JP2017157420A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce many additional facilities although, when a device for supplying hydrogen to a secondary battery utilizing a hydrogen gas as a large-scaled system, it is necessary to connect facilities via long-distance common hydrogen piping and measures to deal with hydrogen leakage such as double piping covering a long distance or many additional facilities such as hydrogen detectors at intervals of a fixed distance and a gas supply cutdown system interconnected therewith may be required.SOLUTION: A power storage system comprises: multiple power storage devices 1 each configured to use a hydrogen gas in the case of discharge and to generate a hydrogen gas in the case of charge; circulation type common anode gas piping 5 for circulating an incombustible common anode gas which is obtained by mixing an inert gas with the hydrogen gas, in one direction; anode gas inlet piping 2 each for supplying the common anode gas which is diverted from the common anode gas piping, to each of the multiple power storage devices; and anode gas outlet piping 4 each for making the common anode gas which is discharged from each of the multiple power storage device, confluent into the common anode gas piping.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage system using a secondary battery in which hydrogen gas is consumed during discharging and hydrogen gas is generated during charging.

A secondary battery in which hydrogen gas is consumed at the negative electrode during discharge and hydrogen gas is generated at the negative electrode during charging is generally known. For example, a regenerative fuel cell such as a redox flow is known. In such a secondary battery using hydrogen gas, a mechanism for supplying hydrogen to the secondary battery and recovering the generated hydrogen gas is required. Patent Document 1 proposes a regenerative fuel cell in which hydrogen gas is circulated in the negative electrode and a positive electrode electrolyte in which metal ions are dissolved in the positive electrode is supplied. In Patent Document 2, the generated hydrogen gas is separated. And a mechanism for supplying hydrogen gas from the tank to the secondary battery during discharge is disclosed.

  Such a secondary battery is provided in the power generation system and used to charge the power generated by the power generation device. For example, in a system such as a solar cell system that can generate electricity only in the daytime, it is conceivable to charge the secondary battery with daytime electricity. In addition, a mechanism for charging the secondary battery once and then supplying the power from the secondary battery, such as charging nighttime power from a general power network (hereinafter referred to as a system), is also common.

  By the way, when supplying hydrogen gas to a secondary battery using hydrogen gas, hydrogen gas has an extremely wide explosion range of 4 to 75% by volume with respect to air, and measures against hydrogen leakage are required. Thus, for example, Patent Document 3 discloses that a pipe for supplying hydrogen is a double pipe. Non-Patent Document 1 discloses that an inactive gas is mixed with a combustible gas to narrow the combustion range of the combustible gas.

Special table 2015-503834 gazette JP 2003-1778738 A JP2013-245741A

Nao Saito, “Combustion range of fuel / air / inert gas mixture and adiabatic fire temperature-Estimation of combustion range”, Report of Fire Research Institute, No. 78, pages 7-14, September 1994 (Fig. 4) )

  When using a mechanism to supply hydrogen to a secondary battery using hydrogen gas as a large-scale system, it is necessary to connect it with a common hydrogen pipe with a long distance, and measures against hydrogen leakage such as a double pipe over a long distance In addition, there is a problem that a lot of additional equipment such as a hydrogen detector for every fixed distance and a gas supply shut-off system linked with the hydrogen detector are required. An object of the present invention is to solve such problems.

In order to solve the above-described problems, the present invention provides a plurality of power storage devices that use hydrogen gas when discharging and generate hydrogen gas when charging, and non-combustible materials obtained by mixing hydrogen gas with an inert gas. A common negative gas pipe that circulates the common negative gas in one direction, a negative gas inlet pipe that supplies the common negative gas branched from the common negative gas pipe to each of the plurality of power storage devices, and a plurality of And a negative electrode outlet pipe for joining the common negative gas discharged from each of the power storage devices to the common negative gas pipe.

When a mechanism for supplying hydrogen gas to a secondary battery using hydrogen gas is to be used as a large-scale system, there is an effect that additional equipment can be largely omitted.

It is a schematic diagram of the daytime of the electric power storage system which concerns on Embodiment 1 of this invention. It is a schematic diagram at night of the electric power storage system which concerns on Embodiment 1 of this invention. It is an enlarged view of the electric power storage device part of the daytime schematic diagram of the electric power storage system which concerns on Embodiment 1 of this invention. It is an enlarged view of the electric power storage device part of the schematic diagram at night of the electric power storage system which concerns on Embodiment 1 of this invention. It is a schematic diagram of the daytime of the electric power storage system which concerns on Embodiment 2 of this invention. It is an enlarged view of the fuel cell part connected to the electric power storage system which concerns on Embodiment 3 of this invention. It is an enlarged view of the fuel cell part connected to the electric power storage system which concerns on Embodiment 4 of this invention. It is an enlarged view of the water electrolyzer part connected to the electric power storage system which concerns on Embodiment 5 of this invention. It is an enlarged view of the water electrolyzer part connected to the electric power storage system which concerns on Embodiment 6 of this invention.

  Hereinafter, preferred embodiments of a power storage system of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for explaining the daytime operation of the power storage system according to Embodiment 1 of the present invention, and FIG. 2 is a schematic diagram for explaining the nighttime operation. In FIG. 1, a power storage device 1 refers to a regenerative fuel cell that is a secondary battery that uses hydrogen when generating and discharging hydrogen when charging power. In FIG. 1, the power storage device 1 has a positive electrode charging liquid tank 15 for storing the positive electrode charging liquid, a positive electrode discharging liquid tank 16 for storing the positive electrode discharging liquid, and a range surrounded by a dotted line inside the negative electrode and the positive electrode. Say.

The common negative electrode gas pipe 5 is a circulation type pipe that circulates a common negative electrode gas of a mixed gas obtained by mixing hydrogen gas with an inert gas in one direction. The common negative gas in the common negative gas pipe 5 is circulated by a pump 8, and the hydrogen concentration in the common negative gas pipe 5 is monitored by a hydrogen concentration monitor 17. The negative gas inlet pipe 2 is a pipe that supplies the common negative gas from the common negative gas pipe 5 to the power storage device 1. The common negative gas is drawn into the power storage device 1 by the pump 3 in the negative gas inlet pipe 2. The negative electrode gas outlet pipe 4 is a pipe for recovering the common negative gas in which hydrogen is used in the power storage device 1 or the hydrogen gas generated in the power storage device 1 from the power storage device 1 to the common negative gas pipe 5.

