as transducers, energy and / or frequency control units.

[0102] Control of storage and / or release pressure can be achieved by separately controlling the flow rates of compressed air storage and / or release. Temperature control during the storage, supply, and / or adsorption of compressed air into and from storage unit 105, as well as the release, desupply, and / or desorption of compressed air from storage unit 105, can be achieved by operating heat exchanger 106. Heat exchanger 106 can be arranged to heat and / or cool storage unit 105 using inflow 124.

[0103] The device 100 may also include a thermal energy storage unit 117, which may include one or more tanks, metal tanks, inflatable polymers (e.g., aramid with carbon fiber external reinforcement), metal tanks with substantially straight walls, such as cuboid or cylindrical tanks, underground caverns, depleted natural gas fields, and / or any other insulated container capable of storing the thermal energy generated by the device 100. The thermal energy storage unit 117 may include one or more heat exchangers, such as first and second heat exchangers 116 and 121, which may be housed in a single compartment or multiple different compartments within the thermal energy storage unit 117. Given that the device 100 may include multiple compressors and requires compressed air to flow and be stored at specific temperatures, the thermal energy storage unit 117 may be arranged to store and release heat at certain locations within the device 100.

[0104] One such location where heat can be released to and / or stored is a storage unit 105. Storage unit 105 may include a heat exchanger 106 connected via an inflow stream 124 to a second heat exchanger 121 located within a thermal energy storage unit 117. Heat stored within the thermal energy storage unit 117 can be exchanged to the second heat exchanger 121, which then exchanges its heat with the heat exchanger 106 located within the storage unit 105 via the inflow stream 124. Furthermore, heat exchanger 106 may be arranged to release heat to the storage unit 105. Conversely, heat exchanger 106 may be arranged to exchange heat generated within the storage unit 105 to the second heat exchanger 121 via an outflow stream 113. The outflow stream 113 (liquid or gas) may be pressurized by a circulation device 120 before reaching the second heat exchanger 121. Heat generated by the circulation device 120 may also be stored within the thermal energy storage unit 117 using one or more heat exchangers. Although the inflow 124 provides heat to the storage unit 105, the temperature of the inflow 124 can also be lower than the temperature of the storage unit 105 (its contents), thereby essentially cooling the storage unit 105 (its contents).

[0105] Another source of heat within device 100 is generated by a compressor, pump, motor, or generator (e.g., used in devices 102, 110, 114, and / or 120). This heat can be reused within device 100 by storing it in a thermal energy storage unit 117 and releasing it to a heat exchanger 106 located in storage unit 105. Compressor 102 is arranged to convert mechanical energy into compressed air 104, which can be coupled to heat exchanger 103. The heat generated by compressor 102 can be exchanged to heat exchanger 103, which transfers the heat to first heat exchanger 116 via outflow 118. Similar to second heat exchanger 121, first heat exchanger 116 is located within thermal energy storage unit 117. The heat exchanged to first heat exchanger 116 via outflow 118 can be released and stored in thermal energy storage unit 117. The heat stored within thermal energy storage unit 117 can then be used, for example, to heat the contents of storage unit 105 to achieve temperature fluctuations during desorption. Once the first heat exchanger 116 releases heat to the thermal energy storage unit 117, new heat can be captured at the compressor 102 via the inflow stream 115. The inflow stream 115 can first be pressurized by the circulation device 114 to obtain the inflow stream 112. The inflow stream 112 then uses the heat exchanger 103 to capture the heat generated by the compressor 102 and transport it back to the first heat exchanger 116.

[0106] Given that adsorption typically requires low temperatures, compressor 102 may also include an intercooler and / or aftercooler to reduce the temperature of compressed air 104. Heat extracted using, for example, an intercooler or aftercooler can be stored in thermal energy storage unit 117 or any other storage unit for storing thermal energy. The cold source providing this cooling energy can be from a low-temperature region within thermal energy storage unit 117, which can be regenerated by any preheater, intermediate heater, or afterheater located upstream, inside, or downstream of expansion device 110. Alternatively, an external cold source can provide additional cooling before the inflow stream 112 to further reduce the temperature of compressed air 104. Another option for further reducing the temperature of compressed air 104 is to introduce an externally powered cooler upstream of storage tank 105.

