JP2004273164A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably supply a necessary flow of hydrogen to a fuel cell even at low temperatures or even with a sudden increase in load. <P>SOLUTION: A hydrogen storage tank 1 is filled with a hydrogen storage material 5 and a heat exchanger 4 is installed therein. A hydrogen buffer tank 2 and a hydrogen storage tank 1 for storing hydrogen in gas phase are connected in parallel by a three-way pipe 8a and supply hydrogen to the negative electrode 31 of a fuel-cell stack 3 from the three-way pipe 8a via a selector-valve-equipped regulator 10 and a flow controller 7. Fluid discharged from the positive electrode 32 of the fuel-cell stack 3 is fed by a pump 6 to the heat exchanger 4 via a three-way valve 9 to promote the release of hydrogen from the hydrogen storage material 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system using hydrogen stored in a hydrogen storage material, and more particularly to a fuel cell system which is suitable as a power source for automobiles and transportation equipment and has improved hydrogen supply performance at start-up and high load. .
[0002]
[Prior art]
2. Description of the Related Art Fuel cells that electrochemically extract energy by using hydrogen as a clean energy source have been attracting attention in order to solve the increasingly serious global environmental problem. As a hydrogen supply source, a high-pressure hydrogen tank in which hydrogen is compressed and filled at a high pressure, or a hydrogen storage tank containing a hydrogen storage material is generally used.
[0003]
When a high-pressure hydrogen tank is used alone, an ultra-high-pressure hydrogen filling (25 to 70 [MPa]) is required in order to secure an operation time per filling or a cruising distance. Since a filling pressure higher than a generally used cylinder pressure is required, a dedicated pressure-resistant design is required, which increases the cost. Further, since the hydrogen storage amount per unit volume is as small as 0.025 to 0.045 [g / cc], the tank volume is increased.
[0004]
On the other hand, when the hydrogen storage tank is used alone, the responsiveness at the start of the fuel cell and the responsiveness at the time of rapid load rise are slow, and there is a problem in the responsiveness for a vehicle.
[0005]
The hydrogen storage alloy filled in the hydrogen storage tank exhibits an endothermic reaction of 30 to 40 [kJ / molH2] to release of hydrogen. For this reason, when attempting to rapidly extract hydrogen from the hydrogen storage alloy, the temperature of the hydrogen storage tank decreases due to an endothermic reaction, and the hydrogen pressure decreases accordingly. As a result, a sufficient hydrogen supply is not achieved during a rapid load. It becomes possible.
[0006]
In order to improve such responsiveness, for example, there is a proposal of a hydrogen supply method described in Patent Document 1. In this hydrogen supply method, a plurality of hydrogen storage tanks adjacent to each other mainly for the temporary storage of hydrogen generated by a reformer, and the hydrogen once stored in the hydrogen storage tank are released and stored in a hydrogen storage alloy. A plurality of discharge tanks adjacent to each other. Then, control is performed so as to heat another discharge tank by utilizing heat generated when storing hydrogen in a certain discharge tank, and to supply hydrogen released from the heated other discharge tank to the fuel cell.
[0007]
[Patent Document 1]
JP 2001-291524 A (page 4, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, the above-described conventional hydrogen supply method has a problem that a large number of tanks must be provided, the number of tanks increases to four or more, and the control of occlusion / release between the tanks becomes very complicated.
[0009]
Further, hydrogen supplied from a hydrogen supply device is generally sent to a negative electrode of a fuel cell via a regulator and a flow rate controller, but there is considerable pressure loss when passing through these devices. In a hydrogen storage alloy such as LaNi5 which has been conventionally used, the pressure at which hydrogen is released at room temperature is 0.15 [MPa] or less.