The pressure regulator 7 supplies the common negative gas from the common negative gas storage tank 6 that stores the common negative gas when the pressure of the common negative gas in the common negative gas pipe 5 decreases, and the common negative gas The pressure in the pipe 5 is adjusted. The common negative gas storage tank 6 is protected by a partition wall 9. In the power generation area 10, the power storage device 1 is charged from, for example, the solar battery 13. In the power consumption area 11, the power storage device 1 discharges and supplies power to the power demand section such as the apartment 14. Here, the power demand section is not limited to the apartment 14 and may be a facility that consumes power, such as an office building, and refers to a place where there is a demand for power. The system 12 refers to a general power network. In the case of nighttime as shown in FIG. 2, in the power consumption area 11, the power of the grid 12 is generally cheap at night, and it is conceivable to charge the power storage device 1 using this power. In the power generation area 10, power is supplied to the grid 12 from the power storage device 1 charged with the solar cell 13 in the daytime.

  In the power storage system of FIGS. 1 and 2, two power storage devices 1 are connected to a common negative gas pipe 5, and are connected to a common negative gas storage tank 6 through a pressure regulator 7. In the present embodiment, the number is two, but the number is not limited to this, and the number is not limited. Since a plurality of power storage devices 1 are connected to the common negative electrode gas pipe 5, it is not necessary for each power storage device 1 to have a negative electrode gas storage tank 6, and the negative electrode gas is collectively put into the common negative electrode gas storage tank 6. The pressure can be stored and the pressure of the common negative gas in the common negative gas pipe 5 can be kept constant by the pressure regulator 7, and an effect of being compact can be obtained. The pressure of the common negative electrode gas is kept at 0.2 MPa in absolute pressure. The common negative electrode gas refers to a gas in which hydrogen gas and inert gas used in the electricity storage device 1 are mixed. An inert gas refers to a gas such as nitrogen or carbon dioxide that can be made into a non-flammable inert gas by mixing with a flammable hydrogen gas. The common negative gas storage tank 6 is a tank that stores the common negative gas, and keeps the pressure of the common negative gas in the common negative gas pipe 5 constant.

  In the power generation area 10 of FIG. 1, the power storage device 1 connected to the solar cell 13 stores the power generated by the solar cell 13 during the daytime. That is, the solar cell 13 charges the power storage device 1. At that time, hydrogen gas is generated on the negative electrode side of the power storage device 1, and the generated hydrogen gas is joined to the common negative gas pipe 5 via the negative gas outlet pipe 4, and the common negative gas is supplied via the common negative gas pipe 5. It is stored in the storage tank 6. On the other hand, the power storage device 1 in the power consumption area 11 connected to the apartment 14 or the like discharges according to the power consumption in the apartment 14 or the like. At that time, hydrogen gas is consumed. If the amount of hydrogen generated by the power generated by the solar cell 13 is the same as the amount of hydrogen consumed by the power consumption in the apartment 14 or the like, the hydrogen gas is supplied via the pressure regulator 7 to the common negative electrode gas storage tank 6. Therefore, the pressure of the common negative gas in the common negative gas pipe 5 is kept constant. That is, by consuming the hydrogen gas generated in the power storage device 1 connected to the solar cell 13 by the power consumption in the apartment 14 or the like, the trouble of storing in the common negative electrode gas storage tank 6 via the pressure regulator 7 or Electric power can be omitted. In the present embodiment, the electric power generated by the solar cell 13 is charged. However, the present invention is not limited to this, and the electric power from the power generator or the electric power from the system 12 may be charged. Here, the power storage device 1 refers to a secondary battery such as a regenerative fuel cell, but is not limited to this term as long as it can store power.

  In FIG. 2, at night, the power storage device 1 connected to the apartment 14 or the like is charged with midnight power with a low unit price from the system 12, and hydrogen gas is generated at that time. The generated hydrogen gas is stored in the common negative electrode gas storage tank 6. On the other hand, the power storage device 1 connected to the solar cell 13 discharges the power stored in the power storage device 1. If the amount of hydrogen generated when the power storage device 1 is charged with midnight power and the amount of hydrogen consumed when the power stored in the power storage device 1 is discharged are the same, the hydrogen gas is a pressure regulator. It is not necessary to store in the common negative electrode gas storage tank 6 via 7, and the hydrogen pressure in the common negative electrode gas pipe 5 is kept constant. That is, the pressure regulator 7 is consumed by consuming the hydrogen gas generated when the power storage device 1 connected to the apartment 14 or the like is charged with cheap late-night power by the discharge of the power storage device 1 connected to the solar cell 13. The labor and electric power stored in the common negative electrode gas storage tank 6 can be omitted.

  As described above, according to the power storage system of the first embodiment, the plurality of power storage devices 1 are connected to the common negative electrode gas pipe 5 via the negative gas inlet pipe 2 and the negative gas outlet pipe 4, and the power By consuming the hydrogen gas generated in the storage device 1 in another power storage device 1 at a distance, the labor and power stored in the common negative gas storage tank 6 via the pressure regulator 7 can be omitted. . Since hydrogen is generated from the power storage device 1 to be charged and the power storage device 1 to be discharged uses hydrogen, hydrogen gas generated from the power storage device 1 to be charged and the amount of hydrogen used by the power storage device 1 to be discharged Is balanced, the amount of hydrogen gas in the common negative gas pipe 5 can be balanced. Further, by storing surplus hydrogen gas in the common negative electrode gas storage tank 6, it is possible to adjust the imbalance between hydrogen gas generation and hydrogen gas consumption in each power storage device 1.

  Furthermore, the hydrogen gas is stored in a safer place by placing the common negative electrode gas storage tank 6 far from the power storage device 1 connected to the solar cell 13 or the power storage device 1 connected to the apartment 14 or the like. In the unlikely event of an accident such as hydrogen gas leakage, it is possible to minimize the influence on the apartment 14 and the like.

  In the power storage system of the first embodiment, when the common negative gas pipe 5 is lengthened, the greatest practical issue is ensuring the safety of the common negative gas pipe 5. As is well known, the hydrogen gas contained in the common negative electrode gas has an explosive range of 4% to 75% in volume% with respect to air, and measures against hydrogen gas leakage, hydrogen detectors, and alarm equipment are required as additional equipment. It becomes. And for long-distance piping, it is practical to use under the road due to infrastructure restrictions, and it is necessary to lay it in a common groove such as electricity or city gas.

  Therefore, in the power storage system according to the first embodiment of the present invention, the common negative gas is circulated inside the power storage device 1 and connected to the common negative gas pipe 5 that circulates the common negative gas in one direction. The pipe 5 was mixed with an inert gas, nitrogen, and filled with a mixed gas that had a volume ratio of 92% nitrogen (N2) and 8% hydrogen (H2).

