WO2018130623A1

WO2018130623A1 - An apparatus for generating hydrogen

Info

Publication number: WO2018130623A1
Application number: PCT/EP2018/050695
Authority: WO
Inventors: Mark Collins
Original assignee: Ihod Ltd
Current assignee: Ihod Ltd
Priority date: 2017-01-16
Filing date: 2018-01-11
Publication date: 2018-07-19
Anticipated expiration: 2019-07-16
Also published as: GB201700702D0; GB2559954A

Abstract

The invention provides apparatus for generating hydrogen; the apparatus comprising: a container formed predominantly from biodegradable material and having dimensions that enable it to be held in a human hand; the container having a hollow interior defining a reaction chamber, a first inlet for admitting a liquid co-reactant into the reaction chamber, and a hydrogen gas outlet for venting hydrogen gas from the reaction chamber, each of the first inlet and hydrogen gas outlet being provided with valves to enable the control of fluid therethrough; wherein the container either contains one or more reactants capable of reacting with or in the presence of the liquid co-reactant to produce hydrogen, the one or more reactants being in dry form; or the container is provided with reactant inlet means enabling one or more reactants to be admitted into the reaction chamber; whereby in use, the one or more reactants in the solid unit dosage form react in the presence of the liquid co-reactant introduced through the first inlet to generate hydrogen.

Description

AN APPARATUS FOR GENERATING HYDROGEN

This invention relates to a handheld apparatus for generating hydrogen. Background of the Invention

In recent years, fuel cells have become increasingly popular as a means of generating electricity in situations where there is no mains power available. Fuel cells typically run on hydrogen and have a number of advantages over internal combustion engines traditionally used in stand-alone power generators. Thus, the waste product of the operation of a fuel cell run on hydrogen is solely water, and no carbon dioxide or carbon monoxide is produced. Fuel cells are also more efficient than internal combustion engines. A further advantage of a fuel cell compared to a conventional petroleum burning generator is that fuel cells can be miniaturised, thereby making them more portable. One example of a portable fuel cell is the proton exchange membrane (PEM) fuel cell. Light weight fuel cells capable of producing a continuous output of 150W and 230V are now

commercially available. One such commercially available fuel cell is the Hymera™ fuel cell generator produced by BOC. The Hymera fuel cell generator has a length of 433mm, a width of 188mm, a height of 278mm and a weight of 7kg.

However, a problem with the use of hydrogen-based fuel cells is that they require a supply of hydrogen. In many remote locations and field situations, a supply of hydrogen may simply be unobtainable. Thus, currently, the use of hydrogen-based fuel cells is limited by the difficulties in obtaining or maintaining a supply of hydrogen.

It is known that hydrogen can be generated by the reaction of various metals with acid or alkali. For example, US4325355 describes a heating system in which an exothermic reaction between a solid metal and a solution takes place in a reactor containing a heat exchanger. In the specific reaction system described, aluminium pieces are lowered into a solution of sodium hydroxide solution. During the reaction between aluminium and sodium hydroxide solution, the aluminium is converted to aluminium hydroxide with the evolution of hydrogen gas. The aluminium hydroxide reacts with the sodium hydroxide to form sodium aluminate. The generation of hydrogen by the reaction of aluminium with sodium hydroxide is also described in US2009/0252671 (Fullerton). The hydrogen generating apparatuses of the type described above are relatively large scale fixed

installations that are not readily suited to portable use. At present, there remains a need for an apparatus that is portable, lightweight and can preferably be carried by a person as part of his or her personal luggage (for example in a ruck sack) and which can provide hydrogen on demand in remote or field situations, for example in humanitarian relief operations, where it is not possible or practicable to use hydrogen storage containers such as gas cylinders.

Summary of the Invention

The present invention provides a portable handheld device for generating hydrogen on demand.

In a first aspect, the invention provides an apparatus for generating hydrogen; the apparatus comprising:

a container formed predominantly from biodegradable material and having dimensions that enable it to be held in a human hand;

the container having a hollow interior defining a reaction chamber, a first inlet for admitting a liquid co-reactant into the reaction chamber, and a hydrogen gas outlet for venting hydrogen gas from the reaction chamber, each of the first inlet and hydrogen gas outlet being provided with valves to enable the control of fluid therethrough;

wherein the container either contains one or more reactants capable of reacting with or in the presence of the liquid co-reactant to produce hydrogen, the one or more reactants being in dry form; or the container is provided with reactant inlet means enabling one or more reactants to be admitted into the reaction chamber;

whereby in use, the one or more reactants in the solid unit dosage form react in the presence of liquid co-reactant introduced through the first inlet to generate hydrogen.

The container has dimensions that enable it to be held in a human hand. Thus the container can typically be grasped or lifted and carried using a single human hand. The "handheld" apparatus of the invention can comprise a container having a minimum dimension (e.g. diameter) of up to about 10cm so that it can be held in a hand. For example, the container can have a width (e.g. diameter) where the container is of circular cross section of up to about 10cm. For example, the container may have a minimum dimension (e.g. width/diameter) of up to about 7 cm. More usually, the container will have a minimum dimension (e.g.

width/diameter) of up to about 6.5cm, for example from 5.5-6.5cm. In one embodiment, the container has a minimum dimension (e.g. width/diameter) of about 5.8-6.2cm.