[0010]
However, at such a pressure, a sufficient hydrogen supply flow rate cannot be secured due to a pressure loss. In particular, when a high output such as rapid acceleration is required, when the temperature of the hydrogen storage tank is low such as at the time of starting, there is a problem that the hydrogen supply capacity is insufficient.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a hydrogen storage tank filled with a hydrogen storage material capable of absorbing hydrogen and releasing hydrogen, a hydrogen buffer tank storing hydrogen in the gas phase, A fuel cell system comprising: a hydrogen supply pipe that variably supplies hydrogen to a negative electrode of a fuel cell stack from at least one of a hydrogen storage tank and the hydrogen buffer tank.
[0012]
【The invention's effect】
According to the present invention, in addition to the hydrogen storage tank filled with the hydrogen storage material, by using a hydrogen buffer tank for storing gaseous hydrogen, the required hydrogen flow rate can be stably maintained even at low temperatures or during a rapid load increase. There is an effect that it can be supplied to the fuel cell.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described in detail with reference to the drawings.
The present invention is characterized by having a hydrogen storage tank filled with a hydrogen storage material capable of absorbing hydrogen and releasing hydrogen, and a hydrogen buffer tank storing hydrogen in a gaseous phase. Alternatively, by supplying hydrogen to the fuel cell by connecting in series, the required hydrogen flow rate can be supplied to the fuel cell stably even at low temperatures or when the load increases rapidly.
[0014]
Although it is possible to provide a gas phase portion in the hydrogen storage tank and form an integrated tank, in the present invention, a hydrogen storage tank filled with a hydrogen storage material, and a hydrogen buffer tank for storing gaseous hydrogen Is characterized in that
[0015]
The problem with the integrated tank is that the tank has a large capacity and requires large-scale manufacturing equipment. When considering a vehicle, etc., it is conceivable that a large tank is not realized in terms of layout.
[0016]
In general, hydrogen storage material requires an endothermic reaction to release hydrogen, so heat needs to be supplied.However, in a large-capacity tank and a tank in which a gas phase exists, heat loss is large. Not suitable. Further, as the tank size increases, the shape change accompanying the pressure change increases, so that the pressure resistance measures also become large.
[0017]
In the present invention, the hydrogen storage tank and the hydrogen buffer tank are different, but since the adsorbent phase and the gas phase are separated, the size of each tank can be reduced. As the tank becomes smaller, the pressure resistance measures become smaller. Further, the heat exchanger may be provided only in the storage tank. As a result, the size of the tank is smaller than that of the integrated type, and since the hydrogen storage tank has no gas phase, the heat exchange performance is improved.
[0018]
Further, the flexibility of the tank layout is increased by separating the tanks, and the tanks can be freely combined in parallel or in series depending on the way of connecting the pipes. Further, by providing a valve or a check valve in the middle of the pipe for fastening each, the supply from the hydrogen storage tank and the hydrogen buffer tank can be more finely controlled. Is low and it is not possible to supply hydrogen at a high flow rate, it is also possible to supply hydrogen only from the buffer tank.
[0019]
Hydrogen supply to the fuel cell requires flow control according to the load. If the hydrogen pressure at the time of supply to the flow controller is too high, delicate flow control becomes difficult, which is not preferable. Although there is a pressure loss in the flow rate controller, if the pressure is low, the supply may be insufficient when a sudden high load is required. The above problem can be solved by adjusting the secondary pressure of the regulator in the range of 0.5 to 1.2 [MPa].
[0020]
In order to make the secondary pressure of the regulator 0.5 [MPa] or more, it is necessary to make the primary pressure 0.5 MPa or more. The release pressure of the hydrogen storage material is preferably at least 0.5 [MPa] or more. On the other hand, when the discharge pressure exceeds 25 [MPa], if the tank temperature rises, the pressure may be further increased.
[0021]
In order to enable supply of hydrogen from the hydrogen storage tank during cold weather, the hydrogen release pressure of the hydrogen storage material at −30 ° C. is preferably 0.15 [MPa] or more. Considering this, the hydrogen release pressure at −30 ° C. is desirably 5 [MPa] or less.