  The explosive range of hydrogen gas is extremely wide as 4 to 75% by volume% with respect to air, but the explosive range is greatly narrowed by a ternary system of nitrogen, air and hydrogen gas. FIG. 4 of Non-Patent Document 1 shows a combustion range (estimated value) and an actual measurement value in a three-component system of nitrogen, air, and hydrogen gas. When 70% of nitrogen is added, the actual value indicates combustion. In fact, the estimated value shows that the combustion range is substantially zero. Since the lower limit of the hydrogen gas explosion range at this time is 6% in absolute volume ratio, if the mixing ratio of nitrogen and hydrogen gas, excluding air, is 70: 6 = 92: 8, it will leak into the air. It turns out that it becomes nonflammable even if it does not burn at all. Here, the inert gas is nitrogen, but the present invention is not limited to this, and any inert gas may be used so long as it does not explode hydrogen gas. For example, carbon dioxide as described below may be used, or a mixed gas may be used.

FIG. 4 of Non-Patent Document 1 also shows a combustion range (estimated value) and an actual measurement value in a ternary system of carbon dioxide (CO2), air and hydrogen gas, and when 55% of carbon dioxide is added. It has been shown that the measured value does not burn, and the estimated value burns in substantially zero range. Since the lower limit of the hydrogen gas explosion range at this time is 10% in absolute volume ratio, the mixing ratio (volume ratio) of carbon dioxide and hydrogen gas excluding air is 55: 10 = 85: 15. It turns out that it does not burn at all even if it leaks in the air.

If the mixing ratio (volume ratio) of hydrogen gas in nitrogen gas is 20% or less, the possibility of burning even if leaked into the air is extremely low, and the mixing ratio (volume ratio) of hydrogen gas in carbon dioxide is 30. % Or less, the possibility of burning even if leaking into the air is extremely low. That is, although it varies depending on the type of inert gas, if the concentration of hydrogen gas in the inert gas is 30% or less, the possibility of burning even if it leaks into the air is low, and it is necessary to make the pipe a double pipe. There is no need for hydrogen detectors and alarm devices.

However, if the hydrogen concentration becomes dilute, the hydrogen concentration in the common negative electrode gas becomes further dilute due to the consumption of hydrogen gas by the power storage device 1, and the negative electrode may be deficient in hydrogen gas. However, in the power storage system according to the present invention, the amount of hydrogen consumed by the power storage device 1 on the side that consumes hydrogen gas is approximately the same as the amount of hydrogen generated by the power storage device 1 on the side that generates hydrogen gas. If it exists, it becomes possible to charge and discharge without causing hydrogen deficiency by circulating the common negative electrode gas inside the power storage device 1 and the common negative electrode gas pipe 5.
Further, it can be confirmed by the hydrogen concentration monitor 17 that the hydrogen concentration is kept below the lower limit of explosion. As the hydrogen concentration monitor 17, it is desirable to always sample a small amount of gas in the common anode gas pipe 5 and measure the hydrogen concentration with a catalytic combustion type hydrogen detector. However, since there is no fear of explosion, there is no need for additional equipment such as a gas supply shut-off system linked to the hydrogen detector, unlike the conventional hydrogen detector, and the hydrogen concentration monitor 17 is not an essential equipment.

Even if hydrogen deficiency occurs, power generation by the power storage device 1 or the fuel cell that consumes hydrogen gas becomes difficult, and power generation may be stopped at that time. In practice, even if the hydrogen concentration falls below 1%, power generation with the power storage device 1 or the fuel cell that consumes hydrogen gas is possible, and power generation can be continued by increasing the flow rate. However, since discharge efficiency and power generation efficiency are lowered, it is economically desirable to stop discharge and power generation if the necessity of power generation is low.
However, if the necessity of power generation is high, the hydrogen generation amount of the power storage device 1 that generates hydrogen gas using new energy such as a solar cell or wind power generation is increased so as to increase the hydrogen concentration. Depending on the quality, a gas containing a large amount of hydrogen gas is supplied into the common anode gas pipe 5, hydrogen gas is replenished from the hydrogen tank, or a small amount of hydrogen tank is located in the vicinity of the power storage device 1 or fuel cell that consumes hydrogen gas. When the hydrogen concentration falls below a certain level, means such as switching to this can be used.

Conversely, when the hydrogen concentration in the common negative electrode gas pipe 5 increases and tends to exceed the upper limit, the power storage device 1 that consumes hydrogen gas and the power generation in the fuel cell are increased, such as solar cells and wind power generation. Stop the hydrogen generation of the power storage device 1 that generates hydrogen gas using new energy, etc., stop the hydrogen gas supply into the common negative gas pipe 5 by the fuel reformer, from the nitrogen tank or carbon dioxide tank, Means such as supplying carbon dioxide can be used.

  As a method for circulating the common negative electrode gas inside the power storage device 1 and the common negative electrode gas pipe 5, the pump 3 installed between the negative gas inlet pipe 2 and the power storage device 1 is used as in the first embodiment. This can be realized by driving, or can be realized by driving the pump 8 provided in the common negative gas pipe 5. Of course, both pumps may be driven.

  Since the cycle of discharging (hydrogen consumption) and charging (hydrogen generation) of the power storage device 1 is one cycle day and night, the common anode gas in the common anode gas pipe 5 is circulated over one day (for example, the length of the pipe) In contrast, a slight movement of the common negative electrode gas of about 1 m to several m / min is sufficient. If the hydrogen concentration of the common negative electrode gas pipe 5 is sufficient, the discharge (hydrogen consumption) of the power storage device 1 is continued only by driving the pump 3 installed between the negative electrode gas inlet pipe 2 and the power storage device 1. be able to. The cycle to be circulated may be reversed between daytime and nighttime, but the effect of stirring the common negative electrode gas to keep the hydrogen concentration constant is diminished. In order to increase the effect of stirring the common negative gas and keeping the hydrogen concentration constant, it is desirable to circulate twice or more a day. However, the power for circulating the common negative electrode gas increases.

Thus, the amount of hydrogen gas in the common negative gas pipe 5 is balanced because the plurality of power storage devices 1 connected to the common negative gas pipe 5 react oppositely to discharge and charge, A method of balancing the hydrogen gas in the common negative electrode gas pipe 5 and a method of balancing the amount of hydrogen gas by changing the discharge and charging operation of the power storage device 1 between day and night for the same power storage device can be considered. In the present embodiment, these two cases are described, but the present invention is not limited to this, and may be a combination thereof.

  Furthermore, instead of the pump, it is possible to circulate the common negative electrode gas inside the power storage device 1 and the common negative electrode gas pipe 5 using a fan, thereby reducing the power for circulating the common negative electrode gas. It becomes possible. In particular, when the common negative gas pipe 5 is thickened, the pressure loss is reduced and the use of the fan is facilitated. Of course, it is not necessary to be an expensive explosion-proof type because the possibility of burning is low.

  Further, the pressure of the common negative electrode gas is preferably 0.1 to 1 MPa in absolute pressure. If it exceeds 1 MPa, it is necessary to make the gas seal structure of the power storage device 1 strong, resulting in high costs. Moreover, if it is less than 0.1 MPa, the negative electrode side of the power storage device 1 becomes a negative pressure, and the performance is deteriorated.