The container typically has a weight which allows it to be lifted and held

comfortable by the user. Typically, the container weighs no more than 5 kg, for example no more than 4 kg, no more than 3 kg, no more than 2 kg or no more than 1 kg.

The container is formed predominantly from a biodegradable material such as a biodegradable plastics material. By "predominantly" it is meant that at least 50% (by weight) of the container is formed from a biodegradable material. Preferably at least 60% (by weight) of the container is formed from a biodegradable material. For example, in various embodiments (i) at least 65% (by weight) of the container may be formed from a biodegradable material; or (ii) or at least 70% (by weight) of the container is formed from a biodegradable material; or (iii) at least 75% (by weight) of the container is formed from a biodegradable material; or (iv) at least 80% (by weight) of the container may be formed from a biodegradable material; or (v) at least 85% (by weight) of the container may be formed from a biodegradable material; or (vi) at least 90% (by weight) of the container may be formed from a biodegradable material; or (vii) at least 95% (by weight) of the container may be formed from a biodegradable material.

For example, structural elements of the container can be formed from a

biodegradable material and components such as valves and seals may be formed from non-biodegradable materials such as metals or non-biodegradable plastics.

The hollow interior of the container, which defines the reaction chamber, has an inner surface which is impermeable to water and has gas barrier properties.

Typically, the surface is substantially impermeable to hydrogen. Where the biodegradable materials from which the container is predominantly formed are not themselves water impermeable and/or do not have gas barrier properties, the reaction chamber may be lined with a material or materials which do have the necessary properties.

The term "biodegradable material" as used herein refers to a material that can be degraded by biological means, e.g. by the action of microorganisms or other living organisms, biological agents or processes.

The biodegradable material is typically a biodegradable plastics material and can be, for example, selected from: (i) biodegradable polyesters;

(ii) biodegradable polyanhydrides;

(iii) biodegradable starch-based polymers;

(iv) biodegradable cellulose-based polymers; and

(v) plastics materials formed from non-biodegradable polymers but containing additives that render them biodegradable.

Examples of biodegradable polyesters (i) include aliphatic polyesters such as polyhydroxyalkanoates (e.g. poly-3-hydroxybutyrate and polyhydroxyhexanoate); polylactic acid; and polybutylene succinate; and copolymers and blends thereof.

Poly-3-hydroxybutyrate has a high melting point (175°C), is not readily soluble in water and is not moisture sensitive. However, it has relatively poor resistance to acids and bases and is gas permeable. Therefore, when poly-3-hydroxybutyrate is used to form the container, the interior surface of the reaction chamber is typically coated or lined with a material which provides the necessary resistance to acids and bases and the necessary degree of impermeability to gases. For example, the interior surface of the reaction chamber may be coated with a vapour deposited layer of polytetrafluoroethylene (PTFE). An example of a biodegradable starch- based polymer is Plastarch Material (PSM) which has a softening temperature of 125°C and a melting temperature of 156°C. Because PSM is hydroscopic, at least the inner surface of the reaction chamber must be coated with a water-repelling material in order that it may be used to form the apparatus of the invention.

Particular examples of biodegradable polymers for use in forming the apparatus of the present invention include polylactic acid (polylactide) polymers and copolymers thereof. The polylactide polymer or copolymer is one which will retain its structural integrity at the temperatures generated within the reaction chamber. Typically, therefore, the polylactide polymer or copolymer has a melting point in excess of 120°C and more preferably a melting point above 140°C. Examples of such high temperature polylactides include Bio-Flex F6513 available from FKuR Kunststoff GmbH, of Willich, Germany. Other examples of high temperature polylactide polymers include the Puralact® polymers available from Corbian Purac of

Gorinchem, Netherlands, and the Ecodear® polylactide polymers available from Toray Industries. The container either contains one or more reactants capable of reacting with or in the presence of the liquid co-reactant (e.g. water) to produce hydrogen; or the container is provided with reactant inlet means enabling one or more reactants to be admitted into the reaction chamber.

In one embodiment, the apparatus comprises a container containing one or more reactants in dry form, the reactants being capable of reacting with or in the presence of liquid co-reactant (e.g. water) to produce hydrogen. The reactants may be introduced into the container during the manufacture of the apparatus. The opening or inlet used to introduce the reactants into the container may be sealed at the point of manufacture to prevent subsequent removal of the reactants. Thus an apparatus according to this embodiment of the invention, as supplied to a user, may have a first inlet for the liquid co-reactant (e.g. water) and a hydrogen gas outlet but no inlet for introducing further reactants. An apparatus according to this embodiment of the invention is therefore intended for single use and disposal.

Alternatively, the container can be provided with an inlet that can be opened by the user for the introduction of the one or more reactants.

In one embodiment, the container has a hollow interior defining a reaction chamber, and is provided with a reactant inlet chamber for receiving solid unit dosage forms comprising one or more reactants capable of reacting in the presence of a liquid co-reactant (e.g. water) to form hydrogen;

wherein the reactant inlet chamber has a first reclosable opening which opens to the container exterior for receiving the solid unit dosage forms; and a second reclosable opening communicating with the reaction chamber through which the solid unit dosage forms can be introduced into the reaction chamber; wherein at least one of the first and second reclosable openings is provided with a gas tight seal to prevent leakage of hydrogen gas from the reaction chamber.

An apparatus according to this embodiment of the invention is intended to be reused.