[0022]
The material used for the hydrogen storage material is an AB5-type hydrogen storage alloy, which is composed of GdNi5, SmNi5, YNi5, CeNi5, SmCo5, NdNi5, PrNi5 alone or a mixture mainly composed of a mixture of these compounds, and -30. The problems of the prior art are solved by using a hydrogen storage alloy containing a substance other than these mixtures, in which the hydrogen release pressure of the hydrogen storage material at [° C.] is in the range of 0.15 to 5 [MPa]. It becomes possible.
[0023]
Further, by using a carbon-based material capable of storing hydrogen, such as activated carbon, carbon nanotubes, graphite, and graphite intercalation compounds, as a hydrogen storage material, it is possible to solve the problems of the conventional technology.
[0024]
[Embodiment 1]
FIG. 1 is a configuration diagram illustrating a configuration of a first embodiment of a fuel cell system according to the present invention. In FIG. 1, a fuel cell system includes a hydrogen storage tank 1 filled with a hydrogen storage material 5, a hydrogen buffer tank 2 for storing gaseous hydrogen, a fuel cell stack 3, and heat exchange installed in the hydrogen storage tank 1. Pump 4, a pump 6 for sending exhaust gas and / or hot water discharged from the positive electrode 32 of the fuel cell stack 3 to the heat exchanger 4, a three-way pipe 8a connecting the hydrogen storage tank 1 and the hydrogen buffer tank 2 in parallel, A regulator 10 with an on-off valve for adjusting the pressure of hydrogen supplied from the pipe 8a, and a flow controller 7 for controlling a flow rate of hydrogen supplied from the on-off regulator 10 to the negative electrode 31 of the fuel cell stack 3 are provided.
[0025]
The filling of hydrogen in the hydrogen storage system is performed using a pipe a. In the present embodiment, the pipe a is connected to the hydrogen storage tank 1. The hydrogen storage tank 1 is connected to the three-way pipe 8a by a pipe b, and the hydrogen buffer tank 2 is connected to the three-way pipe 8a by a pipe c. Thereby, the hydrogen storage tank 1 and the hydrogen buffer tank 2 are connected in parallel, and hydrogen is supplied to the negative electrode 31 of the fuel cell stack 3 via the pipe d also connected to the three-way pipe 8a.
[0026]
A primary pressure gauge 11 is provided in the middle of the pipe b, and a primary pressure gauge 21 and a buffer tank opening / closing valve 20 are provided in the middle of the pipe c.
[0027]
A regulator 10 with an on-off valve and a secondary pressure gauge 22 are installed in the middle of the pipe d. A flow controller 7 is installed in the pipe d, and controls the flow rate of hydrogen supplied to the negative electrode 31 of the fuel cell stack 3.
[0028]
At the negative electrode 31 of the fuel cell stack 3, the supplied hydrogen is dissociated into hydrogen ions and electrons by the electrode catalyst. Hydrogen ions diffuse through the electrolyte 33 toward the positive electrode 32, and electrons reach the positive electrode 32 through an external circuit.
[0029]
Air is supplied to the positive electrode 32 of the fuel cell stack 3 from an air supply device (not shown) at a pressure corresponding to the hydrogen pressure of the negative electrode 31. In the positive electrode 32, water is generated from oxygen in the air, hydrogen ions diffused through the electrolyte 33, and electrons that have reached the positive electrode 32 through an external circuit, and heat of chemical reaction is released. Then, a fluid containing nitrogen in the air, unconsumed oxygen, and generated water (steam or hot water) is discharged from the positive electrode 32.
[0030]
Exhaust gas and / or hot water, which are fluids discharged from the positive electrode 32 of the fuel cell stack 3, are sent to the three-way valve 9 by the pump 6 via the pipe e. When promoting the supply of hydrogen, the three-way valve 9 is opened to the hydrogen storage tank 1 side, and the exhaust gas / hot water is introduced into the heat exchanger 4 to be used for raising the temperature of the hydrogen storage tank 1. The water cooled by the heat exchanger 4 passes through the three-way pipe 8b and is discharged out of the drawing from the pipe f. On the other hand, when it is not necessary to promote the supply of hydrogen, the three-way valve 9 is opened to the three-way pipe 8b and discharged from the pipe f as it is.