  Next, details of the power storage device 1 will be described. FIG. 3 is a schematic diagram of the power storage system according to the first embodiment of the present invention in the daytime and an enlarged view of the power storage device 1 portion, and FIG. 4 is a schematic diagram of the nighttime and the power storage device 1 portion. FIG. The negative electrode 21 of the power storage device 1 includes a negative electrode active material. The electrolyte membrane 22 of the power storage device 1 contains an electrolytic solution. The positive electrode 23 of the power storage device 1 contains a positive electrode active material. The power storage device single cell 24 is a cell in which the negative electrode 21 of the power storage device 1, the electrolyte membrane 22 of the power storage device 1, and the positive electrode 23 of the power storage device 1 are combined.

The negative-side channel plate 25 is a negative-side channel plate, the positive-side channel plate 26 is a positive-side channel plate, the negative-electrode gas channel 27 is a channel through which a common negative-electrode gas passes, and the positive-electrode liquid channel 28 is a positive-electrode liquid. It is a flow path through. The positive electrode charge liquid pipe 29 is a pipe for supplying the positive electrode liquid in the charged state from the positive electrode charge liquid tank 15 to the positive electrode, and the positive electrode discharge liquid pipe 30 is a pipe for discharging the positive electrode liquid in the discharged state to the positive electrode discharge liquid tank 16. The positive charge liquid pump 31 causes the charged positive liquid to flow to the positive electrode, and the positive discharge liquid pump 32 causes the discharged positive liquid to flow to the positive discharge liquid tank 16. Although only one power storage device 1 is shown in FIG. 3, a plurality of power storage devices 1 are connected to the omitted portion. Hereinafter, an example of the power storage device 1 optimum for the power storage system of the present invention will be described in detail.

  The negative electrode 21 of the power storage device 1 contains a hydrogen storage alloy that is a negative electrode active material. The positive electrode 23 of the power storage device 1 contains at least one of nickel hydroxide and nickel oxyhydroxide, which is a positive electrode active material. Nickel hydroxide (Ni (OH) 2) is a positive electrode active material in a discharged state, and nickel oxyhydroxide (NiOOH) is a positive electrode active material in a charged state. The electrolyte membrane 22 of the power storage device 1 holds an alkaline electrolyte. The alkaline electrolyte contains water.

  The negative electrode side flow path plate 25 has a negative electrode gas flow path 27. The common negative electrode gas passes from the common negative electrode gas pipe 5 through the negative electrode inlet pipe 2, enters the negative electrode side flow path plate 25, is supplied to the negative electrode 21 of the power storage device 1, and then passes through the negative electrode gas outlet pipe 4. And discharged to the common negative electrode gas pipe 5. A pump 3 or a fan may be used for circulation of the common negative electrode gas at the negative electrode.

The positive channel plate 26 has a positive liquid channel 28. The positive-side flow path plate 26 is connected to the positive-electrode charging liquid tank 15 via the positive-electrode charging liquid piping 29. In the positive electrode charge liquid pipe 29, a positive electrode charge liquid pump 31 is disposed between the positive electrode liquid flow path 28 and the positive electrode charge liquid tank 15. The positive electrode charging liquid tank 15 stores a suspension containing charged positive electrode active material (nickel oxyhydroxide) particles.

  The positive-side flow path plate 26 is connected to the positive-electrode discharge liquid tank 16 via the polar discharge liquid pipe 30. In the positive electrode discharge liquid pipe 30, a positive electrode discharge liquid pump 32 is disposed between the positive electrode liquid flow path 28 and the positive electrode discharge liquid tank 16. The positive electrode liquid tank 16 stores a positive electrode liquid in a discharged state. The discharged positive electrode liquid is a suspension containing positive electrode active material (nickel hydroxide) particles in a discharged state.

  Next, the operation of the power storage device 1 will be described. The charge / discharge reactions in the negative electrode 21 of the power storage device 1 are shown in the following chemical formulas 1 and 2. In the following chemical formulas 1 and 2, the reaction from the left side to the right side is a charge reaction, and conversely, the reaction from the right side to the left side is a discharge reaction.

Chemical formula 1: (Discharge) M + H2O + e- ← → MH + OH- (Charge)
Chemical formula 2: (Discharge) 2H2O + 2e- ← → H2 + 2OH- (Charge)
In the above chemical formula 1, “M” represents a hydrogen storage alloy, and “MH” represents a hydrogen storage alloy that has absorbed protons (H +). At the time of charging, as shown in the above chemical formula 1, at the negative electrode, protons (H +) and electrons (e −) are taken into the hydrogen storage alloy (M) and hydroxide ions (OH −) are released. In the negative electrode facing the negative electrode gas flow path 27, hydrogen gas (H 2) is generated by the reaction of the above chemical formula 2. At the time of discharge, as shown in Chemical Formula 1, in the discharge reaction at the negative electrode, hydrogen gas contained in the hydrogen storage alloy is released as protons and electrons.

The charge / discharge reactions at the positive electrode 23 of the power storage device 1 are shown in the following chemical formulas 3 and 4. In the following chemical formulas 3 and 4, the reaction from the left side to the right side is a charge reaction, and conversely, the reaction from the right side to the left side is a discharge reaction.

Chemical formula 3: (discharge) Ni (OH) 2 + OH- ← → NiOOH + H2O + e- (charge)
Chemical formula 4: (Discharge) 4OH- ← → O2 + 2H2O + 4e- (Charge)
At the time of charging, as shown in Chemical Formula 3 above, nickel hydroxide (discharged state) changes to nickel oxyhydroxide (charged state) at the positive electrode, electrons are released, and water is generated. When the charging reaction at the positive electrode proceeds and nickel hydroxide is reduced, oxygen gas is generated as shown in Chemical Formula 4 above. However, the generation of oxygen gas can be suppressed by allowing the positive electrode liquid to flow through the positive electrode liquid channel 28. At the time of charging, as shown in Chemical Formula 3, in the discharge reaction at the positive electrode, nickel oxyhydroxide is reduced to produce nickel hydroxide.

  Next, the configuration of each part of the power storage device 1 of the first embodiment will be described.

(Negative electrode)
The negative electrode contains a hydrogen storage alloy. The alloy composition of the hydrogen storage alloy is not limited as long as hydrogen gas can be stored. Examples of the hydrogen storage alloy include an Mm—Ni—Co—Mn—Al alloy (“Mm” represents a mixture of rare earth elements called misch metal), an Mm—Mg—Ni—Al alloy (“cobalt-free”). MmNi5, LaNi5, etc.). The negative electrode may contain 2 or more types of hydrogen storage alloys. The negative electrode may be a hydrogen-absorbing alloy compact, for example. The compact of the hydrogen storage alloy is also used in consumer nickel-metal hydride secondary batteries.

