Hydrogen capture medium fluidized bed control in hydrogen storage applications

Abstract

A method of providing and maintaining a particle bed of particulate hydrogen capture medium in a fluidized state inside a hydrogen storage chamber using hydrogen, includes supplying hydrogen to the particle bed at a superficial velocity of which the magnitude progressively increases over time, in a direction that would cause fluidization of the particle bed at or above a minimum superficial fluidization velocity. The progressive increase in the superficial velocity starts below the minimum superficial fluidization velocity. Intermittently or continuously, over time, the pressure of the hydrogen and the magnitude of the superficial velocity at which the hydrogen is supplied to the particle bed are measured or calculated. The progressive increase in the magnitude of the superficial velocity is ceased when the pressure ceases to increase with increased superficial velocity. The superficial velocity is then maintained at the magnitude which the feed pressure ceased to increase.

Description

[0001] HYDROGEN CAPTURE MEDIUM FLUIDIZED BED CONTROL IN HYDROGEN STORAGE

[0002] APPLICATIONS

[0003] FIELD OF INVENTION

[0004] THIS INVENTION relates to hydrogen storage. More particularly, the invention relates to control of hydrogen capture medium fluidized beds in hydrogen storage applications. The invention provides a method of and a system for providing and maintaining a particle bed, comprising particulate hydrogen capture medium, in a fluidized state in a hydrogen storage application. The invention finds expression in a method of storing hydrogen in a hydrogen capture medium. The invention also finds expression in a method of recovering hydrogen stored in a hydrogen capture medium, from the hydrogen capture medium. The invention further finds expression in a hydrogen storage system and in a method of operating a hydrogen storage system.

[0005] BACKGROUND TO THE INVENTION

[0006] HYDROGEN IS A DESIRABLE STORE OF ENERGY, as it converts to heat or can be used in generating electrical energy without creating carbon based or other undesirable waste products. Hydrogen can also be produced from water without creating carbon or other undesirable waste products.

[0007] A limiting factor to widespread adoption of hydrogen as an energy store is the difficulty of storing and transporting it (or transport and storage together in the case of mobile applications such as trains, ships, buses, or trucks), because of its low energy to volume ratio as a gas and the potentially explosive nature of gaseous hydrogen especially when compressed.

[0008] It is known that certain materials have a capacity for reversible storage of hydrogen, for hydrogen selectively to be adsorbed and / or absorbed on and / or by and desorbed, as hydrogen gas, from such materials. Such materials include metals in elemental metallic format and metal alloys.

[0009] There is a need to provide for the storage of hydrogen in a compact, cost effective and safe way that allows rapid uptake and release of the gas, which need the present invention seeks to address through exploitation of the abovementioned capacity of certain materials for reversible storage of hydrogen.

[0010] Furthermore, when using metals as referenced above in storing hydrogen, such metals are typically used in a particulate format. In this format, repeated adsorption and / or absorption of hydrogen on and / or by the particles and desorption of hydrogen, as hydrogen gas, from the particles cause the particles to fracture, thus becoming finer and finer with repeated cycling from “empty” (desorbed) to “full” (ad / absorbed) states and back. Such fracturing of particles is more typically referred to as “decrepitation”. This presents a challenge in exploiting such particles repeatedly, through successive “empty” and “full” states, in a fluidized bed configuration, particularly from the perspective of particle entrainment. This is a challenge the present invention seeks to address.

[0011] DISCLOSURE OF THE INVENTION

[0012] THE PRESENT INVENTION can be applied in virtually any application which includes a hydrogen storage requirement, which may or may not be related to a hydrogen utilization requirement. Such applications include (i) the use of hydrogen as a fuel source, whether for internal combustion or fuel cell applications, (ii) the bulk transport of hydrogen, e.g. by means of a tanker, and (iii) the bulk storage of hydrogen, e.g. at a hydrogen supply station from which bulk hydrogen is supplied to a vehicle for use as a fuel or for transport.

[0013] Each aspect of the invention hereinafter described can therefore be applied in any one or more of the abovementioned applications.

[0014] IN ACCORDANCE WITH A FIRST ASPECT OF THE INVENTION, THERE IS PROVIDED a method of providing and maintaining a particle bed in a fluidized state, the method including supplying a fluidizing gas to the particle bed at a superficial velocity of which the magnitude progressively increases over time, in a direction that would cause fluidization of the particle bed at or above a minimum superficial fluidization velocity, wherein the progressive increase in the superficial velocity starts below the minimum superficial fluidization velocity; intermittently or continuously measuring or calculating, over time the magnitude of the pressure (“feed pressure”) of the fluidizing gas that is supplied to the particle bed at the progressively increasing superficial velocity, upstream of the particle bed, and the magnitude of the superficial velocity at which the fluidizing gas is supplied to the particle bed; ceasing the progressive increase in the magnitude of the superficial velocity when the feed pressure ceases to increase with increased superficial velocity; and maintaining the superficial velocity at which the fluidizing gas is supplied to the particle bed at a magnitude (“superficial fluidization velocity”) at which the feed pressure ceased to increase with increased superficial velocity. In starting from below the superficial fluidization velocity, the superficial velocity of which the magnitude progressively increases over time may be progressively ramped up incrementally from zero, thus implicitly starting below the superficial fluidization velocity.

[0015] The method of the first aspect of the invention, but also of the other aspects of the invention, finds particular application in addressing the challenge of the exacerbation of particle entrainment in a fluidizing gas that passes through a fluidized particle bed of which the average particle size changes over time, e.g. due to particle fracturing, i.e. decrepitation, that occurs as a result of the fluidizing gas being repeatedly ab / adsorbed by and desorbed from particles of the particle bed. This problem is particularly prevalent in the field of hydrogen capture when repeatedly using a particle bed of particulate hydrogen capture medium in selective ad / absorption and desorption of hydrogen, as fluidizing gas, as discussed in the background section above and in more detail further below in this specification. The particle bed may therefore, in particular, be a particle bed of particulate hydrogen capture medium, while the fluidizing gas may, in particular, be hydrogen.

[0016] The method of the first aspect of the invention, but also of the other aspects of the invention, also find / s application in performing particle bed fluidization more efficiently, particularly in applications in which fluidization contributes to the efficiency of a system requiring such fluidization, e.g. in hydrogen storage applications using a particle bed of particulate hydrogen capture medium in selective ad / absorption and desorption of hydrogen.

[0017] Definitions supplied in the context of any particular aspect of the invention in this specification apply to all other aspects of the invention, and to the examples.

[0018] In this specification, “particle size” refers to the particle size / s of particles included in the particle bed, specifically with reference to the diameters of such particles, preferably being the maximum diameters thereof. As will be appreciated from the characterization of the invention in this specification, the particle bed may either comprise particles of homogenous particle size, i.e. all having substantially the same particle size, or particles of heterogenous particle size, i.e. having particles of different particle sizes.

[0019] In this specification, the term “hydrogen capture medium” describes any material, which would typically be a metal or metallic material, such as a pure metal or a metal alloy, as described below in more detail, capable of reversibly capturing and storing hydrogen therein, typically to form a metal hydride during such storage. The hydrogen capture medium may therefore be a metallic hydrogen capture medium. The term “hydrogen capture medium” is interchangeably used with the term “hydrogen capture material” in this specification, as explained in more detail below.

[0020] Furthermore, in this specification, the term “capturing” (as well as “storing”) in the sense of “hydrogen capture medium” includes the terms “adsorption” and “absorption” within its meaning. In this sense, the terms “adsorption” and “absorption” are used not only to include physical interactions within the conventional scope thereof, but also to include chemical interactions. Therefore, in respect of hydrogen being “captured” and therefore adsorbed on and / or absorbed by the hydrogen capture medium, the invention includes within its scope that a chemical reaction may take place between the hydrogen capture medium and the hydrogen that is adsorbed on and / or absorbed by the hydrogen capture medium. The same applies to “desorption”, i.e. that it includes both physical and chemical interactions. The nature of the interaction relevant to any particular hydrogen capture medium would be readily determinable by those skilled in the art from literature references or through routine experimentation. What is important, however, is that the capture is of a reversible nature, i.e. hydrogen can be captured by the hydrogen capture medium from a supply of hydrogen gas and can then subsequently be released from the hydrogen capture medium as hydrogen gas.

[0021] The term “feed pressure” in this specification refers to the pressure of the fluidizing gas as measured at or immediately upstream of a point at which the fluidizing gas contacts the particle bed, before the particle bed is fluidized. It would be appreciated that, at such a point, there would, as a result of a combination of the pressure at which the fluidizing gas is supplied to the particle bed and the back pressure generated by the resistance of the particle bed to fluidization resulting from the weights of the particles of the particle bed and the pressure above the bed, be a progressive increase in pressure as the superficial velocity of the fluidizing gas is increased, before the superficial fluidizing velocity is reached.

[0022] The term “supply pressure” in this specification refers to the pressure at which the fluidizing gas is supplied to the particle bed after the particle bed has been fluidized. I.e. the “feed pressure” becomes the “supply pressure” after fluidization has been achieved. In this sense, the “supply pressure” would therefore be a “predetermined” pressure, in that it is predetermined by performing the method of the invention. The distinction between “feed pressure” and “supply pressure” is drawn to draw a distinction between the nature of the value of the pressure at which the fluidizing gas is supplied to the particle bed before fluidization (“feed pressure”), which value is variable, and the nature of the value of the pressure at which the fluidizing gas is supplied to the particle bed after fluidization (“supply pressure”), which is preferably constant and is associated with the superficial fluidizing velocity. The supply pressure would typically be a pressure that correlates with the superficial fluidization velocity. For example, the supply pressure may be of a value that approximates or is equal to the value of the feed pressure when the feed pressure ceased to increase with increased superficial velocity of the hydrogen supplied to the bed, i.e. the pressure at which the superficial fluidization velocity was determined.

[0023] The term “predetermined contact pressure” in this specification refers to the pressure that prevails inside of the hydrogen storage vessel after fluidization has been achieved. It is therefore also the pressure at which the fluidizing gas is contacted with the hydrogen capture medium. This pressure would be a value predetermined in the art, as the pressure at which hydrogen ad / absorption or desorption, as the case may be, is favored for a particular species of hydrogen capture medium, at a particular predetermined contact temperature and, typically, also at a particular hydrogen capture medium particle size.

[0024] The predetermined contact pressure is preferably set differently in hydrogen ad / absorption and desorption applications. In a hydrogen ad / absorption application, a source of fresh hydrogen would be provided, to supply fresh hydrogen for ad / absorption. Excess hydrogen that is supplied to the particle bed but is not absorbed by the hydrogen capture medium would be recirculated to the particle bed. Preferably, when there is such recycle, a stream of fresh hydrogen from the source of fresh hydrogen would be in fluid communication with a stream of recirculated hydrogen, e.g. would be supplied to the stream of recirculated hydrogen, upstream of the generation of the supply pressure, which would typically be generated by a pump. Thus, the pressure of the stream of fresh hydrogen that is in fluid communication with the stream of recirculated hydrogen can be used to set the pressure of the stream of recirculated hydrogen and, thus, also the pressure inside of the hydrogen storage chamber, as a back pressure from the supply of fresh hydrogen upstream of the generation of the supply pressure.

[0025] In a hydrogen desorption application, however, there would be no fresh hydrogen supply. Hydrogen supplied to the particle bed to drive desorption of hydrogen would in such a case be obtained from the hydrogen storage chamber. As hydrogen is desorbed, the pressure inside of the hydrogen storage chamber would increase. An increase above the predetermined contact pressure for desorption is naturally undesired, since such a pressure would work against desorption. The predetermined contact pressure for desorption would then be set by a pressure release valve of the hydrogen storage chamber, set to release hydrogen from the hydrogen storage chamber as a hydrogen product gas when the pressure inside of the hydrogen storage chamber reaches or exceeds the predetermined contact pressure for hydrogen desorption. The supply pressure and the predetermined contact pressure would typically not be equal. It is expected that, in one embodiment of the invention, the supply pressure would be higher than the predetermined contact pressure.

[0026] In one embodiment of the invention, where reference in this specification is made to the predetermination, application, and / or communication of the superficial fluidizing velocity, it should be understood as preferably also including predetermination, application, and / or communication of the supply pressure.

[0027] “Superficial velocity” is a term that is well understood in the art of particle bed fluidization, as meaning a hypothetical gas flow velocity calculated as if a gas was solely flowing or present in a given cross-sectional area. It is typically calculated as the ratio ofvolumetric flow rate (typically in a unit of m3 / s) to cross sectional area (typically in a unit of m2) (e.g. providing a value in a unit of m / s).

[0028] Persons skilled in the art would know that an increase in the superficial velocity of a gas flowing in a conduit can be achieved by increasing the volumetric flow rate of the gas or by narrowing the conduit. In the present invention, since a progressive increase in superficial velocity is required, narrowing of the conduit is not expected to be practical and, therefore, increasing the volumetric flow rate is expected to be more typical. As discussed above, such an increase would typically be progressive and would commence from a zero value (i.e. no flow). This can be achieved in any conventional manner, e.g. by using a pump that is controlled to increase volumetric flow rate progressively.

[0029] Reference to “volumetric flow rate” or to “volumetric feed flow rate” (which are used interchangeably) in this specification should be understood in the context of the meaning provided for “superficial velocity” above, and with reference to supply of the fluidizing gas, preferably hydrogen, to the particle bed. In other words, for a particular superficial velocity, there would be a corresponding volumetric flow rate or volumetric feed flow rate. To maintain the superficial fluidizing velocity and typically also the supply pressure, for example, the volumetric flow rate or volumetric feed flow rate of the fluidizing gas would therefore have to be maintained at a corresponding level. Similarly, a superficial velocity sufficient to fluidize the particulate hydrogen capture material (i.e. the superficial fluidizing velocity or, as one embodiment thereof as discussed below, the minimum superficial fluidization velocity) would be associated with a corresponding volumetric flow rate or volumetric feed flow rate. Also similarly, as discussed above, progressively increasing the superficial velocity would include progressively increasing the volumetric flow rate or volumetric feed flow rate. In one embodiment, the superficial velocity would, in the present invention, typically be that which subsists in a conduit that supplies the fluidizing gas to the particle bed, i.e. immediately upstream of the particle bed.

[0030] In the present invention, the applicant has surprisingly found that a relationship between superficial velocity, feed pressure, and fluidization may usefully and inventively be applied to determine superficial velocities of suitable magnitude (being the abovementioned “superficial fluidization velocity”) for repeatedly fluidizing a particle bed of which the particle size changes over time. In this regard it should be appreciated that “repeatedly” does not mean that the same superficial fluidization velocity is repeatedly used, but rather that the particle bed is repeatedly fluidized by determining an appropriate superficial fluidization velocity suitable for such fluidization at a particular time, with reference to particle bed conditions, most prominently particle size, existing at that time.

[0031] More specifically, the applicant has found that, at progressively increasing superficial fluidizing gas velocities below the minimum superficial fluidization velocity, the feed pressure progressively increases, typically linearly, including as a result of increased back pressure from the particle bed as it resists fluidization for the reasons discussed above. Such an increase continues until the minimum superficial fluidization velocity is reached, at which point the feed pressure ceases to increase with increased superficial velocity, since the particle bed becomes fluidized. Thus, an inflection point is reached at which there is no longer an increase in feed pressure with an increase in superficial velocity.

[0032] The reaching of this inflection point inventively allows for a determination of a minimum superficial fluidization velocity, as one embodiment of the superficial fluidizing velocity, to be made with reference to the superficial velocity at which the inflection point is reached. It also allows for the selection of an appropriate supply pressure, for fluidization to be achieved.

[0033] The method thus allows, with reference to the magnitude and variation of the feed pressure under increasing superficial fluidizing gas velocity, and ultimate reaching of the inflection point, for the determination of a “non-fluidized” state of the particle bed, in which the feed pressure increases with increased superficial velocity; and a “fluidized” state of the particle bed, in which the feed pressure (then becoming characterized as “supply pressure” as defined above) ceases to increase with increased superficial velocity. The method of the invention is particularly advantageous in a hydrogen storage system, as described in more detail elsewhere in this specification, in which repeated cycles of hydrogen storage in and hydrogen recovery from particulate hydrogen capture medium results in particle size reduction over time. Such size reduction is also known as decrepitation in the art of the invention, which is the term that is favored in the remainder of this specification.

[0034] Since such particle size reduction (i.e. decrepitation) causes a change in minimum superficial fluidization velocity, particle size reduction needs to be observed dynamically in effecting fluidization in order to avoid particle entrainment and to allow for efficient fluidization in applications in which fluidization is functionally desired, e.g. hydrogen storage and utilization applications to facilitate hydrogen ad / absorption and desorption respectively. Selecting one superficial velocity for fluidization over a prolonged period of time would have significant loss of particulate hydrogen capture medium to effect and would not achieve optimal fluidization in changing circumstances, leading to a concomitant lack in efficiency in systems requiring fluidization for functional purposes.

[0035] In this regard, it should be further appreciated that, in the applicant’s experience, the particle sizes that would typically be involved in a hydrogen storage environment are difficult to manage, in respect of entrainment and fluidization, by methods other than to select appropriate superficial gas velocities on a case-by-case basis, i.e. per fluidization cycle or pairs of ad / absorption and desorption cycles.

[0036] In at least one respect, this is so because such particle sizes are typically those that fall within the Geldart Group C classification. Such particles would be known by persons skilled in the art to be smaller than 45 microns. In some cases, such particles can be coarse and non-spherical, but in other cases they could be spherical. These particles are often very densely packed and often have a high density compared to other groups of the classification. They are also prone to poor fluidization because they tend to form clumps or agglomerates when subjected to gas flow, as a result of high attractive forces such as Van der Waals or electrostatic forces between such particles.

[0037] In some cases, the particulate hydrogen capture medium can also include nano-sized particles, e.g. of 10 to 30 nanometers, which may also have formed as a result of decrepitation. The presence of such particles could have a lubricating effect on larger particles in the particle bed, resulting in an improved fluidization tendency of the particle bed (i.e. facilitating fluidization), in contrast to an expectation of more challenging fluidization due to decrepitation. This further emphasizes the need for dynamic superficial velocity control to be applied in the fluidization of particle beds to optimize their fluidization.

[0038] What also tends to happen, particularly in hydrogen storage applications, is that the temperature of the fluidizing gas, specifically when hydrogen needs to be recovered from the hydrogen capture medium, is such that sintering of hydrogen capture medium particles may occur. Persons skilled in the art would understand that such sintering causes particle agglomeration, which results in an increase in particle size. Also in this respect, therefore, the characteristics of a bed of particulate hydrogen capture medium can change over time as it repeatedly discharges and is charged with hydrogen, both through decrepitation and agglomeration, further emphasizing the need for dynamic superficial velocity control to be applied in the fluidization of such particle beds, with reference to their particle size characteristics.

[0039] The present invention provides a novel and inventive approach to addressing the above- mentioned challenge, of determining, and applying, the superficial fluidization velocity, which is preferably a minimum superficial fluidization velocity, to a particle bed of which the properties, particularly that of particle size, changes over time, in cases in which repeated fluidization is required. The invention achieves this by exploiting the abovementioned relationship between observed superficial gas velocity and feed pressure variations, which obviates laborious and time-consuming approaches such as theoretically pre-determining flow, temperature, and pressure requirements for particular particle sizes. Significantly, the present invention also allows a determination of particle size to be made, which is advantageous for the selection of optimal hydrogen ad / absorption and desorption parameters.

[0040] More specifically, advantageously, the ability of the invention to determine the superficial fluidization velocity, which is preferably a minimum superficial fluidization velocity, with reference to feed pressure variation under varied superficial velocity also allows for determination of particle size with reference to nomograms of particle size versus fluidisation velocity, or associated values in respect of relevant hydrogen capture media.

[0041] Knowing the superficial fluidization velocity, which is in one preferred embodiment a minimum superficial fluidization velocity, using the method of the invention, therefore enables one to determine the particle size to which that superficial fluidization velocity applies and, therefore, also allows the particle size prevailing in the particle bed to be determined. In turn, having this knowledge for each ad / absorption and desorption cycle allows for a required predetermined hydrogen supply and / or hydrogen contact temperature and a predetermined hydrogen contact pressure for promoting ad / absorption and desorption, respectively, as described in more detail elsewhere in this specification, to be optimally determined for each ad / absorption and desorption cycle.

[0042] Predetermination of temperature and pressure conditions optimal for respectively achieving ad / absorption and desorption of hydrogen by and from any particular species of hydrogen capture medium is within the knowledge and skill of persons skilled in the art and does not require elaboration. Therefore, in the context used in this specification, including in the terms “predetermined contact pressure”, “predetermined contact temperature”, and “predetermined supply temperature”, the term “predetermined” does not mean that there is necessarily a predetermination of the relevant temperature and / or pressure that is performed as part of the method of the invention, although such predetermination is not excluded. Instead, it is meant, at least, that such temperatures and pressures are established in the art or may be predetermined in the art for different materials and typically at different particle sizes thereof. The invention therefore envisages a preferred embodiment in which there is a selection of such predetermined temperatures and pressures from a source, e.g. an electronic database, thereof, based on the determined particle size. As implied, however, in some cases, the method may include making a determination of such temperatures and pressures, e.g. with reference to data obtained using a nomogram or associated values, as described herein.

[0043] It will be appreciated that the superficial velocity at and beyond which feed pressure ceases to increase with increased superficial velocity, thus determining the superficial fluidization velocity and typically also the supply pressure, would approximate or be a minimum superficial fluidization velocity of the particle bed, which is one preferred embodiment of the superficial fluidizing velocity.

[0044] The superficial fluidization velocity of the invention is preferably a minimum superficial fluidization velocity. It is particularly preferred for the superficial fluidization velocity to be a minimum fluidization velocity, to avoid negative effects of using higher velocities, including the negative effect of particle entrainment, but also to optimize energy utilization in achieving fluidization.

[0045] In one embodiment thereof, the minimum superficial fluidization velocity is the superficial velocity of the fluidizing gas at which the particles in the bed begin to move and the bed transitions from a packed (or stationary) state to a fluidized state, where the particles behave like a fluid rather than a solid mass. Conventionally, this may be the case when the upward force exerted by the fluidizing gas on the particle bed equals the downward force resulting from the weight (i.e. the product of particle mass and the force of gravity) of the respective particles making up the particle bed, including other forces resisting fluidization of the bed such as interparticle forces as hereinbefore discussed.

[0046] In other words, the minimum superficial fluidization velocity is the superficial velocity of the fluidizing gas at which the drag force exerted by the flow of fluidizing gas on the particle bed is sufficient to overcome the weight of the particles in the particle bed and interparticle forces within the particle bed, causing the particle bed, or rather particles of the particle bed, to become suspended in the flow of fluidizing gas. At this velocity, the bed starts to exhibit characteristics like that of a fluid, such as uniform particle movement and the ability to flow and expand.

[0047] As discussed, it is preferred for the superficial fluidization velocity to be a minimum superficial fluidization velocity, since superficial velocities in excess of the minimum superficial fluidization velocity may cause the particles to become prone to entrainment in the gas stream that leaves the particle bed, leading to loss of particles from the particle bed. This is due to the fineness of particles that provide the particle bed, as they fracture, i.e. are subject to decrepitation, and become progressively more reduced in particle size.

[0048] In a hydrogen storage environment in which the particle bed comprises a particulate hydrogen capture medium that stores or is provided to store hydrogen, such entrainment and loss would be significantly detrimental since it would result in a loss of hydrogen storage capacity and, when storing hydrogen, in a loss of stored hydrogen. It can also cause clogging of filters resulting in reduced efficiency.

[0049] As alluded to earlier, the fluidizing gas is preferably hydrogen.

[0050] As also alluded to earlier, and as described in more detail further below, the particles of the particle bed are preferably a particulate hydrogen capture medium.

[0051] The particulate hydrogen capture medium is preferably a metallic hydrogen capture medium, i.e. comprising one or more metals or metal compounds such as metal alloys. As has been stated, the hydrogen capture medium is preferably one that forms one or more metal hydrides when contacted with hydrogen under suitable conditions, thus capturing the hydrogen in a manner in which the hydrogen can again be released therefrom under suitable conditions, as hydrogen gas. The hydrogen capture medium may either comprise one species of hydrogen capture medium or multiple species of hydrogen capture medium. It is preferred that the particle bed comprises, more preferably consists of, only one species of hydrogen capture medium.

[0052] Since the preferred form of the particle bed is particulate hydrogen capture medium, this term is favored, although not used exclusively, in the remainder of this specification. It should nevertheless be understood that the invention, in a broad sense, may also find application to other particles. Furthermore, since the preferred fluidizing gas is hydrogen, this term is also favored, although not used exclusively, in the remainder of this specification. It should nevertheless be understood that the invention, in a broad sense, may also find application to other fluidizing gases.

[0053] In one embodiment of the invention, supplying hydrogen to the bed of particulate hydrogen capture medium at the superficial fluidization velocity causes hydrogen to be ad / absorbed by the particulate hydrogen capture medium. The nature of ad / absorption of hydrogen by the hydrogen capture medium is described in more detail elsewhere in this specification.

[0054] While the following paragraphs discuss features of the invention with reference to ad / absorption of hydrogen, the principles relevant to the determination of the superficial fluidization velocity and particle size, and the application and benefits thereof, apply equally to desorption, which is discussed in more detail herein in relation to this, first, aspect of the invention and inter alia in relation to the second aspect of the invention.