[0031]
Next, an example behavior at the time of starting the fuel cell according to the present embodiment will be described.
Assuming that the steady output of the fuel cell is 6 [kW], the required hydrogen flow rate required by the fuel cell stack 3 was examined at 67.2 [L / min].
[0032]
The hydrogen storage tank 1 used had a hydrogen storage amount of 1 [m3] when fully filled, and an NdNi5 alloy was used as a hydrogen storage material. The initial filling state was 1.2 [wt%] of hydrogen filling with respect to the alloy weight, and the hydrogen storage tank temperature was 20 [° C]. FIG. 2 shows a PCT curve when the NdNi5 alloy was used. The internal volume of the buffer tank was 10 L, and the secondary pressure of the regulator 10 was 0.5 [MPa].
[0033]
[Comparative Example 1]
In Comparative Example 1, a system configuration similar to that of Embodiment 1 was used, but LaNi5, which has been widely used, was used as the hydrogen storage material. The initial filling state was 1.2 [wt%] of hydrogen filling with respect to the alloy weight, and the hydrogen storage tank temperature was 20 [° C]. FIG. 3 shows a PCT curve in the case of using LaNi5. The internal volume of the buffer tank was 10 L, and the secondary pressure of the regulator 10 was 0.5 [MPa].
[0034]
FIG. 4 shows the change over time in the hydrogen supply flow rate when the embodiment 1 (NdNi5) and the comparative example 1 (LaNi5) are used. The hydrogen release pressure of NdNi5 at 20 [° C] exceeds 1 [MPa] in a hydrogen absorption state of 1.2 [wt%]. Since the secondary pressure of the regulator 10 can be maintained at 0.5 [MPa] without any problem, it is possible to maintain a flow rate of 67.2 [L / min].
[0035]
On the other hand, in the case of LaNi5, the hydrogen release pressure at 20 [° C] is 0.15 [MPa]. It is impossible for the secondary pressure of the regulator 10 to secure the set value of 0.5 [MPa]. Although the flow rate of 67.2 [L / min] is secured instantaneously immediately after the start due to the hydrogen gas remaining in the pipe, the flow rate decreases immediately thereafter, and only about 20 [L / min] can be supplied. There was found. Also in the case of LaNi5, if the temperature of the hydrogen storage tank rises to 60 [° C.] by receiving waste heat from the fuel cell, the pressure of the system also increases, and the secondary pressure also becomes 0.5 [MPa] or more, which is 67.2. [L / min] can be supplied, but it takes time until the supply becomes possible.
[0036]
In the first embodiment, NdNi5 was used as the hydrogen storage material. However, the use of the following compound having a hydrogen release pressure of 0.5 [MPa] or more at 20 [° C.] can also be performed stably from the start. 0.2 [L / min] can be secured.
[0037]
PrNi 5: 1 [MPa], YCo 5: 2 [MPa], SmCo 5: 4 [MPa], CeNi 5: 7 [MPa], YNi 5:10 [MPa], SmNi 5:10 [MPa], GdNi 5:11 [MPa].
[0038]
Further, as the hydrogen storage material, a carbon-based hydrogen storage material capable of storing hydrogen, such as activated carbon, carbon nanotubes, graphite, and graphite intercalation compounds, can be used.
[0039]
[Embodiment 2]
In the second embodiment, a case where a sudden load is applied to the fuel cell system shown in FIG. 1 will be described. As a condition, a rapid output of 30 [kW] is taken out from 20 seconds to 40 seconds after the fuel cell continues to be in a stable state with a steady output of 6 [kW]. The case of returning to 6 [kW] will be described. The hydrogen flow rate required for an output of 30 [kW] of the fuel cell was 336 [L / min].
[0040]
NdNi5 was used as the hydrogen storage material, the initial condition was 1.2 [wt%] adsorption state, and the temperature of the hydrogen storage tank was 40 [° C] assuming that the warm-up operation was completed. did.