  Even if the negative electrode of the power storage device 1 of Embodiment 1 does not necessarily contain a hydrogen storage alloy, the present invention can be applied to the negative electrode provided with a catalyst that facilitates oxidation and reduction of hydrogen gas, such as a platinum-based catalyst. Functions as a power storage system. When the negative electrode contains a hydrogen storage alloy, an effect of improving the responsiveness to charge / discharge is obtained.

(Positive electrode)
The positive electrode contains at least one of nickel hydroxide and nickel oxyhydroxide. As described above, nickel hydroxide is a positive electrode active material in a discharged state, and nickel oxyhydroxide is a positive electrode active material in a charged state. These positive electrode active materials may contain, for example, cobalt (Co) or the like in addition to nickel, oxygen and hydrogen gas which are essential constituent elements.

  The configuration of the positive electrode in a consumer nickel metal hydride secondary battery may be applied to the positive electrode. In that case, the positive electrode may be sintered or non-sintered. The sintered positive electrode is produced, for example, as follows. First, a paste containing nickel particles is applied to both main surfaces of a punching metal that has been plated with nickel, and sintered at about 1000 ° C. Thereby, a sintered plate is obtained. The sintered plate is impregnated with a nickel salt solution. After impregnation, the sintered plate is immersed in an aqueous alkaline solution. By repeating the impregnation of the nickel salt solution and the immersion in the alkaline aqueous solution, nickel hydroxide can be supported on the sintered plate to obtain a positive electrode.

  The non-sintered positive electrode is produced by impregnating a nickel porous substrate with a paste containing nickel hydroxide particles, followed by drying and rolling. For the porous substrate, for example, foamed nickel, mat-like nickel fiber, or the like is used.

(Cathode liquid)
The positive electrode liquid is a suspension containing positive electrode active material particles containing at least one of nickel hydroxide and nickel oxyhydroxide. The positive electrode liquid may be in a gel form. The liquid component of the positive electrode liquid may be an alkaline aqueous solution. The positive electrode liquid refers to an electrolytic solution.

  As the positive electrode active material particles, for example, particles obtained by pulverizing sintered nickel hydroxide particles or particles obtained by pulverizing non-sintered positive electrodes can be used. In consideration of contact efficiency with the positive electrode and fluidity in the positive electrode liquid, the particle shape of the positive electrode active material particles is preferably a spherical shape. Therefore, for example, the pulverized particles may be spheroidized. The spheronization process can be performed using, for example, a ball mill. The positive electrode active material particles may contain, for example, cobalt hydroxide and manganese hydroxide.

  The particle diameter of the positive electrode active material particles is preferably about 0.1 μm or more and 1 mm or less. When the particle size is 0.1 μm or more, the contact efficiency between the positive electrode plate and the positive electrode active material particles is improved, and the delivery of electrons is facilitated. By setting the particle size to 1 mm or less, for example, problems such as positive electrode active material particles agglomerating in the liquid channel and causing clogging are suppressed. However, this does not apply when the cross-sectional area of the liquid channel is increased.

  The positive electrode liquid may contain a thickening component. This is to stabilize the dispersion state of the positive electrode active material particles. The thickening component is desirably alkali-resistant. Examples include alkali-resistant thickening fibers. The positive electrode liquid is desirably a thixotropic fluid. As a method for improving the thixotropy of the positive electrode liquid, for example, mixing carbon powder with the positive electrode liquid can be considered.

(Alkaline electrolyte)
The alkaline electrolyte may be an alkaline aqueous solution. The alkaline electrolyte preferably has high ionic conductivity. The alkaline electrolyte may be, for example, a high concentration potassium hydroxide (KOH) aqueous solution. The KOH concentration is, for example, about 10 to 40% by mass. The alkaline electrolyte may contain a plurality of hydroxides. The alkaline electrolyte may contain, for example, two kinds of hydroxides of KOH and sodium hydroxide (NaOH), or three kinds of hydroxides of KOH, NaOH and lithium hydroxide (LiOH). It may be.

  In the example of the power storage device 1 optimum for the power storage system of the present embodiment, the positive electrode contains at least one of nickel hydroxide and nickel oxyhydroxide, and the positive electrode liquid is nickel hydroxide or oxyhydroxide. In the case of a suspension containing positive electrode active material particles containing at least one of nickel, the positive electrode contains at least one of manganese dioxide, manganese hydroxide or manganese oxyhydroxide, and the positive electrode liquid contains It may be a suspension containing positive electrode active material particles containing at least one of manganese dioxide, manganese hydroxide, and manganese oxyhydroxide, and can be used similarly.

  Moreover, although an example of the power storage device 1 optimal for the power storage system of the present embodiment has been described in detail, the power storage device 1 used in the power storage system of the present embodiment is the power storage device 1 described above. In addition, it may be a regenerative fuel cell such as a redox flow battery that generates hydrogen gas by charging at the negative electrode and consumes hydrogen gas by discharging, and is a secondary battery that charges and discharges using hydrogen gas. It ’s fine. Further, various types of power storage devices 1 may be mixed. The same applies to the second embodiment described later.

  In the first embodiment, the power storage device 1 is schematically shown as a “single cell”, but may be a stacked power storage device 1 in which a large number of cells are stacked in series. In the solar power generation area 10, the MWh level power storage device 1 is assumed. In the power consumption area 11, the home use is assumed to be the 10 kWh level, and the apartment 14 and the like are assumed to operate the 100 kWh level power storage device 1.

  The variable capacity type common negative electrode gas storage tank 6 is, for example, a metal container having a bellows structure. If there is a certain hydrogen gas barrier property, the container may be made of resin or rubber. As a method for improving the hydrogen gas barrier property in a resin container or the like, it is conceivable to perform lining with a metal thin film. The container may be a composite material of metal and resin, for example. The hydrogen storage tank may be a balloon, for example. Alternatively, the common negative gas storage tank 6 may be a variable pressure type.

  The material of the common negative electrode gas pipe 5 may be a steel pipe made of copper or stainless steel having corrosion resistance, but a polyethylene pipe excellent in flexibility is more desirable, and it is more resistant to earthquakes than other steel pipes and resin pipes. It has the characteristic of being strong. And since it is excellent in flexibility, it can be transported in a reel-like state with a straight pipe wound, and can be installed while straightening at the installation site, so long installation without connection is possible In this respect, it is also excellent in earthquake resistance. Polyethylene pipes can be connected without long connections, and can be easily electrofused with a power supply, so they are highly reliable in preventing gas leakage and can be used to connect pipes. The economy is very good and the material cost is low.