[0055] In such an embodiment, i.e. of hydrogen ad / absorption, the method may include, based on the value of the superficial fluidization velocity, determining a particle size, e.g. an average particle size, of the particulate hydrogen capture medium with reference to a nomogram, or equivalent values thereof, of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate hydrogen capture medium. Such a particle size would therefore be a particle size that subsists at the time of fluidization.

[0056] The existence and use of nomograms that plot superficial velocity for fluidization against particle size for different species of particles is well known and understood in the art of particle bed fluidization. Such nomograms may either be created empirically or theoretically. In the context of the invention, reference to “nomogram” should be understood as being to such a nomogram or to a set, e.g. a table, of values that would provide such a nomogram. The method may in such an embodiment, i.e. when hydrogen is ad / absorbed by the hydrogen capture medium, further include contacting the hydrogen that is supplied to the particulate hydrogen capture medium with the particulate hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate hydrogen capture medium at the determined average particle size. Providing the predetermined temperature and the predetermined pressure is discussed in more detail elsewhere in this specification, with reference to the earlier referenced predetermined contact pressure, as well as with reference to a predetermined supply temperature, and a predetermined contact temperature.

[0057] The method of the invention therefore, through establishing the superficial fluidizing velocity, and typically also a supply pressure, in the manner described, conveniently allows for a determination of particle size of the particles of the particle bed to be made for each fluidization cycle or action, in an environment in which there is variability in such particle size, and therefore in fluidization characteristics, due to repeated hydrogen ad / absorption and desorption cycles.

[0058] Such a determination, in turn, can then inventively be employed to select predetermined contact temperature and predetermined contact pressure conditions optimal for achieving ad / absorption of hydrogen by the relevant hydrogen capture medium species, and to inform future fluidization of the particulate hydrogen capture medium, e.g. for the purpose of desorbing hydrogen therefrom.

[0059] As discussed later in this specification in more detail, hydrogen supplied to the particle bed as fluidizing gas for the purpose of ad / absorption of hydrogen by the hydrogen capture medium would typically be supplied from a source of hydrogen remote of the particle bed, whereas hydrogen supplied to the particle bed for the purpose of desorbing hydrogen from the hydrogen capture medium would typically be supplied from excess hydrogen gas that is present above the particle bed, e.g. in a hydrogen storage chamber as hereinafter described, or that is present above another such particle bed, e.g. in another hydrogen storage chamber that forms part of a group of multiple hydrogen storage chambers that also includes the first-mentioned hydrogen storage chamber.

[0060] In another embodiment of the invention, supplying hydrogen to the bed of particulate hydrogen capture medium at the superficial fluidization velocity causes hydrogen that was previously ad / absorbed by the particulate hydrogen capture medium to be desorbed from the particulate hydrogen capture medium. The desorption of hydrogen from the hydrogen capture medium is described in more detail elsewhere herein, e.g. inter alia in relation to the second aspect of the invention.

[0061] In such an embodiment, i.e. of hydrogen desorption, the method may also include, based on the superficial fluidizing velocity, determining an average particle size of the particulate hydrogen capture medium with reference to a nomogram of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate hydrogen capture medium.

[0062] The method may in such an embodiment further include contacting the hydrogen that is supplied to the particulate hydrogen capture medium with the particulate hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate hydrogen capture medium at the determined average particle size. Providing the predetermined temperature and the predetermined pressure is discussed in more detail elsewhere in this specification, with reference to the earlier referenced predetermined contact pressure, predetermined supply temperature, and predetermined contact temperature.

[0063] Considerations relevant to the predetermination of the predetermined temperature and the predetermined pressure optimal for hydrogen to be desorbed from the particulate hydrogen capture medium at the determined average particle size are the same as those that apply to the predetermination of the predetermined temperature and the predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate hydrogen capture medium at the determined average particle size.

[0064] As alluded to above and as discussed elsewhere in this specification in more detail, hydrogen supplied to the particle bed as fluidizing gas for the purpose of desorption of hydrogen from the hydrogen capture medium would typically be supplied from the hydrogen storage chamber in which the particle bed is provided, or from a different hydrogen storage chamber in which another such a particle bed is provided. Such hydrogen, supplied for desorption, would typically be present in such a hydrogen storage chamber as excess gaseous hydrogen and / or as a hydrogen product desorbed from the hydrogen storage medium, in addition to hydrogen previously ad / absorbed by the hydrogen capture medium.

[0065] The method of the first aspect of the invention, and each of its steps, may be performed electronically and automatically, e.g. by means of one or more electronic control systems. Such one or more control systems may be one or more control systems as described in more detail elsewhere in this specification. The control system / s is / are thus also characterised as independent aspects of the present invention.

[0066] Before discussing embodiments of the one or more control systems, it is noted, for the sake of informing the description of the control system / s that the method, insofar the supply of hydrogen to the particulate hydrogen capture medium is concerned, would typically be performed inside a hydrogen storage chamber, as has been indicated above.

[0067] The hydrogen storage chamber may be a hydrogen storage chamber as described in more detail elsewhere in this specification. Such a hydrogen storage chamber may typically be provided by a reactor, a tank, or a vessel, as also described in more detail elsewhere in this specification. Thus, such a hydrogen storage chamber, and therefore also such a reactor, tank, or vessel, may have a hollow interior in which the particle bed is contained.

[0068] Such a hydrogen storage chamber, and thus such a reactor or vessel, may furthermore have an inlet through which fluidizing gas may be fed into the interior; and an outlet through which fluidizing gas passing through the particle bed may be withdrawn from the interior.

[0069] The method may include withdrawing fluidizing gas passing through the particle bed from the hydrogen storage chamber or allowing fluidizing gas passing through the particle bed to leave the hydrogen storage chamber. This may be effected as described in more detail elsewhere in this specification.

[0070] In the interests of addressing the challenge that the invention seeks to address, the hydrogen storage chamber, and therefore the reactor or vessel, may have features that work against entrainment of particles from the particle bed in fluidizing gas leaving the hydrogen storage chamber. Such features may, in particular, include flaring of the diameter of the hydrogen storage chamber downstream of the particle bed; and shielding of the outlet by a baffle, which features are described in more detail elsewhere in this specification.

[0071] The scope of the invention includes, as discussed, one or more control systems that control hydrogen supply and that make the determination of the superficial fluidizing velocity, and typically of supply pressure, electronically, including by progressively increasing the superficial velocity at which hydrogen gas is supplied to the particle bed, and that also apply the predetermined supply and / or contact temperature / s and / or the predetermined contact pressure and / or the supply pressure electronically. It will be understood that the values of such temperatures and pressures are values of temperatures and pressurse at which hydrogen would be supplied to or contacted with the particulate hydrogen capture medium, i.e. a supply and / or contact temperature and a contact pressure, which would be respectively for ad / absorption or desorption of hydrogen by / from the particulate hydrogen capture medium, whereas a supply pressure would be selected for fluidization with reference to the superficial fluidizing velocity.

[0072] In other words, supplying the hydrogen, progressively increasing the superficial velocity, measuring the feed pressure and the superficial velocity, ceasing the progressive increase in the magnitude of the superficial velocity, and maintaining the superficial fluidization velocity, preferably including the supply pressure, are all preferably performed electronically and automatically by means of one or more electronic control systems.

[0073] Setting the predetermined contact pressure is also preferably performed electronically and automatically be means of the one or more such electronic control systems. As has been discussed elsewhere in this specification, such setting of the predetermined contact pressure is, in ad / absorption applications performed by setting the pressure of a fresh hydrogen supply stream that is in fluid communication with an excess hydrogen recycle stream, whereas it is, in hydrogen desorption applications, set by setting the release pressure of a pressure relief valve of the hydrogen storage chamber.

[0074] Typically, to perform the abovementioned functions, the one of more electronic control systems would each include a selection of sensors, one or more processing devices, one of more controlling devices such as programmable logic controllers (PLCs), and devices for performing the required control functions such as pumps, heating devices, cooling devices, and the like. Some of these are discussed in more detail in relation to other aspects of the invention, but based on the description of the invention in this specification a person skilled in the art would be able to select appropriate such control system components to provide for the required control.

[0075] In one embodiment of the invention, particularly but not exclusively when supplying hydrogen for ad / absorption by the hydrogen capture medium, the electronic control system is for ease of reference referred to as an electronic hydrogen supply control system, including to be distinguished from an electronic hydrogen storage control system that is also described below as a possible addition to or replacement for the electronic hydrogen supply control system in some embodiments of the invention.

[0076] Thus, it is in one embodiment of the invention the electronic hydrogen supply control system that may perform the abovementioned acts of supplying the hydrogen, progressively increasing the superficial velocity, measuring the feed pressure and the superficial velocity, ceasing the progressive increase in the magnitude of the superficial velocity, and maintaining the superficial fluidization velocity. It may also preform the abovementioned acts of setting the predetermined contact pressure and determining the supply pressure.

[0077] Determining a particle size, e.g. an average particle size, of the particulate hydrogen capture medium and contacting the hydrogen with the particulate hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate hydrogen capture medium at the determined average particle size are also preferably performed by the electronic hydrogen supply control system.

[0078] Thus, it is provided that the electronic hydrogen supply control system would preferably have access to a nomogram of average particle size against fluidization velocity, or at least to a database providing values thereof, and, furthermore, would also have access to a database of optimal temperatures and pressures for hydrogen ad / absorption for a selection of different hydrogen capture medium species at different particle sizes.

[0079] In one embodiment of the invention, the electronic hydrogen supply control system is comprised by a hydrogen supply station having a source of fresh hydrogen independent of the hydrogen storage chamber. In such an embodiment, supplying hydrogen to the bed of particulate hydrogen capture medium is preferably remote from the source of fresh hydrogen. In other words, the bed of particulate hydrogen capture medium is preferably provided remote of the source of fresh hydrogen. Such remoteness does not necessarily mean at a remote distance, but rather that the hydrogen storage chamber does not form an integral part of the hydrogen supply station, such that the source of hydrogen is selectively connectable to and disconnectable from the hydrogen storage chamber.

[0080] In one embodiment of the invention, the hydrogen supply station may have a feed and supply pressure generator, such as a pump. In such an embodiment, the hydrogen storage chamber would not have such a pressure generator and would therefore be configured only for hydrogen desorption independent of the hydrogen supply station, which desorption would be driven by recycle of hydrogen present in the hydrogen storage chamber, to the hydrogen storage chamber. In this embodiment, connection of the hydrogen storage chamber to the hydrogen supply station would be such that the source of fresh hydrogen is in fluid communication with a hydrogen recirculation stream of the hydrogen storage chamber, upstream of the pressure generator, to allow for the predetermined contact pressure to be set by setting the pressure of the source of fresh hydrogen. It would further be such that the pressure generator supplies hydrogen, comprising fresh hydrogen and recirculated hydrogen, to the hydrogen storage chamber, which supply would either first be at the free pressure and thereafter at the supply pressure, or would directly be at the superficial fluidizing velocity and supply pressure based on an earlier determination thereof in the manner described.

[0081] In another embodiment, of the invention, the pressure generator may be integral with the hydrogen storage chamber, in which case only connection of the source of fresh hydrogen would be required, upstream of the pressure generator such that it is in fluid communication with the hydrogen recirculation stream.

[0082] In this regard, it is envisaged that the hydrogen supply station would be a fixed, i.e. immovable, installation. This does not exclude, however, that the hydrogen supply station may be a movable installation, e.g. comprising a vehicle such as a hydrogen tanker or the like.

[0083] The hydrogen storage chamber is preferably provided separate of the hydrogen supply station, i.e. not as an integral part thereof, as described above. For example, the hydrogen storage chamber may be provided on a vehicle. Such vehicles may include vehicles having hydrogen fueled internal combustion engines and vehicles providing for hydrogen storage and transport, e.g. tankers, as well as electric vehicles operating with hydrogen fuel cells.

[0084] Typically, in such a case, it is preferred that the hydrogen storage chamber has an electronic hydrogen storage chamber control system that is in communication with the electronic hydrogen supply control system.

[0085] Such an electronic hydrogen storage chamber control system would typically be necessary to provide for hydrogen desorption from hydrogen-carrying I hydrogen-storing hydrogen capture medium independently of the electronic hydrogen supply control system, e.g. to desorb hydrogen from hydrogen capture medium in the hydrogen storage chamber to be supplied to a hydrogen fueled internal combustion engine or to a hydrogen fuel cell of an electric vehicle operating with such a fuel cell. The method may then include communicating the superficial fluidization velocity and the determined average particle size as determined by the electronic hydrogen supply control system during supply of hydrogen for hydrogen ad / absorption (i.e. during a “filling” cycle) to the electronic hydrogen storage chamber control system by means of the electronic hydrogen supply control system. The method may then further include electronically storing the superficial fluidization velocity and the determined average particle size in an electronic hydrogen storage chamber control system database by means of the electronic hydrogen storage chamber control system.

[0086] Thus, the electronic hydrogen storage chamber control system would be in a condition in which it has knowledge of critical parameters associated with the hydrogen capture medium in the hydrogen storage chamber, to allow the electronic hydrogen storage chamber control system to select optimal operating conditions, including superficial fluidization velocity and predetermined temperature and pressure conditions, for hydrogen to be released from the hydrogen capture medium.

[0087] The abovementioned embodiment of the invention does not exclude an alternative embodiment in which the electronic hydrogen supply control system is integral with the hydrogen storage chamber, i.e. in which the hydrogen storage chamber accordingly does not have the electronic hydrogen storage control system, but instead has the hydrogen supply control system that is connectable to a remote source of hydrogen.

[0088] The invention therefore envisages two possibilities. In one case, there would be a hydrogen filling station having the source of hydrogen remote of the hydrogen storage chamber and having the electronic hydrogen supply control system. The hydrogen storage chamber would then be provided on a vehicle that would have the electronic hydrogen storage chamber control system, which is also alluded to in the second aspect of the invention and is the subject of the third aspect of the invention. The two systems would then operate as hereinbefore described, with reference also to the discussions in relation to the second and third aspects of the invention. In another case, there would also be a hydrogen filling station having the source of hydrogen remote of the hydrogen storage chamber. The hydrogen storage chamber would then also be provided on a vehicle but, in such a case, the vehicle would have the electronic hydrogen supply control system, to control supply of hydrogen from the remote source of hydrogen from the side of the vehicle as opposed to controlling it from the side of the hydrogen filling station.

[0089] In a case in which the electronic hydrogen supply control system is integral with the hydrogen storage chamber, determining the particle size, e.g. an average particle size, of the particulate hydrogen capture medium and contacting the hydrogen with the particulate hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be desorbed from the particulate hydrogen capture medium at the determined average particle size would then also be performed by the electronic hydrogen supply control system, as opposed to being based on a communication received from the electronic hydrogen supply control system.

[0090] As alluded to earlier, in such an embodiment, the electronic hydrogen supply control system would typically be comprised by a vehicle having a hydrogen fueled internal combustion engine or an electric vehicle operating with a hydrogen fuel cell. For hydrogen desorption, supplying hydrogen to the bed of particulate hydrogen capture medium would then be from the hydrogen storage chamber, or from another such hydrogen storage chamber of the vehicle, the vehicle in such a case having multiple hydrogen storage chambers. Supplying hydrogen from another hydrogen storage chamber would typically be required if the concerned hydrogen storage chamber to which supply is required does not have sufficient gaseous hydrogen contained in it to perform such supply and effect fluidization, for hydrogen release from the hydrogen capture medium. It will be appreciated that the first-mentioned hydrogen storage chamber would therefore typically be part of a group of hydrogen storage chambers in which the first-mentioned hydrogen storage chamber is included.

[0091] It is reiterated that the particulate hydrogen capture medium is preferably particulate hydrogen capture medium that has repeatedly been subjected to hydrogen ad / absorption and desorption cycles and, as a result, has been fractured, i.e. decrepitated, into particle sizes smaller than an original particle size thereof.

[0092] It will by now be understood that the method finds particular expression as a method of storing hydrogen in a hydrogen capture medium, which hydrogen capture medium is provided by particles of the particle bed referenced hereinbefore.

[0093] In this regard, the method includes contacting the hydrogen capture medium, in particulate format, with gaseous hydrogen such that at least some hydrogen of the gaseous hydrogen is captured and thus stored by the hydrogen capture medium through adsorption and / or absorption (ad / absorption) of hydrogen from the gaseous hydrogen on or by the hydrogen capture medium as a result of such contact. Hydrogen desorption from hydrogen-storing hydrogen capture medium is also provided for. Being provided as a particle bed, the hydrogen capture medium would be provided in loose particulate format. It should, however, be understood that, in certain cases, when the particle size of the hydrogen capture medium has reduced due to fracturing, i.e. decrepitation, the looseness of the particles may have been negatively influenced, e.g. due to interparticle forces, as discussed earlier. The invention provides for addressing such a situation, and the associated increased resistance against fluidization, with reference to the use of ultrasonic waves and pulsating flow, as discussed in more detail further below.

[0094] More particularly, the method may include pulsating the hydrogen (i.e. the flow of hydrogen) that is supplied to the particle bed of hydrogen capture medium and / or by applying ultrasonic agitation to the particle bed. Such pulsating and / or ultrasonic agitation may be performed, in particular, if it is determined that the particle bed is severely resistant to fluidization. This may be the case, for example, if the feed pressure and / or the superficial fluidization velocity exceed respective threshold values therefor.

[0095] Such a determination may be made by the electronic hydrogen supply control system or by the electronic hydrogen storage control system. Accordingly, pulsating the hydrogen that is supplied to the particle bed and / or applying ultrasonic agitation to the particle bed may be performed by the electronic hydrogen supply control system or by the electronic hydrogen storage control system.

[0096] After fluidization has been effected, continued supply of hydrogen to the hydrogen capture medium may be effected at the supply pressure hereinbefore defined, which would, as defined, be a pressure that is of magnitude that is sufficient maintain to fluidization of the bed, at the superficial fluidization velocity. Such pressure would typically be a pressure that correlates with the superficial fluidization velocity. For example, the supply pressure may be of a value that approximates or is equal to the value of the feed pressure when the feed pressure ceased to increase with increased superficial velocity of the hydrogen supplied to the bed, i.e. the pressure at which the superficial fluidization velocity was determined. As has been noted above, a distinction should therefore be drawn between the term “feed pressure”, which is the term that is used for the pressure at which hydrogen is supplied to the particle bed before fluidization is achieved and that is measured and varies with progressively increased fluidization velocity, and the term “supply pressure”, which is the term that is used for the pressure at which hydrogen is supplied to the particle bed after fluidization has been achieved, to maintain fluidization in conjunction with the superficial fluidizing velocity. In an embodiment of the invention, the supply pressure is higher than the predetermined contact pressure. As has also been indicated, supply of hydrogen to the hydrogen capture material may, furthermore, be effected at a predetermined supply temperature. Such a temperature may, as described in more detail elsewhere in this specification, be a temperature sufficient to provide and maintain a predetermined contact temperature at which the hydrogen should be contacted with the hydrogen capture medium to promote ad / absorption of hydrogen thereof by the hydrogen capture medium. Achieving these pressures and temperatures is discussed in more detail, below.

[0097] The invention also provides, however, for activation energy to promote ad / absorption of hydrogen, e.g. at start-up, to be supplied to the particle bed. More specifically, at least during initiation of an ad / absorption cycle, the temperature at which hydrogen needs to be contacted with hydrogen capture medium to promote ad / absorption of hydrogen may need to be fairly warm, e.g. above the predetermined contact temperature required for ad / absorption at a particular predetermined contact pressure for a particular hydrogen capture material, to overcome the activation energy required for ab / adsorption to commence. Thus, the method may include subjecting the hydrogen to temperature treatment prior to supply thereof to the particle bed, which may be temperature treatment as described below in accordance with the invention, but to a predetermined supply temperature above the predetermined contact temperature.

[0098] Shortly thereafter, as ad / absorption commences, the exothermic nature of the ad / absorption would cause the temperature of the particle bed to increase. This is obviously undesired, particularly in hydrogen storage applications in which such an increase in temperature may promote hydrogen desorption. The method may therefore include monitoring the temperature at which ad / absorption is occurring in the particle bed, which may comprise measuring the temperature of hydrogen that passes through the particle bed and comparing it to the predetermined supply temperature. If an increase in temperature is noted, then the method may comprise an intervention to restore the temperature of the bed to or to establish the temperature of the bed at the predetermined contact temperature. This may also be achieved by temperature treatment of the hydrogen gas prior to supply thereof to the particle bed, which temperature treatment may be as described in more detail elsewhere in this specification and may be effected automatically by the control system.

[0099] In one embodiment of the invention, the hydrogen capture medium, in other words the hydrogen capture material thereof, would typically comprise a metal. In such a case, the hydrogen capture material may be either in elemental metallic format or a metal compound. When the hydrogen capture material is in elemental metallic format, the hydrogen capture material may for example be palladium (Pd). Persons skilled in the art would appreciate that numerous other examples exist and that Pd is therefore not the only possible hydrogen capture material in elemental metallic format, which is identified herein only as an example.

[0100] When the hydrogen capture material is a metal compound, it would typically be a metal alloy, i.e. a compound of two or more metals.

[0101] For example, the hydrogen capture material may be selected from TiFe, Ti0.22Cr0.39V0.39, Tii.iCrMn, TiFeo.85Mno.o5, LaNi^gSno.i, NaAl, and Lao.sCeo.2Ni5 and metal alloys of metal alloy hydrides selected from AI(BH4)s, AIH3, BaReHg, Ca(BH4)2, FeTiHu, KBH4, LaNisHe, LiAIH4, LiBH4, LiH, Mg(BH4)2, Mg2FeH6, Mg2Ni5H4, MgH2, Mn(BH4)2, NaAIH4, NaBH4, and Zn(BH4)4, wherein the hydride denotes the form of the metal alloy in which hydrogen has already been adsorbed or absorbed on or by the metal alloy. Persons skilled in the art would appreciate that numerous other examples exist and that the metal alloys and metal alloy hydrides identified here are therefore not the only possible metal alloy hydrogen capture materials, these being identified herein only as examples.

[0102] The present invention is, in fact, not distinguished in any particular hydrogen capture material.

[0103] As has been mentioned above, contacting the hydrogen capture medium with gaseous hydrogen may be effected at a predetermined contact temperature that promotes capturing and storing of hydrogen by the hydrogen capture medium through adsorption and / or absorption of hydrogen on or by the hydrogen capture medium from the gaseous hydrogen.

[0104] Typically, the predetermined contact temperature would be associated with a corresponding predetermined contact pressure at which, at the predetermined contact temperature, capturing and storing of hydrogen by the hydrogen capture medium through adsorption and / or absorption of hydrogen on or by the hydrogen capture medium from the gaseous hydrogen is promoted.

[0105] Therefore, the method may include contacting the hydrogen capture medium with gaseous hydrogen at a predetermined contact temperature, being the abovementioned predetermined contact temperature, and at a corresponding predetermined contact pressure, being the abovementioned predetermined contact pressure, that promote capturing and storing of hydrogen by the hydrogen capture medium through adsorption and / or absorption of hydrogen, from the gaseous hydrogen, on or by the hydrogen capture medium. The predetermined contact temperature and corresponding predetermined contact pressure, at which adsorption and / or absorption of hydrogen from the gaseous hydrogen on or by the hydrogen capture medium is promoted, would depend on the hydrogen capture medium that is used and would be readily determinable by persons skilled in the art from literature references and through routine experimentation. It would also depend on the particle size of the particles of the particulate hydrogen capture medium, which would be determined as described hereinbefore or communicated from an earlier such determination. This is preferred to the invention generally, including all of its aspects.

[0106] Examples of predetermined contact temperatures and pressures of some metal alloys that may be used in the method of the invention, include those set out in Table 1 , below:

[0107] Table 1 : Metal alloy contact temperature and pressure examples for adsorption / absorption of hydrogen

[0108] As alluded to above, achieving and / or maintaining the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium may at least in part be driven by the temperature of the gaseous hydrogen that is contacted with the hydrogen capture medium.

[0109] In other words, the gaseous hydrogen that is contacted with the hydrogen capture medium may be used, or may be employed or may act, as a working fluid to achieve and / or maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium.

[0110] The term “working fluid” is in this context used in a heat transfer sense, meaning that it is the temperature of the gaseous hydrogen that drives any required temperature change to achieve and / or maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium. The gaseous hydrogen is therefore used, and the method therefore includes using, the gaseous hydrogen to bring the hydrogen capture medium to a temperature that promotes adsorption and / or absorption or that promotes desorption, such a temperature being the abovementioned predetermined contact temperature.

[0111] Put differently, the gaseous hydrogen that is contacted with the hydrogen capture medium may provide a contact environment that is at the predetermined contact temperature, thereby to bring the hydrogen capture medium to the predetermined contact temperature and thus effect contacting between the gaseous hydrogen and the hydrogen capture medium at the predetermined contact temperature.

[0112] In one embodiment of the invention, for the gaseous hydrogen to be used, employed, or to act as a working fluid in achieving and / or maintaining the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium or, put differently, to provide a contact environment that is at the predetermined contact temperature, the gaseous hydrogen may be subjected to temperature treatment prior to being contacted with the hydrogen capture medium.

[0113] Such temperature treatment may be performed selectively to cool or heat the gaseous hydrogen, as may be required for the gaseous hydrogen to be contacted with the hydrogen capture medium at the predetermined contact temperature.