[0041]
[Comparative Example 2]
In Comparative Example 2, the hydrogen buffer tank 2 was removed from the configuration in FIG. 1 as shown in FIG. 5, and the other conditions were exactly the same as those in Embodiment 2.
[0042]
FIG. 6 shows a change in the flow rate in the second embodiment and the comparative example 2.
In Comparative Example 2, although a flow rate of 336 [L / min] was once secured, it immediately dropped to about 200 [L / min], and it was found that the flow rate as controlled could not be secured. In this method, a flow rate of 336 [L / min] can be obtained temporarily by the hydrogen staying in the pipe, but the subsequent supply is performed only by extracting hydrogen from the hydrogen storage tank. Indicates that you cannot catch up. It is considered that the reason is that it takes time to start the chemical reaction, and that the temperature of the hydrogen storage material decreases due to rapid removal of hydrogen.
[0043]
On the other hand, in the second embodiment, it can be seen that the control is performed from 67.2 [L / min] to 336 [L / min] after 20 seconds as controlled. It is confirmed that the above problem is solved by the presence of the hydrogen buffer tank 2 supplementing the hydrogen that is temporarily in short supply from the hydrogen storage tank 1 with the presence of the hydrogen stored in the hydrogen buffer tank 2. Was done.
[0044]
[Embodiment 3]
In the third embodiment, the behavior at the time of starting at 0 [° C.] in the fuel cell system shown in FIG. 1 will be described.
[0045]
As a condition, assuming that the steady output of the fuel cell is 6 [kW], the required hydrogen flow rate required by the fuel cell stack is 67.2 [L / min]. Was set to 1 [m3], and an NdNi5 alloy was used as a hydrogen storage material. The initial filling state was hydrogen filling of 1.2 [wt%] with respect to the alloy weight, and the hydrogen storage tank temperature was 0 [° C].
[0046]
[Comparative Example 3]
In Comparative Example 3, the fuel cell system configuration shown in FIG. 5 was used as an example in which the buffer was removed, and other conditions were the same as those in Embodiment 3.
[0047]
FIG. 7 shows a change in the hydrogen flow rate in the third embodiment and the comparative example 3.
The hydrogen release pressure at 0 [° C.] of NdNi5 exceeds 0.8 [MPa] in a state of absorbing 1.2 [wt%] of hydrogen. Although the secondary pressure of the regulator 10 can be maintained at 0.5 [MPa], the flow rate is reduced in Comparative Example 3 having no hydrogen buffer tank.
[0048]
This is presumably because the temperature of the hydrogen storage material decreased due to the removal of hydrogen, and the pressure decreased. The reason why the flow rate recovers after 30 seconds is presumed to be that the heat exchanger 4 is heated by the waste heat of the fluid discharged from the positive electrode 32 of the fuel cell stack 3 and the temperature of the hydrogen storage tank 1 gradually increases. Is done. By attaching the hydrogen buffer tank 2, even at 0 [° C.], hydrogen can be supplied without any problem, and the above problem can be solved.
[0049]
[Embodiment 4]
In the fourth embodiment, a case where the fuel cell system is started at −30 ° C. will be described. In the fourth embodiment, as shown in FIG. 8, a case will be described in which a backflow prevention valve 13 for preventing backflow of hydrogen from the hydrogen buffer tank 2 to the hydrogen storage tank 1 is attached to the pipe b. Other configurations are the same as those in FIG.
[0050]
As initial conditions, the system was shut down while operating at a tank temperature of 60 ° C. using NdNi 5 as a hydrogen storage material, and the system pressure was maintained at 4 [MPa] by a check valve 13. Thereafter, the system was lowered to -30 [° C]. As a condition at the time of starting, assuming that the steady output of the fuel cell is 6 [kW], a required hydrogen flow rate required by the fuel cell stack is supplied at 67.2 [L / min].
[0051]
[Comparative Example 4]
In comparison with the fourth embodiment, a case where the check valve 13 is not used is referred to as a comparative example 4.
