Power generation equipment

Abstract

To provide a power generator in which an anode electrode can be easily replaced.SOLUTION: A power generator 100 that generates electricity using the metabolic reaction of microorganisms includes an anode holder 12 to which an anode electrode A can be attached, and a cathode holder 13 to which the cathode electrode C can be attached so as to be electrically connected to the anode electrode attached to the anode holder, and the anode holder is configured such that the anode electrode can be detachably attached thereto.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power generation device.

Background Art

[0002] There is a power generation device that converts a fuel, which is an organic substance, into electrical energy by utilizing the metabolic reaction of microorganisms and generates electricity. This power generation device is also called a microbial fuel cell. The microbial fuel cell includes an anode electrode and a cathode electrode. The anode electrode collects electrons generated when an organic substance as a fuel is decomposed by microorganisms. The collected electrons are moved from the anode electrode to the cathode electrode via an external circuit. In addition, protons are generated at the anode electrode. The protons generated at the anode electrode react with the electrons that have moved to the cathode electrode and oxygen to generate water.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In a microbial fuel cell, since electron transfer occurs on the surface of the anode electrode, the surface of the anode electrode may deteriorate as power generation progresses. In that case, the power generation efficiency decreases. Therefore, a power generation device in which the anode electrode can be easily replaced is desired.

[0005] According to an embodiment, a power generation device is a power generation device that generates power by utilizing the metabolic reaction of microorganisms, and includes an anode holder to which an anode electrode can be attached, and a cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder. The anode holder is configured to be detachable from the anode electrode.

[0006] Further details will be described as embodiments below. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic perspective view of the power generation device according to the first embodiment, taken from diagonally above. [Figure 2] Figure 2 is a schematic perspective view showing the power generation device in Figure 1 with the anode and cathode electrodes attached. [Figure 3] Figure 3 is a front view of a plug-in member included in the power generation device according to the first embodiment. [Figure 4] Figure 4 is a side view of the insertable member shown in Figure 3. [Figure 5] Figure 5 is a plan view of the insert member shown in Figure 3. [Figure 6] Figure 6 is a cross-sectional view of AA in Figure 5. [Figure 7] Figure 7 is a front view of a cathode holder included in the power generation device according to the first embodiment. [Figure 8] Figure 8 is a plan view of the cathode holder shown in Figure 7. [Figure 9] Figure 9 is a cross-sectional view of BB in Figure 8. [Figure 10] Figure 10 is a diagram illustrating how the power generation device according to the first embodiment is used. [Figure 11] Figure 11 shows the results of a first experiment on a power generation device according to the first embodiment, illustrating the time change of the measured open-circuit voltage (OCV). [Figure 12] Figure 12 shows the results of the first experiment on the power generation device according to the first embodiment, and illustrates the time change of the maximum power density under the first and second conditions in the first experiment. [Figure 13] Figure 13 shows the results of a second experiment on a power generation device according to the first embodiment, illustrating the time change of the measured open-circuit voltage (OCV). [Figure 14] Figure 14 shows the results of a second experiment on the power generation device according to the first embodiment, illustrating the time change of the maximum power density under the first and second conditions in the second experiment. [Figure 15] FIG. 15 is a schematic perspective view of the power generation device according to the second embodiment, seen from obliquely above. [Figure 16] FIG. 16 is a schematic perspective view showing how the anode electrode and the cathode electrode are attached to the power generation device of FIG. 15. [Figure 17] FIG. 17 is a schematic perspective view showing the state in which the anode electrode and the cathode electrode are attached to the power generation device of FIG. 15. [Figure 18] FIG. 18 is a plan view of the power generation device according to the second embodiment. [Figure 19] FIG. 19 is a plan view of the power generation device according to the second embodiment, in a state where the conducting wires from the anode electrode and the cathode electrode are wired respectively. [Figure 20] FIG. 20 is a side view of the power generation device according to the second embodiment. [Figure 21] FIG. 21 is a front view of the power generation device according to the second embodiment. [Figure 22] FIG. 22 is a cross-sectional view taken along the line C-C of FIG. 18, and is a cross-sectional view of only the anode holder portion of the power generation device. [Figure 23] FIG. 23 is a diagram for explaining how the power generation device according to the second embodiment is used. [Figure 24] FIG. 24 shows the results of the first experiment on the power generation device according to the second embodiment, and represents the time change of the open circuit voltage (OCV) measured in each cycle using the first anode electrode. [Figure 25] FIG. 25 shows the results of the first experiment on the power generation device according to the second embodiment, and represents the time change of the open circuit voltage (OCV) measured in each cycle using the second anode electrode. [Figure 26] FIG. 26 shows the results of the first experiment on the power generation device according to the second embodiment, and represents the time change of the maximum power density measured in each cycle using the first anode electrode. [Figure 27]FIG. 27 shows the results of the first experiment on the power generation device according to the second embodiment, and represents the time change of the maximum power density measured in each cycle using the second anode electrode. [Figure 28] FIG. 28 shows the results of the second experiment on the power generation device according to the second embodiment, and represents the time change of the open circuit voltage (OCV) measured using the first cathode electrode and the second cathode electrode, respectively.