[0114] Therefore, the method may include subjecting the gaseous hydrogen that is contacted with the hydrogen capture medium to temperature treatment upstream of the hydrogen capture medium, selectively to cool or heat the gaseous hydrogen as may be required to achieve and / or maintain the predetermined contact temperature in contacting the hydrogen capture medium with the gaseous hydrogen.

[0115] The extent and nature of the temperature treatment may be determined with reference to a temperature of the hydrogen capture medium or a temperature to which the hydrogen capture medium is cooled or heated independently of its contact with the gaseous hydrogen (e.g. through indirect heat exchange with a heat transfer medium, induction, etc.).

[0116] Thus, the method does not exclude, and may in fact include, cooling or heating the hydrogen capture medium independently of its contact with the gaseous hydrogen, in which case combined - (i) cooling or heating of the capture medium independently of its contact with the gaseous hydrogen, and

[0117] (ii) contact of the gaseous hydrogen with the capture medium, would provide the predetermined contact temperature. In another embodiment, the hydrogen storage chamber herein referenced may, itself, be subjected to temperature treatment to achieve and maintain the predetermined contact temperature.

[0118] More typically, however, the temperature treatment may selectively heat or cool the gaseous hydrogen to the predetermined contact temperature.

[0119] Thus, achieving the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium would typically, and in fact preferably, result from or be driven by the temperature of the gaseous hydrogen. Put differently, as mentioned above, in having been heated or cooled to the predetermined contact temperature, the gaseous hydrogen that is contacted with the hydrogen capture medium may thus provide a contact environment that is at the predetermined contact temperature.

[0120] While both cooling and heating have been referenced above as possible temperature treatments it would, in relation to ad / absorption steps of this first aspect of the invention, be more typical for cooling to be employed.

[0121] As has been noted earlier, the hydrogen capture medium may be provided, and contacting of the hydrogen capture medium with gaseous hydrogen may therefore be performed, inside a hydrogen storage chamber.

[0122] The hydrogen storage chamber may be pressure-tight, i.e. it may be capable of withstanding internal pressures exceeding atmospheric pressure. For example, the hydrogen storage chamber may be capable to withstanding internal pressures of up to 3MPa, or even up to 35MPa.

[0123] The hydrogen storage chamber may for example be provided by a pressure-tight vessel. In one embodiment of the invention, the pressure-tight vessel may be a pressure-tight tank.

[0124] Contacting the hydrogen capture medium with the gaseous hydrogen at the predetermined contact temperature and the predetermined contact pressure may therefore be performed inside the hydrogen storage chamber, such that the predetermined contact temperature and the predetermined contact pressure are provided and maintained inside the hydrogen storage chamber.

[0125] In other words, a contact environment, as referenced above, at the predetermined contact temperature and predetermined contact pressure may be provided inside the hydrogen storage chamber to promote adsorption and / or absorption of hydrogen by the hydrogen capture medium when contacting the gaseous hydrogen with the hydrogen capture material, wherein, in one embodiment of the invention, the predetermined contact temperature may be provided by the gaseous hydrogen.

[0126] As has been indicated, the hydrogen storage chamber may have an inlet, through which to feed gaseous hydrogen into the hydrogen storage chamber to be contacted with the hydrogen capture medium.

[0127] As has also been indicated, the hydrogen storage chamber may also have an outlet, through which to withdraw gaseous hydrogen from the hydrogen storage chamber.

[0128] Gaseous hydrogen that may be withdrawn from the hydrogen storage chamber may, for example, be or comprise gaseous hydrogen comprising unabsorbed hydrogen, i.e. gaseous hydrogen fed into the hydrogen storage chamber and having been contacted with the hydrogen capture medium but not having had hydrogen absorbed and / or adsorbed from it. Such gaseous hydrogen may be described as “excess” gaseous hydrogen.

[0129] Gaseous hydrogen withdrawn from the outlet may, in other words, comprise or consist of excess gaseous hydrogen, which would be in excess with reference to the volume of hydrogen, or the volumetric rate of hydrogen over time, that the hydrogen capture medium is able to adsorb and / or absorb.

[0130] In an embodiment of the invention in which stored hydrogen is recovered from the hydrogen capture medium as gaseous hydrogen, including in accordance with the second aspect of the invention, gaseous hydrogen that is withdrawn from the outlet may comprise or consist of a hydrogen product gas. This foresees that, in such an embodiment, either one or both of excess gaseous hydrogen and a hydrogen product gas may be recovered through the outlet at a particular time. There would typically be excess hydrogen to withdraw from the outlet if the volumetric feed flow rate at which gaseous hydrogen is fed to the hydrogen storage chamber exceeds the rate at which hydrogen can be adsorbed on and / or absorbed by the hydrogen capture medium and, by extension, if the hydrogen capture medium is saturated with hydrogen and therefore can no longer adsorb and / or absorb hydrogen thereon and / or therein. The excess may, in chemical terms, be a stoichiometric excess.

[0131] As also alluded to above, in an embodiment of the invention in which hydrogen is recovered, as gaseous hydrogen, from a hydrogen capture medium storing hydrogen, e.g. as provided for in this first aspect of the invention or in accordance with the method of the second or third aspects of the invention, gaseous hydrogen that is withdrawn from the hydrogen storage chamber through the outlet may, alternatively additionally, be or comprise a hydrogen product gas.

[0132] The outlet may comprise at least one outlet valve.

[0133] The outlet valve may be configured automatically to release excess gaseous hydrogen and / or hydrogen product gas from the hydrogen storage chamber above a predetermined release pressure, for release thereof, inside the hydrogen storage chamber. Therefore, the outlet valve may be a pressure relief valve. This would preferably be the case in hydrogen desorption applications.

[0134] Additionally, or alternatively, the outlet valve may be configured to be selectively opened to allow such release and shut to prevent such release, independent of pressure. This would preferably be the case in hydrogen ad / absorption applications.

[0135] When the outlet valve is a pressure relief valve, the pressure relief valve may be an adjustable pressure relief valve, in the sense that the pressure at which the valve would release gaseous hydrogen from the hydrogen storage chamber may be selectively changed, e.g. respectively to release excess gaseous hydrogen and to release hydrogen product gas from the hydrogen storage chamber.

[0136] Typically, the outlet would comprise two outlet valves, each being selected from a pressure relief valve, selectively operable or respectively selectable to release gaseous hydrogen from the hydrogen storage chamber at respective predetermined release pressures, which may be different, or a valve that is capable of being selectively opened or shut independent of pressure, or a valve that possesses both such functionalities. As described in more detail herein, including with reference to the second aspect of the invention, providing more than one outlet valve, and more specifically providing two outlet valves, would typically be motivated respectively to provide for recirculation of gaseous hydrogen, and more specifically for recirculation of excess gaseous hydrogen, to the hydrogen storage chamber, and for release of a hydrogen product gas from the hydrogen storage chamber. One valve may therefore be a gaseous hydrogen recirculation valve, which is preferably operated as an open / shut valve, and the other may be a hydrogen product gas release valve, which is preferably operated as a pressure relief valve.

[0137] In being provided for release of a hydrogen product gas from the hydrogen storage chamber, in accordance with the method of the second aspect of the invention, having two valves would also allow for hydrogen product gas to be released from the hydrogen storage chamber while gaseous hydrogen is simultaneously being recirculated.

[0138] In the context of the method of the present, first, aspect of the invention, when hydrogen ad / absorption is being provided for, no simultaneous withdrawal or release of a hydrogen product gas while gaseous hydrogen is being recirculated is provided for in the context of hydrogen ad / absorption. Thus, in such an application, any additional valve that is provided at the outlet of the hydrogen storage chamber for the release of a hydrogen product gas from the hydrogen storage chamber would typically remain shut during the performance of the method of this first aspect of the invention for hydrogen ad / absorption.

[0139] Therefore, in the method of this, first, aspect of the invention, for hydrogen ad / absorption, the gaseous hydrogen recirculation valve would allow excess gaseous hydrogen to leave the hydrogen storage chamber, while the hydrogen product gas release valve would remain shut.

[0140] As alluded to earlier, the hydrogen storage chamber, or the reactor or vessel providing it, may be specially configured in the interests of addressing the challenge of particle entrainment that the invention seeks to address.

[0141] More specifically, the hydrogen storage chamber may be characterized in having a section of substantially constant diameter, e.g. a cylindrical section, in which the particle bed may be provided and be fluidized, and, downstream of the section of substantially constant diameter, having a flared section that progressively increases in diameter in a direction away from the section of constant diameter. In the flared section, as a result of the flaring, the superficial velocity of the fluidizing gas, i.e. the gaseous hydrogen, decreases, thus counteracting particle entrainment.

[0142] The method may include continuously supplying gaseous hydrogen to the hydrogen capture medium. In other words, contacting the hydrogen capture medium with gaseous hydrogen may include continuously supplying gaseous hydrogen to the hydrogen capture medium.

[0143] Continuous supply of gaseous hydrogen to the hydrogen capture medium may be, as alluded to above, at a volumetric feed flow rate, which has a superficial velocity to effect. As also alluded to above, the volumetric feed flow rate may be of a sufficient magnitude, and at a supply pressure of a sufficient magnitude, to effect fluidization of the hydrogen capture medium, which magnitudes would be determined in accordance with the invention. The magnitudes would, more specifically, be that which is required to achieve the superficial fluidizing velocity.

[0144] It must further be understood in the context of the invention generally, i.e. as applicable to each of the aspects of the invention, that the selection of the predetermined contact and supply temperatures and the predetermined contact pressure would in some cases, particularly when recovery of stored hydrogen is required, be affected by hydrogen demand, e.g. that which is required for power generation such as in a vehicle internal combustion engine or fuel cell. Thus, determination of the predetermined contact and supply temperatures and the predetermined contact pressure may in an embodiment of the invention be influenced by such requirement, e.g. may be selectively increased and / or decreased in order to increase or decrease hydrogen recovery from the hydrogen capture medium when it stores hydrogen. Such determination and the resulting control to effect it would typically be performed by a control system as provided for in accordance with the invention, preferably a control system for recovering hydrogen from hydrogen stored in particulate hydrogen capture medium. Such a control system would, as described herein, typically include one or more programmable logic controllers and one or more databases containing reference values of temperatures and pressures required for selected power outputs.

[0145] As described in accordance with the invention, there may in some embodiments be a plurality of hydrogen storage chambers that is provided, e.g. on a vehicle. Such chambers may, for example, comprise a plurality of vessels such as cylinders or the like. Depending on power required by such a vehicle and the corresponding volume of hydrogen that is required, the methods of the invention may be performed on one or more of such hydrogen storage chambers simultaneously, to increase the volume of available hydrogen. Feeding of gaseous hydrogen into the hydrogen storage chamber to be contacted with the hydrogen capture medium would typically be performed through a single inlet. However, discharge of gaseous hydrogen inside the hydrogen storage chamber to be contacted with the hydrogen capture medium would typically be performed through a plurality of discharge nozzles.

[0146] In one embodiment of the invention, gaseous hydrogen that is supplied to the hydrogen capture medium may comprise, or optionally consist of, fresh gaseous hydrogen, i.e. gaseous hydrogen that had not previously been contacted with the hydrogen capture medium. Such fresh gaseous hydrogen may be obtained from a fresh gaseous hydrogen supply source.

[0147] The method may further include recovering uncaptured hydrogen, as gaseous hydrogen, and more specifically as excess gaseous hydrogen as described above, from the hydrogen capture medium. Such recovery would typically be required during hydrogen ab / adsorption, i.e. “hydrogen capture medium filling” applications. More specifically, it will be appreciated that, of the hydrogen that is fed to the particle bed, at least some would be ab / adsorbed by the hydrogen capture medium. If not all of the hydrogen that is supplied to the particle bed is ab / adsorbed, some hydrogen would pass through the particle bed as excess hydrogen. This does not exclude recovery in hydrogen desorption applications, however, in which case recovery of hydrogen contained in I released from hydrogen capture medium contained in the hydrogen storage chamber also has relevance to drive such release of hydrogen from the hydrogen capture medium, as discussed in more detail elsewhere in this specification.

[0148] When the method includes recovering gaseous hydrogen comprising unabsorbed hydrogen (i.e. excess gaseous hydrogen, as referenced above) from the hydrogen capture medium, the method may also include recirculating gaseous hydrogen comprising uncaptured hydrogen, recovered from the hydrogen capture medium (i.e. excess gaseous hydrogen as referenced above), to the hydrogen capture medium, as recirculated gaseous hydrogen, such that the gaseous hydrogen that is contacted with the hydrogen capture medium comprises recirculated gaseous hydrogen.

[0149] Thus, when the method is performed using the hydrogen storage chamber, the method may include recirculating gaseous hydrogen comprising uncaptured hydrogen, as recirculated gaseous hydrogen into the hydrogen storage chamber, such that the gaseous hydrogen that is fed into the hydrogen storage chamber comprises recirculated gaseous hydrogen.

[0150] Such recirculation may originate from the outlet of the gaseous hydrogen chamber, which outlet may therefore comprise a gaseous hydrogen recirculation outlet. The gaseous hydrogen recirculation outlet may comprise the gaseous hydrogen recirculation valve. In addition, the outlet may comprise a hydrogen product gas outlet. The hydrogen product gas outlet may comprise the hydrogen product gas release valve referenced above, which would typically be shut in performing the method of this, first, aspect of the invention when ad / absorbing hydrogen.

[0151] Gaseous hydrogen that is supplied to the hydrogen capture medium, e.g. by being fed into the hydrogen storage chamber, may therefore comprise, or optionally consist of, recirculated gaseous hydrogen.

[0152] When the method includes recirculating gaseous hydrogen comprising unabsorbed hydrogen, recovered from the hydrogen capture medium (i.e. excess gaseous hydrogen that is recirculated as recirculated gaseous hydrogen), to the hydrogen capture medium, the method may include supplementing the recirculated gaseous hydrogen with fresh gaseous hydrogen to the extent necessary to maintain volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium.

[0153] It follows that, to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium, including the superficial fluidization velocity, gaseous hydrogen supplied to the hydrogen capture medium may selectively comprise - fresh gaseous hydrogen; recirculated gaseous hydrogen; or a combination of fresh gaseous hydrogen and recirculated gaseous hydrogen.

[0154] As has been discussed, setting the predetermined contact pressure in a hydrogen storage application may be performed by setting the pressure at which fresh gaseous hydrogen is supplied, preferably to a recirculation stream. It will be appreciated by persons skilled in the art that even in a case in which no fresh gaseous hydrogen is required to maintain a desired volumetric flow rate, the setting of such a pressure of a fresh gaseous hydrogen stream while in communication with such a recirculated gaseous hydrogen stream would have the effect of determining the pressure of the recirculated gaseous hydrogen stream.

[0155] In summary, broadly speaking, supplying the particle bed of hydrogen capture medium with gaseous hydrogen may therefore include - continuously feeding gaseous hydrogen into the hydrogen storage chamber at a volumetric feed flow rate and supply pressure that is sufficient to fluidize the hydrogen capture medium inside the hydrogen storage chamber, while releasing uncaptured hydrogen, as excess gaseous hydrogen, from the hydrogen storage chamber; and recirculating the excess gaseous hydrogen, as recirculated gaseous hydrogen, into the hydrogen storage chamber, such that the gaseous hydrogen that is fed into the hydrogen storage chamber comprises recirculated gaseous hydrogen.

[0156] To set the predetermined contact pressure, in a hydrogen ad / absorption environment, fresh gaseous hydrogen is provided in fluid communication with the recirculated excess gaseous hydrogen at the predetermined contact pressure.

[0157] It will be understood that, in addition, if the temperature of hydrogen gas passing through the particle bed is above that of hydrogen gas being fed to the particle bed, then the conclusion may be drawn that activation energy has been supplied and that ad / absorption is proceeding, in which case the predetermined supply temperature at which hydrogen is supplied to the particle bed needs to be lowered, alternatively that the material in the tank needs to be cooled by another method, to prevent an unwanted rise in temperature in the bed, so as to maintain the predetermined contact temperature.

[0158] The composition of the gaseous hydrogen that is supplied to the hydrogen capture medium, e.g. by being fed into the hydrogen storage chamber, may accordingly be selected such that a supply of gaseous hydrogen to the hydrogen capture medium makes use of recirculated gaseous hydrogen when recirculated gaseous hydrogen is available and such that the gaseous hydrogen is supplied to the hydrogen capture medium at a volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0159] In a case in which there is temperature treatment of gaseous hydrogen that is supplied to the hydrogen capture medium, e.g. in being fed into the hydrogen storage chamber, it would be appreciated that such temperature treatment would therefore be performed either on fresh gaseous hydrogen, or on recirculated gaseous hydrogen, or on a mixture thereof, depending on the composition of the gaseous hydrogen that is supplied to the hydrogen capture medium.

[0160] The composition of gaseous hydrogen supplied to the hydrogen capture medium may change over time, since the capacity of the hydrogen capture medium to store hydrogen would become diminished as the hydrogen capture medium becomes saturated with hydrogen.

[0161] More specifically, under a continuous volumetric supply of gaseous hydrogen, i.e. at the superficial fluidization velocity, when the hydrogen capture medium does not store any hydrogen or while the hydrogen capture medium is in the process or adsorbing and / or absorbing hydrogen and is therefore still hydrogen lean from a hydrogen storage perspective, fresh gaseous hydrogen may initially exclusively or predominantly be provided from the source of fresh gaseous hydrogen as gaseous hydrogen feed to the hydrogen capture medium, with little to no excess gaseous hydrogen being released from or recirculated to the hydrogen storage chamber.

[0162] The recirculation of recirculated gaseous hydrogen to the hydrogen capture medium in turn reduces the volume of fresh gaseous hydrogen that is required to achieve and maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0163] Ultimately, when the hydrogen capture medium is saturated with hydrogen, there would be no more adsorption and / or absorption of hydrogen by the hydrogen capture medium. Thus, all gaseous hydrogen supplied to the hydrogen capture medium would continuously be recirculated as recirculated gaseous hydrogen and would be sufficient to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber. At such a time, no further fresh gaseous hydrogen would be required to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0164] It will be understood that the method may therefore include supplementing recirculated gaseous hydrogen with fresh gaseous hydrogen to the extent necessary to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture medium inside the hydrogen storage chamber.

[0165] Advantageously, the extent of the requirement to supply fresh gaseous hydrogen to the hydrogen capture medium to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber in combination with recirculated gaseous hydrogen, may be used as an indicator of the extent of saturation of the hydrogen capture medium. When there is no more such requirement, it may be concluded that the hydrogen capture medium is saturated with hydrogen.

[0166] Such a conclusion may also be drawn if the volumetric feed flow rate of gaseous hydrogen into the hydrogen storage chamber is equal to a volumetric flow rate at which gaseous hydrogen is recovered from the hydrogen capture medium, e.g. is released from the hydrogen storage chamber (referenced hereinafter as the volumetric rate of recovery of gaseous hydrogen from the hydrogen capture medium). Such a conclusion may also be drawn if there is an absence of a temperature differential between the gaseous hydrogen that is fed into the hydrogen storage chamber and the recirculated gaseous hydrogen when the recirculated gaseous hydrogen is recovered from the hydrogen capture medium.

[0167] Therefore, the method may include measuring, typically electronically, the volumetric rate of supply of fresh gaseous hydrogen to the hydrogen capture medium to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber and concluding, typically electronically, that the hydrogen capture medium is saturated with hydrogen if such a volumetric rate of supply is or approximates zero (0).

[0168] The method may also include measuring, typically electronically, the volumetric rate of recovery of gaseous hydrogen from the hydrogen capture medium, e.g. the volumetric rate of release of gaseous hydrogen from the hydrogen storage chamber, over time, and concluding, typically electronically, that the hydrogen capture medium is saturated with hydrogen if such volumetric rate of recovery or release over time approximates or is equal to the volumetric feed flow rate.

[0169] The method may also include measuring, typically electronically, the temperature of the gaseous hydrogen that is fed into the hydrogen storage chamber (T1) and the temperature of the recirculated gaseous hydrogen when it is recovered from the hydrogen capture medium, i.e. is withdrawn or released from the hydrogen storage chamber when the hydrogen storage chamber is used (T2), and concluding, typically electronically, that the hydrogen capture medium is saturated with hydrogen if a differential between such temperatures (T3) is or approximates zero.

[0170] As suggested above, such measuring and the drawing of such conclusion / s may be performed electronically. For example, the measuring and drawing of such conclusion / s may be performed by an electronic control system, which would also exert corresponding control over the valves herein described, e.g. to effect the pressurized condition of the hydrogen storage chamber as hereinafter described. The control system may be a control system as hereinbefore described with reference to the determination of superficial fluidizing velocity of the fluidizing gas, e.g. the electronic hydrogen supply control system and / or the electronic hydrogen storage chamber control system.

[0171] Such a control system may for example comprise an electronic processing unit in communication with a flow sensor that measures the volumetric rate of supply of fresh gaseous hydrogen to the hydrogen capture medium and / or respective flow sensors that measure the volumetric feed flow rate and the volumetric rate of recovery of gaseous hydrogen from the hydrogen storage chamber and / or respective temperature sensors that measure the temperature of the gaseous hydrogen that is fed to the hydrogen storage chamber and the temperature of the gaseous hydrogen released from the hydrogen storage chamber when it is released from the hydrogen storage chamber.

[0172] In summary, broadly speaking, the method may therefore include - electronically measuring a temperature (T1) of gaseous hydrogen that is fed into the hydrogen storage chamber; electronically measuring a temperature (T2) of gaseous hydrogen that is withdrawn from the hydrogen storage chamber; electronically calculating a temperature differential (T3) as T1 minus T2; electronically measuring the volumetric rate of supply of fresh gaseous hydrogen supplementing recirculated hydrogen to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture material inside the hydrogen storage chamber; electronically measuring a volumetric rate of recovery of recirculated gaseous hydrogen from the hydrogen storage chamber; electronically measuring the volumetric feed flow rate of gaseous hydrogen to the hydrogen storage chamber; and electronically concluding that the hydrogen capture material is sufficiently saturated with hydrogen, if

[0173] T3 is or approximates a value of zero (0), and / or the volumetric rate of supply of fresh gaseous hydrogen to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture material inside the hydrogen storage chamber is or approximates zero (0), and / or the volumetric rate of recovery of recirculated gaseous hydrogen is equal to or approximates the volumetric feed flow rate.

[0174] Supply of gaseous hydrogen to the hydrogen capture medium, e.g. feeding of gaseous hydrogen into the hydrogen storage chamber, may, in response to such a conclusion (i.e. that the hydrogen capture medium is saturated with hydrogen), be ceased, typically automatically, thus providing a pressurized hydrogen storage chamber at a storage pressure. In applications of the invention in which the hydrogen storage chamber is one of a group of multiple hydrogen storage chambers, instead of ceasing supply of fresh hydrogen, the method may include switching supply of fresh hydrogen from one hydrogen storage chamber, of which the hydrogen storage medium has been saturated, to another hydrogen storage chamber of the group of multiple hydrogen storage chambers.

[0175] Such ceasing of supply of gaseous hydrogen to the hydrogen capture medium may, with reference to utilization of the hydrogen storage chamber, include closing the gaseous hydrogen recirculation outlet, e.g. using the gaseous hydrogen recirculation valve referenced above, while also closing a fresh gaseous hydrogen supply conduit against fresh gaseous hydrogen supply. Such closure may be in addition to ceasing of gaseous hydrogen supply to the hydrogen storage chamber, through, for example, ceasing of recirculation of recirculated gaseous hydrogen and supplementing such recirculated gaseous hydrogen with fresh gaseous hydrogen.

[0176] Optionally, with the gaseous hydrogen recirculation outlet closed, the method may, however, include continuing to feed fresh gaseous hydrogen into the hydrogen storage chamber for a limited period of time, thereby to achieve the storage pressure. This may particularly be required if the storage pressure is above the predetermined contact pressure.

[0177] It will be appreciated that, in such an embodiment, there would be excess gaseous hydrogen in the hydrogen storage chamber. Having such excess gaseous hydrogen in the hydrogen storage chamber may be desired, e.g. as discussed above, to supply hydrogen to the particle bed to commence or stimulate hydrogen release from the hydrogen capture medium. In such a case, it would be preferred for such excess hydrogen to be pressurized.

[0178] The storage pressure may be at or above the predetermined contact pressure.

[0179] It will be appreciated that, thus, the hydrogen storage chamber would comprise solid hydrogen capture medium saturated with hydrogen and, in addition, pressurized gaseous hydrogen providing the storage pressure inside of the hydrogen storage chamber.

[0180] The provision of additional, pressurized hydrogen in the hydrogen storage chamber, which would typically be in the headspace of the hydrogen storage chamber, is an advantage of the invention, since it increases the volume of hydrogen stored in a hydrogen storage chamber, i.e. by providing both hydrogen stored in hydrogen capture medium and providing hydrogen stored as gaseous, pressurized hydrogen in the headspace of the hydrogen storage chamber.

[0181] Transport of stored hydrogen and pressurized gaseous hydrogen in the pressurized hydrogen storage chamber, through transport of the hydrogen storage chamber, would thus be allowed. As a safety precaution, it is provided that the hydrogen storage chamber would be configured to withstand internal pressures significantly higher than the predetermined contact pressure, to provide for possible increases in pressure through release of stored hydrogen by the capture medium as a result of temperature fluctuations.