In Comparative Example 4, since there is no check valve, the hydrogen release pressure is reduced to 0.2 [MPa] by lowering to −30 [° C.]. Accordingly, the pressure of the hydrogen buffer tank also becomes 0.2 [MPa].
[0052]
FIG. 9 shows a change in the hydrogen flow rate in the fourth embodiment and the comparative example 4.
In Comparative Example 4, the pressure of the system was as low as 0.2 [MPa], and it was not possible to secure the set value of the regulator 10 of 0.5 [MPa]. Although a flow rate of 67.2 [L / min] was secured instantaneously immediately after the start, it was found that the flow rate decreased immediately thereafter, and only about 20 [L / min] could be supplied.
[0053]
On the other hand, in Embodiment 4 in which the check valve 13 is attached, since the pressure 3 [MPa] at the temperature 60 [° C.] at the end of the operation is maintained, the secondary side pressure of the regulator 10 is 0.5. [MPa] can be secured, and a hydrogen flow rate of 67.2 [L / min] can be obtained. Since the hydrogen in the hydrogen buffer tank 2 is consumed, the pressure of the system gradually decreases for a while, but the heat exchanger 4 is gradually heated by the waste heat of the fluid discharged from the positive electrode 32 of the fuel cell stack 3. Then, the temperature of the hydrogen storage tank 1 rises, the tank pressure also rises, and hydrogen supply from the hydrogen storage tank 1 becomes possible.
[0054]
By determining the size of the capacity of the hydrogen buffer tank 2 by calculating the hydrogen consumption required for the warm-up operation of the fuel cell system at extremely low temperatures, it is possible to avoid shortage of hydrogen supply at the time of startup.
[0055]
FIGS. 10 and 11 show the tank installation methods of Embodiments 1 to 4 described above. The hydrogen buffer tank 2 may be arranged in parallel on the hydrogen storage tank 1 as shown in FIG. 10, or the hydrogen buffer tank 2 may be arranged upright as shown in FIG. These tank arrangements can be selected according to the layout requirements of the system.
[0056]
[Embodiment 5]
As a method of connecting the hydrogen storage tank and the hydrogen buffer tank, in addition to the method of connecting them in parallel as shown in the above-described first to fourth embodiments, they can also be connected in series as shown in the fifth embodiment. 12 and 13, the hydrogen buffer tank 2 has two openings, one of which is connected to the hydrogen storage tank 1, and the other of which is connected to a pipe d which is connected to the negative electrode 31 of the fuel cell stack 3. It is connected. The other components are the same as those of the first embodiment shown in FIG. 1, and therefore, the same components are denoted by the same reference numerals, and overlapping description will be omitted. In this embodiment, the same effects as those described in the above embodiment can be obtained.
[0057]
The hydrogen storage tank 1 and the hydrogen buffer tank 2 may be arranged in parallel as shown in FIG. 12, or the hydrogen buffer tank 2 may be arranged upright as shown in FIG. These tank arrangements can be selected according to the layout requirements of the system.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram illustrating a configuration of a fuel cell system according to a first embodiment of the present invention.
FIG. 2 is a view showing a hydrogen release curve of NdNi5 used in Embodiment 1.
FIG. 3 is a diagram showing a hydrogen release curve of LaNi5 used in Comparative Example 1.
FIG. 4 is a diagram showing hydrogen supply flow rate curves of Embodiment 1 and Comparative Example 1.
FIG. 5 is a diagram illustrating a system configuration of Comparative Example 2.
FIG. 6 is a diagram showing a hydrogen supply flow rate curve of Embodiment 2 and Comparative Example 2.
FIG. 7 is a diagram showing hydrogen supply flow rate curves of Embodiment 3 and Comparative Example 3.
FIG. 8 is a system configuration diagram illustrating a configuration of a fourth embodiment of the fuel cell system according to the present invention.
FIG. 9 is a diagram showing a hydrogen supply flow rate curve of Embodiment 4 and Comparative Example 4.
