MXPA03011759A

MXPA03011759A - Method for storing hydrogen in a hybrid form.

Info

Publication number: MXPA03011759A
Application number: MXPA03011759A
Authority: MX
Inventors: Larochelle Patrick
Original assignee: Hera Hydrogen Storage Systems
Priority date: 2001-06-29
Filing date: 2002-06-28
Publication date: 2005-04-19
Also published as: EP1404611A1; US20030042008A1; JP2004530628A; KR20040012993A; BR0210764A; RU2004101771A; WO2003002451A1; CN1522224A; CA2452067A1

Abstract

A method for storing hydrogen which combines the advantages of at least two known methods for storing hydrogen, selected amongst the methods for storing hydrogen in a gaseous form, in a liquid form and in a solid form. More specifically, the above method consists in coupling and using in a single tank at least two of the methods for storing hydrogen mentioned hereinabove, namely: A) the method for storing hydrogen in a gaseous form; B) the method for storing hydrogen in a liquid form; and C) the method for storing hydrogen in a solid form, in volume or surface, preferably by means of a suitable hybride. The only condition is that each of the above methods be used for storing at least 5% by weight of the total amount of hydrogen to be stored within a tank. Such a method permits to obtain fast release of hydrogen whenever required while ensuring high storage capacities. It also permits to satisfy transitory periods especially during the accelerations of a hydrogen-powered automotive vehicle.

Description

METHOD FOR STORING HYDROGEN IN A HYBRID FORM FIELD OF THE INVENTION The present invention relates to a method for storing hydrogen in a hybrid form. More specifically, this refers to a method for storing hydrogen in two different forms within a single tank. The invention also relates to tanks referred to hereinafter as "hybrid tanks", which are specially adapted to carry out the above method when hydrogen is stored in a liquid form and in solid forms and when Hydrogen is stored in solid and gaseous forms, respectively.

BACKGROUND OF THE INVENTION Methods for storing hydrogen can be classified into three main categories: (A) storage in gaseous state in high-pressure tanks; (B) liquid storage in cryogenic tanks; and (C) solid state storage in tanks containing materials that absorb (by volume) or adsorb (on the surface) hydrogen. The last category listed above as category (C) is one that uses metal hydride storage tanks. Each of the above categories has the advantages and disadvantages that are summarized in the following Table I: TABLE I Characteristics of the different methods for storing hydrogen Sale Method as Disadvantages storage (A) gas • The filling kinetics and • Storage capacity per discharge (seg-min) is very low volume unit and, for very low consequent, the need to use very large tanks • Gas pressure required • Tanks made at very high to have a sufficient quantity of hydrogen materials per unit mixed are of very high volume weight (up to 10,000 psi 690 light bars) • Significant loss of energy due to mechanical compression required to obtain the requested pressure level (15-20%) • Risk of explosion or deflagration due to very high pressure (B) Liquid • Excellent capacity of • Storage evaporation problem by liquid hydrogen (vaporization) volume unit • Significant loss of energy due to the fact that refrigeration is required to reach the required temperatures (30%).