[0182] In operation, in performing the method of this first aspect of the invention starting with a hydrogen storage chamber comprising hydrogen capture medium as hereinbefore described, the method may therefore include, initially, before any gaseous hydrogen has been contacted with the hydrogen capture medium, contacting the hydrogen capture medium with gaseous hydrogen from a supply of fresh gaseous hydrogen, i.e. gaseous hydrogen that has not yet been contacted with the hydrogen capture medium, e.g. supplied along a fresh gaseous hydrogen supply conduit, inside the hydrogen storage chamber, by feeding fresh gaseous hydrogen to a pump that can progressively increase the superficial velocity thereof and, by the pump, into the hydrogen storage chamber at the progressively increasing superficial velocity while monitoring the feed pressure.

[0183] As soon as the feed pressure ceases to increase with increasing superficial velocity, increasing the superficial velocity is ceased and the superficial velocity is maintained at the relevant level, as the superficial fluidizing velocity, including at an associated supply pressure.

[0184] The superficial fluidizing velocity is then used to determine, preferably to look up from a database such as that which is discussed earlier, the particle size, e.g. an average particle size, of the particles of the hydrogen capture medium, as well as the predetermined contact temperature and the predetermined contact pressure corresponding to such a particle size. This would typically be performed by the electronic hydrogen supply control system. If appropriate, values of these are then also communicated to the electronic hydrogen storage control system. These values may also include the superficial fluidizing velocity and the supply pressure.

[0185] The fresh gaseous hydrogen is also, if needed, subjected to temperature treatment upstream of the hydrogen capture medium, for the fresh gaseous hydrogen to be used, employed, or act as a working fluid to achieve and maintain, i.e. to provide a contact environment inside the hydrogen storage chamber at, the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium. At start-up, such temperature treatment may bring the gas to above the predetermined contact temperature, in the interests of activating the hydrogen capture medium. Continuous monitoring of the outlet gas temperature may be implemented, in order to apply appropriate restorative temperature treatment for maintenance of the predetermined contact temperature if there is a further increase in temperature arising from the ad / absorption of hydrogen by the hydrogen capture medium.

[0186] Feeding of fresh gaseous hydrogen into the hydrogen storage chamber would result in the pressure inside the hydrogen storage chamber increasing, as gaseous hydrogen comprising unabsorbed hydrogen (i.e. excess gaseous hydrogen) accumulates inside the hydrogen storage chamber, unless excess gaseous hydrogen is recirculated.

[0187] As mentioned, the method may then include recirculating the excess gaseous hydrogen by withdrawing it from the hydrogen storage chamber through the gaseous hydrogen recirculation outlet, as recirculated gaseous hydrogen. A stream of the recirculated hydrogen then preferably meets a stream of the fresh hydrogen upstream of the pump, which fresh hydrogen is at the predetermined contact pressure applicable to the hydrogen capture medium in the hydrogen storage chamber. Fluid communication between he recirculated hydrogen and the fresh hydrogen sets, through back pressure from the fresh hydrogen, the pressure in the hydrogen storage chamber at the predetermined contact pressure. From there, recirculated hydrogen, optionally combined with fresh hydrogen if required to maintain a sufficient volumetric feed flow rate, is then supplied to the hydrogen storage chamber by the pump and, thus, to the hydrogen capture medium, at a volumetric feed flow rate and a supply pressure sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0188] In this specification, where reference is made to “a volumetric feed flow rate” and “a supply pressure” that are “sufficient” to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, it should be understood, in a preferred embodiment, as being a volumetric feed flow rate that corresponds to the superficial fluidizing velocity and corresponding feed pressure (“supply pressure” after fluidization) at which the superficial fluidizing velocity was established. The use of the indefinite article in this context should not be seen as introducing a new integer in each case, but rather as providing that the values of the “sufficient” volumetric feed flow rate and “sufficient” supply pressure are to be determined, as described in this specification.

[0189] Optionally, the method may include supplementing the recirculated gaseous hydrogen with fresh gaseous hydrogen from the fresh gaseous hydrogen supply source, to maintain the volumetric feed flow rate and the supply pressure at which the recirculated hydrogen is fed into the hydrogen storage chamber sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium. The method may then further include subjecting the recirculated gaseous hydrogen, and the fresh gaseous hydrogen if used, to temperature treatment upstream of the hydrogen capture medium, for the recirculated gaseous hydrogen, and the fresh gaseous hydrogen, to be used, employed, or act as a working fluid to achieve and maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium, i.e. provide a contact environment inside the hydrogen storage chamber at the predetermined contact temperature.

[0190] Once the conclusion that the hydrogen capture medium is saturated with hydrogen has been reached, e.g. by the control system, as hereinbefore described, the method may include ceasing, typically automatically, supply of gaseous hydrogen to the hydrogen storage chamber once the storage pressure has been reached inside the hydrogen storage chamber as a result of continued feeding of gaseous hydrogen into the hydrogen storage chamber, and closing or closing off the hydrogen storage chamber pressure tightly at the storage pressure.

[0191] The method may therefore include pressure-tightly closing, or closing off, the hydrogen storage chamber at a storage pressure above the predetermined contact pressure and at a temperature that does not exceed the predetermined contact temperature. Such closing, or closing off, may be performed electronically in response to the conclusion that the hydrogen capture material is sufficiently saturated with hydrogen

[0192] Thus, the method of the invention provides a hydrogen storage chamber comprising hydrogen capture medium laden with hydrogen, closed off and pressurized with gaseous hydrogen at the predetermined storage pressure.

[0193] IN ACCORDANCE WITH A SECOND ASPECT OF THE INVENTION, THERE IS PROVIDED a method of recovering, in gaseous form, hydrogen that has been previously captured, and is thus stored, by a hydrogen capture medium through adsorption and / or absorption of the hydrogen on or by the hydrogen capture medium in particulate format, the method including contacting the hydrogen capture medium with gaseous hydrogen such that hydrogen is desorbed from the hydrogen capture medium as gaseous hydrogen as a result of such contact, wherein the contact fluidizes the hydrogen capture medium.

[0194] Hydrogen that is supplied to the hydrogen capture medium would preferably be heated / warmed to provide a predetermined contact temperature that would be conducive to desorption of hydrogen from the hydrogen capture medium. Storage of hydrogen “by” the hydrogen capture medium therefore includes storage of hydrogen in and storage of hydrogen on the hydrogen capture medium, respectively by one or both of adsorption and absorption, within the meanings of these terms hereinbefore characterized.

[0195] In relation to this, second, aspect of the invention, it must be understood that reference to the “hydrogen capture medium” is to hydrogen capture medium storing hydrogen to be recovered, typically being saturated with hydrogen, unless otherwise indicated. This is in contrast to the hydrogen capture medium of the method of the first aspect of the invention, which is hydrogen capture medium that is, at least initially, in a condition in which hydrogen would be stored therein instead of released therefrom, although that aspect does in certain respects also cover hydrogen capture medium storing hydrogen and the desorption of hydrogen from such hydrogen storage capture medium. Such features described in relation to the method of the first aspect of the invention should be understood to apply to this method of the second aspect of the invention too.

[0196] Hydrogen capture medium in a condition in which it stores hydrogen would typically be a hydride of the hydrogen capture medium, as hereinbefore described, in a case in which it was previously a metal or metal compound as hereinbefore described.

[0197] The hydrogen capture medium may therefore be as described with reference to the first aspect of the invention, including that it may be provided in loose particulate format as a bed thereof, subject to the abovementioned proviso that, in the case of the method of this, second, aspect of the invention, the hydrogen capture medium stores hydrogen that has been adsorbed on and / or absorbed by the hydrogen capture medium. Thus, when the hydrogen capture material is a metal alloy, the hydrogen capture medium may, in this second aspect of the invention, typically be a metal alloy hydride.

[0198] The hydrogen that is stored by the hydrogen capture medium may have been so stored by performing the method of the first aspect of the invention to effect ad / absorption of hydrogen on “empty” or “bare” hydrogen capture medium, i.e. hydrogen capture medium substantially free of hydrogen. The method of this, second, aspect of the invention may therefore include, as a prior step, performing the method of the first aspect of the invention effect ad / absorption of hydrogen on “empty” or “bare” hydrogen capture medium.

[0199] It follows that terms that characterize the method of this, second, aspect of the invention that align with terms of the method of the first aspect of the invention may be as characterized with reference to the method of the first aspect of the invention, except where otherwise indicated. Contacting the hydrogen capture medium with the gaseous hydrogen is therefore, as described with reference to the first aspect of the invention, effected such that the hydrogen capture medium is fluidized by such contact. Put differently, the hydrogen capture material in loose particulate format is be fluidized by contact of the gaseous hydrogen with the hydrogen capture material. In other words, gaseous hydrogen supplied to the hydrogen capture medium is supplied at a superficial velocity, including a volumetric feed flow rate, and typically also at a supply pressure, sufficient to fluidize the hydrogen capture medium.

[0200] A sufficient volumetric feed flow rate may, in this method of the second aspect of the invention, be determined, and fluidization may be effected, as in the case of the method of the first aspect of the invention, i.e. with reference to the inflection point at which there is no longer an increase in feed pressure with an increase in superficial velocity at which hydrogen gas is fed to the particle bed. The relevant sections of the specification that relate to the first aspect of the invention and provide for this are not repeated here, but should be understood as applying here as well.

[0201] Contacting the gaseous hydrogen and the hydrogen capture medium may be effected at a predetermined contact temperature and at a corresponding predetermined contact pressure (as mentioned above) that promote desorption of hydrogen from the hydrogen capture medium as gaseous hydrogen. In respect of the superficial velocity, the superficial velocity is preferably the superficial fluidizing velocity described according to the first aspect of the invention.

[0202] This, second, aspect of the invention may either include determining the superficial fluidizing velocity as described above and according to the first aspect of the invention, or it may include directly applying the superficial fluidizing velocity when it was previously determined by performing the method of the first aspect of the invention to effect ad / absorption of hydrogen on “empty” or “bare” hydrogen capture medium. It will be appreciated that, in such a case, the use of respective electronic hydrogen supply and electronic hydrogen storage chamber control systems, as described according to the first aspect of the invention, would be involved.

[0203] It should be understood that the predetermined contact temperature and the predetermined contact pressure that are referenced, or that apply, in relation to this, second, aspect of the invention would typically be different from the predetermined contact temperature and predetermined contact pressure characterized with reference to the method of the first aspect of the invention, since the conditions for adsorption and / or absorption of hydrogen on or by a particular hydrogen capture medium and the conditions for desorption of hydrogen, as gaseous hydrogen, from the same hydrogen capture medium, would be different. Their selection would however again be informed by a determination of particle size of the hydrogen capture medium, either by performing the method of the first aspect of the invention or from a value previously determined by performing the method of the first aspect of the invention.

[0204] The predetermined contact temperature and corresponding predetermined contact pressure, at which desorption of hydrogen from the hydrogen capture medium is promoted, would, as has been described in relation to the first aspect of the invention for hydrogen ad / absorption, depend on the hydrogen capture medium that is used and would be readily determinable by persons skilled in the art from literature references and through routine experimentation. It would also depend on the particle size of the particles of the particulate hydrogen capture medium, which would be determined as described hereinbefore or communicated from an earlier such determination.

[0205] Preferably, the predetermined contact temperature and corresponding predetermined contact pressure are determined with reference to the average particle size of the particles of the hydrogen capture medium, as determined by having performed the method of the first aspect of the invention to effect ad / absorption of hydrogen on “empty” or “bare” hydrogen capture medium or to effect desorption of hydrogen from hydrogen storing hydrogen capture medium.

[0206] Examples of predetermined contact temperatures and pressures of some other metal alloys include those set out in Table 2, below:

[0207] Table 2: Metal alloy contact temperature and pressure examples for desorption of hydrogen

[0208] As in the case of the method of the first aspect of the invention, achieving and / or maintaining the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium may at least in part be driven by the temperature of the gaseous hydrogen that is contacted with the hydrogen capture medium.

[0209] In other words, as in the case of the method of the first aspect of the invention, the gaseous hydrogen that is contacted with the hydrogen capture medium may be used, or may be employed or may act, as a working fluid to achieve and maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium. As before, the term “working fluid” is in this context used in a heat transfer sense, meaning that it is the temperature of the gaseous hydrogen that drives any required temperature change to achieve and / or maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium.

[0210] Put differently, and as also noted above in relation to the method of the first aspect of the invention, the gaseous hydrogen that is contacted with the hydrogen capture medium may therefore provide a contact environment that is at the predetermined contact temperature, being a temperature at which desorption of hydrogen stored by the hydrogen capture medium, as gaseous hydrogen, is promoted.

[0211] In one embodiment of the invention, for the gaseous hydrogen to be used, employed, or to act as a working fluid in achieving and / or maintaining the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium or, put differently, to provide a contact environment that is at the predetermined contact temperature, the gaseous hydrogen may be subjected to temperature treatment prior to being contacted with the hydrogen capture medium.

[0212] The method may therefore include subjecting the gaseous hydrogen that is contacted with the hydrogen capture medium to temperature treatment upstream of the hydrogen capture medium, selectively to cool or heat the gaseous hydrogen as may be required to achieve and / or maintain the predetermined contact temperature in contacting the hydrogen capture medium.

[0213] Such temperature treatment may be performed selectively to cool or heat the gaseous hydrogen, as may be required for the gaseous hydrogen to be contacted with the hydrogen capture medium at the predetermined contact temperature.

[0214] Thus, the method may include subjecting the gaseous hydrogen that is contacted with the hydrogen capture medium to temperature treatment upstream of the hydrogen capture medium, selectively to cool or heat the gaseous hydrogen as may be required to achieve and / or maintain the predetermined contact temperature in contacting the hydrogen capture medium.

[0215] The extent and nature of the temperature treatment may be determined with reference to a temperature of the hydrogen capture medium or a temperature to which the hydrogen capture medium is cooled or heated independently of its contact with the gaseous hydrogen (e.g. through indirect heat exchange with a heat transfer medium, induction, etc.).

[0216] Thus, the method does not exclude, and may in fact include, cooling or heating the hydrogen capture medium independently of its contact with the gaseous hydrogen, in which case combined -

[0217] (i) cooling or heating of the hydrogen capture medium independently of its contact with the gaseous hydrogen, and

[0218] (ii) contact of the gaseous hydrogen with the hydrogen capture medium, would provide the predetermined contact temperature. In another embodiment, the hydrogen storage chamber herein referenced may, itself, be subjected to temperature treatment to achieve and maintain the predetermined contact temperature.

[0219] More typically, however, the temperature treatment may selectively heat or cool the gaseous hydrogen to the predetermined contact temperature.

[0220] Thus, achieving the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium would typically, and in fact preferably, result from or be driven by the temperature of the gaseous hydrogen. Put differently, as mentioned above, in having been heated or cooled to the predetermined contact temperature, the gaseous hydrogen that is contacted with the hydrogen capture medium may provide a contact environment that is at the predetermined contact temperature.

[0221] While both cooling and heating have been referenced above, as possible temperature treatments, it would, in relation to this second aspect of the invention, be more typical for heating to be employed in a case in which desorption of hydrogen from the hydrogen capture medium, as gaseous hydrogen, is desired. Preferably, the temperature treatment selectively heats or cools the gaseous hydrogen that would be contacted with the hydrogen capture medium to the predetermined contact temperature.

[0222] The hydrogen capture medium may be provided, and contacting of the hydrogen capture medium with gaseous hydrogen may therefore be performed, inside a hydrogen storage chamber, which may be a hydrogen storage chamber as described with reference to the first aspect of the invention.

[0223] Contacting the hydrogen capture medium with the gaseous hydrogen at the predetermined contact temperature and the predetermined contact pressure may therefore be performed inside the hydrogen storage chamber, such that the predetermined contact temperature and the predetermined contact pressure are provided and maintained inside the hydrogen storage chamber.

[0224] In other words, a contact environment, as also referenced above, at the predetermined contact temperature and predetermined contact pressure may be provided inside the hydrogen storage chamber to promote desorption, of hydrogen by the hydrogen capture medium when contacting the gaseous hydrogen with the hydrogen capture material. As noted above, in one embodiment of the invention the predetermined contact temperature may be provided by the gaseous hydrogen.

[0225] Contacting the hydrogen capture medium with gaseous hydrogen may include continuously supplying gaseous hydrogen to the hydrogen capture medium, e.g. by continuously feeding gaseous hydrogen into the hydrogen storage chamber. It will be appreciated that such continuous supply may, as described above, be such that the hydrogen capture medium is continuously fluidized.

[0226] As has also been indicated above, gaseous hydrogen that is supplied to the hydrogen capture medium, e.g. by being fed into the hydrogen storage chamber, is supplied at a volumetric feed flow rate, and typically also at a supply pressure, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber. The manner in which a sufficient volumetric feed flow rate is determined has been described in accordance with the method of the first aspect of the invention, above, and the same principles apply here.

[0227] The hydrogen storage chamber may, before contacting the hydrogen capture medium with gaseous hydrogen at the predetermined contact temperature and predetermined contact pressure, be in a condition in which it is, orwas, pressurized with gaseous hydrogen at a storage pressure and at a storage temperature different from the predetermined contact temperature and predetermined contact pressure, which pressure and temperature do not promote, i.e. that avoid, desorption of hydrogen from the hydrogen capture medium as gaseous hydrogen. Typically, such a storage temperature may be a temperature below the predetermined contact temperature and such a storage pressure may be a pressure above the predetermined contact pressure.

[0228] In such a case, the method may include that, at least initially, the gaseous hydrogen that is contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure such that hydrogen is desorbed from the hydrogen capture material as gaseous hydrogen as a result of such contact, either comprises or, more typically and preferably consists of, gaseous hydrogen with which the hydrogen storage chamber is, or was previously, pressurized.

[0229] Thus, in recovering hydrogen from the hydrogen capture medium inside the hydrogen storage chamber, pressurized gaseous hydrogen contained inside the hydrogen storage chamber, typically being located above the hydrogen capture medium, may be withdrawn from the outlet of the hydrogen storage chamber, more specifically from the gaseous hydrogen recirculation outlet, and recirculated to the inlet of the hydrogen storage chamber.

[0230] The pressurized hydrogen may, in another embodiment of the invention, be pressurized hydrogen from another hydrogen storage chamber, which would typically be part of a group of hydrogen storage chambers in which the first-mentioned hydrogen storage chamber is included. This would typically apply when there is insufficient pressurized hydrogen in the first-mentioned hydrogen storage chamber, e.g. due to hydrogen of the hydrogen storage chamber having been partially used.

[0231] Such recirculated gaseous hydrogen may then be supplied to and contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure.

[0232] In such a case, as in the case of the method of the first aspect of the invention, the recirculated gaseous hydrogen may be used, or employed, or may act as a working fluid as hereinbefore described, which may include subjecting the recirculated gaseous hydrogen to temperature treatment as hereinbefore described. As an alternative, or in addition, the gaseous hydrogen that is contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure to effect desorption of hydrogen from the hydrogen capture medium may either comprise or consist of fresh gaseous hydrogen from a fresh gaseous hydrogen supply source. In one embodiment of the invention, fresh gaseous hydrogen may be used to supplement recirculated gaseous hydrogen to achieve and / or maintain the volumetric feed flow rate at which gaseous hydrogen is supplied to the hydrogen capture medium sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0233] As a further alternative, or in addition, the gaseous hydrogen that is contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure to effect desorption of hydrogen from the hydrogen capture medium may either comprise or consist of gaseous hydrogen desorbed from the hydrogen capture medium as a result of the hydrogen capture medium having been contacted with recirculated gaseous hydrogen or fresh gaseous hydrogen. The method may therefore include recirculating, preferably continuously, a portion of the desorbed gaseous hydrogen to the inlet of the hydrogen storage chamber.

[0234] Pressurized and / or desorbed gaseous hydrogen that is withdrawn from the hydrogen storage chamber for recirculation to the inlet of the hydrogen storage chamber may be withdrawn, or released, from the hydrogen storage chamber freely, i.e. continuously and without any determination of volumetric flow rate.

[0235] Contacting the hydrogen capture medium with gaseous hydrogen may therefore, as noted above, include withdrawing a portion of the desorbed gaseous hydrogen from the outlet of the hydrogen storage chamber, and more specifically through the gaseous hydrogen recirculation valve, recirculating it to the inlet of the hydrogen storage chamber, and feeding it into the interior of the hydrogen storage chamber at the volumetric feed flow rate, and typically also at the supply pressure, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber. As will be understood, such a sufficient volumetric feed flow rate would be that which corresponds to the superficial fluidization velocity.

[0236] Such recirculation may, as mentioned above, be continuous. Therefore, for example, the gaseous hydrogen recirculation valve, as referenced in relation to the method of the first aspect of the invention, may, in performing the method of this, second, aspect of the invention, be fully open for the duration of the performance of the method of this second aspect of the invention. Given that the temperature adjustment of the hydrogen capture medium by the recirculated hydrogen and the decrease in pressure resulting from pressurized hydrogen being released from the hydrogen storage chamber to fluidize the hydrogen storage medium will cause desorption of the hydrogen from the hydrogen capture medium as gaseous hydrogen, the pressure within the hydrogen storage chamber will rise due to accumulation of gaseous hydrogen inside the hydrogen storage chamber. Such a pressure increase would continue, under continuous recirculation of gaseous hydrogen, until such time as a hydrogen product gas release pressure is reached upon which a valve, typically a pressure relief valve on the outlet, more one specifically the hydrogen product gas outlet, will open, allowing a hydrogen product gas to be released for use. Such valve would typically be the second valve characterised with reference to the first aspect of the invention, i.e. the hydrogen product gas release valve described with reference to the method of the first aspect of the invention, and its opening, and thus withdrawal of the hydrogen product gas, may therefore occur concurrently with recirculation of gaseous hydrogen.

[0237] It will be appreciated that the gaseous hydrogen that is contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure to effect desorption of hydrogen from the hydrogen capture medium may therefore, selectively, comprise only gaseous hydrogen that pressurized the hydrogen storage chamber before such contact, or only fresh gaseous hydrogen, or only recirculated desorbed gaseous hydrogen, or any combination of two or more hereof, each of which may be supplied to the hydrogen capture medium, e.g. by being fed into the interior of the hydrogen storage chamber, at the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0238] Most typically, in performing the method starting with a hydrogen storage chamber comprising hydrogen capture medium storing hydrogen and pressurized gaseous hydrogen, the hydrogen capture medium would be contacted, at a volumetric feed flow rate, and typically at the supply pressure, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, with - recirculated gaseous hydrogen that pressurizes, or previously pressurized, the hydrogen storage chamber, typically at the predetermined contact temperature and at the predetermined contact pressure, and then with recirculated desorbed gaseous hydrogen, optionally mixed with fresh gaseous hydrogen, at the predetermined contact temperature and at the predetermined contact pressure. The method may also include continuing recirculation after hydrogen desorption from the hydrogen capture medium has commenced, thus recirculating desorbed gaseous hydrogen to the hydrogen storage chamber. Such recirculation and continued desorption of hydrogen as gaseous hydrogen would result in the pressure inside of the hydrogen storage chamber increasing, up to a point at which the hydrogen product gas release pressure referenced herein is reached, at which time release of hydrogen product gas would occur. The pressure at which such release occurs would preferably be sufficient for sufficient back pressure into the hydrogen storage chamber to be maintained that recirculation continues.

[0239] Therefore, in summary, typically and preferably, the gaseous hydrogen that is contacted with the hydrogen capture medium at the predetermined contact temperature and at the predetermined contact pressure such that hydrogen is desorbed from the hydrogen capture material as gaseous hydrogen as a result of such contact, comprises or consists of pressurized gaseous hydrogen contained in the hydrogen storage chamber, the method therefore including withdrawing pressurized gaseous hydrogen contained in the vessel from the vessel; recirculating such gaseous hydrogen to the vessel at a volumetric feed flow rate sufficient to fluidize the hydrogen capture material; and contacting the gaseous hydrogen so recirculated with the hydrogen capture material at the predetermined contact temperature and at the predetermined contact pressure such that the hydrogen capture material is fluidized by such contact and such that hydrogen is desorbed from the hydrogen capture material as gaseous hydrogen as a result of such contact.

[0240] Again, it will be appreciated that fluidization would be monitored, effected, and maintained as hereinbefore described in accordance with the method of the first aspect of the invention, with reference to superficial velocity and feed pressure magnitude and variation, or would be known from having been previously determined by performing the method of the first aspect of the invention in ad / absorbing hydrogen to the hydrogen capture medium.

[0241] When the required superficial fluidization velocity is determined as part of the method of this second aspect of the invention and is therefore not known from having performed the method of the first aspect of the invention to ad / absorb hydrogen, the superficial fluidization velocity as determined will be used to determine the particle size of the hydrogen capture medium for the particular desorption cycle, from which value the required predetermined contact temperature and predetermined contact pressure (such temperature and pressure being particle size dependent) would be determined. Contacting the hydrogen capture medium storing hydrogen with gaseous hydrogen at the predetermined contact temperature and at the predetermined contact pressure causes desorption of hydrogen from the hydrogen capture medium and release thereof from the capture medium as gaseous hydrogen.

[0242] Such a release of gaseous hydrogen would, at the superficial fluidization velocity including a corresponding volumetric feed flow rate of gaseous hydrogen that is fed into the hydrogen storage chamber and that is sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, cause an increase in pressure inside of the hydrogen storage chamber, which pressure increase would be determinative of release of gaseous hydrogen from the hydrogen capture medium as a hydrogen product gas, typically through the hydrogen product gas outlet and through the hydrogen product gas release valve once the hydrogen product gas release pressure has been reached inside the hydrogen storage chamber.