[0107] Certain types of mechanical devices 110 cannot operate with compressed air outside a certain temperature range; that is, an inlet temperature that is too low may cause ice to form inside the device due to a temperature drop associated with expansion. This is why device 100 may also include a heat exchanger 108, arranged to further control the temperature of the compressed air 107. To control the temperature of the compressed air 107, heat exchanger 108 uses an inflow flow 122 from a second heat exchanger 121 located inside the thermal energy storage unit 117. Furthermore, heat exchanger 108 uses an outflow flow 123 to release heat energy to the second heat exchanger 121, which in turn releases and / or stores heat energy to the thermal energy storage unit 117.

[0108] In the illustrated apparatus 100, a method 199 for storing and releasing compressed air is also provided, comprising the steps of: i) providing an adsorbent 125, ii) supplying air 104 to the adsorbent 125, and iii) releasing the adsorbed air to a mechanical device 110. Apparatus 100 and method 199 may use a gas selected from nitrogen, oxygen, carbon dioxide, and / or mixtures thereof instead of compressed air. Furthermore, each of these gases (including air) may contain a certain amount of water vapor.

[0109] Figure 2 The water absorption properties of aluminum fumarate and zeolite-13X are shown. For example... Figure 2 As shown, zeolite 13X has a high affinity for water even at low pressure, which causes water vapor to fill the pores at ambient pressure and block sites that can be used for air adsorption.

[0110] Therefore, it has been recognized that although zeolite 13X is a good air adsorbent and has been used in the prior art, its moisture absorption-release can lead to performance problems. Unintentionally, very low pressures are required during desorption to remove water from the occupied sites. Given that the stored air is preferably used at minimal pressure to simplify operations, such as for converting energy to mechanical energy using an expander or pneumatic motor, this can detrimentally lead to the use of temperature fluctuations for complete dehydration, which, for zeolite 13X, may be at least as high as 200°C. This, in turn, results in greater energy consumption and reduced storage and release efficiency. Figure 2 Furthermore, it was found that some MOFs, such as Al-Fum, have a much weaker affinity for water vapor at lower pressures.

[0111] Figure 3 (a) shows the water absorption properties of aluminum fumarate and zeolite-13X at 20%, 30%, and 40% relative humidity (RH). The adsorbent material was completely dehydrated prior to adsorption. From Figure 3 (a) It can be seen that at low RH, the amount of water adsorbed by Al-Fum is very low (almost negligible) compared to zeolite 13X. Furthermore, the adsorption kinetics (or adsorption rate) of Al-Fum is much slower than that of zeolite-13X. Therefore, even from a kinetic perspective, there may be more sites available for air adsorption on the Al-Fum surface.

[0112] Figure 3 (b) shows the dehydration characteristics of aluminum fumarate and zeolite-13X at 20%, 30%, and 40% relative humidity and at temperatures of 65°C, 85°C, and 120°C, with 0% RH. The adsorbent material was saturated at 30°C and 40% RH prior to desorption. Zeolite-13X exhibited significantly slower desorption kinetics. Even at 120°C, none of the adsorbed water molecules were desorbed or removed after 100 minutes.

[0113] In methods involving the adsorption of air (especially atmospheric air) (such as method 199 illustrated), the supply air for compression can be adjusted to have a relative humidity of less than 40%, preferably less than 35%, less than 30%, less than 25%, less than 20%, and most preferably less than 20% under supply position conditions. The method may include a step of drying the incoming air prior to adsorption, for example by heating or drying.

[0114] Figure 4The pore size distribution of aluminum fumarate is shown. It can be observed that Al-Fum is primarily microporous with a slight mesoporous component. The pore size distribution of metal-organic frameworks is typically microporous (pore size up to 2 nm) and includes some mesoporous components (pore size from 2 nm to a maximum of 50 nm). This is particularly advantageous for adsorbing air molecules because: i) micropores have a small diameter, providing a large surface area per unit volume. They are very efficient at adsorbing smaller molecules such as nitrogen. Adsorbents with micropores ensure that a significant portion of the surface area is available for adsorption, thus enhancing the overall adsorption capacity; and ii) mesopores allow gas molecules to diffuse efficiently into deeper parts of the adsorbent structure during adsorption and, for the same reason, allow for rapid desorption, resulting in a well-balanced adsorption process.