The apparatus of the invention may be connected or connectable to a device (e.g. a portable or handheld device) that consumes hydrogen. For example, the apparatus may be connected or connectable to a fuel cell (e.g. a hydrogen fuel cell). Alternatively, the apparatus of the invention may comprise a hydrogen fuel cell. The fuel cell is typically a portable fuel cell such as a proton exchange membrane (PEM) fuel cell. An example of a commercially available portable fuel cell is the Hymera fuel cell generator described above.

Thus, in a further aspect, the invention provides an apparatus as defined herein in combination with a fuel cell, e.g. a PEM fuel cell.

The apparatus and fuel cell combinations are of particular use in situations where there is no direct access to electricity. They may be used, for example, in field situations to charge devices such as computers, mobile phones and other portable electronic devices such as military communication units or for the continuous cooling of essential medical items within a small fridge.

The apparatus of the invention makes use of solid unit dosage forms containing one or more reactants that react in the presence of a liquid co-reactant to generate hydrogen. The solid dosage forms can take the form of tablets, the term tablets as used herein referring to a unitary dosage form typically formed by moulding and/or compression although it may also be formed by casting and by division of a larger dosage form. As an alternative to tablets, the solid dosage form can take the form of a capsule containing one or more reactants in solid, semi-solid or gel form. The solid unit dosage forms are typically constructed to provide an (at least

approximately) known amount of hydrogen after reaction in the presence of the liquid co-reactant.

Where the apparatus is intended for single use, and the one or more reactants are loaded into the reaction chamber at the point of manufacture, the reactant(s) may alternatively be presented in the form of powders or pellets.

The dry dosage forms may contain a single reactant or more than one reactant. In one embodiment, the dry dosage form contains only a single reactant that reacts directly with a liquid co-reactant to form hydrogen. In another embodiment, the dry dosage form contains a first reactant that reacts with one or more further reactants in the presence of a liquid co-reactant to form water. In one particular embodiment, the solid unit dosage form contains two or more reactants that react together in the presence of liquid co-reactant to generate hydrogen. In another embodiment, a plurality (e.g. two or three, more usually two) different dry dosage forms are provided, each comprising a different reactant or combination of reactants. In each of the foregoing embodiments, the dry dosage forms may be unit dosage forms constructed to provide an (at least approximately) known amount of hydrogen after reaction in the presence of liquid co-reactant.

Preferably, the reactants necessary for the generation of hydrogen in the presence of liquid co-reactant are present in a single unit dosage form.

Where a unit dosage form contains more than one reactant, a barrier may be provided so as to separate the reactants. For example, in a tablet, two or more reactants may be presented as different layers of a tablet. In order to prevent premature reaction in the dry state between the reactants, a barrier film (e.g. a polymeric barrier film) may be interposed between at least two of the reactants. The barrier film may comprise a soluble or dispersible polymer which breaks down to release the reactants when contacted with the liquid co-reactant. In alternative form, the tablet may comprise particles (e.g. beads or pellets or granules) of one or more reactants wherein the particles of at least one reactant are coated with a protective coating that breaks down or dissolves once the unit dosage form comes into contact with the liquid co-reactant. Similarly, in a capsule formulation, particles (e.g. beads or pellets or granules) of at least one reactant may be provided with a protective coating such as a polymeric coating.

The dry dosage forms (e.g. unit dosage forms) may be provided with a protective wrapping or outer container that the user removes or opens to give access to the dosage form prior to use. The protective wrapping or outer container is typically constructed to protect the dry dosage form from attack by moisture.

Where the reaction between a reactant and liquid co-reactant, or two or more reactants in the presence of liquid co-reactant, is particularly vigorous, controlled release technology may be used to control the rate of release of one or more reactants so as to slow down the hydrogen-generating reaction and prevent excessive heat generation. For example, one or more reactants may be coated in a slowly dissolving or eroding polymer that releases reactants at a controlled rate.

The solid dosage form may be in the form of a slow-release dosage form where the release rate of the reactant(s) is modified from the release profile of the reactant(s) alone. For example, the solid dosage form may comprise one or more reactants that react in the present of a liquid co-reactant (e.g. an aqueous medium, such as water) and a water-degradable compound in the form of a matrix. In another embodiment, the solid dosage form may comprise a water-degradabie coating, or be contained in water-degradable packaging, wherein the water- degradable coating or protective packaging serves to delay the release of the reactants when the solid dosage form is brought into contact with the aqueous medium. The use of a slow-release or coated or protectively packaged dosage form results in a delay between when the solid dosage form is brought into contact with the aqueous medium and when hydrogen is first generated. This delay should be of sufficient length to allow the user to ensure that the container is sealed before hydrogen gas is evolved in order to minimise any hydrogen lost from the container via openings other than the hydrogen gas outlet.

Accordingly, in a further aspect of the invention, there is provided an apparatus described herein in combination with a slow-release solid dosage form (for example, a solid dosage form described herein) comprising one or more reactants that react in the presence of a liquid co-reactant (e.g. an aqueous medium, such as water) to generate hydrogen.

Protective coatings and release-controlling coatings and polymers are well known in the art, particularly in the pharmaceutical sciences and need not be discussed in detail here.

Where water-degradable packaging is used, this may for example take the form of an outer wrapping or bag formed from a water-degradable polymer such as polyvinyl alcohol (PVA).