[0243] It is emphasized that such withdrawal or discharge would typically be automatic at or above the hydrogen product gas release pressure, e.g. through a pressure-sensitive valve such as the second pressure relief valve, more specifically the hydrogen product gas release valve, referenced in relation to the method of the first aspect of the invention.

[0244] In other words, release of gaseous hydrogen through desorption of hydrogen from the hydrogen capture medium as a result of the contacting the hydrogen capture medium with gaseous hydrogen increases the pressure inside of the hydrogen storage chamber and causes automatic discharge of gaseous hydrogen from the hydrogen storage chamber as a hydrogen product gas, as referenced above, above a predetermined hydrogen product gas release pressure, as referenced above.

[0245] Discharge or release of gaseous hydrogen from the hydrogen storage chamber may originate from the outlet of the hydrogen storage chamber, which may therefore comprise hydrogen product gas outlet hereinbefore described, preferably in addition to the gaseous hydrogen recirculation outlet referenced in relation to the method of the first aspect of the invention.

[0246] The method may include continuously recirculating gaseous hydrogen to the hydrogen storage chamber, including while hydrogen is being desorbed from the hydrogen capture medium and while hydrogen product gas is being released from the hydrogen capture medium. Such gaseous hydrogen may be recirculated from the hydrogen storage chamber, being recovered from the hydrogen storage chamber through the gaseous hydrogen recirculation outlet of the hydrogen storage chamber.

[0247] Thus, a hydrogen product gas, comprising gaseous hydrogen released from the hydrogen capture medium, may be obtained.

[0248] As in the case of the method of the first aspect of the invention, the method of this second aspect of the invention may be performed by an electronic control system.

[0249] Such an electronic control system may be an electronic control system as described with reference to the first aspect of the invention, and may therefore be an electronic hydrogen supply control system or an electronic hydrogen storage chamber control system.

[0250] IN ACCORDANCE WITH ONE SPECIFIC EMBODIMENT OF THE SECOND ASPECT OF THE INVENTION, AS A THIRD ASPECT OF THE INVENTION, THERE IS PROVIDED a method of providing and maintaining a bed of particulate metallic hydrogen capture medium in a fluidized state inside a hydrogen storage chamber having an electronic hydrogen storage chamber control system, to cause hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium to be desorbed from the particulate metallic hydrogen capture medium, the method including recalling a previously determined superficial fluidization velocity for fluidizing the bed of particulate metallic hydrogen capture medium and a previously determined average particle size of the particulate metallic hydrogen capture medium from an electronic hydrogen storage chamber control system database of the electronic hydrogen storage chamber control system, which database has the fluidization superficial velocity stored therein by performing the steps of the method of the first aspect of the invention providing for the determination of the superficial fluidization velocity and the average particle size and communication thereof to be stored in the electronic hydrogen storage chamber control system database; and supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size, wherein recalling the superficial fluidization velocity and supplying the hydrogen gas are performed by the electronic hydrogen storage chamber control system.

[0251] Supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at the predetermined temperature and the predetermined pressure, would then cause hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium being desorbed from the particulate metallic hydrogen capture medium.

[0252] The method may include performing the steps of the method of the first aspect of the invention providing for the determination of the superficial fluidization velocity and the average particle size and communication thereof to be stored in the electronic hydrogen storage chamber control system database.

[0253] Supplying hydrogen to the hydrogen storage chamber may either comprise using excess gaseous hydrogen that is contained in the hydrogen storage chamber or may comprise using hydrogen from another hydrogen storage chamber, which would typically be part of a group of hydrogen storage chambers in which the first-mentioned hydrogen storage chamber is included. Supplying hydrogen from another hydrogen storage chamber would typically be required if the concerned hydrogen storage chamber to which hydrogen supply is required does not have sufficient gaseous hydrogen contained in it to perform such supply and effect fluidization, for hydrogen release from the hydrogen capture medium. Such insufficiency would typically arise from partial use of hydrogen contained in the first-mentioned hydrogen storage chamber.

[0254] Therefore, hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium may comprise gaseous hydrogen that is contained in the hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen capture medium, and wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium includes withdrawing hydrogen from the hydrogen storage chamber.

[0255] Alternatively, or in addition, hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium may comprise gaseous hydrogen that is contained in another hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen capture medium thereof, and wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium includes withdrawing hydrogen from the other hydrogen storage chamber.

[0256] The hydrogen storage chamber and the other hydrogen storage chamber preferably form part of a group comprising multiple interlinked hydrogen storage chambers. Such a group of multiple interlinked hydrogen storage chambers may, as discussed earlier, be provided on a vehicle, for successive discharge of hydrogen therefrom on the vehicle. IN ACCORDANCE WITH A FOURTH ASPECT OF THE INVENTION, THERE IS PROVIDED a hydrogen storage system for selective storage and recovery of hydrogen by or from a hydrogen capture medium in accordance with the methods of the first and second aspects of the invention respectively, the system comprising - a hydrogen storage chamber containing a hydrogen capture medium in its interior, the hydrogen storage chamber having an inlet to and an outlet from its interior; a gas dispersal system located downstream of the inlet of the hydrogen storage chamber and upstream of the hydrogen capture medium and providing gas inlet openings into the hydrogen storage chamber, optionally having a plurality of gas feed nozzles located inside the interior of the hydrogen storage chamber, to feed gaseous hydrogen into the interior of the hydrogen storage chamber in use; a gaseous hydrogen recirculation outlet provided by the outlet of the hydrogen storage chamber, for gaseous hydrogen to be released from the hydrogen storage chamber, at a gaseous hydrogen recirculation pressure, and be recirculated to the gas dispersal system as recirculated gaseous hydrogen, in use; a gaseous hydrogen recirculation pump located and configured to supply gaseous hydrogen from the gaseous hydrogen recirculation outlet and / or fresh gaseous hydrogen from a fresh gaseous hydrogen supply source to the gas dispersal system in use; and a hydrogen product gas outlet provided by the outlet of the hydrogen storage chamber, for gaseous hydrogen to be released from the hydrogen storage chamber, and thus from the system, in use, as a hydrogen product gas, at a hydrogen product gas release pressure inside the hydrogen storage chamber, for use.

[0257] The hydrogen storage chamber, the hydrogen capture medium, the inlet to the hydrogen storage chamber the gas dispersal system, the gaseous hydrogen, the outlet from the hydrogen storage chamber, the gaseous hydrogen recirculation outlet, the gaseous hydrogen product gas outlet, the gaseous hydrogen recirculation valve, the hydrogen product gas release valve, and all other components of the system described directly or indirectly in or by terms also used to characterize the method aspects of the invention, including the control system itself, may be as characterized with reference to the method aspects of the invention, or may be configured to perform the functions characterized in terms of the method aspects of the invention.

[0258] The gas dispersal system may be located to feed gaseous hydrogen into the interior of the hydrogen storage chamber, in use, preferably such that the hydrogen capture medium is fluidized by such feeding of gaseous hydrogen into the interior of the hydrogen storage chamber. The manner in which the development of fluidization is monitored and maintained would be as described according to the method of the first aspect of the invention, and would preferably be controlled by means of the control system herein described.

[0259] In one embodiment of the invention, with respect to a particular operative orientation of the hydrogen storage chamber, the gas dispersal system may be located at a base of the hydrogen storage chamber, such that the hydrogen capture medium essentially rests on or is supported by the gas dispersal system, or a part thereof.

[0260] The system may also include a gas cooling device and a gas heating device located downstream of the gaseous hydrogen recirculation pump and upstream of the gas dispersal system, respectively to be supplied with fresh and / or recirculated gaseous hydrogen by the gas recirculation pump and selectively to cool or heat such gaseous hydrogen before it is fed to the gas dispersal system and into the interior of the hydrogen storage chamber.

[0261] In the interests of addressing the challenge that the invention seeks to address, the hydrogen storage chamber, or reactor or vessel, may have features that work against entrainment of particles from the particle bed, such features including flaring of the diameter thereof downstream of the particle bed and shielding of the outlet thereof by a baffle.

[0262] More specifically, the hydrogen storage chamber may be characterized by having a section of substantially constant diameter, e.g. a cylindrical section, in which the particle bed may be provided and fluidized, and, downstream of the section of substantially constant diameter, having a flared section that progressively increases in diameter away from the section of constant diameter.

[0263] In the flared section, as a result of the flaring, the superficial velocity of the fluidizing gas, i.e. the gaseous hydrogen, decreases, thus counteracting particle entrainment.

[0264] The system may be adapted to prevent loss of capture medium from the storage chamber, e.g. by means of baffles and / or filters located in the path of flow of gaseous hydrogen in the system.

[0265] In one respect, such baffles may comprise a baffle that shields the outlet of the hydrogen storage chamber, leaving or defining openings through which openings gas is allowed to access the outlet. Such openings may be fitted with filters to prevent particles leaving the hydrogen storage chamber. The methods of the invention may include, and the systems of the invention may provide for, unclogging filters included in a path of hydrogen flow. This may for example include, but would not be limited to, the direct or indirect application of ultrasound to the filters and / or applying back-flow through the filters. The need for such unclogging may be determined with reference to an increase in pressure across the filters, or in a system implementing the invention.

[0266] The system may also comprise stirring means, to stir the hydrogen capture medium to assist its fluidization.

[0267] The gaseous hydrogen recirculation outlet and the hydrogen product gas outlet may be provided by one or more outlet valves, as characterised with reference to the first and second aspects of the invention respectively, i.e. comprising the gaseous hydrogen recirculation valve and the hydrogen product gas release valve. The outlet valves may be a pressure-sensitive, or pressure relief, outlet valves, for gaseous hydrogen to be discharged, or released, automatically from the hydrogen storage chamber as a hydrogen product gas, and thus from the system, at a predetermined release pressures inside the hydrogen storage chamber, which predetermined release pressures may respectively be the hydrogen product gas release pressure and the gaseous hydrogen recirculation release pressure. The valves may, however, also be configured to be made fully open or fully shut, independent of pressure. As has been discussed, in hydrogen ad / absorption applications, the gaseous hydrogen recirculation valve would preferably be an open / shut valve and would be open. The same would apply in hydrogen desorption applications, except that the hydrogen product gas release valve would then preferably be a pressure relief valve set at a product release pressure. Such a valve would in hydrogen ad / absorption applications preferably be set to a sufficiently high release pressure to avoid any release of hydrogen, except perhaps to ensure the hydrogen storage vessel remains within acceptable operating pressure limits.

[0268] Where the gaseous hydrogen recirculation outlet and the hydrogen product gas outlet comprise respective outlet valves, as is preferred, the system may be adapted such that the valves are respectively selectable, or opened, or closed, or activated for discharge, or release, of gaseous hydrogen from the hydrogen storage chamber. Alternatively, a single, adjustable valve may be provided, which may be adjustable in respect of its release pressure.

[0269] More specifically, the gaseous hydrogen recirculation outlet preferably comprises a gaseous hydrogen recirculation valve that can selectively be opened and shut independent of pressure. Furthermore, the hydrogen product gas outlet preferably comprises a hydrogen product gas release valve that is configured automatically to release gaseous hydrogen from the interior of the hydrogen storage chamber at the hydrogen product gas release pressure and that can selectively be opened and shut independent of pressure.

[0270] The system may include one or more electronic control systems, for controlling operation of the system to perform the methods of the first, second, and / or third aspects of the invention jointly or respectively.

[0271] The one or more electronic control systems may comprise one or more electronic processing units and one or more electronic controllers such as programmable logic controllers (PLCs), configured to control the system as hereinbefore and hereinafter described, selectively to perform the methods of the first, second, and third aspects of the invention jointly or respectively.

[0272] Reference hereinafter to “control system” includes, unless the context indicates otherwise, reference to both the control system of the various aspects of the invention generally, and respectively to the electronic hydrogen supply control system and the electronic hydrogen storage chamber control system.

[0273] In one respect, the control system, particularly when it is an electronic hydrogen supply control system as hereinbefore described may include means for supplying gaseous hydrogen to the hydrogen storage chamber at a progressively increasing superficial flow rate, typically using the pump, and for monitoring the feed pressure as characterised in accordance with first and second aspects of the invention. The control system may in this respect be configured to monitor the feed pressure and cease or interrupt increasing of the superficial velocity of the fluidizing gas when there is no longer a corresponding increase in the feed pressure, in accordance with the method of the first aspect of the invention, thus establishing the superficial fluidizing velocity, which is preferably a minimum superficial fluidizing velocity as described earlier.

[0274] In such a respect, the system may be a system for supplying hydrogen to the hydrogen storage chamber from a remote source of hydrogen, as hereinbefore described. For example, it may be a system of a hydrogen supply station, in which case the hydrogen storage chamber may be a hydrogen storage chamber separate of the hydrogen supply station, e.g. on a vehicle.

[0275] Alternatively, in such a respect, the system may be a system for supplying hydrogen to the hydrogen storage chamber from the hydrogen storage chamber, or from another such hydrogen storage chamber. As discussed previously, the, or each, hydrogen storage chamber may contain excess gaseous hydrogen in addition to hydrogen ad / absorbed by the hydrogen capture medium. Such supply from the hydrogen storage chamber and / or another hydrogen storage chamber would typically be applicable when desorbing hydrogen from the hydrogen capture medium. Supplying hydrogen from another hydrogen storage chamber would typically be required if the concerned hydrogen storage chamber to which supply is required does not have sufficient gaseous hydrogen contained in it to perform such supply and effect fluidization, for hydrogen release from the hydrogen capture medium. It will be appreciated that the first- mentioned hydrogen storage chamber would therefore typically be part of a group of hydrogen storage chambers in which the first-mentioned hydrogen storage chamber is included.

[0276] The system of the invention includes such a configuration of a grouping of multiple interconnected hydrogen storage containers within its scope, and a practice of selectively supplying hydrogen to one or more of the respective hydrogen storage containers, optionally simultaneously, from hydrogen to be ad / absorbed by or desorbed from the hydrogen capture medium.

[0277] In another respect, the control system, particularly when it is an electronic hydrogen storage chamber control system as hereinbefore described, may include an electronic database, e.g. the electronic hydrogen storage chamber control system database hereinbefore described, containing a value of the superficial fluidizing velocity and preferably also of supply pressure applicable to the particle size of hydrogen capture medium in the hydrogen storage compartment, as determined independently, e.g. by means of the electronic hydrogen supply control system, and communicated to the electronic database. The electronic database may then also contain values for the predetermined contact temperature and predetermined contact pressure hereinbefore described, required for hydrogen desorption from the hydrogen capture medium at the particle size thereof. In such a case, supply of hydrogen would preferably be from the hydrogen storage chamber itself, as described above, for desorbing hydrogen from the hydrogen storage medium.

[0278] In another respect, the control system may include means for monitoring the outlet temperature of gaseous hydrogen leaving the hydrogen storage chamber and for adjusting the temperature of gaseous hydrogen fed to the hydrogen storage chamber to provide an environment inside the hydrogen storage chamber that is at the predetermined contact temperature.

[0279] In another respect, the control system may be configured to operate the recirculation pump, i.e. to activate the pump and pump gaseous hydrogen, comprising fresh gaseous hydrogen and / or recirculated gaseous hydrogen, i.e. from the fresh gaseous hydrogen supply source and / or from the gaseous hydrogen recirculation outlet, into the interior of the hydrogen storage chamber at a volumetric feed flow rate, and typically at a supply pressure, sufficient to achieve and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber. The magnitude or such sufficient volumetric feed flow rate and supply pressure may be determined and maintained as hereinbefore described.

[0280] In another respect, the control system may be configured to supplement gaseous hydrogen from the recirculation outlet with fresh gaseous hydrogen from the fresh gaseous hydrogen supply source to the extent necessary to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture material.

[0281] In another respect, the control system may be configured to direct flow of gaseous hydrogen, driven by the gaseous hydrogen recirculation pump, selectively to the gas cooling device or to the gas heating device, and selectively to activate the gas cooling device or the gas heating device, if activation is needed, for the gaseous hydrogen to be selectively heated or cooled to the predetermined contact temperature.

[0282] In another respect, the control system may be configured to measure pressure inside the interior of the hydrogen storage chamber.

[0283] Preferably, in this regard, the control system is configured selectively to - shut the hydrogen product gas release valve and set the gaseous hydrogen recirculation valve open for recirculation of excess gaseous hydrogen at the predetermined contact pressure, and open the gaseous hydrogen recirculation valve and set the hydrogen product gas release valve to operate as a pressure relief valve at the hydrogen product gas release pressure, wherein sufficient back pressure from the hydrogen product release valve is provided to maintain recirculation.

[0284] In another respect, and as alluded to above, the control system may be configured to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, using fresh gaseous hydrogen from the fresh gaseous hydrogen supply source, recirculated gaseous hydrogen, or a combination thereof, wherein, when recirculated gaseous hydrogen is available, then at least recirculated gaseous hydrogen is supplied to the hydrogen storage chamber and is supplemented with fresh gaseous hydrogen only to the extent necessary to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0285] The control system may further be configured - to measure a temperature (T1) of gaseous hydrogen that is fed into the hydrogen storage chamber; to measure a temperature (T2) of gaseous hydrogen that is withdrawn from the hydrogen storage chamber; to calculate a temperature differential (T3) as T1 minus T2; to measure a volumetric rate of supply of fresh gaseous hydrogen supplementing recirculated hydrogen to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture material and to achieve and maintain the predetermined contact pressure inside the hydrogen storage chamber; to measure a volumetric rate of recovery of recirculated gaseous hydrogen from the hydrogen storage chamber through the gaseous hydrogen recirculation outlet; to measure the volumetric feed flow rate of gaseous hydrogen supplied to the hydrogen storage chamber through the inlet of the hydrogen storage chamber; and to conclude that the hydrogen capture material is sufficiently saturated with hydrogen, if -

[0286] T3 is or approximates a value of zero (0), and / or the volumetric rate of supply of fresh gaseous hydrogen to maintain the volumetric feed flow rate sufficient to fluidize the hydrogen capture material and to achieve and maintain the predetermined contact pressure inside the hydrogen storage chamber is or approximates zero (0), and / or the volumetric rate of recovery of recirculated gaseous hydrogen is equal to or approximates the volumetric feed flow rate.

[0287] In this regard, and in another respect, the control system may include a fresh gaseous hydrogen supply volumetric flow meter located to measure, and that measures in use, the volumetric rate at which fresh gaseous hydrogen, required to achieve or maintain the predetermined gaseous hydrogen feed flow rate constant over time, is withdrawn from the fresh gaseous hydrogen supply source. It will be appreciated that, thus, if sufficient recirculated gaseous hydrogen is available to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber using the recirculation pump, then no fresh gaseous hydrogen would be required. As has been discussed elsewhere in this specification, once the hydrogen capture medium is no longer ab / adsorbing hydrogen, i.e. is saturated or “filled” with hydrogen, then the feed flow rate to the hydrogen capture medium would be equal to the rate at which hydrogen is available for withdrawal from above the hydrogen capture medium. This applies to “filling” conditions.

[0288] Furthermore, the control system may include a gaseous hydrogen feed volumetric flow meter located to measure, and that measures in use, the volumetric feed flow rate at which gaseous hydrogen is fed to the hydrogen storage chamber over time.

[0289] In another respect, the control system may include a gaseous hydrogen recovery volumetric flow meter located to measure, and that measures in use, the volumetric rate of recovery, e.g. discharge or release, of gaseous hydrogen, and more specifically recirculated gaseous hydrogen, from the hydrogen storage chamber over time.

[0290] In another respect, the control system may be configured to close or close off the hydrogen storage chamber pressure-tightly, or to cease feeding of gaseous hydrogen into the interior of the hydrogen storage chamber, and thus provide a pressurized condition at a storage pressure after, it has been noted by the control system that, at the volumetric feed flow rate of gaseous hydrogen fed into the hydrogen storage chamber through the gas dispersal system, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, the volumetric flow rate of fresh gaseous hydrogen supply over time is, or approximates, zero (0).

[0291] In another respect, the control system may be configured to withdraw, from the hydrogen storage chamber in the pressurized condition, pressurized gaseous hydrogen from the hydrogen storage chamber through the gaseous hydrogen recirculation outlet and to pump such gaseous hydrogen into the interior of the hydrogen storage chamber at the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber.

[0292] The methods and system of the first to third aspects of the invention may further provide for passage of ultrasonic waves through the hydrogen capture medium when contacting the hydrogen capture medium with the gaseous hydrogen.

[0293] In one embodiment, configuration of the system may be such, and the methods of the invention may include, applying ultrasound to the hydrogen storage chamber, e.g. the reactor or vessel, itself, to assist with fluidisation etc. Such application of ultrasonic waves I ultrasound may serve one or more of (i) cleaning and preventing or addressing clogging of filters, (ii) assisting with settling of particles that have escaped the fluidized bed, and (iii) adding kinetic and thermal energy to hydrogen-particle interactions in promoting ad / absorption and desorption.

[0294] Such passage may increase kinetic energy that is imparted onto the hydrogen capture medium in being contacted with the gaseous hydrogen.

[0295] ACCORDING TO A FIFTH ASPECT OF THE INVENTION, THERE IS PROVIDED a system for providing and maintaining a particle bed of particulate metallic hydrogen capture medium in a fluidized state for hydrogen to be ad / absorbed by or desorbed, as hydrogen gas, from the particulate metallic hydrogen capture medium, the system including a hydrogen storage chamber containing a hydrogen capture medium in its interior, the hydrogen storage chamber having an inlet to and an outlet from its interior; a gas dispersal system located downstream of the inlet of the hydrogen storage chamber and upstream of the hydrogen capture medium and providing gas inlet openings into the hydrogen storage chamber, optionally having a plurality of gas feed nozzles located inside the interior of the hydrogen storage chamber, to feed gaseous hydrogen into the interior of the hydrogen storage chamber in use; a hydrogen supply conduit located to supply hydrogen to the particle bed of particulate metallic hydrogen capture medium; and an electronic hydrogen supply control system as described with reference to the method of the first aspect of the invention, configured to supply hydrogen to the hydrogen capture medium according to the method of the first aspect of the invention.

[0296] The system may be comprised by the system according to the third aspect of the invention.

[0297] Alternatively, the system may comprise the system according to the third aspect of the invention.

[0298] ACCORDING TO A SIXTH ASPECT OF THE INVENTION, THERE IS PROVIDED a system for providing and maintaining a particle bed of particulate metallic hydrogen capture medium in a fluidized state for hydrogen to be ad / absorbed by or desorbed, as hydrogen gas, from the particulate metallic hydrogen capture medium, the system including a hydrogen storage chamber containing a hydrogen capture medium in its interior, the hydrogen storage chamber having an inlet to and an outlet from its interior; a gas dispersal system located downstream of the inlet of the hydrogen storage chamber and upstream of the hydrogen capture medium and providing gas inlet openings into the hydrogen storage chamber, optionally having a plurality of gas feed nozzles located inside the interior of the hydrogen storage chamber, to feed gaseous hydrogen into the interior of the hydrogen storage chamber in use; a hydrogen supply conduit located to supply hydrogen to the particle bed of particulate metallic hydrogen capture medium; and an electronic hydrogen storage control system as described with reference to the method of the first aspect of the invention, configured to supply hydrogen to the hydrogen capture medium according to the method of the second or third aspects of the invention.

[0299] The system may be comprised by the system according to the third aspect of the invention.

[0300] Alternatively, the system may comprise the system according to the third aspect of the invention.

[0301] IN ACCORDANCE WITH A SEVENTH ASPECT OF THE INVENTION, THERE IS PROVIDED a method of operating a hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself of from pressurized hydrogen contained in another hydrogen storage chamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part, such that the hydrogen capture medium is fluidized by such supply, wherein the method includes repeatedly and successively performing the method of the first aspect of the invention for hydrogen to be ad / absorbed by the hydrogen capture medium; and the method of the third aspect of the invention for hydrogen to be desorbed from the hydrogen capture medium, including the steps of the method of the first aspect of the invention that provide for the determination of the superficial fluidization velocity and the average particle size by the electronic hydrogen storage control system and communication thereof to be stored in an electronic hydrogen storage chamber control system database of the electronic hydrogen storage chamber control system.

[0302] The hydrogen supply station, the hydrogen storage chamber, the electronic hydrogen supply control system, the electronic hydrogen storage chamber control system, the source of hydrogen, the other hydrogen storage chamber, the group of hydrogen storage chambers, and hydrogen capture medium may all be as hereinbefore described with reference to other aspects of the invention, whether independently of such aspects or dependent thereon.

[0303] It will be appreciated that the successive and repeated performance of the methods of the first and third aspects of the invention in the manner described would, as discussed in herein, result in fracturing, i.e. decrepitation, of the particles of the particulate hydrogen capture medium, in which environment the invention inventively applies the combination of the methods of the first and third aspects of the invention to ensure that fluidization of the particle bed is maintained while avoiding entrainment of particles.