[0115] The surface area of ​​the adsorbent can be measured using the Brunauer-Emmett-Teller (BET) method, specifically according to ISO 9277:2022. Pore volume and pore size distribution can be measured according to ISO 15901-2:2022. Water absorption can be measured using thermogravimetric analysis (TGA) or dynamic vapor adsorption (DVS) techniques.

[0116] For water absorption measurements, prior to adsorption measurements in thermogravimetric analysis (TGA), the material can be activated under a dry nitrogen stream at 150°C (for metal-organic frameworks) and 300°C (for zeolite 13X) until the sample mass stabilizes for at least one hour. After activation, the sample is cooled to 30°C under a dry nitrogen stream. Adsorption measurements are initiated immediately upon reaching 30°C. The temperature is maintained constant at 30°C during adsorption, and the relative humidity can be adjusted by varying the appropriate ratio of the drying and humidifying nitrogen streams. The mass change measured by a microbalance in the TGA is the mass of adsorbed water vapor.

[0117] In the following text, numbered items define embodiments of the present invention.

[0118] Item 1. A method for storing and releasing an adsorbent-enhanced compressed gas, comprising the following steps:

[0119] i) Provide adsorbent solids inside a pressurized container;

[0120] ii) The gas is preferably compressed air to provide compressed gas;

[0121] iii) Supplying the compressed gas to the adsorbent in the pressurizable container and allowing the gas to be adsorbed onto the adsorbent under pressure;

[0122] iv) Storing the compressed gas in a pressurizable container; and

[0123] v) Release the compressed gas and adsorbed gas from the pressurizable container to drive the mechanical device.

[0124] Item 2. The method according to Item 1, wherein the adsorbent comprises a metal-organic framework.

[0125] Item 3. The method according to Item 2, wherein the metal-organic framework comprises a metal-organic framework (MOF) selected from Al-Fum (aluminum fumarate), HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from aluminum fumarate, HKUST-1, and / or MOF-177, and most preferably comprises aluminum fumarate.

[0126] Item 4. The method according to any one of items 2-3, wherein the metal-organic framework has the following air adsorption capacity: in a pressure range of 5-100 bar, preferably 5-30 bar, and in a temperature range of 5-85°C, preferably 15-30°C, the density of adsorbed air is at least about 2 times greater than the density of free air at the same ambient pressure and volume.

[0127] Item 5. The method according to any one of items 2-4, wherein the metal-organic framework has a water absorption of less than 0.25 g / g at a temperature of 5-85°C and a relative humidity of less than 25%; preferably, it has a water absorption of less than 0.05 g / g at a temperature of 5-85°C and a relative humidity of less than 25%.

[0128] Item 6. The method according to any one of items 2-5, wherein the gas is cooled using a cooler, heat exchanger, intercooler and / or precooler before being supplied to the adsorbent.

[0129] Item 7. The method according to any one of items 2-6, wherein the metal-organic framework has a length of at least 0.4-2.5 cm. 3 / g, preferably 0.6-1.5 cm 3 / g, more preferably 0.8-1.3 cm 3 / g pore volume / porosity.

[0130] Item 8. The method according to any one of items 2-7, wherein the metal-organic framework has a diameter of at least 700 m. 2 / g, more preferably at least 2000 m 2 / g, more preferably at least 3000 m 2 / g of surface area.

[0131] Item 9. The method according to any one of items 1-8, wherein the adsorbent comprises aluminum fumarate and / or aluminum particles, and / or a combination of different MOFs.

[0132] Item 10. The method according to any one of items 1-9, wherein the adsorbent comprises particles, powder, cartridges and / or granules.

[0133] Item 11. The method according to Item 10, wherein the adsorbent in particulate form comprises a thermally conductive binder, preferably wherein the binder has a higher thermal conductivity than the adsorbent.

[0134] Item 12. The method according to Item 11, wherein the thermally conductive adhesive comprises aluminum, graphene, and / or carbon nanotubes.

[0135] Item 13. The method according to any one of items 1-12, wherein supplying gas to the adsorbent comprises supplying gas at a pressure of 5-100 bar.

[0136] Item 14. The method according to any one of items 1-13, wherein releasing the adsorbed gas to the mechanical device comprises releasing the adsorbed gas at a pressure of 2 bar or higher.