The liquid co-reactant is typically water or a liquid medium containing water. The water may be the sole reactive component of the liquid co-reactant or the liquid co- reactant may contain other reactive substances. In one embodiment, water is the sole reactive component in the liquid co-reactant.

The reactants can be any substances that react with the liquid co-reactant (e.g. water) or with other reactants in the presence of the liquid co-reactant (e.g. water) to generate hydrogen.

For example, the reactants can take the form of or comprise a metal (e.g. a finely divided metal) that reacts with the liquid co-reactant (e.g. water) to form hydrogen.

In another embodiment, the reactants can take the form of a metal (e.g. a finely divided metal such as a metal powder) and an acid or an alkali that reacts with the metal to generate hydrogen. Where the reactant comprises an acid or an alkali, the acid or alkali will be in solid form or will be contained within a solid dosage form.

The metal can be, for example, an alkali metal or alkaline earth metal, a group III metal such as aluminium, a non-transition metal such as zinc, or a transition metal.

Examples of acids include solid acids such as citric acid and tartaric acid, or mineral acids such as sulphuric acid and hydrochloric acid contained in a protective matrix (see for example WO2009/022123 (Concentrated Solutions Limited).

Examples of alkalis include sodium hydroxide and potassium hydroxide.

In one particular embodiment, the reactants comprise a metal powder such as zinc or aluminium and an alkali metal hydroxide.

A particular pair of reactants that may be used to generate hydrogen comprises finely divided (e.g. powdered) aluminium and sodium hydroxide.

In one embodiment, the container has a reactant inlet chamber for receiving the solid unit dosage forms. The reactant inlet chamber has a first reclosable opening which opens to the container exterior for receiving the solid unit dosage forms and a second reclosable opening communicating with the reaction chamber through which the solid unit dosage forms can be introduced into the reaction chamber.

At least one of the first and second reclosable openings is provided with a gas-tight seal to prevent leakage of hydrogen gas from the reaction chamber. In one embodiment, both the first and second reclosable openings are provided with gas- tight seals and hence the reactant inlet chamber functions as an air-lock between the reaction chamber and the container exterior.

The first reclosable opening can be closed by a closure device that can be opened to receive the solid unit dosage form and then closed to bring the solid unit dosage form into the inlet chamber. The closure device can be, for example, a lid or a drawer. In one embodiment, the closure is a drawer set into a side wall of the container.

The drawer may be configured so that it can hold a solid dosage form such as a tablet but is unable to hold materials in liquid or powder form. Thus, for example, the draw may have one or more bottom openings through which any liquid or powdered materials would fall before they could enter the reactant inlet chamber.

The first reclosable closable opening may be provided with sealing means for providing a gas-tight seal between the inlet chamber and the container exterior. For example, where the closure device is a lid or drawer, the sealing means may comprise a sealing gasket around the opening and/or a sealing gasket on the lid or drawer.

The second reclosable opening provides communication with the reaction chamber and enables the solid unit dosage forms to be introduced into the reaction chamber. The second reclosable opening can be closed by means of a valve or door which can be opened to permit the solid unit dosage form to pass (e.g. fall) into the reaction chamber. The valve or door, when closed, preferably forms a gas tight seal that prevents hydrogen from escaping from the reaction chamber into the reactant inlet chamber.

Alternatively, the container may comprise a pair of body elements (e.g. a base and a lid) that can be separated to allow the introduction of the one or more reactants into the reaction chamber. The body elements are then reconnected together to form a substantially gas-tight seal therebetween (e.g. through use of one or more elastomeric sealing members). In one embodiment, the body elements are provided with complementary threads to enable them to be connected together.

The reactants are introduced into the reaction chamber in the form of solids. In the presence of liquid co-reactant (e.g. water) introduced into the reaction chamber through the liquid co-reactant inlet (e.g. water inlet), the reactants react to form hydrogen. The hydrogen then passes out through the hydrogen gas outlet and on to a coupled device such as a PEM fuel cell that consumes hydrogen.

Both the water inlet and the hydrogen gas outlet are controlled by valves. Thus, for example, the hydrogen gas can be provided with a one way valve allowing the escape of hydrogen but not allowing gases or other fluids to enter the reaction chamber. Alternatively, the hydrogen gas can be provided with an on-off valve or a two way valve that can be closed to prevent escape of hydrogen. In this latter case, means (e.g. a vent such as a valved opening may be provided for venting hydrogen to the atmosphere) if the gas pressure within the reaction chamber exceeds a predetermined limit. The liquid co-reactant inlet (e.g. water inlet) may likewise be provided with a one way valve, which allows liquid co-reactant (e.g. water) to be introduced into the reaction chamber but does not allow gas or other material to escape from the reaction chamber.

The apparatus of the invention is a handheld apparatus. During the hydrogen generation reaction, the container may become very hot. It may therefore be provided with a layer of thermal insulation so that it can be held in the hand without burning the hand of the user. The layer of thermal insulation may take the form of a jacket or sleeve of a thermally insulating material disposed around an outer side wall of the container. The jacket or sleeve may, for example, be formed from a cellulose-based material such as paper or card or may be formed from an insulating polymer. Examples of insulating polymers include polymer foams such as polyurethane foams and polymers such as heat resistant silicone polymers.

In one embodiment, the layer of thermal insulation is bonded (e.g. adhesively) to an outer surface of the container.

In another embodiment, the layer of thermal insulation is retained on the outer surface of the container by virtue of a tight friction fit.