Embodiments for Carrying Out the Invention

[0008] <1. Overview of the Power Generation Device>

[0009] (( (1) The power generation device according to the embodiment is a power generation device that generates electricity using the metabolic reaction of microorganisms, and includes an anode holder to which an anode electrode can be attached, and a cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder. The anode holder is configured to be detachable from the anode electrode.

[0010] Since the anode holder is configured to be detachable from the anode electrode, in the power generation device, the anode electrode can be easily replaced. Thereby, even when power generation progresses and the surface of the anode electrode deteriorates, the anode electrode can be easily replaced. Therefore, a decrease in power generation efficiency can be suppressed.

[0011] (( (2) Preferably, the power generation device further includes an insertion member for inserting into an environment where microorganisms exist, and the anode holder is provided on the insertion member. The environment where microorganisms exist is, for example, soil where microorganisms exist. In that case, the insertion member is inserted into the soil and used. Thereby, it becomes easier to generate electricity using the metabolic reaction of microorganisms in the power generation device.

[0012] (( (3) Preferably, the cathode holder can attach the cathode electrode with a variable relative position with respect to the insertion member. Thereby, it becomes easier to position the cathode electrode at an appropriate position.

[0013] (4) Preferably, the insertion member has a reservoir inside for storing wastewater supplied to the cathode electrode attached to the cathode holder. The wastewater is a liquid containing organic matter that is decomposed by microorganisms, and may be, for example, kitchen wastewater. In this way, the power generation device generates electricity using the organic matter contained in the wastewater.

[0014] (5) Preferably, the reservoir has a drain port through which wastewater is discharged to the outside by passing through the anode electrode attached to the anode holder, and the cathode holder is located outside the reservoir. As a result, the wastewater stored in the reservoir is discharged into an environment where microorganisms exist, such as soil, by passing through the anode electrode. Therefore, electrons generated when organic matter is decomposed by microorganisms are easily recovered by the anode electrode. In addition, by having the cathode holder located outside the reservoir, the cathode electrode can be prevented from being submerged in the wastewater. As a result, the cathode electrode can be used as an air cathode.

[0015] (6) Preferably, the reservoir is provided with a mark based on the position of the cathode holder. This allows for an indication of the amount of wastewater to be injected into the reservoir, and prevents the cathode electrode from being submerged in the wastewater.

[0016] (7) Preferably, the cathode holder has a float member. This allows the cathode electrode to float on the water surface and allows air to be supplied to the cathode electrode.

[0017] (8) Preferably, the power generation device further includes a restricting member for restricting the movement of the cathode electrode attached to the cathode holder. Restriction of movement may be, for example, restriction of vertical position, restriction of horizontal position, etc. This prevents the position of the cathode electrode from becoming an inappropriate position due to water flow or water volume.

[0018] (9) Preferably, the insertion member has one or more tapered protrusions that gradually narrow in the direction of insertion into the environment. This makes the power generation device easier to use by insertion.