TABLE I (cont.) By way of example, in the case of a method for storing hydrogen in a gaseous form (category A), a one (1) liter tank will contain the following quantities of hydrogen at the various pressures indicated in Table II: TABLE II Storage in gaseous form In the case of a method for storing hydrogen in a liquid form (category B), a one (1) liter tank will contain 0.0708 kg of hydrogen because the density of the liquid hydrogen at -252.8 ° C (ie at the of conventional boiling of hydrogen) is equal to 0.0708 kg / 1. Finally, in the case of a method for storing hydrogen in a solid form with a metal hydride (category C), a one (1) liter tank containing a hydride of the formula AB5 such as LaNi5H6 (density: 6.59 kg / 1, hydrogen storage capacity = 1.4%) occupying the entire volume of the tank, will contain 0.0923 kg of hydrogen, this is almost double the amount of hydrogen stored in a gaseous form in a tank of one liter at 1,035 bars ( 15,000 psig). The results of this comparative example are given in Table III: TABLE III Comparison of the storage capacity of the three basic methods for storing hydrogen Amount of hydrogen stored Method inside a one liter tank (A) storage in gaseous form at 1,035 bars (15,000 0.0512 kg psig) at room temperature (B) storage in liquid form 0.0708 kg at -252.8 ° C (1 bar) (C) storage in solid form in a LaNi5 hydride 0.0923 kg (10 bars) at room temperature Of course, in the case of the method for storing hydrogen in a liquid form (category B), there is always some gaseous hydrogen in equilibrium with the liquid due to some evaporation in the last one. In addition, in the case of the method for storing hydrogen in a solid form with a metal hydride (category C), typically working at low pressure (10 bars), there is some gaseous hydrogen because the hydride never occupies all the space in the tank. Also, in the case of the method for storing hydrogen in a gaseous form at a very high pressure (category A), there is always some hydrogen adsorbed (said hydrogen adsorbed is also called "solid hydrogen" according to the above terminology) on the inner walls of the tank. Therefore, in each method listed above in the present invention (gaseous, liquid and solid), there is always a small amount of hydrogen that is stored in accordance with another storage method. By way of example, the maximum percentage of hydrogen that comes from another storage method can be evaluated in the case of a one liter tank containing a metal hydride powder (LaNi5H6). Assuming that the powder is not compacted and that, therefore, it occupies about half the volume of the tank, that is about half a liter, also considering that the density of LaNi5H6 is equal to 6.59 kg / 1 and assuming that the gaseous hydrogen inside the tank (approximately half a liter) is at a pressure of 10 bars, the amount of hydrogen that is not solid inside the one liter tank will be like that reported in table IV: TABLE IV This example clearly demonstrates that for any given method of storage, there can normally be 1% of hydrogen stored in a different form. However, in all cases, this amount will always be less than 5% by weight. It has already been suggested above that there may be some advantages in coupling different means to store hydrogen within an individual category. By way of example, the patent E.U.A. No. 5,906,792 entitled "Nanocrystalline composite for hydrogen storage" in the name of Applicant and cGill University, describes that there are advantages when combining a low temperature metal hydride with a high temperature metal hydride in contact in the same tank. one with the other. When a mixture as such is used for an internal combustion engine, the low temperature metal hydride allows the cold start of the engine by supplying the hydrogen at startup. When the engine is heated, the heat generated by it allows inducing the desorption of hydrogen from the high temperature metal hydride (see column 3 of this patent E.U.A. No. 5,906,792 for further details). Likewise, the international patent application No. O 01/16021 published in March 2001 in the name of David G. SNOW et al., Describes that there are some advantages in combining storage in solid form in the volume ( absorption) with the storage in solid form on the surface (adsorption) in nanoparticles of a hydride in order to improve, among other things, the kinetics of absorption and desorption of hydrogen. The patent E.U.A. No. 5,872,074 entitled "Leached nanocrystalline materials, process for manufacturing the same and use thereof in the energetic field" in the name of the Applicant, also discloses that the kinetics of hydrogen sorption can be improved when a hydride having a high specific surface area is used. Regardless of the above, it is also known that the method (C) for storing hydrogen in a solid form usually has a response time (loading and unloading) much slower than that of the method (A) for storing hydrogen in a gaseous form and slower than method (B) to store hydrogen in a liquid form. Actually, it takes at least 15 minutes and sometimes more than 1 hour to fill a hydride storage tank. Despite this impediment, the method for storing hydrogen in a solid form has the highest storage capacity per unit volume (see again Table III above in the present invention). It is known that some technical applications require a response time much faster than one minute. Thus, for example, UPS systems (power supply without interruption) that use fuel cells powered by hydrogen normally require a response time of around 100 milliseconds. Of course, a hydrogen storage tank that uses metal hydride can not meet this particular requirement. However, in such a case, a tank in which the hydrogen is stored in a gaseous form at high pressure can be used. Similarly, in vehicles powered by hydrogen, there are different types of transient periods, such as: short-duration accelerations (seconds) which normally require a response time of approximately 100 milliseconds by the propulsion system; and power increases when the vehicle climbs a hill, which can last a few minutes. In hybrid vehicles that use a fuel cell and batteries, the batteries can satisfy the very short accelerations (second) while the transient periods of a longer duration (a few minutes) could require hydrogen stored in a gaseous form. On the other hand, the average power which is about 20 KW for a typical vehicle, could easily be satisfied by a metal hydride tank. The energy contained in the batteries of said vehicle normally represents about 1% of the available energy. Therefore, an amount of hydrogen greater than 1% is needed to face the transitory periods. To summarize, in view of the foregoing, it is evident that there is currently a great need for a method for storing hydrogen that can combine the advantages of the different methods listed above in the present invention.