In another embodiment, the surface of the outer wall of the container is coated with an insulating material thereby allowing the user to handle the container.

In a further embodiment, the container may comprise an outer wall having a sandwich structure in which a layer of insulating material is held between inner and outer skins.

In an alternative embodiment, the apparatus may be provided with a liquid cooling jacket around the container, for example a jacket or outer container containing cooling water.

In one embodiment, the apparatus comprises an outer container and, contained therein, an inner container;

the inner container having a hollow interior which defines the reaction chamber;

a void for holding cooling water being present between an inner wall of the outer container and an outer wall of the inner container, a cooling water inlet being provided for introducing water into the void; wherein the reactant inlet chamber extends from within the inner container through the outer container so that the first reclosable opening is accessible from the exterior of the outer container; and wherein the hydrogen gas outlet and liquid co-reactant inlet (e.g. water inlet) for the reaction chamber extend from the reaction chamber through the outer container and are accessible from the exterior of the outer container.

The cooling water can be clean cooling water or impure or dirty water.

An inlet is provided for admitting cooling water into the void between the said inner and outer walls. The inlet can take the form of, for example, a reclosable opening in a wall of the outer container or a removable portion of the outer wall. When the inlet takes the form of a removable portion of the outer wall, it may, for example, comprise a removable cap.

Heat generated in the reaction chamber will heat the water in the void between the inner and outer container walls causing it to evaporate. The outer water vapour produced in this way can be collected by a suitable condensing means typically located at an upper end of the outer container.

Accordingly, in one preferred embodiment, the invention provides an apparatus comprising inner and outer containers as defined herein, wherein the outer container is provided with condensate collection means for condensing and collecting evaporated cooling water. The condensate collection means is preferably connected to a clean water outlet mounted in an outer wall of the outer container.

Thus, an ancillary use of an apparatus of the invention having inner and outer containers is to provide a means of purifying dirty water. Water introduced into the void and caused to evaporate by the heat produced in the reaction chamber is condensed and collected as clean water.

Alternatively, a liquid channel may be provided between the condensate collection and an inlet of the inner container and thereby forms a passage through which water can enter the inner container to react with the reactants described above to generate hydrogen. The inlet to which the channel is connected may form part of the liquid co-reactant inlet as described above. Alternatively, the liquid channel may be connected to the interior of the inner container by a further inlet. The collection means for condensing and collecting evaporated cooling water can take the form of a sloping condensation surface at an upper end of the outer container, the sloping condensation surface sloping downwardly to a collection point linked to the clean water outlet. Thus, for example, where the outer container is cylindrical, the sloping condensation surface can be an inverted conical surface, with a collection point at the tip of the inverted cone.

The collection means can be at least partially housed within a removable cap, the removal of which enables cooling water to be introduced into the void.

A benefit of the apparatus of the invention is that it does not require a source of clean water in order to function. Any available source of water, clean or dirty can be used for both the aqueous medium in the reaction chamber and any cooling water used in the water cooled version of the apparatus. A further benefit of the apparatus is that, when the apparatus has outer and inner containers with a void for cooling water, the apparatus can be employed to purify dirty water by the simple expedient of allowing the cooling water to be evaporated by the heat from the reaction chamber and then condensing and collecting the evaporated water.

The container (or the inner and outer container when present) is formed predominantly from a biodegradable material as hereinbefore defined. The container (or inner container) can comprise a cylindrical main body portion and separately formed base and cap portions each made predominantly from a biodegradable plastics material. The base may be configured so as to be removable to give access to the interior of the reaction chamber for cleaning and inspection purposes. For example, the base and main body portion may be secured together by means of a screw thread. Similarly, the cap and main body portion may be secured together by means of a screw thread. In each case, sealing elements such as sealing rings or gaskets may be used to ensure that the connection between the base and main body portion, or between main body portion and cap, is gas-tight. The biodegradable materials from which the container (or inner container) are made will be resistant to the chemical reactants and reaction products inside the reaction chamber. Where the materials are

insufficiently chemical resistant in their own right, the inner walls (i.e. the walls defining the reaction chamber) may be coated with an inert substance as a fluoropolymer (e.g. PTFE). The PTFE or other fluoropolymer may be applied, for example, by means of vapour deposition in accordance with known methods.

In a further aspect of the invention there is provided a method of generating hydrogen using an apparatus as described above, which method comprises introducing into the reaction chamber one or more reactants in a solid unit dosage form and then introducing a liquid co-reactant (e.g. water) into the reaction chamber to bring about chemical reaction and the generation of hydrogen.

In the method above, the chemical reaction is usually exothermic and heat generated by the reaction may be used for the purification of water by distillation.

The invention also provides a method of generating hydrogen, the method comprising the steps of:

i) providing a container formed predominantly from biodegradable material having a hydrogen gas outlet, the container having a minimum dimension (e.g. diameter) of up to about 10cm so that it can be held in a hand, wherein the container is provided with a layer of thermal insulation and the interior of the container defines a reaction chamber;

ii) introducing a solid dosage form of a reactant which reacts with water to generate hydrogen into the reaction chamber via an opening in the container;

iii) introducing an aqueous medium into the reaction chamber;

iv) sealing the container to form a substantially gas-impermeable reaction chamber (excluding the hydrogen gas outlet); and

v) channelling off hydrogen gas produced by the reaction of the solid dosage form of reactant with the aqueous medium through the hydrogen gas outlet.