[0137] Item 15. The method according to any one of items 1-14, wherein the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube, or an expansion valve.

[0138] Item 16. The method according to any one of items 1-15, wherein releasing the adsorbed gas to the mechanical device comprises desorbing the adsorbed gas from the adsorbent.

[0139] Item 17. The method according to Item 16, wherein the gas desorbed from the adsorbent includes thermal desorption, such as by temperature fluctuation or electromagnetic radiation, and / or mechanical desorption, i.e. by mechanical disturbance, such as by applying pressure waves using air or other gases, by pressure fluctuation and / or by ultrasonic technology.

[0140] Item 18. The method according to any one of items 1-17, wherein the gas comprises one of nitrogen, oxygen, carbon dioxide, air, and / or a mixture thereof.

[0141] Item 19. An apparatus for storing and releasing compressed gas, comprising:

[0142] i) A compressor for compressing gases, preferably air;

[0143] ii) A storage unit in communication with the compressor gas, the storage unit comprising a pressurizable container having an internal volume containing an adsorbent for adsorbing the compressed gas; and

[0144] iii) A mechanical device in gas communication with the storage unit, the mechanical device being arranged to receive released compressed gas from the storage unit and thereby generate mechanical energy.

[0145] Item 20. The apparatus according to Item 19, wherein the gas from the compressor is cooled by an intercooler or aftercooler before entering the storage unit, and the heat extracted therefrom is stored in the thermal energy storage unit.

[0146] Item 21. The device according to any one of items 19-20, wherein the storage unit comprises a metal can or a polymer, such as aramid, preferably having an external reinforcement (e.g., carbon fiber), and a metal can having substantially straight walls, such as a cuboid can or a cylindrical can.

[0147] Item 22. The device according to any one of items 19-21, wherein the storage unit further comprises means for heat exchange, an intermediate heater, heat tracing lines and / or a preheater.

[0148] Item 23. The apparatus according to Item 22, wherein the means for heat exchange is arranged to circulate a cold fluid or a hot fluid when heat is charged in and released, respectively.

[0149] Item 24. The device according to any one of items 19-23, wherein the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube or an expansion valve.

[0150] Item 25. The device according to any one of items 19-24, wherein the device further comprises a thermal energy storage unit for storing thermal energy.

[0151] Item 26. The apparatus of Item 25, wherein the heat exchanger, intermediate heater and / or preheater use heat extracted from thermal energy storage.

[0152] Item 27. The device according to any one of items 19-26, wherein the device is arranged to use excess electrical energy and / or thermal energy to drive a compressor and / or add heat to a thermal energy storage unit.

[0153] Item 28. The apparatus according to any one of items 19-27, wherein the apparatus is arranged to release compressed gas from a storage tank filled with adsorbent and to extract heat from a thermal energy storage unit for conversion into mechanical energy, and may further convert it to deliver electrical and / or thermal energy to an external load.

[0154] Item 29. A method for storing gas under pressure, comprising:

[0155] i) Compressed gas, preferably compressed to 5-100 bar;

[0156] ii) Supplying compressed gas into a sealable container containing adsorbent material;

[0157] iii) The compressed gas is adsorbed onto the adsorbent.

[0158] Item 30. The method according to item 29 further includes at least one of the following steps:

[0159] iv) Storing the gas for a limited period of time; and

[0160] v) Release the adsorbed gas to drive a turbine to generate electricity.

[0161] Item 31. The method according to any one of items 29-30, wherein the compressed gas in the sealable container is heated using a heat exchanger, intermediate heater and / or preheater provided before or inside the storage unit.

[0162] Item 32. An adsorbent material composition, comprising:

[0163] Metal-organic framework (MOF) adsorbents; and

[0164] Thermally conductive materials.

[0165] Item 33. The adsorbent material according to Item 32, wherein the MOF is selected from Al-Fum (aluminum fumarate), HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from aluminum fumarate, HKUST-1, and / or MOF-177, and most preferably contains aluminum fumarate.

[0166] Item 34. The adsorbent material according to any one of items 32-33, wherein the thermally conductive material is a binder material having a higher thermal conductivity than MOF and binding the particles of the MOF material together.

[0167] Item 35. The adsorbent material according to any one of items 32-34, wherein the adsorbent material is provided in particulate form and comprises an MOF adsorbent and a thermally conductive binder.