BRIEF DESCRIPTION OF THE INVENTION OBJECTIVES An objective of the present invention is to satisfy the aforementioned need by providing a novel method for storing hydrogen that combines the advantages of at least two of the aforementioned hydrogen storage methods, specifically the methods for storing hydrogen in a form gaseous, in a liquid form and in a solid form. The present invention basically consists of coupling and using in a single tank, hereinafter called "hybrid tank for storing hydrogen", at least two of the methods for storing hydrogen mentioned above in the present invention, namely : A) the method for storing hydrogen in a gaseous form; B) the method for storing hydrogen in a liquid form; and C) the method for storing hydrogen in a solid form. One condition is that each of the above methods be used to store at least 5% by weight of the total amount of hydrogen inside the tank. More specifically, the invention as claimed later therein, is directed to a method for storing hydrogen in a hybrid form, which comprises the step of coupling and using within a single tank at least two storage means of hydrogen which are selected from the group consisting of: a) means for storing hydrogen in a gaseous form; b) means for storing hydrogen in a liquid form; and c) means for storing hydrogen in a solid form by absorption, with the proviso that: each of the storage means a) through c) that is used is sized to store at least 5% by weight of the total amount of hydrogen stored inside the tank; and when a combination of storage means a) to c) is used, then said means c) consists of a metal hydride having an equilibrium plateau pressure greater than 40 bars at the tank operating temperature. The means mentioned above in the present invention for storing hydrogen in different forms are those commonly used to carry out each of the aforementioned methods. These are very conventional and it is not necessary to describe them further in greater detail. The only requirement is that these can be coupled within the same tank so that they are used simultaneously so that each one stores at least 5% by weight of the hydrogen. Another object of the present invention is to provide a hybrid tank for storing hydrogen in both liquid and solid forms, comprising two concentric containers, one of the containers, hereinafter referred to as the "internal" container located within the other one. , which is referred to hereinafter as the "outer container", the containers are separated by an insulating sheath to keep the inner container at a low temperature. The internal container is used to store hydrogen in a liquid form. The external container is in communication with the internal container. It is not under vacuum and contains a metal hydride to store hydrogen in a solid form. A further object of the present invention is to provide a hybrid tank for storing hydrogen in both solid and gaseous forms, comprising: a container having a metallic liner or inner wall coated with a polymeric outer shell, said container is intended to store hydrogen in a gaseous form at a higher pressure and for receiving and storing a metal hydride for storing hydrogen in a loose form; - at least one heating tube mounted inside the container to allow circulation of a heat carrier fluid; and - a heat exchanger located inside the container in order to ensure the thermal connection between said at least one heating tube and the hydride.

BRIEF DESCRIPTION OF THE FIGURES The invention and the manner in which it is reduced to practice will be better understood after reading the following non-limiting examples provided with reference to the accompanying figures in which: Figure 1 is a diagram illustrating the equilibrium plateau of the hydride used in a hybrid tank for solid-gas storage described in Example 1. Figure 2 is a schematic cross-sectional view of the hybrid tank for solid-liquid storage described in Example 2. Figure 3 is a diagram that illustrates the equilibrium plateau of the hydride used in a hybrid tank for gas-solid storage described in Example 3. Figure 4 is a schematic cross-sectional view of the hybrid tank for solid-gas storage described in Example 3; and Figures 5 and 6 are diagrams showing the equilibrium plateaus of various hydrides as a function of temperature and indicating which could be used in the hybrid tank for solid-gas storage described in Examples 1-3.