The container and solid dosage form used in the method above may have the features of the container described in relation to the apparatus described above.

The container may also be provided with a liquid co-reactant inlet through which the aqueous medium can be introduced into the reaction chamber. The liquid co- reactant is typically a sealed or sealable opening such that once the aqueous medium has been introduced, the inlet is sealed to prevent hydrogen gas generated in the reaction chamber from escaping the container through this inlet.

In a further aspect, the invention provides a method of generating electricity, the method comprising the steps of:

i) providing a container formed predominantly from biodegradable material having a hydrogen gas outlet, the container having a minimum dimension (e.g. diameter) of up to about 10cm so that it can be held in a hand, the interior of the container defines a reaction chamber, wherein the container is provided with a layer of thermal insulation and wherein the hydrogen gas outlet is connected or connectable to a hydrogen fuel cell (e.g. a PEM cell);

iv) introducing an aqueous medium into the reaction chamber;

iii) sealing the container to form a substantially gas-impermeable reaction chamber (excluding the liquid co-reactant inlet and the hydrogen gas outlet); and

v) drawing off electrical power produced by the hydrogen fuel cell.

The container, solid dosage form and hydrogen fuel cell used in the method above may have the features of the container described in relation to the apparatus described above.

Each of the embodiments set out above in relation to the apparatus of the invention apply equally to the methods of the invention.

The invention will now be illustrated in more detail (but not limited) by reference to the specific embodiment shown in the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a perspective view of an apparatus according to a first embodiment of the invention.

Figure 2 is a view from one side of the apparatus of Figure 1. Figure 3 is a side view of the apparatus of Figure 2 rotated through 90°. Figure 4 is a view from above of the apparatus of Figures 1 to 3. Figure 5 is a side sectional view through the apparatus of Figures 1 to 4

Figure 6 is an enlarged view of part of Figure 5.

Figure 7 is an enlarged view corresponding to Figure 6 but rotated through 90°. Detailed Description of the Invention

Figure 1 is a perspective view of an apparatus according to a first embodiment of the invention. The apparatus comprises an outer container 2 and, contained therein, an inner container 4. The outer container 2 comprises a cylindrical main body portion 6, a base 8 and a cap 10. In this embodiment, the main body portion 6 is formed from a biodegradable plastics material which is either impermeable to water or has been treated (e.g. to provide a surface layer of a water-impermeable polymer such as silicone polymer or fluoropolymer) to render it impermeable to water. The base 8 is also formed from a biodegradable plastics material and, in this embodiment, is removably secured to the main body portion by means of a screw thread. The biodegradable plastics materials can be, for example, higher temperature resistant polylactide polymers or copolymers as described herein. A PTFE gasket (not shown) provides a gas-tight seal between the base 8 and main body portion 6. The cap 10 is likewise formed from a biodegradable plastics material and is removably attached to the main body portion 6.

Located inside the outer container 2 is an inner container 4 which comprises a main body portion 12, a base 14 and a cap 16. The main body portion 12, base 14 and cap 16 together form a hollow container, the interior of which serves as a reaction chamber 50. The inner container is either formed from a biodegradable plastics material which is resistant to attack by the reactants and reaction products, or it is formed from a biodegradable plastics material which has been treated to render it resistant to attack by the reactants and reaction products. For example, the inner surfaces of the main body portion 12, base 14 and cap 16 may advantageously be coated with a fluoropolymer such as PTFE to increase resistance to attack by the reactants and reaction products.

Set into the cap 16 of the inner container 4 are a valved internal water inlet 18 and a valved internal gas outlet 20 which communicate via short lengths of tubing 22, 24 with corresponding external water inlet port 26 and external gas outlet port 28 mounted in the cap 10 of the outer container.

The main body portion 12 of the inner container and the main body portion 6 of the outer container 2 are provided with aligned inner and outer openings 30 and 32 respectively in which in which is mounted a sliding drawer 34. The innermost end of the drawer 34 is slidably mounted within a reactant inlet chamber 36 defined by a roof 38, a sliding floor panel 40, side walls 42 and an end wall 44 mounted within the body of the inner container 4. The drawer 34 is provided with sealing elements (not shown) so that when it is in a closed position, a fluid-tight seal is formed between the drawer 34 and the surrounding walls of the inner opening 30. The inner opening 30 thus constitutes a first reclosable opening for the reactant inlet chamber.

A drawer release button 46 is mounted in the wall of the outer container 2 beneath the drawer opening 32 and is linked by an actuating bar or rod 48 to a spring loaded drawer-retaining latch (not shown). The drawer-retaining latch holds the drawer in the reactant inlet chamber against the force of a spring or other resilient element (not shown) located between the end wall 44 and the inner end of the drawer 34. Depressing the button 46 releases the latch thereby enabling the drawer 34 to move out of the reactant inlet chamber under the force of the resilient element and into an open position. When the drawer 34 is pushed back into the reactant inlet chamber to its closed position, the spring loaded drawer-retaining latch re-engages the drawer 34 to hold it in place. The resilient element is preferably damped to prevent the drawer 34 from being ejected from the reactant inlet chamber too quickly.