[0168] Item 36. The adsorbent material according to any one of items 32-35, wherein the MOF is mixed or blended with a solid material having higher thermal conductivity.

[0169] Item 37. The adsorbent material according to Item 36, wherein the thermally conductive material comprises aluminum.

Claims

1. A method for storing and releasing adsorbent-enhanced compressed gas, comprising the following steps: i) Provide adsorbent solids inside a pressurized container; ii) The gas is preferably compressed air to provide compressed gas; iii) Supplying the compressed gas to the adsorbent in the pressurizable container and allowing the gas to be adsorbed onto the adsorbent under pressure; iv) Storing the compressed gas in the pressurizable container; v) Release the compressed gas and adsorbed gas from the pressurized container; and vi) Drive mechanical devices.

2. The method according to claim 1, wherein the adsorbent comprises a metal-organic framework.

3. The method of claim 2, wherein the metal-organic framework comprises aluminum fumarate.

4. The method according to claim 2, wherein the metal-organic framework comprises a metal-organic framework (MOF) selected from HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from HKUST-1 and / or MOF-177.

5. The method according to any one of claims 1-4, wherein the method further comprises: - The released gas is supplied directly to the mechanical device.

6. The method according to any one of claims 1-5, wherein the method further comprises: - The mechanical device is used to convert the potential energy of the compressed gas into electrical energy, thermal energy, or mechanical energy.

7. The method of claim 6, wherein the gas is non-flammable.

8. The method according to any one of claims 2-7, wherein the metal-organic framework has the following air adsorption capacity: in a pressure range of 5-100 bar, preferably 5-30 bar, and in a temperature range of 5-85°C, preferably 15-30°C, the density of the adsorbed air is at least about 2 times greater than the density of free air at the same ambient pressure and volume.

9. The method according to any one of claims 2-8, wherein the metal-organic framework has a water absorption of less than 0.25 g / g at a temperature of 5-85°C and a relative humidity of less than 25%; preferably, it has a water absorption of less than 0.05 g / g at a temperature of 5-85°C and a relative humidity of less than 25%.

10. The method according to any one of claims 2-9, wherein the gas is cooled using a cooler, heat exchanger, intercooler and / or precooler before being supplied to the adsorbent.

11. The method according to any one of claims 2-10, wherein the metal-organic framework has a length of at least 0.4-2.5 cm. 3 / g, preferably 0.6-1.5 cm 3 / g, more preferably 0.8-1.3 cm 3 / g pore volume / porosity.

12. The method according to any one of claims 2-11, wherein the metal-organic framework has a diameter of at least 700 m. 2 / g, more preferably at least 2000 m 2 / g, more preferably at least 3000 m 2 / g of surface area.

13. The method according to any one of claims 1-12, wherein the adsorbent comprises aluminum fumarate and / or aluminum particles, and / or a combination of different MOFs.

14. The method according to any one of claims 1-13, wherein the adsorbent comprises particles, powder, barrel and / or granules.

15. The method of claim 14, wherein the adsorbent in particulate form comprises a thermally conductive binder, preferably wherein the binder has a higher thermal conductivity than the adsorbent.

16. The method of claim 15, wherein the thermally conductive adhesive comprises aluminum, graphene, and / or carbon nanotubes.

17. The method according to any one of claims 1-15, wherein supplying the gas to the adsorbent comprises supplying the gas at a pressure of 5-100 bar.

18. The method according to any one of claims 1-16, wherein releasing the adsorbed gas to the mechanical device comprises releasing the adsorbed gas at a pressure of 2 bar or higher.

19. The method according to any one of claims 1-18, wherein the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube or an expansion valve.

20. The method according to any one of claims 1-19, wherein releasing the adsorbed gas to the mechanical device comprises desorbing the adsorbed gas from the adsorbent.

21. The method of claim 20, wherein desorption of the gas from the adsorbent comprises thermal desorption, such as by temperature fluctuations or electromagnetic radiation, and / or mechanical desorption, i.e. by mechanical disturbance, such as by applying pressure waves using air or other gases, by pressure fluctuations, and / or by ultrasonic technology.

22. The method according to any one of claims 1-21, wherein the gas comprises one of nitrogen, oxygen, carbon dioxide, air, and / or mixtures thereof.