[0304] IN ACCORDANCE WITH AN EIGHTH ASPECT OF THE INVENTION, THERE IS PROVIDED a hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, the system being configured for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself or from pressurized hydrogen contained in another hydrogen storage chamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part and are included in the system, such that the hydrogen capture medium is fluidized by such supply, such configuration including to repeatedly and successively perform the method of the first aspect of the invention for hydrogen to be ad / absorbed by the hydrogen capture medium; and the method of the third aspect of the invention for hydrogen to be desorbed from the hydrogen capture medium, including the steps of the method of the first aspect of the invention that provide for the determination of the superficial fluidization velocity and the average particle size by the electronic hydrogen storage control system and communication thereof to be stored in an electronic hydrogen storage chamber control system database of the electronic hydrogen storage chamber control system.

[0305] The hydrogen supply station, the hydrogen storage chamber, the electronic hydrogen supply control system, the electronic hydrogen storage chamber control system, the source of hydrogen, the other hydrogen storage chamber, the group of hydrogen storage chambers, and hydrogen capture medium may all be as hereinbefore described with reference to other aspects of the invention, whether independently of such aspects or dependent thereon.

[0306] It will be appreciated that the successive and repeated performance of the methods of the first and third aspects of the invention in the manner described would, as discussed in herein, result in fracturing, i.e. decrepitation, of the particles of the particulate hydrogen capture medium, in which environment the invention inventively applies the combination of the methods of the first and third aspects of the invention to ensure that fluidization of the particle bed is maintained while avoiding entrainment of particles.

[0307] THE INVENTION EXTENDS TO applications of hydrogen stored and / or recovered in accordance with the invention, including, for example, as a source of hydrogen for propulsion of a vehicle (whether for electricity generation or as a fuel in an internal combustion engine or and as a fuel gas for a hydrogen fueled fuel cell of an vehicle operating with such a fuel cell), bulk storage of hydrogen at locations where benefit may be derived from using stored hydrogen to generate electricity or for chemical purposes, the bulk transport of hydrogen from production facilities or depots to where it is required and the activation of capture medium, e.g. of metal alloys I metal hydrides, for use as activated capture medium.

[0308] In exploiting the invention to activate the hydrogen capture medium, the methods of the invention may include successively and repeatedly charging the hydrogen capture medium with hydrogen in accordance with the method of the first aspect of the invention and discharging hydrogen from it until the hydrogen capture medium has fractured, i.e. decrepitated, into irregular particles.

[0309] Finally, regarding the embodiments of the invention that describe the use of a grouping of multiple hydrogen storage chambers, or tanks as these chambers may also be referred to, the following is added, applicable to each aspect of the invention independently: Hydrogen flow rate requirements for usage are typically low. Therefore, it is possible to divide the total storage tank into multiple smaller tanks (mini tanks) each to be emptied in turn. This is advantageous as it allows for a smaller pump and heating capacity. This means that a programmable logic controller (PLC) is required to determine if a mini tank is becoming empty and another must be fluidised and heated to start producing hydrogen.

[0310] At startup the tanks will have hydrogen in the hydrogen capture medium and some gaseous pressurised hydrogen above it, as discussed earlier. A battery may be provided which will allow instant start of, e.g. a vehicle carrying the mini tanks, and pumping of hydrogen through the storage medium to fluidise it. The PLC will allow pressurised hydrogen to flow into the fuel cel of the vehicle which will start producing electricity and waste heat to heat the circulating hydrogen and the hydrogen tank being drained. Sensors will tell the PLC the temperatures and pressures in various parts of the system as well as the number of amps of electricity being produced. It will determine if this is sufficient to charge the battery and run the electric engines of the vehicle at the required rate. The PLC will adjust pump flow rate, temperature to obtain optimal hydrogen release from the hydrogen capture medium.

[0311] If a mini-tank is partially used at shutdown, it will not have pressurised gaseous hydrogen in the space above it and such gas will therefore not be available or useful at startup, even though it has hydrogen still stored in the metal hydride. The PLC will need to use a little gaseous hydrogen from another tank to initiate circulation and fuel cel electricity and heat production. Once heat is available the PLC will switch to the half empty tank to empty it, leaving some pressurised gaseous hydrogen still in the tank used at start up.

[0312] Hydrogen production by each mini tank will decay as the amount of hydrogen remaining as hydride falls, this will mean that the PLC may need to fluidise a second tank by controlling the required valves - to obtain adequate hydrogen flow rate - allowing the first tank to be run to the “empty state” despite it producing insufficient hydrogen flow alone. Similarly, if the vehicle operator required a high-power output, the PLC will need to activate a second or third mini-tank simultaneously.

[0313] In embodiments of the invention in which multiple hydrogen storage chambers are provided, it is also provided that, conveniently, filling of all such hydrogen storage chambers with hydrogen can occur simultaneously. This may be possible since, in embodiments of the invention in which a group of multiple hydrogen storage chambers are provided on a vehicle and need to be filled from a remote filling station, there is essentially no limit on the size of the hydrogen supply pump that can be provided at such a filling station. A sufficiently large pump may therefore be provided that would allow for such simultaneous supply. This will be understood to have an improved filling rate to effect.

[0314] PREFERRED EMBODIMENTS OF THE VARIOUS ASPECTS OF THE INVENTION, set out hereinabove, are characterised by the following statements:

[0315] In a first preferred embodiment, which is a preferred embodiment of the first aspect of the invention, the invention provides a method of providing and maintaining a particle bed of particulate metallic hydrogen capture medium in a fluidized state inside a hydrogen storage chamber using hydrogen as a fluidizing gas, for hydrogen to be ad / absorbed by or desorbed, as hydrogen gas, from the particulate metallic hydrogen capture medium, the method including supplying hydrogen to the particle bed of particulate metallic hydrogen capture medium at a superficial velocity of which the magnitude progressively increases over time, in a direction that would cause fluidization of the particle bed at or above a minimum superficial fluidization velocity, wherein the progressive increase in the superficial velocity starts below the minimum superficial fluidization velocity; intermittently or continuously measuring or calculating, over time the magnitude of the pressure (“feed pressure”) of the hydrogen that is supplied to the particle bed at the progressively increasing superficial velocity, upstream of the particle bed, and the magnitude of the superficial velocity at which the hydrogen is supplied to the particle bed; ceasing the progressive increase in the magnitude of the superficial velocity when the feed pressure ceases to increase with increased superficial velocity; and maintaining the superficial velocity at which the hydrogen is supplied to the particle bed at a magnitude (“superficial fluidization velocity”) at which the feed pressure ceased to increase with increased superficial velocity.

[0316] Supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity preferably causes hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium. In this regard, the method preferably includes based on the value of the superficial fluidization velocity, determining an average particle size of the particulate metallic hydrogen capture medium with reference to a nomogram of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate metallic hydrogen capture medium; and contacting the hydrogen that is supplied to the particulate metallic hydrogen capture medium with the particulate metallic hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium at the determined average particle size.

[0317] Alternatively, supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity preferably causes hydrogen that was previously ad / absorbed by the particulate metallic hydrogen capture medium to be desorbed from the particulate metallic hydrogen capture medium. In this regard, the method preferably includes based on the superficial fluidizing velocity, determining an average particle size of the particulate metallic hydrogen capture medium with reference to a nomogram of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate metallic hydrogen capture medium; and contacting the hydrogen that is supplied to the particulate metallic hydrogen capture medium with the particulate metallic hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size.

[0318] In the method, supplying the hydrogen, progressively increasing the superficial velocity, measuring or calculating the feed pressure and the superficial velocity, ceasing the progressive increase in the magnitude of the superficial velocity, and maintaining the superficial fluidization velocity, are performed electronically and automatically by means of an electronic hydrogen supply control system.

[0319] In hydrogen ad / absorption applications, i.e. providing steps for hydrogen ad / absorption, determining the average particle size of the particulate metallic hydrogen capture medium and contacting the hydrogen with the particulate metallic hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium at the determined average particle size are preferably also performed by the electronic hydrogen supply control system. The electronic hydrogen supply control system is then preferably comprised by a hydrogen supply station having a source of hydrogen independent of the hydrogen storage chamber, and supplying hydrogen to the bed of particulate metallic hydrogen capture medium is preferably from the source of hydrogen. In such a case, the hydrogen storage chamber is preferably provided on a vehicle separate of the hydrogen supply station. The hydrogen storage chamber then preferably has an electronic hydrogen storage chamber control system that is in communication with the electronic hydrogen supply control system, and wherein the method includes communicating the superficial fluidization velocity and the determined average particle size to the electronic hydrogen storage chamber control system by means of the electronic hydrogen supply control system; and electronically storing the superficial fluidization velocity and the determined average particle size in an electronic hydrogen storage chamber control system database by means of the electronic hydrogen storage chamber control system.

[0320] In hydrogen desorption applications, i.e. providing steps for hydrogen desorption, determining the average particle size of the particulate metallic hydrogen capture medium and contacting the hydrogen with the particulate metallic hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size are preferably also performed by the electronic hydrogen supply control system. The electronic hydrogen supply control system is then preferably comprised by a vehicle having a hydrogen fueled internal combustion engine or by an electric vehicle operating with a hydrogen fuel cell. Supplying hydrogen to the bed of particulate metallic hydrogen capture medium is then preferably from the hydrogen storage chamber, or from another such hydrogen storage chamber of the vehicle, the vehicle in such a case having multiple hydrogen storage chambers.

[0321] The particulate metallic hydrogen capture medium preferably comprises particulate metallic hydrogen capture medium that has repeatedly been subjected to hydrogen ad / absorption and desorption cycles and, as a result, has been fractured, i.e. decrepitated, into particle sizes smaller than an original particle size thereof.

[0322] In a second preferred embodiment, which is a preferred embodiment of the second aspect of the invention and, more preferably, of the third aspect of the invention, the invention provides a method of providing and maintaining a bed of particulate metallic hydrogen capture medium in a fluidized state inside a hydrogen storage chamber having an electronic hydrogen storage chamber control system, to cause hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium to be desorbed from the particulate metallic hydrogen capture medium, the method including recalling a previously determined superficial fluidization velocity for fluidizing the bed of particulate metallic hydrogen capture medium and a previously determined average particle size of the particulate metallic hydrogen capture medium from an electronic hydrogen storage chamber control system database of the electronic hydrogen storage chamber control system, which database has the fluidization superficial velocity and the previously determined average particle size stored therein by having performed method steps of the first preferred embodiment of the invention for hydrogen ad / absorption; and supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size, wherein recalling the superficial fluidization velocity and supplying the hydrogen gas are performed by the electronic hydrogen storage chamber control system.

[0323] Supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at the predetermined temperature and the predetermined pressure, preferably causes hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium being desorbed from the particulate metallic hydrogen capture medium.

[0324] Hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium preferably comprises gaseous hydrogen that is contained in the hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen storage medium. Supplying hydrogen to the bed of particulate metallic hydrogen storage medium then preferably includes withdrawing hydrogen from the hydrogen storage chamber.

[0325] Hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium alternatively or additionally preferably comprises gaseous hydrogen that is contained in another hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen storage medium thereof. Supplying hydrogen to the bed of particulate metallic hydrogen storage medium then preferably includes withdrawing hydrogen from the other hydrogen storage chamber. The hydrogen storage chamber and the other hydrogen storage chamber preferably form part of a group comprising multiple interlinked hydrogen storage chambers.

[0326] The method of the second preferred embodiment of the invention preferably includes the prior step of performing the method according to the first preferred embodiment of the invention. In a third preferred embodiment, which is a preferred embodiment of the seventh aspect of the invention, the invention provides a method of operating a hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself of from pressurized hydrogen contained in another hydrogen storage chamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part, such that the hydrogen capture medium is fluidized by such supply, wherein the method includes repeatedly and successively performing method steps of the first preferred embodiment of the invention for hydrogen to be ad / absorbed by the hydrogen capture medium; and method of steps of the second preferred embodiment of the invention for hydrogen to be desorbed from the hydrogen capture medium.

[0327] In a fourth preferred embodiment, which is a preferred embodiment of the eighth aspect of the invention, the invention provides a hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, the hydrogen storage system being configured for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself or from pressurized hydrogen contained in another hydrogen storage chamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part and is included in the system, such that the hydrogen capture medium is fluidized by such supply, such configuration including to repeatedly and successively perform method steps of the first preferred embodiment of the invention for hydrogen to be ad / absorbed by the hydrogen capture medium; and method steps of the second preferred embodiment of the invention for hydrogen to be desorbed from the hydrogen capture medium.

[0328] BRIEF DESCRIPTION OF DRAWINGS

[0329] The invention will now be described in more detail by way of non-limiting example, with reference to the accompanying drawings.

[0330] In the drawings:

[0331] FIGURE 1 shows a hydrogen storage system in accordance with the invention;

[0332] FIGURE 2 shows a gas dispersal system of the hydrogen storage system of Figure 1 ;

[0333] FIGURE 3 shows the metal hydride reactor tank used in the example of the invention, including the view of the 4 nozzles supplying hydrogen and driving fluidization at the bottom of the tank;

[0334] FIGURE 4 shows a process and instrumentation diagram (P&ID) created for the example of the invention;

[0335] FIGURE 5 shows adsorption / absorption results from Test 4A of the example of the invention;

[0336] FIGURE 6 shows desorption results from Test 4B of the example of the invention; and

[0337] FIGURE 7 shows a sorption graph for the whole of Test 4 (A and B) of the example of the invention.

[0338] DETAILED DESCRIPTION OF A NON-LIMITING EMBODIMENT OF THE INVENTION

[0339] REFERRING TO THE DRAWINGS, and in particularto Figure 1 , reference numeral 10 generally indicates a hydrogen storage system in accordance with the invention, for performing the method aspects of the invention.

[0340] The hydrogen storage system 10 comprises a hydrogen storage chamber in the form of a hydrogen storage vessel that comprises a tank 12 that is located in a substantially upright orientation. The tank 12 is a pressure tank, capable of withstanding up to about 3MPa (30atm) of internal pressure, or even up to as much as 300bar of pressure, alternatively even up to 35MPa (350 atm).

[0341] The tank 12 defines an interior 14 that holds a hydrogen capture medium 100 in accordance with the invention. The hydrogen capture medium 100 comprises a hydrogen capture material in particulate solid format, arranged as a packed particle bed thereof inside the interior 14.

[0342] In accordance with the invention, the hydrogen capture medium 100 is of a hydrogen capture material which is preferably a metal, e.g. a metal in elemental metallic form, or a metal compound, e.g. a metal alloy, in particulate format.

[0343] In use, the hydrogen capture medium 100 would be contacted with gaseous hydrogen inside the interior 14 by feeding gaseous hydrogen into the interior 14 from beneath the packed bed of hydrogen capture medium 100, e.g. in the manner described below with reference to Figure 1 , such that the gaseous hydrogen that is thus fed into the interior 14 fluidizes the hydrogen capture medium 100, respectively for hydrogen of the gaseous hydrogen to be captured (through adsorption and / or absorption), and thus stored, by the hydrogen capture medium 100, or for hydrogen previously captured by the hydrogen capture medium by adsorption and / or absorption to be desorbed and thus recovered from the hydrogen capture medium 100 as gaseous hydrogen.

[0344] It will be understood that achieving and maintaining fluidization of the particle bed would be effected by the control system as described below and in accordance with the invention, through the establishment of a superficial fluidization velocity, as defined earlier, with reference to the relationship between superficial gas velocity and feed pressure, as also explained in accordance with the aspects of the invention.

[0345] The tank 12 comprises a base 16 that provides a gas dispersal system, which is also referenced by reference numeral 16. The gas dispersal system 16, in turn, comprises a lower base member 16.1 and an upper base member 16.2 of the tank 12. The upper base member 16.2 is vertically spaced from the lower base member 16.2 in the illustrated configuration of the tank 12.

[0346] The lower base member 16.1 and upper base member 16.2 define a gaseous hydrogen feed chamber 16.3 therebetween, below the interior 14. The upper base member 16.2 is apertured, defining a plurality of inlet openings 16.4 (only some of which are referenced, by way of example). The openings 16.4 are provided with nozzles, as described hereinafter, noting that the provision of such nozzles is optional, but preferred.

[0347] Gaseous hydrogen that is in use fed into the gaseous hydrogen feed chamber 16.3 can thus pass into the interior 14 through the openings 16.4.

[0348] The tank 12 further comprises a roof 22 and side walls 24 that extend between the roof 22 and base 16.

[0349] The side walls 24 comprise a cylindrical portion 24.1 and a preferred flared portion 24.2, thus defining lower, cylindrical, and upper, flared, portions of the interior 14.

[0350] Flaring of the upper, flared, portion of the interior 14 in use serves to slow the rise of gaseous hydrogen and particles of the capture medium entrained therein that in use rise inside the interior 14 beyond the limits of the fluidized hydrogen capture medium 100, such that the particles fall back down in in the interior 14 of the tank 12, to be re-established as part of the fluidized hydrogen capture medium.

[0351] In the roof 22 of the tank 12 an outlet 30 is defined, leading into an outlet conduit 54 which will be described in more detail below.

[0352] The outlet 30 is preferably shielded from direct gas contact and from the hydrogen capture medium 100 by a cone shaped baffle or shield 28 which projects centrally downwardly from the roof 22.

[0353] The baffle 28 defines apertures (not shown) around its upper edge to allow passage of gaseous hydrogen therethrough.

[0354] The apertures in the baffle are fitted with filters (not shown) capable of preventing hydrogen capture medium from leaving the tank 12 through the outlet conduit 54. Typically, the filter is configured to prevent passage of particles larger than about 1 micron.

[0355] The upper base member 16.2 of the gas dispersal system 16 is shown in more detail in Figure 2. As mentioned above, the openings 16.4 in the upper base member 16.2 may be mounted with nozzles. Such nozzles may, for example, be Tuyere-type nozzles, fitted within the tank 12 such that they extend through and project beyond the upper base member 16.2, thereby preventing hydrogen capture medium held in the tank 12 from falling through the upper base member 16.2 under the effect of gravity and thus into the gaseous hydrogen feed chamber 16.3.

[0356] More specifically, as shown in Figure 2, each opening 16.4 may open into a feed conduit 16.5 and each opening 16.4 and its associated conduit 16.5 may be covered by a cone-shaped diverter 16.6 which would be mounted to the feed conduit 16.5 of its associated opening 16.4.

[0357] Each diverter 16.6 comprises a conical body that terminates in an apex. The apex of each diverter 16.4 is spaced above an outlet of their associated inlet conduits 16.5, such that the body of each diverter 16.6 extends downwardly and partly covers their associated inlet conduits 16.5. Thus, a gas supply mouth 16.4 that circumscribes each inlet conduit 16.5 is defined by each diverter 16.6.

[0358] It will be appreciated that the abovementioned configuration provides for gaseous hydrogen that is fed into the interior 14 to be directed operatively downwardly onto the upper base member 16.2 as opposed to operatively upwardly into the interior 14. Thus, accumulation of hydrogen capture medium 100 on the upper base member 16.2 is prevented, and preferred fluidization of the hydrogen capture medium 100 is promoted. Egress of hydrogen capture medium through the openings 16.4 is also prevented.

[0359] As mentioned above, the tank 12 has an outlet 30 in its roof 22, which leads into an outlet conduit 54.

[0360] The outlet conduit 54 branches - through a hydrogen product gas outlet, into a hydrogen product gas conduit 56, from which hydrogen product gas can be withdrawn, or released, from the interior 14, and through a gaseous hydrogen recirculation outlet, into a gaseous hydrogen recirculation conduit 58, along which gaseous hydrogen recovered, e.g. withdrawn or released, from the interior 14 may be recirculated, as recirculated gaseous hydrogen, to the interior 14 and therefore to the hydrogen capture medium 100.

[0361] The hydrogen product gas conduit 56 is provided with a valve 60, which is a hydrogen product gas release valve, to allow withdrawal of hydrogen product gas from the interior 14 based on the pressure inside of the interior 14 when desorption of hydrogen from the hydrogen capture medium is effected, as discussed below in more detail.

[0362] More specifically, the valve 60 is a pressure relief valve, configured automatically to release gaseous hydrogen from the interior 14 above a predetermined release pressure, more particularly at a hydrogen product gas release pressure. The valve 60 may also be selectively opened or shut.

[0363] Release of gaseous hydrogen from the interior 14 at the hydrogen product gas release pressure would typically in use only occur from the pressurized condition of the tank 12, as hereinafter described, to release hydrogen product gas from the tank 12 in desorbing hydrogen from the hydrogen capture medium 100. In effecting adsorption and / or absorption of hydrogen by the hydrogen capture medium 100, the valve 60 would typically be shut.

[0364] The valve 60 would typically operate, or be set as, as a pressure relief valve, or would be controlled to be open or shut by the control system hereinafter described, at the hydrogen product gas release pressure.

[0365] The gaseous hydrogen recirculation conduit 58 has a valve 61 similar to the valve 60, which is a gaseous hydrogen recirculation valve.

[0366] The valve 61 can also be a pressure relief valve that automatically releases gaseous hydrogen from the interior 14 above a predetermined release pressure, more specifically at a gaseous hydrogen recirculation pressure. More preferably, however, the valve 61 can be selectively opened or shut and is, in most applications, i.e. both desorbing applications and ad / absorbing applications, open. It is this, preferred, embodiment that is discussed further herein.

[0367] During performance of the method aspects of the invention to effect adsorption and / or absorption of hydrogen, the valve 61 would therefore preferably be open for the pressure inside the hydrogen storage chamber 12 to be established at a predetermined hydrogen contact pressure (being the predetermined contact pressure provided for in the various aspects of the invention).

[0368] The predetermined hydrogen contact pressure would, in a hydrogen ad / absorption application, be set in the hydrogen storage chamber 12 by setting the pressure at which fresh hydrogen is supplied from a source of fresh hydrogen along conduit to the conduit 58 along which recirculated gaseous hydrogen is withdrawn from the hydrogen storage chamber 12, essentially by providing back pressure at the predetermined hydrogen contact pressure. It should be understood in accordance with the invention that the conduit 62 may be a removable conduit, e.g. being selectively connectable to and disconnectable from the conduit 58. For example, it may be a conduit of a hydrogen supply station having a bulk source of hydrogen, while the conduit 58 and the hydrogen storage chamber 12 may be those of e.g. a vehicle. In some embodiments of the invention, the pump 66 may also be that of such a hydrogen supply station, in which case the conduit 58 may be connectable to the conduit 64 which is already connected to the conduit 62 at the hydrogen supply station. It is however also provided that the pump 66 may be a pump of a vehicle having the hydrogen storage chamber 12.

[0369] During performance of the method aspects of the invention in effecting desorption of hydrogen, the valve 61 would typically also be open, to allow for free and continuous recirculation of gaseous hydrogen from and to the interior 14. In such a case, the predetermined contact pressure would be set by the valve 60 as herein described, which would then act as a pressure relief valve.

[0370] Thus, in use, in a hydrogen ad / absorption application, hydrogen is supplied to the particle bed 100 by the pump 66 thus establishing the predetermined contact pressure inside the hydrogen storage chamber 12, through the recirculation conduit 58 to the pump 66 with excess hydrogen leaving the particle bed 100 and exiting the hydrogen storage chamber 12 through open valve 61 (valve 60 is closed, or set to a high release pressure above the predetermined contact pressure) to be recycled to the particle bed 100 by the pump 66. Back pressure in the conduit 58 thus balances the pressure across the system, at the predetermined contact pressure.

[0371] Furthermore, in use, with reference to the valve 60, to recover hydrogen stored in the hydrogen capture medium 100, in accordance with the method aspects of the invention providing for hydrogen desorption, continuous feeding of gaseous hydrogen into the interior 14 and release of hydrogen from the hydrogen capture medium 100 as gaseous hydrogen would result, without any release of gaseous hydrogen from the interior 14, in the pressure inside the interior 14 increasing. In a preferred embodiment in which the valve 61 is open in performing the method of the second aspect of the invention, such a pressure increase would extend across the entire system 10.

[0372] Such pressure increase would continue, subject to continued withdrawal and recirculation of excess gaseous hydrogen through the valve 61 , until the predetermined contact pressure that promotes hydrogen desorption is reached or exceeded, which would typically be the same as the hydrogen product release pressure, with gaseous hydrogen then being released from the interior 14 by the valve 60, which would be set as a pressure relief valve.

[0373] The valve 60 is therefore the means by which the pressure inside the interior 14 of the tank 12 is regulated for achieving and maintaining the predetermined contact pressure for hydrogen recovery from the hydrogen capture medium 100, and thus also for determining the hydrogen product gas release pressure. Preferably, the hydrogen product release pressure is sufficiently high so as to maintain a sufficient pressure inside the tank 12 for recirculation of hydrogen.

[0374] As mentioned above, the valves 60, 61 may be configured such that they may be selectively shut or fully opened, typically by the control system hereinafter described, against any release of gaseous hydrogen.

[0375] As also mentioned above, when performing the method aspects of the invention providing for hydrogen storage, the valve 60 would be shut while the valve 61 would be open, to set the predetermined contact pressure for hydrogen storage inside the interior 14.

[0376] As also mentioned above, when performing the method aspects of the invention providing for hydrogen desorption, the valve 61 would also be fully open while the valve 60 would operate as a pressure relief valve at the hydrogen product gas release pressure, to maintain the predetermined contact pressure for hydrogen recovery inside the interior 14

[0377] The recirculation conduit 58 is, downstream of the valve 60, met by a fresh gaseous hydrogen feed conduit 62, downstream of which the recirculation conduit 58 leads, as a pump inlet conduit 64, to a gas recirculation pump 66.

[0378] The fresh gaseous hydrogen feed conduit 62 is also provided with an open / shut valve 67 to control feed of fresh gaseous hydrogen from a fresh gaseous hydrogen supply source.