  The length of the common negative electrode gas pipe 5 can be extended from 100 m to several km or several tens of km. If necessary, a plurality of common negative electrode gas storage tanks 6 can be installed to increase the pressure of the common negative electrode gas. It is possible to keep the hydrogen concentration appropriate. The common negative electrode gas pipe 5 is desirably thicker in order to facilitate the circulation of the common gas, but is preferably a pipe having a diameter of 30 mm to 300 mm from the viewpoint of piping space and economy. In addition, the pipe thickness may be changed depending on the location, and the closer to the common negative electrode gas storage tank 6, the thicker the pipe, and the closer to the power storage device 1, the thinner the pipe. It becomes possible to keep on. The common negative electrode gas storage tank 6 has a very low risk of burning, but it is desirable that it be isolated from electrical facilities by walls or the like as much as possible.

If the power storage device 1 is connected to the common negative electrode gas pipe 5 having a long distance and the hydrogen gas generated by charging at the power storage device 1 at one end is consumed by the discharge at the power storage device 1 at the other end, The pressure inside the hydrogen pipe is kept constant (if the charge / discharge amount is almost the same). In the power storage system according to the present invention, the common negative electrode gas is circulated inside the power storage device 1 and the common negative electrode gas pipe 5, so that charge / discharge can be performed without causing hydrogen deficiency even with hydrogen gas mainly composed of inert gas. Make it possible to do. By drastically diluting hydrogen gas with inert gas, a lot of additional facilities such as measures against hydrogen leaks such as long double pipes, hydrogen detectors at regular distances, and gas supply shut-off systems linked to this are greatly increased. An effect that can be omitted is obtained.

Embodiment 2. FIG.
FIG. 5 is a schematic diagram of the daytime of the energy storage system according to Embodiment 2 of the present invention. In the figure, a high-pressure hydrogen cylinder 41 refers to a cylinder that stores hydrogen gas, and a high-pressure nitrogen cylinder 42 is a cylinder that stores nitrogen, which is an inert gas. In the present embodiment, the high-pressure nitrogen cylinder is used. However, the present invention is not limited to this, and any tank that stores an inert gas may be used, and an inert gas cylinder may be used.

  In the first embodiment, the case where there is one each of the power storage device 1 connected to the solar cell 13 and the power storage device 1 connected to the apartment 14 or the like is shown, but in the second embodiment, two power storage devices 1 each. Connected one by one. Of course, the number of the power storage devices 1 is not limited to this, and may be large, and the power storage devices 1 having the same number or the same capacity (kWh) are not necessarily required.

  In the second embodiment, a hydrogen cylinder 41 and a nitrogen cylinder 42 are installed to adjust the hydrogen concentration of the common negative electrode gas. The hydrogen concentration is monitored by a hydrogen concentration monitor. When the hydrogen concentration is too low, the hydrogen gas is released from the high-pressure hydrogen cylinder 41 to increase the hydrogen concentration, and when the hydrogen concentration is too high, the nitrogen gas is discharged from the high-pressure nitrogen cylinder 42. Release to reduce hydrogen concentration. Adjustment of the hydrogen concentration of the common negative electrode gas is performed slowly on a daily basis. Further, the high-pressure hydrogen cylinder 41 and the high-pressure nitrogen cylinder 42 are replaced with new ones when they become empty. In order to increase the hydrogen concentration when the hydrogen concentration of the common negative electrode gas pipe 5 is equal to or lower than a predetermined threshold value, hydrogen gas is supplied from the hydrogen cylinder 41, and when the hydrogen concentration exceeds the predetermined threshold value, the hydrogen concentration is decreased. For this purpose, nitrogen is supplied from the nitrogen cylinder 42. Here, the nitrogen cylinder 42 is not limited to nitrogen, and any inert gas may be used, and it may be supplied from the inert gas cylinder.

  In addition to the catalytic combustion type hydrogen sensor, for example, a hydrogen sensor using an amorphous hydrogen storage alloy (Pd—Cu—Si) can be used for the hydrogen concentration monitor, and 1 to 100% even if oxygen is not included. The hydrogen concentration can be measured in a wide concentration range, and is hardly affected by inert gas (nitrogen or carbon dioxide) or water.

In addition, even if the common negative electrode gas piping 5 is not in a loop shape, it is sufficient that the common negative electrode gas is circulated as a whole. As the scale increases, the imbalance between the generation and consumption of hydrogen gas is eliminated, and the pressure management of the pressure regulator 7 and the common negative electrode gas tank 6 becomes easier. In the present embodiment, the parts different from the first embodiment have been described. The other parts are the same as those in the first embodiment.

Embodiment 3 FIG.
FIG. 6 is an enlarged view of a fuel cell portion connected to the power storage system according to Embodiment 3 of the present invention. In the figure, the fuel cell fuel electrode (negative electrode) 51 is the negative electrode of the fuel cell, the fuel cell electrolyte membrane 52 is the electrolyte membrane of the fuel cell, and the fuel cell air electrode (positive electrode) 53 is the positive electrode of the fuel cell. The single fuel cell 54 is a cell in which a fuel cell fuel electrode (negative electrode) 51, a fuel cell electrolyte membrane 52, and a fuel cell air electrode (positive electrode) 53 are combined. The fuel electrode flow channel plate 55 is a negative electrode side flow channel plate, and the air electrode flow channel plate 56 is a positive electrode side flow channel plate.

The fuel channel 57 is a channel through which fuel passes, and the air channel 58 is a channel through which air passes. The air electrode inlet pipe 59 is a pipe for taking air into the positive electrode, and the air electrode outlet pipe 60 is a pipe for discharging air from the positive electrode via the positive electrode. The air blower 61 is a device that sends air to the positive electrode, the dehydrator 62 is a device that removes moisture, and the digestion gas reformer 63 is a device that converts methane into a reformed gas containing hydrogen gas and carbon dioxide by steam reforming. . The digestion gas inlet pipe 64 is a pipe for taking in methane, and the sewage treatment plant digestion gas purification area 65 is an area for purifying methane from the sewage treatment plant. Although only the fuel cell is shown in FIG. 6, a plurality of regenerative fuel cells and the like are connected to the omitted portion.

  In the third embodiment, a fuel cell that consumes hydrogen gas and generates electric power is connected to a common negative electrode gas pipe 5 to which a plurality of power storage devices 1 are connected in a power consumption area. In the first embodiment, an example in which a regenerative fuel cell is assumed is described, but in this embodiment, a non-regenerative fuel cell is further added to the regenerative fuel cell. In other words, it is effective use of the common negative electrode gas pipe 5 having hydrogen gas and circulating in one direction. As the fuel cell, a polymer electrolyte fuel cell (PEFC), a solid electrolyte fuel cell (SOFC), or the like can be used, and power and hot water can be supplied to each house in a power consumption area.