EXAMPLE 1 Hybrid storage tank for storing hydrogen in gaseous and solid forms A tank for storage of hydrogen, which has a volume of 1 liter, is filled with a powder of nanoparticles of a LaNi5 hydride having an average diameter of 5 nanometers. The dust occupies 50% of the tank in volume, that is 0.5 liters, because it is not compacted. The number of atoms on the surface of these nanoparticles represents about 28% of the total amount of atoms within each particle, considering a layer of 0.4 to 0.5 nanometers on the surface of each nanoparticle. The tank is then filled with gaseous hydrogen at different pressures ranging from 10 bars (typical use pressure of metal hydride tanks) to 700 bars (typical pressure used in gaseous high pressure tanks). It is considered that the total amount of hydrogen in the volume and surface of the metal hydride corresponds to H / M = 1 (H = hydrogen, M = metal), which is typical for most metal hydrides. Under these conditions, the quantities of hydrogen associated with the two different means of storage used are calculated and reported in the following table V-.

TABLE V It is worth mentioning that in the first case reported in Table V, that is when the pressure is 10 bars (150 psi), the amount of hydrogen in the gas phase represents about 1% of the total amount. This example is illustrative of what is currently obtained in conventional metal hydride tanks and is therefore outside the scope of the present invention. However, in the other three cases reported earlier in the present invention in which the pressures are 248 bars (3,600 psi), 345 bars (5,000 psi) and 690 bars (10,000 psi), the quantities of hydrogen in the gas phase represent about 15%, 19% and 28% respectively of the total amount of hydrogen inside the tank. This is much higher than the 5% limit indicated above in the present invention. The tank described in example 1 is illustrative of a tank that can be used in a "backup" system based on a fuel cell or a hydrogen source generator. In the event of a power failure, the hydrogen in the gas phase initially supplies the fuel cell or generator which is slowly heated. The pressure inside the tank is reduced. When the pressure reaches the hydride equilibrium plateau, ie about 2 bars for an AB5 alloy at room temperature, almost no more hydrogen exists in the gas phase. Then, the hydride is responsible for providing hydrogen to the system thanks to the heat generated by the fuel cell or the generator. It is worth mentioning that, in this example, the equilibrium plateau of LaNi5 which is a conventional low temperature metal hydride (which typically varies between 0 and 100 ° C), is slightly higher than the hydrogen pressure required at the fuel cell inlet, which is typically around 2 bars. If the tank contains 50% by volume of hydride and the rest is occupied with gaseous hydrogen at 690 bar (10, 000 psi), the situation will correspond to that of the diagram provided in figure 1. Under such circumstances, during the operation of the system , the hydrogen comes out first from the gas phase. Then, when the amount of hydrogen and the gas pressure become low, the hydride is responsible for supplying hydrogen to the system. The pressure inside the tank is then maintained at the level of the desorption plateau of the hydride. Therefore the kinetics of the system will be quite high at the beginning (response time of the gas system) and low after this (response time of the hydride system).

There are also other advantages when using said hybrid system that combines the storage of gas and solid. In particular, it can be mentioned: a) the refueling of the tank can be carried out in a short time in comparison with the conventional metal hydride tanks; b) the design of the heat transfer components is simplified; and c) the high volume storage capacity of the metal hydride and the high storage capacity by weight of the novel tanks for high pressure gas storage are combined.