[0379] A gaseous hydrogen feed outlet conduit 68 leads from the recirculation pump 66, to a three-way valve 70 having an inlet 70.1 , a first outlet 70.2, and a second outlet 70.3.

[0380] A heating device gaseous hydrogen supply conduit 78 connects the first outlet 70.2 to a gaseous hydrogen heating device 80. A cooling device gaseous hydrogen supply conduit 82 connects the second outlet 70.3 to a gaseous hydrogen cooling device 84. A heating device outlet conduit 86 and a cooling device outlet conduit 88 lead from the heating device 80 and the cooling device 84 respectively, and connect to a manifold conduit 90, respectively through first and second inlet openings 92, 94 of the manifold conduit 90.

[0381] An outlet 96 of the manifold conduit 90 provides a gaseous hydrogen feed chamber inlet opening in the lower base member 16.1 of the gas dispersal system 16, thus leading into the gaseous hydrogen feed chamber 16.3.

[0382] It will be appreciated that the heating device 80 and cooling device 84 are respectively provided to heat and cool the hydrogen that is supplied to the hydrogen storage chamber 12, selectively for hydrogen desorption and hydrogen ad / absorption.

[0383] The system 10 further includes a control system (not illustrated), for controlling operation of the system 10. The control system is an electronic control system, as described with reference to the aspects of the invention. Hereinafter reference to the “system” is to the system 10 and reference to the “control system” is to the electronic control system. Various embodiments of the control system are described.

[0384] The control system comprises a pressure sensor at a location upstream of the bed 100 and downstream of the pump 66, e.g. in the hydrogen feed chamber 16.3, or in the manifold conduit 90, to measure the pressure of hydrogen gas that is supplied to the bed 100 (“feed pressure”).

[0385] The control system also comprises a temperature sensor at a location downstream of the outlet 30, e.g. in the outlet conduit 54, to measure the temperature of hydrogen gas withdrawn from the tank 12 through the outlet 30, and a temperature sensor at a location upstream of the bed 100 and downstream of the pump 66, preferably also downstream of the heating and cooling devices 80, 84, to measure the temperature of hydrogen gas supplied to the bed 100. These temperature sensors would assist, in accordance with the invention, to determine when the exothermic ad / absorption reaction has started to that control over the temperature of hydrogen gas fed to the particle bed 100 may be exercised so as to establish or maintain the predetermined contact temperature.

[0386] The control system is further configured to control and operate the recirculation pump 66 to supply gaseous hydrogen, including recirculated gaseous hydrogen when supplied to the pump 66 along recirculation conduit 58 and fresh gaseous hydrogen supplied to the pump 66 along feed line 62, to the interior 14 at a superficial velocity and corresponding volumetric feed flow rate, and typically at a supply pressure, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14. The volumetric feed flow rate and the supply pressure sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14 would be as characterised in relation to the various aspects of the invention.

[0387] The superficial fluidizing gas velocity, and associated volumetric feed flow rate, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium is, in accordance with the method aspects of the invention, determined by the control system with reference to the feed pressure.

[0388] More specifically, the control system interfaces with the pump 66 to supply hydrogen to the bed 100 at a progressively increasing superficial velocity, which commences below the minimum superficial fluidization velocity for fluidizing the bed. Such commencement below the minimum superficial fluidization velocity may be implicit, since the progressive increase may commence from a value of zero, i.e. no flow. While doing so, the control system monitors the feed pressure using the pressure sensor between the bed 100 and the pump 66, as referenced above. The control system also monitors the superficial velocity, as a function of the volumetric feed rate which is the parameter that is increased to increase the superficial velocity progressively.

[0389] Before fluidization occurs (i.e. before the bed 100 is developed into a fluidized state), the feed pressure increases with increasing superficial velocity. When the bed 100 develops into a fluidized state, however, the feed pressure ceases to increase with increased superficial velocity, thus allowing for determination of fluidized conditions.

[0390] The control system is further configured to cease increasing of the superficial velocity when such a ceasing in feed pressure increase is detected by the pressure sensor between the bed 100 and the pump 66, and to maintain the superficial velocity at the level at which such a change occurred, being the superficial fluidization velocity described with reference to the various aspects of the invention, thereby to maintain fluidization of the bed 100.

[0391] In accordance with the invention, the control system as described above may either be a control system of a hydrogen supply station remote of the hydrogen storage chamber 12, or may be a control system of the hydrogen storage chamber 12.

[0392] When the control system is a control system of the hydrogen storage chamber 12, the control system would operate the system 10 as described above in respect of the determination of the superficial fluidization velocity, integral with the hydrogen storage chamber 12. When the control system is a control system of a hydrogen supply station, however, the control system would operate as described above from the hydrogen supply station, but then the hydrogen storage chamber would preferably have an electronic hydrogen storage chamber control system separate of the hydrogen supply control system.

[0393] In such a case, the electronic hydrogen supply control system would communicate with the electronic hydrogen storage chamber control system in the manner described in accordance with the various aspects of the invention, so that the electronic hydrogen storage chamber control system would know or have access to values that include the superficial fluidization velocity and preferably of supply pressure, and a particle size corresponding to the determined superficial fluidization velocity, obtained from an appropriate nomogram as described herein, as determined by the electronic hydrogen supply control system in supplying hydrogen to the hydrogen storage chamber 12.

[0394] Such knowledge or access would allow the electronic hydrogen storage chamber control system to know and readily to supply hydrogen to the hydrogen storage chamber to fluidize and desorb hydrogen from the hydrogen capture medium at the appropriate predetermined temperature and pressure values for stimulating such desorption, the provision of which is described in more detail further below.

[0395] Configuration of the control system to supply gaseous hydrogen to the bed 100 is such that fresh gaseous hydrogen is only used to supplement recirculated gaseous hydrogen to the extent necessary to achieve and maintain the superficial fluidizing velocity and the corresponding volumetric feed flow rate, sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14.

[0396] The control system is also configured to measure the volumetric rate of supply of fresh gaseous hydrogen along the fresh gaseous hydrogen supply conduit 62, that is required to maintain the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14, and to conclude that the hydrogen capture medium is saturated with hydrogen if such a supply is or approximates zero (0).

[0397] The control system is also configured to measure the volumetric rate of recovery of gaseous hydrogen, and more specifically excess gaseous hydrogen, from the interior 14 along the recirculation conduit 58, over time, and to conclude that the hydrogen capture medium is saturated with hydrogen if such volumetric rate of recovery over time approximates or is equal to the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14.

[0398] The control system is also configured to measure the temperatures of the gaseous hydrogen that is supplied to the gas dispersal system 16 (T1) and of the recirculated gaseous hydrogen that is recovered along the recirculation conduit 58 (T2), and to conclude that the hydrogen capture medium is saturated with hydrogen if there is no differential, or not a significant differential (T3, as T1 minus T2), between such temperatures.

[0399] The control system is also configured selectively to - shut the hydrogen product gas release valve and set the gaseous hydrogen recirculation valve open for recirculation of excess gaseous hydrogen at the predetermined contact pressure, and open the gaseous hydrogen recirculation valve and set the hydrogen product gas release valve to operate as a pressure relief valve at the hydrogen product gas release pressure, wherein sufficient back pressure from the hydrogen product release valve is provided to maintain recirculation..

[0400] As has been indicated, the control system is an electronic control system. It is accordingly configured to perform the abovementioned control, operation, measuring, and concluding electronically, using an electronic processing unit that is in communication with the recirculation pump 66 and respective flow and temperature sensors that measure the volumetric rate of supply of fresh gaseous hydrogen to the hydrogen capture medium, the volumetric feed flow rate at which gaseous hydrogen is supplied to the interior, the volumetric rate of recovery of gaseous hydrogen from the interior 14 through the gaseous hydrogen recirculation outlet, and the temperatures of gaseous hydrogen fed to the interior 14 and of the recirculated gaseous hydrogen.

[0401] The control system is also configured to discontinue pumping of gaseous hydrogen to the interior 14 based on the conclusion being drawn that the hydrogen capture medium 100 is saturated with hydrogen. Such configuration may be for discontinuation to be effected at a desired storage pressure inside the interior 14, which may be or may exceed the predetermined contact pressure. Thus, the control system would effectively close or close off the interior 14 and provide a pressurized condition of the system 10, wherein the interior 14 comprises hydrogen saturated capture medium and pressurized gaseous hydrogen at the storage pressure. The control system is further configured, from the pressurized condition of the system 10, to withdraw pressurized gaseous hydrogen from the interior 14 and recirculate such hydrogen to the gas dispersal system 16 at a volumetric feed flow rate and at a supply pressure sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the hydrogen storage chamber, at the predetermined contact temperature at which, at the corresponding predetermined contact pressure, release of hydrogen from the hydrogen capture medium 100 is promoted, to monitor pressure inside of the interior 14, and to release hydrogen from the interior through the gas product outlet line 56 by opening valve 60 if the hydrogen product gas release pressure is detected. Such release may, however, be automatic at the hydrogen product gas release pressure, in which case the control system would be configured to open the hydrogen product gas release valve 60 for operation as a pressure relief valve as hereinbefore described.

[0402] In this regard, it is provided in accordance with the invention that withdrawal of pressurized hydrogen can, in contrast, be from another hydrogen storage chamber, separate of the hydrogen storage chamber 12 but included in a grouping of multiple such hydrogen storage chambers, e.g. on a vehicle having a hydrogen-fuelled engine, such as a hydrogen internal combustion engine or a hydrogen-oxidising fuel cell supplying electricity to a battery system. This would, for example, be necessary if there is insufficient pressurised hydrogen in the hydrogen storage chamber 12, e.g. as a result of partial utilisation of hydrogen contained in it.

[0403] While, in relation to the supply of pressurised hydrogen from the interior of the hydrogen storage chamber to effect desorption of hydrogen form the hydrogen capture medium, reference is made to “the control system” which has thus far been described essentially as the electronic hydrogen supply control system of the invention, it is included within the scope of the invention that the control system effecting supply of pressurised hydrogen from the interior of the hydrogen storage chamber to effect desorption of hydrogen form the hydrogen capture medium is, instead, the electronic hydrogen storage chamber control system as described with reference to the various aspects of the invention.

[0404] In such a case, the electronic hydrogen supply control system would have communicated the superficial fluidizing velocity and preferably also the supply pressure, and corresponding particle size to the electronic hydrogen storage chamber control system, which would then, as discussed above, allow the electronic hydrogen storage chamber control system readily to supply hydrogen to the hydrogen storage chamber to fluidize and desorb hydrogen from the hydrogen capture medium at the appropriate predetermined temperature and pressure values for stimulating such desorption. In use, to effect hydrogen capture and storage, fresh gaseous hydrogen is pumped I released into the fresh gaseous hydrogen feed conduit 62 at a first pressure, that is typically equal to the predetermined contact pressure, as determined by the type of hydrogen capture medium 100 and the predetermined contact temperature at which contacting of the gaseous hydrogen with the hydrogen capture medium 100 would be effected, from a hydrogen supply source, by opening the valve 67.

[0405] The fresh gaseous hydrogen feed conduit 62 delivers the fresh gaseous hydrogen to the recirculation pump 66 along the pump inlet conduit 64 at a first pressure, which is preferably the predetermined contact pressure that determines the predetermined contact pressure in the hydrogen storage chamber 12 which, in turn, delivers the gaseous hydrogen, at the superficial fluidization velocity and the corresponding volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14, determined as described hereinbefore, to the three-way valve 70 at a second pressure, being a supply pressure.

[0406] In effecting hydrogen capture and storage, gaseous hydrogen is directed by the valve 70 to the cooling device 84 along the cooling device gas supply conduit 82, to be cooled to the predetermined contact temperature at which adsorption / absorption of gaseous hydrogen by the capture medium 100 would be promoted, whether in combination with independent cooling of the hydrogen capture medium 100 or not. While, in the case of absorption / adsorption, cooling is more typical, the possibility that heating may occur using the heating device is not excluded.

[0407] Heating or cooling of the gaseous hydrogen to be fed into the interior 14 is effected so that the gaseous hydrogen would act as working fluid to achieve and / or maintain the predetermined contact temperature in contacting the gaseous hydrogen with the hydrogen capture medium 100.

[0408] Cooled gaseous hydrogen then passes, at the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14 and at the supply pressure, along the manifold conduit 90 and is delivered to the gas inlet chamber 26, from where it feeds into the interior 14 through the openings 16.4 and associated nozzles described above, thus contacting and fluidizing the hydrogen capture medium bed 100.

[0409] Contacting the hydrogen capture medium 100 with cooled gaseous hydrogen, in addition to achieving and maintaining the predetermined contact temperature, prevents an excessive rise in temperature in the hydrogen capture medium 100 which may otherwise be caused by an exothermic reaction that takes place between the hydrogen capture medium 100 and the gaseous hydrogen as hydrogen is absorbed by the hydrogen capture medium 100.

[0410] Contact between the gaseous hydrogen and the fluidized hydrogen capture medium 100 causes hydrogen to be adsorbed / absorbed by the capture medium 100. Excess gaseous hydrogen, comprising unabsorbed hydrogen, rises beyond the capture medium bed 100 and leaves the interior 14 through the outlet 30, being directed along the recirculation conduit 58 to be recirculated to the interior 14 by the recirculation pump 66, in this respect optionally combining with fresh gaseous hydrogen from the fresh gas supply source along supply line 62, to maintain the volumetric feed flow sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14.

[0411] When the control system concludes that the hydrogen capture medium 100 is saturated with hydrogen, as hereinbefore described, and the desired storage pressure is detected inside the interior 14, the control system discontinues supply of gaseous hydrogen to the interior 14, thus closing or closing off the interior at the storage pressure. Thus, a transportable tank 12 comprising hydrogen stored in saturated solid capture medium 100 and pressurized residual gaseous hydrogen is provided as a storage condition of the system 10.

[0412] To effect hydrogen recovery, with the system 10 in the storage condition as described above, pressurized gaseous hydrogen is withdrawn from the hydrogen storage camber 12 interior 14 along the recirculation conduit 58 by opening the valve 61 fully and, using the recirculation pump 66, is delivered by the pump 66 at the superficial fluidisation velocity and associated volumetric flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14 and at the supply pressure to the valve 70 which directs the gas to the heating device 80, where it is heated to the predetermined contact temperature for hydrogen recovery from the hydrogen capture medium 100, subsequent to which it is fed into the interior 14 along the manifold conduit 90 and gas dispersal system 16, such that the gas contacts the bed of capture medium 100 preferably such that the bed 100 is fluidized. Thus, again, the gaseous hydrogen to be fed into the interior 14 is heated so that it would act as the working fluid in achieving and / or maintaining the predetermined contact temperature inside the interior 14 in contacting the gaseous hydrogen with the hydrogen capture medium 100. As has been discussed, supply of hydrogen to the hydrogen capture medium at the superficial fluidisation velocity and associated volumetric flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium would either be determined by an electronic hydrogen supply control system integral with the hydrogen storage chamber 12, as hereinbefore described, or would be known or accessible by an electronic hydrogen storage chamber control system integral with the hydrogen storage chamber 12, as hereinbefore described. Also, instead of supplying hydrogen from pressurized hydrogen contained in the interior 14 of the hydrogen storage chamber 12, hydrogen may be supplied from pressurized hydrogen contained in the interior of another hydrogen storage chamber of a grouping of hydrogen storage chambers that include the hydrogen storage chamber 12 and the other hydrogen storage chamber, e.g. being provided on a vehicle.

[0413] Contact between the heated gaseous hydrogen and the saturated capture medium 100 results in gaseous hydrogen being released from the capture medium.

[0414] Continued recirculation, at the volumetric feed flow rate sufficient to fluidize and / or maintain fluidization of the hydrogen capture medium inside of the interior 14, of initial residual gaseous hydrogen and gaseous hydrogen released from the capture medium 100 (i.e. “desorbed” gaseous hydrogen), results in an accumulation of hydrogen inside the interior 14 and a resulting rise in pressure.

[0415] Detection, by the control system, of such a rise in pressure inside the interior 14 would result, if a threshold pressure is reached, such as the hydrogen product gas release pressure, in the control system opening the valve 60, or would result in the valve 60 being opened automatically if it is set as a pressure relief valve once the pressure reaches the hydrogen product gas release pressure, for product gaseous hydrogen to be discharged from the interior 14.

[0416] The tank 12 is made of a composite material and can contain 3 Mpa (30 atm), or even up to 35MPa (350 atm), of pressure. The tank 12 may, instead, be made of any other suitable material.

[0417] The hydrogen storage chamber 12 may then be re-charged, or re-filled, with hydrogen by performing the steps outlined above for hydrogen ad / absorption. However, the heating step for releasing hydrogen from the hydrogen storage medium may have caused fracturing, i.e. decrepitation, of the hydrogen storage medium into a smaller average particle size. This would result in the fluidization conditions changing, which would be readily determinable by the electronic hydrogen supply control system in the manner hereinbefore described, when recharging or re-filling the hydrogen storage chamber 12. EXAMPLE

[0418] Introduction

[0419] THIS EXAMPLE describes a test protocol that was followed as a practical implementation of certain aspects of the invention, and discusses the results thereof.

[0420] The test protocol provides details of the steps of test work that was conducted on lanthanum pentanickel (LaNis) alloyed with tin (Sn) (“metal alloy”), as hydrogen capture medium. The results recorded during testing exemplify the performance of the invention in exploiting a fluidized particulate metal hydride with gaseous hydrogen as the heat transfer working fluid and fluidizing gas.

[0421] More specifically, the viability of certain features of the invention, particularly to effect successive hydrogen ad / absorption by and subsequent desorption from lanthanum pentanickel (LaNis) alloyed with tin (Sn), as LaNi^gSno.i (“metal alloy”) as hydrogen capture medium, was experimentally tested, including to prove the ability of the invention to determine “filling” and “emptying” of hydrogen capture medium contained in a hydrogen storage chamber according to the invention.

[0422] It will be appreciated that “filling” refers to effecting ab / adsorption of hydrogen by the hydrogen capture medium, typically to a maximum extent, while “emptying” refers to effecting desorption of hydrogen from the hydrogen capture medium, typically also to a maximum extent.

[0423] As has been discussed, during filling, the metal alloy reacts with hydrogen to produce a hydride and heat, which must be withdrawn through cooling to allow the reaction to run to completion. In accordance with the invention this cooling is achieved by pre-cooling the hydrogen used to fluidise the metal alloy.

[0424] Conversely, as has also been discussed, during emptying, the metal hydride of the metal alloy (i.e. the metal alloy in a condition in which it stores hydrogen), when heated, produces free hydrogen gas and causes the metal hydride to revert to the metal alloy. The heating is, in accordance with the invention, effected by heating the hydrogen used to fluidize the hydride.

[0425] To show that — 1) fluidisation of the metal alloy, in particulate format, in a hydrogen storage chamber, such as a tank, with hydrogen as the fluidisation medium, is an effective way of performing adsorption and / or absorption of hydrogen by the metal alloy (by forming a hydride of the metal alloy);

[0426] 2) fluidisation of the resulting metal hydride of the metal alloy is an effective way of performing desorption of hydrogen from said hydride; and

[0427] 3) hydrogen can effectively be used as the working fluid to transfer and remove heat to and from the hydrogen capture medium.

[0428] Choice of hydrogen capture medium

[0429] LaNi4.9Sno.i was selected as hydrogen capture medium based thereon that parameters for its exploitation as a hydrogen capture medium are reported in literature. For example, reference is made to Yartys, V et al., 2016, Metal hydride hydrogen compression: recent advances and future prospects, Applied Physics A, 122(4) and Somo, T et al., 2022, Improvement of hydriding kinetics of LaNi5-type metal alloy through substitution of nickel with tin followed by palladium deposition, Bulletin of Materials Science, 45(1).

[0430] Overview of experimental setup

[0431] A process and instrumentation diagram of the experimental setup that was used is shown in Figure 4

[0432] The experimental setup comprised - a hydrogen storage chamber provided by a reactor tank “Reactor 1”; a fresh hydrogen supply tank C1 ; a recirculation pump C2; a pressure regulator PR1 for regulating the pressure of supply of fresh hydrogen from the hydrogen supply tank; valves V1 to V7 as illustrated, of which V1 is a needle valve and the remainder are ball valves, more specifically needle valve V1 in line 300, immediately downstream of the pressure regulator PR1 , serving selectively to allow and disallow supply of fresh hydrogen from the supply tank C1 ; flow directing ball valve V2 in line 306, to direct flow of fresh hydrogen gas along line 306 if flow directing ball valve V4 is closed; flow directing ball valve V3 in line 316, to provide for discharge of hydrogen from Reactor 1 ; flow directing ball valve V4 in line 318, to direct hydrogen for discharge flowing through line 316 along discharge line 318 when needle valve V1 and ball valve V2 are closed; flow directing ball valve V5 shutoff ball halves V6 and V7, for shutting off Reactor 1 from any charge or discharge; a fresh hydrogen supply gas flow meter QM1 ; a tank hydrogen supply gas flow meeting QM2; a heating / cooling unit C4 selectively operable as a heating oil bath and a cooling ice bath, having a tank hydrogen supply line passing through it with heat tracing applied to it downstream of the heating / cooling unit; several temperature gauges (Tl), temperature transmitters (TT), pressure gauges (PI), pressure transmitters (PT), more specifically

[0433] P11 , in line 300 immediately downstream of pressure regulator PR1 ;

[0434] PT1 , in line 308;

[0435] TT1 , in line 308;

[0436] TT2, in line 310;

[0437] PI2, in line 310;

[0438] TT3, in line 310, downstream of the heating / cooling unit;

[0439] PT3, in line 310, downstream of the heating / cooling unit;

[0440] PI3, in line 310, downstream of the heating / cooling unit;

[0441] PI4, in line 312, downstream of Reactor 1 and shutoff valve V7;

[0442] PT4, in line 312, downstream of Reactor 1 and shutoff valve V7; and

[0443] TT4, in line 312, downstream of Reactor 1 and shutoff valve V7. System concept description

[0444] The system used to perform the tests herein reported consisted of a network of high pressure 316SS tubing, looped through a gaseous hydrogen recirculation pump, a gaseous hydrogen heat exchanger coil, a metal hydride reactor tank (as the hydrogen storage chamber of the invention), and then past a junction point back into the line from a fresh hydrogen supply source (hydrogen cylinder) to the pump, creating a loop for closed cycle system testing.

[0445] Four points were measured for pressure and temperature. These were -

[0446] • Point 1 - upstream of the pump (PT 1 ; TT1 )

[0447] • Point 2 - after the pump, before the heat exchanger coil (PTI, TT2)

[0448] • Point 3 - after the heat exchanger coil, before the metal hydride reactor tank (PI3, PT3, TT3)

[0449] • Point 4 - after the tank (PI4, PT4, TT4)

[0450] It will be appreciated that point 2 and, more specifically, point 3 are particularly useful for monitoring, in accordance with the invention, when fluidization occurs, in combination with a monitoring of superficial velocity, which is determinable with reference to the volumetric flow rate produced by the pump and the diameter of the conduit supplying hydrogen to the metal hydride reactor tank.

[0451] Metal hydride fluidization tank (hydrogen storage chamber)

[0452] The metal hydride reactor tank (“Reactor 1”) consisted of a 1000 mm long tube, 50mm in diameter (OD) and a thickness of 2mm. It had a 250 mm base plate of 5mm thickness at the bottom thereof and an inlet port and chamber that made up about the bottom 50mm of the tank.

[0453] 50mm above the bottom of the tank, a separator plate with 4 fluidisation nozzles, each having 8 equidistant holes on the sides, in a 150° downward direction from vertical, were provided. Reference is in this regard made for Figure 3, wherein the whole reactor is shown on the left and the fluidization nozzles are shown on the right.

[0454] Metal hydride

[0455] The metal hydride being tested was, as indicated above, an alloy of lanthanum pentanickel (LaNis) with tin (Sn), of which alloy the molecular formula is LaNi^gSno.i. It will be appreciated that, in the absence of hydrogen ad / absorbed thereon / thereby, the alloy is not in its hydride form, while it becomes a hydride after ad / absorption of hydrogen. Reference to “the metal hydride” should be understood as including respective of these embodiments of the hydrogen capture medium, as would be apparent from the context.

[0456] The density of the metal hydride is somewhere between 7950 and 8210 kg / m3. Based on research literature, ~8080 kg / m3was used for calculation purposes. This density was not experimentally confirmed.

[0457] Working / heat transfer fluid

[0458] Gaseous hydrogen was used as the working fluid for heat transfer. It will be appreciated in this regard that the gaseous hydrogen also supplies hydrogen to be absorbed and, furthermore, acts as fluidizing gas.

[0459] A tube coil was installed for use as an indirect heat exchanger, to transfer heat to the gaseous hydrogen.

[0460] A 9 m coil, with an approximate diameter of 210mm, made from 8mm OD, 316SS tube, was installed as a heat exchanger after the pump outlet.

[0461] Methodology

[0462] The methodology for testing is described in this section, including with reference to the sensors, data acquisition system used, and various other relevant aspects of the test setup.

[0463] Test facility

[0464] A test room and control room were constructed for the purpose of the tests.

[0465] The test room was a 3 x 3m (9 m2) room, with insulation panels for walling and a lifted room region for ventilation of buoyant hydrogen gas, should there be discharge or leakage.