FIG. 10 is a configuration diagram illustrating an example of a tank layout in a parallel configuration.
FIG. 11 is a configuration diagram illustrating an example of a tank layout having a parallel configuration.
FIG. 12 is a configuration diagram illustrating an example of a tank layout of a series configuration according to a fifth embodiment.
FIG. 13 is a configuration diagram illustrating an example of a tank layout of a series configuration according to a fifth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Hydrogen storage tank 2 ... Hydrogen buffer tank 3 ... Fuel cell stack 4 ... Heat exchanger 5 ... Hydrogen storage material 6 ... Pump 7 ... Flow controller 8a, 8b ... Three-way pipe 9 ... Three-way valve 10 ... Regulator 11 ... Primary pressure 13: check valve 20: buffer tank opening / closing valve 21: primary pressure gauge 22: secondary pressure gauge 31: negative electrode 32: positive electrode 33: electrolyte

Claims (11)

A hydrogen storage tank filled with a hydrogen storage material capable of absorbing hydrogen and releasing hydrogen,
A hydrogen buffer tank for storing gaseous hydrogen,
A hydrogen supply pipe that variably supplies hydrogen to the negative electrode of the fuel cell stack from both or one of the hydrogen storage tank and the hydrogen buffer tank,
A fuel cell system comprising: The hydrogen supply pipe,
A three-way pipe that connects the hydrogen storage tank and the hydrogen buffer tank in parallel, and variably supplies hydrogen to the negative electrode of the fuel cell stack from both or one of these tanks,
A regulator and a flow controller arranged from the three-way tube to the negative electrode,
The fuel cell system according to claim 1, further comprising: A regulator disposed on each of the pipes connecting the three-way pipe with the hydrogen storage tank and the hydrogen buffer tank;
A flow controller disposed in the pipe from the three-way pipe to the fuel cell anode,
The fuel cell system according to claim 2, further comprising: The hydrogen buffer tank is a buffer tank that can be connected in series with two openings,
A pipe connecting one opening of the hydrogen buffer tank and the hydrogen storage tank, a pipe connecting the other opening of the hydrogen buffer tank and the negative electrode of the fuel cell stack,
A regulator and a flow controller arranged in a pipe extending from the other opening of the hydrogen buffer tank to the negative electrode,
The fuel cell system according to claim 1, further comprising: A heat exchanger disposed in the hydrogen storage tank;
A pipe that communicates the heat exchanger with the positive electrode outlet of the fuel cell,
The fuel cell according to any one of claims 1 to 4, wherein a fluid discharged from a positive electrode of the fuel cell is supplied to the heat exchanger to promote the generation of hydrogen from the hydrogen storage tank. system. The fuel cell system according to any one of claims 1 to 5, further comprising a check valve for preventing backflow of hydrogen from the hydrogen buffer tank to the hydrogen storage tank. 7. The hydrogen flow rate is adjusted by a flow rate controller after the secondary pressure of the regulator for adjusting the supply pressure of hydrogen is adjusted in the range of 0.5 to 1.2 [MPa]. The fuel cell system according to claim 1. The fuel cell system according to any one of claims 1 to 7, wherein a hydrogen release pressure of the hydrogen storage material at normal temperature is in a range of 0.5 to 25.0 [MPa]. The fuel cell system according to any one of claims 1 to 8, wherein a hydrogen release pressure of the hydrogen storage material at -30 [° C] is in a range of 0.15 to 5 [MPa]. . The hydrogen-absorbing material is an AB5-type hydrogen-absorbing alloy, and has a composition containing, as a main component, any one of GdNi5, SmNi5, YNi5, CeNi5, SmCo5, NdNi5, and PrNi5, or a mixture of these compounds. The fuel cell system according to any one of claims 1 to 9, wherein: The fuel cell according to any one of claims 1 to 9, wherein the hydrogen storage material is a carbon-based material capable of storing hydrogen, such as activated carbon, carbon nanotubes, graphite, and graphite intercalation compounds. system.

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