EXAMPLE 2 Hybrid tank to store hydrogen in liquid and solid forms A hybrid tank 1 for storing hydrogen having a total volume of one liter is contemplated from two concentric containers 3, 5 (see Figure 2). The inner container 3 has a volume of 0.8 liters while the outer container 5 has a volume of 0.2 liters. An insulating sheath 7 is placed between the inner and outer containers 3, 5 to keep the inner container 3 at a low temperature. During use, the internal container 3 of tank 1 is filled with liquid hydrogen. It contains around 0.0708 kg / 1 x 0.8 liters = 0.0566 kg of hydrogen. The outer container is filled with a metal hydride powder of the LaNi5H6 type which occupies about 50% of the volume, ie about 0.1 liters. Therefore, external container 5 contains 6.59 kg / 1 x 0.1 liter x 1.4% = 0.0092 kg of hydrogen. The total amount of hydrogen stored in tank 1 equals 0.0658 kg (14% in the external tank and 86% in the internal tank). In comparison with a conventional tank for storing hydrogen in a liquid form, the tank described in example 2 has the advantage of not showing hydrogen loss over a period that could exceed two weeks. In effect, the problem with any tank for conventional liquid hydrogen storage is that the hydrogen evaporates (vaporization). Up to 1% of the amount of liquid hydrogen can be evaporated every day from a conventional tank (1% x 0.0566 kg = 0.0006 kg / day). In the hybrid tank described in example 2, the vaporized hydrogen is absorbed by the metal hydride which extends to the periphery of the inner container and up to its maximum capacity (ie 0.0092 kg / 0.0006 kg / day = 15 days) . It is worth mentioning that the idea of using metal hydrides to "trap" the evaporated hydrogen from a tank for storage of liquid hydrogen had already been suggested, but by means of two separate systems that must be related to each other, connected and controlled independently . In this sense, reference can be made to the patent E.U.A. No. 5,728,483 for SANYO ELECTRIC CO. In contrast, in the present invention, these two different means are combined to store hydrogen within a single tank and therefore operate in a simpler manner.

EXAMPLE 3 Hybrid tank for storing hydrogen in a gas-solid form to be used in a system that has transient periods In the tank described in Example 1, LaNi5HB is used as the hydride. It is known that this compound has a low equilibrium plateau (ie, less than 40 bars) at the operating temperature. Another hydride with a low equilibrium plateau, such as NaAlH4, LiAlH4 or gH2, can also be used. However, in accordance with the invention, it is also possible to use a hydride having an equilibrium plateau which is much higher at the operating temperature (which typically varies between 0 ° and 100 ° C) than the equilibrium plateau of the conventional hydrides (which typically vary between 1 and 10 bars). Said high equilibrium plateau is 40 bars or higher. An example of such hydrides is TiCri.s which has a plateau equilibrium at room temperature much higher than 100 bars (see figure 6). There are also medium temperature hydrides with equilibrium plateau at high pressures, such as TiMn2-y, Hf2Cu, Zr2Pd, TiCu2 or V0.855Cr0.145, which may be of interest for this type of application (see figures 5 and 6). Under these circumstances, when there is a need for hydrogen, the gaseous system of the storage tank will allow to satisfy such need with a very short response time (ti) of approximately one second (for example in the case of a vehicle that accelerates). When the pressure inside the tank drops and changes from a value (1) to a value (2) (see figure 3), the hydride will generate the gaseous system with a shorter response time (t2) of a few minutes, until the next accelerated. This hybrid method makes it possible to substantially simplify the structural components required for heat transfer in order to induce desorption from the hydride or absorption therein. Also, this hybrid method allows, thanks to high pressure, to solve the problem of replenishment of hydrides such as the alanatos (NaAlH4 or LiAlH4). As for the type of hydrides that can be used, reference can be made to figure 5 (hydrides of type AB5) and to figure 6 (hydrides of type AB2) attached to the present invention. As an example of the manner in which this method can be performed, reference can be made to Figure 4 which shows a hybrid tank 11 for storing hydrogen in both solid and gas form. Tank 11 comprises a container having a metallic liner or inner wall 15 coated with an outer polymeric shell 13. This type of container is conventional and is commonly used to store hydrogen in gaseous form at high pressure. This is preferably cylindrical in shape and is provided with an axial opening 17. The lining 15 is usually made of aluminum while the outer shell is made of a mixed material reinforced with carbon fibers. In practice, the hybrid tank container 11 is designed to be used to store hydrogen in gaseous form at a pressure normally greater than 40 bars and to simultaneously receive and store a metal hydride in order to also store hydrogen in solid form. At least one heating tube 19 is mounted inside the container to allow circulation of a heat carrier fluid within the container 11. As shown, the tank 11 preferably comprises only one heating tube 19 which is inserted into the container a through the opening 17 and extends axially therein. The tank 11 also comprises a heat exchanger located inside the container to ensure the thermal connection between the heating tube 19 and the hydride. The heat exchanger preferably consists of at least one metal grid, or of a porous metal structure or fibers 21 which extends transversely within the container and is in direct contact with the axial heating tube 19, the metal lining wall 15 of the container, and the hydride stored inside it. The use of said heating tube and heat exchanger system to operate a metal hydride is already known (see, for example, U.S. Patent No. 6,015,041 issued in the year 2000 in the name of WESTINGHOUSE SAVANNAH RIVE CO.). In the present case, the invention is essentially based on the incorporation of said system in a tank used until now only to store hydrogen in a gaseous form at high pressure in order to benefit from the advantages of both technologies simultaneously.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the content of the following is claimed as property: CLAIMS