[0466] An adjacent control room comprising a 3 x 3m (9 m2) room, sealed from the outside to ensure no potential ingress of hydrogen gas that could create a safety hazard, was also constructed. Test setup

[0467] A test setup was built using the following material:

[0468] • 8mm OD 316 SS tubing (ASTM 269), suitable for up to ~400 bar.

[0469] • Double ferrule compression 316SS fittings for high pressure joint application, also up to -400 bar

[0470] • Various components as referenced above, including a needle valve, ball valves, check valves, flow directing valves, pressure regulating valves, pressure gauges, pressure sensors, temperature sensors, temperature gauges, the metal hydride reactor tank, gas circulating pump, fresh hydrogen supply cylinder, main pressure regulator, and filter elements.

[0471] Gaseous hydrogen

[0472] The gaseous hydrogen used for the tests was hydrogen 5.0 (UN 1049 - Hydrogen Compressed) rated at 173 bar at 20°C, 0.62 kg H2.

[0473] Material safety data sheet reference from the supplier (Air Products and Chemicals, Inc.) for this gas product is MSDS 067A. The tank was filled January 2023 and specified an expiry date in 2028. The UN1049 hydrogen product is 99.999% (5N) hydrogen with trace amounts of CO2, N2 and other non-combustible gases.

[0474] An Afrox Scientific gas regulator W019220, rated for hydrogen use, was used as the main pressure regulator to the system, capable of 300 bar max input and 16 bar max output.

[0475] Recirculation pump

[0476] The pump used for the circulation of the gaseous hydrogen was a Maximator Air-amplifier GPLV-5, which is a single stage, double acting, positive displacement pump with a pressure ratio capability of up to 1 :5 (1 bar to 5 bar). It is an ATEX rated pump due to its non-electrical drive nature, being an air driven pump. The pump can be driven at various input (drive) pressure levels ranging from a minimum of 4 bar to maximum of 10 bar. At the desired max flow rate of 120 L / min, this pump consumes more than 300 L / min of air at 4 bar. It was noted that there was a chance of a minute amount of gaseous hydrogen leakage through the piston sleeve of the pump, which would be blown out by the driven air exhaust. Such leakage was not quantified in the tests herein reported.

[0477] A petrol driven compressor was acquired to ensure that the circulation pump can be run at required speed for continued operation during tests. The compressor has a 150 L tank and can supply 360 L / min continuous at 8 bar.

[0478] Heating and cooling of gaseous hydrogen

[0479] The cooling and heating of gaseous hydrogen was done primarily through a heat source or heat sink, with a long coil of 8mm tube submerged in it. The tube was made from 3x 3m pieces of ASTM 269, 316 SS tube, with helix diameter of 210 mm and a pitch of roughly 25mm.

[0480] Cooling method

[0481] Cooling of the gaseous hydrogen was accomplished using an indirect heating method. This involved submerging a coil of 9m length into a bucket of ice water at 0°C.

[0482] Heating method

[0483] Heating of the gaseous hydrogen was done indirectly, using two heating methods:

[0484] 1) A 9m coil submerged in an oil bath heated by an element (hot water urn)

[0485] 2) Heat tracing on the out-going section of the tube from the heat exchange coil.

[0486] Method 1 : Hot Oil bath

[0487] • Method: oil heating method

[0488] • Brand: Cryspa Gold Premium Sunflower Frying Oil

[0489] • 230°C boil point; 232°C smoke point

[0490] • Specific Heat: 3.1927 kJ / kg.K

[0491] • Volume heated: 19.5 Litres

[0492] • Heating mechanism: 3.5 kW hot water heating urn Method 2: Heat tracing

[0493] In addition to the hot oil bath, the outgoing tube of the heat exchanger coil was wrapped in heat tracing with an output of 22 W / m heat. The heat tracing was wound directly and tightly against the tube of approximately 700mm in length. 3.5 m of heat tracing was used, totalling and additional 77W of heat input into the tube. The heat tracing raised the temperature of the pipe to roughly 130-140°C and was able to increase the temperature of the hydrogen from around 90°C to ~120°C.

[0494] Handling of the alloy metal hydride

[0495] The metal alloy was in crystalline form and was ground down into a fine powder.

[0496] 500.2g of the metal hydride powder was loaded into the metal hydride reactor, thus establishing a bed thereof, before the reactor was sealed.

[0497] The following were followed in sequence.

[0498] Filling cycle (hydrogen adsorption / absorption)

[0499] For the filling cycle, or absorption cycle, for hydrogen ad / absorption into the metal hydride, the following steps were adhered to:

[0500] 1) Set point 4 relief valve (RV2) to ~6 Bar

[0501] 2) Set gaseous hydrogen pressure regulator to ~6 bar.

[0502] 3) Open valve V2

[0503] 4) Close valves V3 and V4

[0504] 5) Place heat exchange coil in ice

[0505] 6) Open needles valve from gaseous hydrogen tank (V1)

[0506] 7) Switch on pump

[0507] 8) Watch output from QM1 - when it is zero, the tank is full as a result of all hydrogen entering the tank being recirculated

[0508] 9) Switch off pump, leaving the system in a pressurised state with pressurised hydrogen contained in the tank Emptying cycle (hydrogen desorption)

[0509] For the emptying cycle or cesorption cycle for hydrogen to be desorbed from the metal hydride, the following steps are to be adhered to:

[0510] 1) Close needle valve (V1)

[0511] 2) Close valve V2

[0512] 3) Open valve V3

[0513] 4) Place heat exchanger coil in hot oil

[0514] 5) Set relief valve to ~2.5 Bar

[0515] 6) Keep valve V4 tight shut

[0516] 7) Switch on pump

[0517] 8) When pressure PI4 / PT4 starts increasing indicating that desorption and fluidisation occurring, open V4 to discharge hydrogen through the flow meter QM1

[0518] 9) Watch QM1 , TT3 and TT4 and PI4 / PT4. When tank is empty T3 is effectively equal to T4, QM1 is effectively zero and P4 falls to setting of relief valve (PRV)

[0519] 10) Switch off pump

[0520] As mentioned above, a process and instrumentation diagram (P&ID) created for the test setup is provided as Figure 4.

[0521] The following test setup description refers to Figure 4:

[0522] • ABSORPTION / ADSORPTION: During absorption, no pressure relief valve (PRV) was present between the outflow from the fluidisation tank and the recirculation pump. Rather, the predetermined pressure was set by adjusting the pressure of fresh gas supplied from the cylinder, by means of the pressure regulator PR1. This sets the reactor pressure at the required level for absorption. The amount of “excess” hydrogen gas flowing through recirculating system from the tank was not constant. It varies according to how much hydrogen is being pumped into the fluidisation chamber less the amount absorbed into the metal hydride at any point in time. The rate of absorption is dependent on pressure and temperature of the system. The temperature of the system is reduced by pre-cooling the hydrogen by passing it through the heat exchanging stainless steel coil to a temperature where the metal hydride is at the most optimal temperature for absorption.

[0523] • The pump outflow of hydrogen is essentially constant and is sufficient to maintain fluidisation of the metal alloy in the tank and will draw any extra hydrogen needed to achieve this from the fresh gas supply via needle valve V1 and through the mass flow meter QM1 . The primary means of knowing when the tank is “full” is when the inflow of fresh gas required to do this is zero (or a predetermined low flow rate) through valve V1 and gas flow meter QM1 . At that point no hydrogen is being absorbed into the metal alloy and all the gas being pumped to fluidise the medium is passing out of the tank through the pressure relief valve to the recirculation system.

[0524] • In practice a comparison of feed flow rate and flow rate out of the tank could also indicate a “full” status when the two are approximately the same. In these experiments, we did not monitor flow rates at those points.

[0525] • A third way to determine full is when there is no further exothermic reaction happening - so the temperature of hydrogen entering and leaving becomes the same, (ie in this setup T3 and T4 become essentially equal).

[0526] • DESORPTION: During desorption, the control is different. The relief valve on the circuit on diagram is set to a low pressure sufficient to maintain recirculation flows but low enough to allow desorption and valves V1 and V2 are tight shut. The pump sucks a sufficient essentially constant volume per time out of the previously pressurised tank to recirculate, heat treat and cause fluidisation - irrespective of pressure in the tank. As the hydride desorbs hydrogen, the pressure in the tank therefore increases and the pressure relief valve opens at the predetermined pressure to allow hydrogen to leave the system for use. The tank is empty when there is no more hydrogen desorbing and so the pressure in the tank falls below that required to open the relief valve. During desorption, the endothermic reaction of desorption removes heat from the incoming fluidising hydrogen (i.e.: T4 is lower than T3). When the tank is “empty” the temperatures of hydrogen entering the tank and leaving it therefore tend towards equalising.

[0527] Test results

[0528] The following test cycles were performed:

[0529] • Test 1 - Flow determination of pump in closed cycle test

[0530] • Test 2 - First Absorption test

[0531] • Test 3 - First Desorption test

[0532] • Test 4 - 2ndAbsorption and Desorption Test • Test 5 - 3rdAbsorption and Desorption Test, using automatic pressure relief blow off and then manual pulsatile relief.

[0533] Only test 4 is thoroughly discussed herein.

[0534] Test 4 (split into parts A and B)

[0535] Test 4A was an absorption test - selected sensor readings are presented in Figure 5.

[0536] Note the temperature of hydrogen entering the tank (value T3 of TT3 - top-to-middle trace) was initially high as test three had just been completed to empty the tank.

[0537] The cooling by passing the hydrogen through the coil immersed in water and ice rapidly brings the temperature down.

[0538] As would be expected, while the input hydrogen was warm, there was no flow of fresh hydrogen from the storage tank into the system (bottom trace).

[0539] As soon as the recirculating hydrogen started cooling, hydrogen acting as a working fluid cooled the metal alloy in the tank and it therefore started taking up hydrogen.

[0540] This allowed fresh hydrogen to flow into the system (yellow / bottom trace) since insufficient hydrogen was being recirculated to maintain fluidization.

[0541] The T4 temperature from TT4 of hydrogen leaving the tank and re-circulating (red / middle-to-top trace) rose as soon as the exothermic reaction between the alloy and the hydrogen began.

[0542] As the amount of unreacted metal alloy diminishes, TT4 slowly falls until at the “tank full” state they are essentially equal. Note that at this point the flow of new gas into the system also falls to near zero. The residual slight difference between TT3 and TT4 reflects heat stored in the metal hydride which has not yet been cooled by inflowing cool hydrogen.

[0543] Test 4B was a desorption test - selected sensor readings are presented in Figure 6.

[0544] As in test 4B the input hydrogen temperature (T3) starts low (at the end of test 4A) and rapidly climbs as the hydrogen is heated in the coil immersed in hot oil. Despite being fed with warming hydrogen, the temperature of the gas leaving the tank initially falls. This is as expected as it reflects the endothermic reaction of desorption of hydrogen from the metal hydride when the pressure in the tank was lowered. As expected hydrogen was then released via the pressure relief valve through the flow meter to waste (yellow / bottom trace).

[0545] This in practice would be hydrogen available for use on emptying the tank. The pulsatile nature of the yellow trace reflects the pulsatile pump that was used to cause fluidization - so each stroke of the pump caused better fluidization and provided a burst of released hydrogen.

[0546] Unfortunately, the filters that were used were not fine enough and the high hydrogen flow rates caused entrainment of the powdered metal hydride which made the relief valve “sticky”. The resultant flow was therefore not continuous but in discrete bursts at high flow rates.

[0547] In comparing overall results to expected results, with reference to Figure 7, as can be seen in the sorption curves for this metal hydride reported in literature, the approximate maximal amount of hydrogen that would be expected to be absorbed I adsorbed by 500 g of the hydride when it is taken from zero atmospheric pressure to 6 bar (7 bar absolute) is 80NI (160 / kg).

[0548] The approximate maximal amount of hydrogen expected to be released when heated to 60 degrees and taken from that “full state” at 6 bar down to a pressure of 2 bar absolute is 72NL.

[0549] The actual amounts absorbed and desorbed were as shown in the table below.

[0550] Table 8: Results of Sorption tests on Test 4 and the volumes of H2 measured

[0551] Test 4 proved all three of the objectives for the test work. It was proven specifically that hydrogen can be used to fluidise a metal hydride and simultaneously to act as a heat transfer fluid to cause absorption and desorption of hydrogen by that metal hydrides at the expected gravimetric density.

[0552] It is of note that T4 exit temperature only reached 40 degrees during test 4B - implying that hydrogen that was recirculated was not adequately heated. As a result, during the subsequent test (test 5) where the hydride was heated to a higher temperature to ensure that the tank was fully empty a further 20.03 SL of hydrogen was recovered. This should be added to the hydrogen recovered during test 4B given a total recovery of 81 .9 SL which is then greater than that which was expected.

[0553] The fact that less hydrogen appears to have been put into the tank in test 4A than was recovered in total from tests 4B and 5.0 is similarly due to incomplete emptying of the tank in test 3.

[0554] Discussion of test results

[0555] The tests herein reported were conducted to prove the core conceptual features of invention, namely

[0556] 1) fluidisation of the metal alloy in a container, with hydrogen as the fluidisation medium, is an effective way of performing adsorption I absorption of hydrogen by the metal alloy (forming a hydride);

[0557] 2) fluidisation of the resulting metal hydride is an effective way of performing desorption of hydrogen from said hydride; and

[0558] 3) hydrogen can effectively be used as the working fluid to transfer and remove heat to and from the metal hydride reactor.

[0559] From the results of Test 4, it is believed that these objectives have been achieved since - a) the expected exothermic (absorption) and endothermic (desorption) profiles were shown; b) fresh gas flow was shown to be absorbed by the metal alloy in volumes as expected; and c) on desorption, pressure increased downstream of the tank as would be expected with hydrogen release from the hydride and outflow hydrogen was measure leaving the system as expected in test 4.

[0560] DISCUSSION

[0561] THE PRESENT INVENTION has multiple advantages that contributes toward seeking to meet the need identified in the background to the invention. These include that recirculation of gaseous hydrogen allows a sufficient volume of hydrogen gas to be contacted with the hydrogen capture medium to achieve fluidization and affords multiple opportunities for hydrogen to be adsorbed or absorbed by the hydrogen capture medium.

[0562] When any gas is used to fluidize a particulate solid, the gas initially rises through the material in a few columns and escapes the solid material without fluidizing it. In an open system with a limitless supply of gas (such as air) continued pumping over time achieves the fluidized state. With hydrogen being the gas, the system cannot be open as the objective is to contain hydrogen. If hydrogen was simply blown into the base of the container via a diffuser, the pressure of gas above the material would rapidly rise and prevent more hydrogen being introduced. This invention includes a pump which takes this uncaptured hydrogen off the top of the tank and reintroduces it to the bottom of the tank to allow adequate gas flow to cause fluidization and to reexpose the hydrogen to the medium to allow its ab or adsorption.

[0563] Typically, ab- or adsorption of hydrogen is an exothermic process and has been found to be slowed and even stopped by rising temperature of the hydrogen capture medium. To achieve maximal uptake, it has been found desirable to cool the hydrogen capture medium. This is usually achieved by building a cooling system into the tank. In this invention, the cooling and recirculation of hydrogen contacted with hydrogen capture medium, optionally combined with fluidization, provides an advantageously efficient approach of effecting temperature control.

[0564] Conversely, releasing the hydrogen from the hydrogen capture medium has been found to be promoted by heating the hydrogen capture medium. Again, the present invention avoids the need to employ a heating system in the tank, since the invention achieves heating by, instead, heating the recirculated hydrogen which heats the material as the hydrogen fluidizes it.

[0565] Fluidization is also advantageous from the perspective that hydrogen capture media, such as metal hydrides, typically fracture, i.e. decrepitate, and become finer and finer particles which pack until hydrogen can no longer permeate between them to react with anything save the surface particles. Fluidization by its nature separates the particles such that they become an emulsion within a bath of hydrogen achieving maximal contact each cycle. In addition, capture media such as metal hydrides require activation by means of exposure to high pressure hydrogen and I or mechanical fracturing by ball-milling. This changes the shape of particles to be more irregular so that they do not pack as tightly, thereby allowing the hydrogen to penetrate the material. This invention spaces the particles by fluidizing them so that they are surrounded by hydrogen - irrespective of their shape. Activation of the metal hydrides is therefore avoided.

[0566] While the invention has been described in detail with respect to a specific embodiment and / or example thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily conceive of alterations to, variations of and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the claims and any equivalents thereto, which claims shall be appended hereto upon completion of this patent application. A significant advantage of fluidization of the capture medium is that the particles of the medium are separated from each other, thus allowing more intimate contact of hydrogen with the particles across their surfaces.

[0567] A further advantage of fluidization for temperature dependant processes is that fluidization has been shown to result in a very even distribution of temperature throughout the vessel with an absence of hotspots or cold spots - so that reaction is rapid and complete and controllable without formation of unwanted products because of such typical uneven temperatures in other systems.

[0568] In addition to the inherent advantages of fluidization, the invention has the advantage of allowing dynamic determination of hydrogen capture medium particle size on each filling and / or emptying cycle, with reference to the relationship between superficial gas velocity and feed pressure. This is a particular novel and inventive feature of the invention, since it speaks to the operability of hydrogen storage systems using hydrogen storage media of the type used by the invention. In this regard, the invention overcomes the existing operating challenges associated with such systems, such as particle entrainment, by providing for variable superficial gas velocities matched to the particle size of the hydrogen capture medium existing at a particular point in time.

Claims

CLAIMS1. A method of providing and maintaining a particle bed of particulate metallic hydrogen capture medium in a fluidized state inside a hydrogen storage chamber using hydrogen as a fluidizing gas, for hydrogen to be ad / absorbed by or desorbed, as hydrogen gas, from the particulate metallic hydrogen capture medium, the method including supplying hydrogen to the particle bed of particulate metallic hydrogen capture medium at a superficial velocity of which the magnitude progressively increases over time, in a direction that would cause fluidization of the particle bed at or above a minimum superficial fluidization velocity, wherein the progressive increase in the superficial velocity starts below the minimum superficial fluidization velocity; intermittently or continuously measuring or calculating, over time the magnitude of the pressure (“feed pressure”) of the hydrogen that is supplied to the particle bed at the progressively increasing superficial velocity, upstream of the particle bed, and the magnitude of the superficial velocity at which the hydrogen is supplied to the particle bed; ceasing the progressive increase in the magnitude of the superficial velocity when the feed pressure ceases to increase with increased superficial velocity; and maintaining the superficial velocity at which the hydrogen is supplied to the particle bed at a magnitude (“superficial fluidization velocity”) at which the feed pressure ceased to increase with increased superficial velocity.

2. The method according to claim 1 , wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity causes hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium.

3. The method according to claim 2, which includes based on the value of the superficial fluidization velocity, determining an average particle size of the particulate metallic hydrogen capture medium with reference to a nomogram of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate metallic hydrogen capture medium; and contacting the hydrogen that is supplied to the particulate metallic hydrogen capture medium with the particulate metallic hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium at the determined average particle size.

4. The method according to claim 1 , wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity causes hydrogen that was previously ad / absorbed by the particulate metallic hydrogen capture medium to be desorbed from the particulate metallic hydrogen capture medium.

5. The method according to claim 4, which includes based on the superficial fluidizing velocity, determining an average particle size of the particulate metallic hydrogen capture medium with reference to a nomogram of hydrogen capture medium particle size against fluidization velocity for the hydrogen capture medium species of the particulate metallic hydrogen capture medium; and contacting the hydrogen that is supplied to the particulate metallic hydrogen capture medium with the particulate metallic hydrogen capture medium at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size.

6. The method according to any one of claims 1 to 5, wherein supplying the hydrogen, progressively increasing the superficial velocity, measuring or calculating the feed pressure and the superficial velocity, ceasing the progressive increase in the magnitude of the superficial velocity, and maintaining the superficial fluidization velocity, are performed electronically and automatically by means of an electronic hydrogen supply control system.

7. The method according to claim 3 and claim 6, wherein determining the average particle size of the particulate metallic hydrogen capture medium and contacting the hydrogen with the particulate metallic hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be ad / absorbed by the particulate metallic hydrogen capture medium at the determined average particle size are also performed by the electronic hydrogen supply control system.

8. The method according to claim 7, wherein the electronic hydrogen supply control system is comprised by a hydrogen supply station having a source of hydrogen independent of the hydrogen storage chamber, and wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium is from the source of hydrogen.

9. The method according to claim 8, wherein the hydrogen storage chamber is provided on a vehicle separate of the hydrogen supply station and wherein the hydrogen storage chamber has an electronic hydrogen storage chamber control system that is in communication with the electronic hydrogen supply control system, and wherein the method includes communicating the superficial fluidization velocity and the determined average particle size to the electronic hydrogen storage chamber control system by means of the electronic hydrogen supply control system; and electronically storing the superficial fluidization velocity and the determined average particle size in an electronic hydrogen storage chamber control system database by means of the electronic hydrogen storage chamber control system.

10. The method according to claim 5 and claim 6, wherein determining the average particle size of the particulate metallic hydrogen capture medium and contacting the hydrogen with the particulate metallic hydrogen capture medium at the predetermined temperature and the predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size are also performed by the electronic hydrogen supply control system.

11. The method according to claim 10, wherein the electronic hydrogen supply control system is comprised by a vehicle having a hydrogen fueled internal combustion engine or by an electric vehicle operating with a hydrogen fuel cell, and wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium is from the hydrogen storage chamber, orfrom another such hydrogen storage chamber of the vehicle, the vehicle in such a case having multiple hydrogen storage chambers.

12. The method according to any one of claims 1 to 11 , wherein the particulate metallic hydrogen capture medium comprises particulate metallic hydrogen capture medium that has repeatedly been subjected to hydrogen ad / absorption and desorption cycles and, as a result, has been fractured, i.e. decrepitated, into particle sizes smaller than an original particle size thereof.

13. A method of providing and maintaining a bed of particulate metallic hydrogen capture medium in a fluidized state inside a hydrogen storage chamber having an electronic hydrogen storage chamber control system, to cause hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium to be desorbed from the particulate metallic hydrogen capture medium, the method includingrecalling a previously determined superficial fluidization velocity for fluidizing the bed of particulate metallic hydrogen capture medium and a previously determined average particle size of the particulate metallic hydrogen capture medium from an electronic hydrogen storage chamber control system database of the electronic hydrogen storage chamber control system, which database has the fluidization superficial velocity and the previously determined average particle size stored therein by having performed the method of claim 9; and supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at a predetermined temperature and a predetermined pressure optimal for hydrogen to be desorbed from the particulate metallic hydrogen capture medium at the determined average particle size, wherein recalling the superficial fluidization velocity and supplying the hydrogen gas are performed by the electronic hydrogen storage chamber control system.

14. The method according to claim 13, wherein supplying hydrogen to the bed of particulate metallic hydrogen capture medium at the superficial fluidization velocity and at the predetermined temperature and the predetermined pressure, causes hydrogen previously ad / absorbed by the particulate metallic hydrogen capture medium being desorbed from the particulate metallic hydrogen capture medium.

15. The method according to claim 13 or claim 14, wherein hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium comprises gaseous hydrogen that is contained in the hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen storage medium, and wherein supplying hydrogen to the bed of particulate metallic hydrogen storage medium includes withdrawing hydrogen from the hydrogen storage chamber.

16. The method according to any one of claims 13 to 15, wherein hydrogen that is supplied to the bed of particulate metallic hydrogen capture medium comprises gaseous hydrogen that is contained in another hydrogen storage chamber under pressure as excess gaseous hydrogen to the hydrogen ad / absorbed by the hydrogen storage medium thereof, and wherein supplying hydrogen to the bed of particulate metallic hydrogen storage medium includes withdrawing hydrogen from the other hydrogen storage chamber.

17. The method according to claim 16, wherein the hydrogen storage chamber and the other hydrogen storage chamber form part of a group comprising multiple interlinked hydrogen storage chambers.

18. The method according to any one of claims 13 to 17, which includes the prior step of performing the method according to claim 9.

19. A method of operating a hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself of from pressurized hydrogen contained in another hydrogen storage chamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part, such that the hydrogen capture medium is fluidized by such supply, wherein the method includes repeatedly and successively performing the method of claim 9, for hydrogen to be ad / absorbed by the hydrogen capture medium; and the method of any one of claims 13 to 18, for hydrogen to be desorbed from the hydrogen capture medium.

20. A hydrogen storage and utilization system comprising a hydrogen supply station having a source of hydrogen and an electronic hydrogen supply control system; and a hydrogen storage chamber having an electronic hydrogen storage chamber control system and a particle bed of particulate hydrogen capture medium contained in an interior of the hydrogen storage chamber, wherein the hydrogen storage chamber is separate of the hydrogen supply station, the hydrogen storage system being configured for hydrogen to be repeatedly successively ad / absorbed and desorbed from the hydrogen capture medium by supplying hydrogen to the hydrogen capture medium respectively when ad / absorbing hydrogen, from the source of hydrogen; or when desorbing hydrogen, from pressurized hydrogen contained in the hydrogen storage chamber itself or from pressurized hydrogen contained in another hydrogen storagechamber of a group of hydrogen storage chambers of which the first mentioned hydrogen storage chamber forms part and is included in the system, such that the hydrogen capture medium is fluidized by such supply, such configuration including to repeatedly and successively perform the method of claim 9 for hydrogen to be ad / absorbed by the hydrogen capture medium; and the method of any one of claims 13 to 18 for hydrogen to be desorbed from the hydrogen capture medium.

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