The sliding floor panel 40 of the reactant inlet chamber 36 can be opened to allow communication between the reactant inlet chamber and the reaction chamber 50. The sliding floor panel 40 is provided with sealing elements (not shown) that form a fluid tight seal around the edges of the panel when the panel is in a closed position to prevent fluids from passing into or out of the reaction chamber 50. Thus, the sliding floor panel constitutes a second reclosable opening for the reactant inlet chamber.

The drawer 34 has a lower wall or floor on which a tablet or other solid dosage form containing reactants may be placed when the drawer 34 is pushed back into the reactant inlet chamber. The lower wall of the drawer has an opening (not shown) large enough to enable the tablet or other dosage form to pass through.

By virtue of the gas-tight seals preventing escape of gas through the first and second reclosable openings when they are in the closed position, the reactant inlet chamber 36 can function as an airlock. When the drawer is in its open position, the second reclosable opening in the floor of the reactant inlet chamber can remain sealed. Once the drawer is pushed back into the reactant inlet chamber and the first reclosable opening is thus resealed, the second reclosable opening may then be opened by releasing the sliding floor panel 40 to allow the reactant tablet to fall into the reaction chamber 50.

In the reaction chamber 50, hydrogen can be generated through the chemical reaction of two or more chemical reactants. The reactants are introduced in dry unit dose form through the reactant inlet chamber 36 as described above. Water (or an aqueous medium) is then introduced into the reaction chamber 50 through the water inlet 26, 22, 18. The water can be clean water or, in the absence of clean water, dirty water (e.g. river water) can be used. The water dissolves or causes the disintegration of the reactant tablet so that either a reactant reacts with water to generate hydrogen gas, or two or more reactants react with each other to generate hydrogen gas. In order to assist disintegration of the reactant tablet, the apparatus can be shaken in the user's hand.

Hydrogen gas generated by the chemical reaction is vented from the container through the gas outlet 20, 24, 28 which, in use, is typically connected to a device such as a fuel cell that uses hydrogen as a fuel. The fuel cell is typically a portable fuel cell such as a proton exchange membrane (PEM) fuel cell.

The quantity of reactant in the unit dosage form is sufficient to provide hydrogen pressures within the reaction chamber 30 of 2-3 bar, which is of the order of magnitude required for a PEM fuel cell. A pressure gauge (not shown) may be provided to enable the user to determine whether a fresh charge of reactant is required.

The chemical reactants are provided in dry unit dose form and the dry unit doses are constructed so that the reactants do not react to generate hydrogen until they come into contact with water. The dry unit doses can contain a single reactant that reacts with water to generate hydrogen or they can contain two or more reactants that react together in water to generate hydrogen.

Where the unit doses contain two reactants, the individual reactants can be presented in separate unit doses or as part of a single integrated unit dose. Where there are more than two reactants, each reactant can be presented in a separate unit dose or two or more of the reactants may be presented in a single integrated dosage form.

The unit doses can take the form of a tablet. In order to prevent premature reaction between the reactants, the reactants can be separated by a barrier material, for example, a water soluble polymeric material. In one embodiment, reactants that might otherwise react in the dry state are separated into layers, with a layer of a barrier material such as a water soluble or water dispersible polymer being interposed between the layers. For example, in one particular embodiment, a tablet may comprise two layers separated by a barrier film of a water-soluble or water- dispersible material, one layer containing a first reactant and the other layer containing a second reactant. In another embodiment, the tablet may comprise a compressed mixture of the reactants in which one or more of the reactants is present in the form of pellets or granules coated with a water-soluble or water dispersible protective coating, for example a water-soluble or water-dispersible polymer.

The reactants may be any one or more chemical entities that react together to form hydrogen. In one embodiment, the reactants are aluminium powder or aluminium pellets or microbeads and an alkali metal hydroxide such as sodium hydroxide.

The reaction used to generate hydrogen is typically an exothermic reaction and high temperatures (e.g. up to about 130°C) are generally produced within the reaction chamber. The container may therefore be insulated to prevent burns to the user during operation. Alternatively, a cooling system may be employed to carry away the heat generated inside the reactor. In one embodiment, the apparatus may comprise an outer container containing a coolant liquid and an inner container within which the reaction takes place.

In the apparatus illustrated in the drawings 1 to 7, a cooling liquid is used to remove heat generated in the reaction chamber 50. The cooling water is held in a void 52 between the outer wall of the inner container 2 and the inner wall of the outer container 2. The cooling water can be introduced into the void through an inlet port (not shown) or it can be introduced into the outer container by removing the cap 10 of the outer container 2. To enable the cap to be removed and replaced, it may be provided with a screw thread (not shown) that engages a mating screw thread (not shown) on the inner surface of the main body portion 6 of the outer container. Where the cap is removable, sealing means such as a sealing gasket (not shown) are provided to give a fluid tight seal between the cap and container body.

The cap is provided on its inner side with a downwardly oriented conical condenser surface 54 which is formed from a thermally conductive but substantially biodegradable plastics material. The condenser surface may be coated with a thin layer of a metal in order to enhance its thermal conductivity. Immediately below the apex of the conical surface is an open-topped collector vessel 56 which is connected via tubing 58 to a clean water outlet 60.

In use, heat generated by the exothermic chemical inside the reaction vessel 50 heats up the water in the void 52, causing it to evaporate. The water vapour condenses on the conical condenser surface 54 and is collected and channelled to the clean water outlet 60. Although a source of clean water may be used to provide the cooling water where such clean water is plentiful, the apparatus of the invention will more usually be used in circumstances where no clean water is available. In such cases, dirty water (e.g. water from a well or river, or other sources such as urine) can be used as the cooling water. The apparatus of the invention can thus be used as a means of purifying water by distillation as well as providing a source of hydrogen.