23. An apparatus for storing and releasing compressed gas, comprising: i) A compressor for compressing gases, preferably air; ii) a storage unit in communication with the compressed gas, the storage unit comprising a pressurizable container having an internal volume containing an adsorbent for adsorbing the compressed gas; and iii) A mechanical device in gas communication with the storage unit, the mechanical device being arranged to receive released compressed gas from the storage unit and thereby generate mechanical energy, electrical energy or thermal energy.

24. The device of claim 23, wherein the adsorbent comprises a metal-organic framework.

25. The device of claim 24, wherein the metal-organic framework comprises aluminum fumarate.

26. The apparatus according to any one of claims 23-25, wherein the gas is non-flammable.

27. The device according to any one of claims 23-26, wherein the gas from the compressor is cooled by an intercooler or aftercooler before entering the storage unit, and the heat extracted therefrom is stored in the thermal energy storage unit.

28. The device according to any one of claims 23-27, wherein the storage unit comprises a metal can or a polymer, such as aramid preferably having an outer reinforcement such as carbon fiber, a metal can having substantially straight walls, such as a cuboid can or a cylindrical can.

29. The device according to any one of claims 23-28, wherein the storage unit further comprises means for heat exchange, an intermediate heater, heat tracing lines and / or a preheater.

30. The apparatus of claim 29, wherein the means for heat exchange is arranged to circulate a cold fluid or a hot fluid when heat is charged in and released, respectively.

31. The device according to any one of claims 23-30, wherein the mechanical device is a power recovery expander, such as a pneumatic motor, a turbine, or a thermodynamic converter, such as a vortex tube, or an expansion valve.

32. The device according to any one of claims 23-31, wherein the device further comprises a thermal energy storage unit for storing thermal energy.

33. The device of claim 32, wherein the heat exchanger, intermediate heater and / or preheater uses heat extracted from thermal energy storage.

34. The device according to any one of claims 23-33, wherein the device is arranged to use excess electrical energy and / or thermal energy to drive the compressor and / or add heat to the thermal energy storage unit.

35. The device according to any one of claims 23-34, wherein the device is arranged to release compressed gas from a storage tank filled with adsorbent and extract heat from a thermal energy storage unit to convert it into mechanical energy, and may further convert it to deliver electrical energy and / or thermal energy to an external load.

36. A method for storing gas under pressure, comprising: i) Compressed gas, preferably compressed to 5-100 bar; ii) Supplying the compressed gas into a sealable container in which an adsorbent material is provided; iii) The compressed gas is adsorbed onto the adsorbent.

37. The method of claim 36, wherein the supply step comprises supplying the adsorbent material comprising a metal-organic framework.

38. The method of claim 37, wherein the supply step comprises supplying the metal-organic framework comprising aluminum fumarate.

39. The method according to any one of claims 26-28, wherein the method further comprises at least one of the following steps: iv) Storing the gas for a limited period of time; and v) Release the adsorbed gas to drive a turbine to generate electricity.

40. The method according to any one of claims 36-39, wherein the compressed gas in the sealable container is heated using a heat exchanger, intermediate heater and / or preheater provided before or inside the storage unit.

41. An adsorbent material composition, comprising: Metal-organic framework (MOF) adsorbents; as well as Thermally conductive materials.

42. The adsorbent material according to claim 41, wherein the metal-organic framework (MOF) adsorbent comprises aluminum fumarate.

43. The adsorbent material according to any one of claims 41-42, wherein the MOF is selected from HKUST-1 (Cu-BTC), MOF-177 (IRMOF-1), MIL-101 (Cr), ZIF-8, MOF-5, UiO-66, and / or mixtures thereof, preferably wherein the MOF is selected from HKUST-1 and / or MOF-177.

44. The adsorbent material according to any one of claims 41-43, wherein the thermally conductive material is a binder material having a higher thermal conductivity than MOF and binding the particles of the MOF material together.

45. The adsorbent material according to any one of claims 41-44, wherein the adsorbent material is provided in particulate form and comprises an MOF adsorbent and a thermally conductive binder.

46. ​​The adsorbent material according to any one of claims 41-45, wherein the MOF is mixed or blended with a solid material having higher thermal conductivity.

47. The adsorbent material according to claim 46, wherein the thermally conductive material comprises aluminum.

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