  The fuel cell fuel electrode 51 takes in the common negative electrode gas containing hydrogen gas from the common negative electrode gas pipe 5, consumes only the hydrogen gas to generate power, removes moisture by the dehydrator 62, and then removes the common negative gas pipe. Eject to 5. Unlike the case of the first and second embodiments, the hydrogen gas is completely consumed without being generated, so that it is necessary to replenish the common negative electrode gas pipe 5 with hydrogen gas. Air is fed into the fuel cell air electrode 53 by the air blower 61, and oxygen is consumed and discharged.

  In a non-regenerative fuel cell, hydrogen gas is only consumed by the fuel cell and cannot be charged, and it is considered that the common negative electrode gas is steadily decreasing and deficient. Therefore, hydrogen gas may be replenished from the hydrogen tank as in the second embodiment as a mechanism for replenishing hydrogen, but hydrogen gas may be replenished by the following method. In the sewage treatment plant digestion gas purification area 65 installed in the sewage treatment plant, digestion gas containing methane is generated from sewage sludge by methane fermentation, and the fuel cell is passed through a desulfurizer and a siloxane removal device (not shown). After removing harmful sulfur compounds and siloxane, methane is converted to reformed gas containing hydrogen gas and carbon dioxide by steam reforming (Chemical Formula 5) in the digestion gas reformer 63 and released to the common negative gas pipe 5 To do.

  Chemical formula 5 (steam reforming reaction): CH4 + 2H2O-> CO2 + 4H2. As a result, the common negative gas pipe 5 is replenished with a hydrogen mixed gas of hydrogen concentration of 80% and the remainder carbon dioxide, and balances with the hydrogen consumption in the fuel cell, so only the pressure adjustment by the common negative gas storage tank 6 is required. The hydrogen concentration and pressure of the common negative electrode gas are maintained within a certain range. In FIG. 6, the fuel cell is represented by the fuel cell single cell 54, but of course, a stacked fuel cell in which a large number of single cells are stacked may be used. In the present embodiment, the parts different from the first or second embodiment have been described. The other parts are the same as those in the first or second embodiment.

Embodiment 4 FIG.
FIG. 7 is an enlarged view of a fuel cell portion connected to the power storage system according to Embodiment 4 of the present invention. In the figure, a hydrogen separator 66 is a device for extracting pure hydrogen from a common negative electrode gas, a hydrogen circulation line 67 is a pipe for circulating the extracted quasi-hydrogen, and a hydrogen circulation pump 68 is a pump for circulating the extracted pure hydrogen to the hydrogen circulation line. Say. Although only the fuel cell is shown in FIG. 7, a plurality of regenerative fuel cells are connected to the omitted portion.

  The difference from the third embodiment is the configuration of the negative electrode portion of the fuel cell. In the fourth embodiment, pure hydrogen is extracted from the common negative electrode gas pipe 5 using the hydrogen separator 66 and supplied to the fuel cell fuel electrode 51, and then passed through the hydrogen circulation line 67 using the hydrogen circulation pump 68. Circulate to the battery fuel electrode 51. As a result, hydrogen gas having a concentration close to that of pure hydrogen is always supplied to the fuel cell, and the power generation capacity can be increased. Further, it is possible to obtain an effect that the output can be easily followed according to the load fluctuation. In the present embodiment, parts different from the third embodiment have been described. The other parts are the same as those in the third embodiment.

Embodiment 5. FIG.
FIG. 8 is an enlarged view of a water electrolyzer part connected to the power storage system according to Embodiment 5 of the present invention. In the figure, a water electrolysis tank hydrogen electrode (negative electrode) 71 is a negative electrode of a water electrolysis tank, a water electrolysis tank electrolyte membrane 72 is an electrolyte membrane of a water electrolysis tank, a water electrolysis tank oxygen electrode (positive electrode) 73 is a positive electrode of a fuel cell, and water electrolysis. A tank single cell 74 is a cell in which a water electrolysis tank hydrogen electrode (negative electrode) 71, a water electrolysis tank electrolyte membrane 72 and a water electrolysis tank oxygen electrode (positive electrode) 73 are combined, and a water electrolysis tank hydrogen flow path plate 75 is a flow on the negative electrode side. Road plate, water electrolyzer oxygen flow path plate 76 is a flow path plate on the positive electrode side, hydrogen flow path 77 is a flow path through which hydrogen passes, oxygen flow path 78 is a flow path through which oxygen passes, and water inlet pipe 79 uses water as a positive electrode. An intake pipe, an oxygen outlet pipe 80 is a pipe that discharges oxygen from the positive electrode, a water supply pump 71 is a device that sends water to the positive electrode, and a water tank 62 is a tank that stores water. Although only the water electrolyzer is shown in FIG. 8, a plurality of regenerative fuel cells and the like are connected to the omitted portion.

In the fifth embodiment, a water electrolyzer that generates hydrogen gas using electric power and water in the solar power generation area in the common negative electrode gas pipe 5 of the power storage system including the plurality of fuel cells of the third embodiment. Is connected. In the third embodiment, hydrogen gas and carbon dioxide are emitted in the sewage treatment plant digestion gas purification area 65 installed in the sewage treatment plant. In the fifth embodiment, hydrogen gas is obtained by electrolyzing water. The part that generates is different.

The water electrolyzer is an apparatus that electrolyzes water to generate hydrogen gas and oxygen. Alkaline water electrolyzers and solid polymer water electrolyzers can be used practically.
In Embodiment 5, water is supplied from the water electrolysis tank oxygen electrode (positive electrode) 73, and the generated oxygen is discarded to the atmosphere. A common negative electrode gas containing hydrogen gas is taken from the common negative electrode gas pipe 5, and pure hydrogen generated by water electrolysis is added at a water electrolysis tank hydrogen electrode (negative electrode) 71 to remove water, and then the hydrogen concentration is increased. The raised negative gas is returned to the common negative gas pipe 5. As a result, hydrogen gas is replenished to the common negative electrode gas pipe 5 and balances with hydrogen consumption in the fuel cell, so that the hydrogen concentration and pressure of the common negative electrode gas are constant only by adjusting the pressure by the common negative electrode gas storage tank 6. Kept in range. In the present embodiment, parts different from the third embodiment have been described. The other parts are the same as those in the third embodiment.

Embodiment 6 FIG.
FIG. 9 is an enlarged view of the water electrolyzer part connected to the power storage system according to Embodiment 6 of the present invention. In the figure, a hydrogen pump 83 is a pump for sending out hydrogen. Although only the water electrolyzer is shown in FIG. 9, a plurality of regenerative fuel cells and the like are connected to the omitted portion.

  The difference from the fifth embodiment is only the configuration of the negative electrode portion of the water electrolysis tank. In the sixth embodiment, only pure hydrogen generated by water electrolysis is supplied to the common negative electrode gas pipe 5 using the hydrogen pump 83. As a result, only pure hydrogen is supplied to the common negative gas pipe 5. Accordingly, there is an effect that the piping can be simplified as compared with the case of the fifth embodiment. Specifically, as compared with the fifth embodiment of FIG. 8, the negative gas inlet pipe 2 is not required and can be simplified. However, since the hydrogen concentration of the pipe in the negative electrode part of the water electrolysis tank exceeds the lower limit of explosion, safety measures such as a hydrogen detector are required in the water electrolysis tank part. In the present embodiment, parts different from the fifth embodiment have been described. The other parts are the same as in the fifth embodiment.