1. - A method for storing hydrogen in a hybrid form, characterized in that it comprises coupling and using within a single tank at least two hydrogen storage means which are selected from the group consisting of: a) means for storing hydrogen in a form soda; b) means for storing hydrogen in a liquid form; and c) means for storing hydrogen in a solid form by absorption, with the proviso that: each of the storage means a) through c) that is used is sized to store at least 5% by weight of the total amount of hydrogen stored inside the tank; and when a combination of storage means a) to c) is used, then said means c) consists of a metal hydride having an equilibrium plateau pressure greater than 40 bars at the tank operating temperature.

2. The method according to claim 1, characterized in that: a combination of said storage means a) and e) is used, and said storage means c) consist of a hydride based on Ti or alanate (A1HX).

3. The method according to claim 1, characterized in that: a combination of said storage means b) and e) is used, and said means c) consists of a metal hydride.

4. - A hybrid tank for storing hydrogen in both liquid and solid forms, characterized in that it comprises two concentric containers, one of the containers, hereinafter referred to in the present invention as "internal container" is located within the other, which hereinafter referred to as "outer container" in the present invention, the containers are separated by an insulating sheath to keep the internal container at a low temperature, said internal container is used to store hydrogen in a liquid form, said outer container is in communication with the internal container, which is not under vacuum and contains a metal hydride to store hydrogen in a solid form.

5. - The hybrid tank according to claim 4, characterized in that the hydride used inside the external container is a hydride having low equilibrium plateau pressure at the tank operating temperature.

6. - The hybrid tank according to claim 5, characterized in that the hydride used inside the external container is selected from the group consisting of MaAlH4, LiAlH4, LaNi5H6 and MgH2.

7. - The hybrid tank according to claim 4, characterized in that the hydride within the external container is a hydride having a high equilibrium plateau pressure at the operating temperature of the tank.

8. - The hybrid tank according to claim 7, characterized in that the hydride used inside the external container is selected from the group consisting of TiCri.8, TiMn2-y, Hf2Cu, Zr2Pd, TiCu3 and V0.gB5 0.14S ·

9. - A hybrid tank for storing hydrogen in both solid and gaseous form, characterized in that it comprises: - a container that has a metallic lining or inner wall coated with a polymeric outer shell, said container is intended to store hydrogen in gaseous form at a high pressure and to receive and store a metal hydride to also store hydrogen in solid form; - at least one heating tube mounted inside the container to allow circulation of a heat carrier fluid within said container; and - a heat exchanger located inside the container in order to ensure the thermal connection between said at least one heating tube and the hydride.

10. - The hybrid tank according to claim 9, characterized in that: the container is cylindrical and is provided with an axial opening; the tank comprises only one of said at least one heating tube which is inserted into the container through the opening thereof and extends axially within said container, and - the heat exchanger consists of at least one element which it is selected from the group consisting of metal grid, fibers or porous metallic structure that extends transversely within the container, each of said at least one grid being in direct contact with the axial heating tube, the metal liner of the container and the hydride .

11. - The hybrid tank according to claim 9 or 10, characterized in that the hydride used in the container is a hydride having low equilibrium plateau pressure at the operating temperature of the tank.

12. - The hybrid tank according to claim 11, characterized in that the hydride used in the container is selected from the group consisting of NaAlH, LiAlH, LaNi5H6 and MgH2.

13. - The hybrid tank according to claim 9 or 10, characterized in that the hydride in the container is a hydride having a high equilibrium plateau pressure at the operating temperature of the tank.

14. - The hybrid tank according to claim 13, characterized in that the hydride used in the container is selected from the group consisting of TiCri.8, TiM 2-y, Hf2Cu, Zr2Pd, TiCu3 and Vo.sssCro.ias -