The apparatus of the invention is preferably formed from materials that are substantially biodegradable making them particularly suitable for single use and disposal. In one embodiment intended for single use, the apparatus may be preloaded with reactants in solid form which are then caused to react by introducing water into the apparatus. In this embodiment, the construction of the apparatus can be simplified by omitting the reactant inlet chamber and drawer arrangement. The apparatus may thus comprise inner and outer containers having inlets for water and outlets for hydrogen, but wherein the inner container is pre-loaded with a charge of reactants in solid dry form. Once the apparatus has been activated by the introduction of water, hydrogen will be generated until the reactants are spent. The apparatus can then be discarded and will decay or degrade over a period of time.

The embodiments described above and illustrated in the accompanying figures and tables are merely illustrative of the invention and are not intended to have any limiting effect. It will readily be apparent that numerous modifications and alterations may be made to the specific embodiments shown without departing from the principles underlying the invention. All such modifications and alterations are intended to be embraced by this application.

Claims

An apparatus for generating hydrogen; the apparatus comprising:

An apparatus according to claim 1 wherein the container has a hollow interior defining a reaction chamber, and is provided with a reactant inlet chamber for receiving solid unit dosage forms comprising one or more reactants capable of reacting in the presence of the liquid co-reactant (e.g. water) to form hydrogen;

wherein the reactant inlet chamber has a first reclosable opening which opens to the container exterior for receiving the solid unit dosage forms; and a second reclosable opening communicating with the reaction chamber through which the solid unit dosage forms can be introduced into the reaction chamber;

wherein at least one of the first and second reclosable openings is provided with a gas tight seal to prevent leakage of hydrogen gas from the reaction chamber

An apparatus according to claim 2 wherein both the first and second reclosable openings are provided with gas-tight seals and hence the reactant inlet chamber functions as an air-lock between the reaction chamber and the container exterior. An apparatus according to claim 3 wherein the first reclosable opening is closed by a closure device that can be opened to receive the solid unit dosage form and then closed to bring the solid unit dosage form into the inlet chamber.

An apparatus according to claim 4 wherein the closure device is a drawer.

An apparatus according to any one of the preceding claims, the apparatus comprising an outer container and, contained therein, an inner container; the inner container having a hollow interior which defines the reaction chamber;

a void for holding cooling water being present between an inner wall of the outer container and an outer wall of the inner container, a cooling water inlet being provided for introducing water into the void;

wherein the reactant inlet chamber extends from within the inner container through the outer container so that the first reclosable opening is accessible from the exterior of the outer container; and wherein the hydrogen gas outlet and water inlet for the reaction chamber extend from the reaction chamber through the outer container and are accessible from the exterior of the outer container.

An apparatus according to claim 6 wherein the outer container is provided with condensate collection means for condensing and collecting evaporated cooling water, the condensate collection means being connected to a clean water outlet mounted in an outer wall of the outer container.

An apparatus according to claim 7 wherein the collection means for condensing and collecting evaporated cooling water takes the form of a sloping condensation surface at an upper end of the outer container, the sloping condensation surface sloping downwardly to a collection point linked to the clean water outlet.

An apparatus according to any one of clams 1 to 7 in combination with a hydrogen fuel cell (e.g. a PEM cell).

An apparatus according to claim 8 which comprises or is connectable to a hydrogen fuel cell (e.g. a PEM cell). An apparatus according to any one of claims 1 to 9 having a minimum dimension (e.g. diameter) of up to 10 cm, for example up to 7 cm or up to 6.5 cm.

An apparatus according to any one of claims 1 to 10 having a weight of no more than 5 kg, for example no more than 4 kg, no more than 3 kg, no more than 2 kg or no more than 1 kg.

A method of generating hydrogen using the apparatus of any one of claims 1 to 10, which method comprises introducing into the reaction chamber one or more reactants in a solid unit dosage form and then introducing water into the reaction chamber to bring about chemical reaction and the generation of hydrogen.

A method according to claim 13 wherein the chemical reaction is exothermic and heat generated by the reaction is used for the purification of water by distillation.

A method of generating hydrogen, the method comprising the steps of: i) providing a container formed predominantly from biodegradable material having a hydrogen gas outlet, the container having a minimum dimension (e.g. diameter) of up to about 10cm so that it can be held in a hand, wherein the container is provided with a layer of thermal insulation and the interior of the container defines a reaction chamber;

iii) introducing an aqueous medium into the reaction chamber;

A method of generating electricity, the method comprising the steps of: i) providing a container formed predominantly from biodegradable material having a hydrogen gas outlet, the container having a minimum dimension (e.g. diameter) of up to about 10cm so that it can be held in a hand, the interior of the container defines a reaction chamber, wherein the container is provided with a layer of thermal insulation and wherein the hydrogen gas outlet is connected or connectable to a hydrogen fuel cell (e.g. a PEM cell); ii) introducing a solid dosage form of a reactant which reacts with water to generate hydrogen into the reaction chamber via an opening in the container;

iv) introducing an aqueous medium into the reaction chamber;

v) drawing off electrical power produced by the hydrogen fuel cell.