  In the fifth embodiment and the sixth embodiment, as shown in FIGS. 8 and 9, respectively, the water electrolysis tank is represented by the water electrolysis tank single cell 74. A stacked water electrolyzer having a large number of stacked layers may be used.

As described above, as means for increasing the hydrogen concentration, in addition to the power storage device 1 that generates hydrogen gas from the negative electrode by charging, a methane steam reformer using city gas, digestion gas, etc., solar power generation, wind power, etc. In addition to the power storage device 1 that consumes hydrogen gas at the negative electrode due to discharge, hydrogen gas can be used as a water electrolysis tank using hydrogen surplus power or a hydrogen cylinder. Fuel cells, nitrogen cylinders, carbon dioxide gas cylinders, argon gas cylinders, and the like that consume and generate electric power can be used, and the power storage system using the common negative electrode gas pipe 5 of the present invention is further diversified and used for a wide range of applications. It becomes possible.

The average hydrogen concentration of the entire common negative electrode gas pipe 5 can be obtained by averaging the hydrogen concentrations of hydrogen concentration monitors arranged in several places. In addition to this, the operation of the hydrogen concentration increasing means and the hydrogen concentration decreasing means It is also possible to simply calculate from the amount of hydrogen generated and the amount of hydrogen consumed, the total volume of the common negative electrode gas pipe 5 and the pressure of the common negative electrode gas pipe 5. Then, it is desirable to control the operation of the hydrogen concentration increasing means and the hydrogen concentration decreasing means so that the average hydrogen concentration of the entire common negative gas pipe 5 is kept constant.

  1 Power storage device, 2 Negative gas inlet piping, 3 Pump, 4 Negative gas outlet piping, 5 Common negative gas piping, 6 Common negative gas storage tank, 7 Pressure regulator, 8 Pump, 9 Bulkhead, 10 Solar power generation area, DESCRIPTION OF SYMBOLS 11 Electricity consumption area, 12 systems, 13 Solar cells, 14 Condominiums, etc. 15 Positive charge liquid tank, 16 Positive discharge liquid tank, 17 Hydrogen concentration monitor, 21 Negative electrode of power storage device 1, 22 Electrolyte membrane of power storage device 1, 23 positive electrode of power storage device 1, 24 single cell of power storage device, 25 negative electrode side channel plate, 26 positive electrode side channel plate, 27 negative electrode gas channel, 28 positive electrode liquid channel, 29 positive electrode charge liquid pipe, 30 positive electrode discharge Liquid piping, 31 Positive charge liquid pump, 32 Positive discharge liquid pump, 41 High pressure hydrogen cylinder, 42 High pressure nitrogen cylinder, 51 Fuel cell Fuel electrode (negative electrode), 52 Fuel cell electrolyte membrane, 53 Fuel cell air electrode (positive electrode), 54 Fuel cell single cell, 55 Fuel electrode channel plate, 56 Air electrode channel plate, 57 Fuel channel, 58 Air channel , 59 Air electrode inlet piping, 60 Air electrode outlet piping, 61 Air blower, 62 Dehydrator, 63 Digestion gas reformer, 64 Digestion gas inlet piping, 65 Sewage treatment plant digestion gas purification area, 66 Hydrogen separator, 67 Hydrogen Circulation line, 68 Hydrogen circulation pump, 71 Water electrolysis tank hydrogen electrode (negative electrode), 72 Water electrolysis tank electrolyte membrane, 73 Water electrolysis tank oxygen electrode (positive electrode), 74 Water electrolysis tank single cell, 75 Water electrolysis tank hydrogen flow path plate , 76 Water electrolyzer oxygen channel plate, 77 Hydrogen channel, 78 Oxygen channel, 79 Water inlet piping, 80 Oxygen outlet piping, 81 Water supply pump, 82 Water tank, 83: Hydrogen pump.

Claims (10)

A plurality of power storage devices that use hydrogen gas when discharging and generate hydrogen gas when charging; and
A circulation type common negative electrode gas pipe that circulates the nonflammable common negative electrode gas in which an inert gas is mixed with the hydrogen gas in one direction;
Each negative gas inlet pipe that supplies the common negative gas branched from the common negative gas pipe to each of the plurality of power storage devices;
And a negative electrode outlet pipe that joins the common negative gas discharged from each of the plurality of power storage devices to the common negative gas pipe. The power storage system according to claim 1,
From the negative electrode outlet pipe, the common negative gas in which the hydrogen gas is used in the power storage device or the common negative gas mixed with the hydrogen gas generated in the power storage device joins the common negative gas pipe. A power storage system characterized by being made. The power storage system according to claim 1 or 2,
The second power storage device is discharged when the first power storage device of the plurality of power storage devices is charged. The power storage system according to claim 1 or 2,
The plurality of power storage devices include at least a power storage device that charges at night and discharges in the daytime, and a power storage device that discharges at night and charges in the daytime. The power storage system according to any one of claims 1 to 4,
A common negative electrode gas storage tank for storing the common negative electrode gas;
The electric power storage system characterized by keeping the pressure of the common negative electrode gas in the common negative electrode gas piping constant by using the common negative electrode gas storage tank as a buffer. The power storage system according to any one of claims 1 to 5,
The power storage system, wherein the hydrogen gas is supplied to the common negative electrode gas pipe when the hydrogen concentration of the common negative gas pipe becomes a threshold value or less. The power storage system according to claim 6,
The power storage system, wherein the inert gas is supplied to the common negative electrode gas pipe when the hydrogen concentration of the common negative electrode gas in the common negative electrode gas pipe exceeds a threshold value. The power storage system according to any one of claims 1 to 5,
A non-regenerative fuel cell that consumes the hydrogen gas when discharged and cannot be recharged;
The power storage system further comprising the negative gas inlet pipe for supplying the common negative gas from the common negative gas pipe to the non-regenerative fuel cell. The power storage system according to claim 8,
Furthermore, a digestion gas reformer that reforms the methane of the digestion gas of the sewage treatment plant to generate a reformed gas containing the hydrogen gas,
The power storage system further comprising the negative gas inlet pipe for supplying the reformed gas generated from the digestion gas reformer to the common negative gas pipe. The power storage system according to claim 8,
A water electrolyzer that generates hydrogen gas by electrolysis of water;
The power storage system further comprising the negative electrode outlet pipe for supplying the hydrogen gas generated from the water electrolysis tank to the common negative electrode gas pipe.

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