[0019] (10) Preferably, the insertion member has a plurality of protrusions, and an anode holder is provided on each of the plurality of protrusions. This allows a plurality of anode electrodes to be attached to the power generation device. The plurality of anode electrodes may be connected in parallel or in series.

[0020] (11) Preferably, the insertion member is provided with a slit for inserting the anode electrode. This allows the anode electrode to be easily attached and removed.

[0021] (12) Preferably, the insertion member is provided with wiring for electrically connecting the anode electrode attached to the anode holder and the cathode electrode attached to the cathode holder. This electrically connects the anode electrode and the cathode electrode in the power generation device, enabling power generation. Furthermore, the internal wiring of the device increases the portability of the power generation device and expands the range of environments in which it can be used, such as external environments.

[0022] (13) Preferably, the power generation device further comprises a support member for supporting equipment that supplies the generated power. This makes it easier for the power generation device to supply the generated power to the equipment.

[0023] <2. Examples of power generation equipment>

[0024] [First Embodiment]

[0025] Figure 1 is a schematic perspective view of the power generation device 100 according to the first embodiment, taken from diagonally above. Figure 2 is a schematic perspective view showing the power generation device 100 of Figure 1 with the anode electrode A and cathode electrode C attached.

[0026] Figures 3 to 6 are diagrams illustrating the insertion member 14 of the power generation device 100. Figure 3 is a front view of the insertion member 14. Figure 4 is a side view of the insertion member 14. Figure 5 is a top view of the insertion member 14. Figure 6 is a cross-sectional view of AA in Figure 5.

[0027] Figures 7 to 9 are diagrams illustrating the cathode holder 13 of the power generation device 100. Figure 7 is a front view of the cathode holder 13. Figure 8 is a top view of the cathode holder 13. Figure 9 is a cross-sectional view of BB in Figure 8.

[0028] Figure 10 is a diagram illustrating how the power generation device 100 is used. The power generation device 100 is a so-called microbial electrolysis cell that generates electricity by utilizing the metabolic reaction in which microorganisms 20 decompose organic fuel, and uses soil S as an electrolyte (biofuel).

[0029] Referring to Figures 1 and 2, the power generation device 100 includes an anode holder 12 to which an anode electrode A can be attached, and a cathode holder 13 to which a cathode electrode C can be attached. The anode holder 12 and the cathode holder 13 are detachable from the anode electrode A and the cathode electrode C, respectively, and have insertion slits 121 and 131 for inserting the anode electrode A and the cathode electrode C.

[0030] Anode electrode A is attached to the anode holder 12 by being inserted through the insertion slit 121 and removed by being pulled out through the insertion slit 121. Cathode electrode C is attached to the cathode holder 13 by being inserted through the insertion slit 131 and removed by being pulled out through the insertion slit 131.

[0031] The power generation device 100 is used by inserting it into an environment where microorganisms 20 are present, as shown in Figure 10. The environment where microorganisms 20 are present is, for example, soil S in which microorganisms are present. That is, the power generation device 100 is used by inserting it into the soil S in the direction of arrow R in Figures 1 and 2. Therefore, the power generation device 100 is further provided with an insertion member 14 for inserting the power generation device 100 into the environment where microorganisms 20 are present. Arrow R indicates the direction in which the power generation device 100 is inserted into the soil S.

[0032] The insertable member 14 has a housing 141. The housing 141 is formed from a polymer and is formed, for example, using a 3D printer. This makes it easy to form complex shapes such as the convex portion 14A described later.

[0033] Preferably, the housing 141 is formed of a biodegradable polymer. The biodegradable polymer is, for example, polylactide. This allows it to be decomposed by microorganisms, and even when the power generation device 100 is installed in the external environment, the impact on the external environment can be minimized.

[0034] The interior of the housing 141 constitutes a water storage section 142. The water storage section 142 is used to store wastewater (waste liquid) 30. The wastewater 30 is a liquid containing organic matter that is decomposed by microorganisms 20, and one example of this is kitchen wastewater. As will be described later, the wastewater 30 is supplied to the cathode electrode C attached to the cathode holder 13.

[0035] The water reservoir 142, that is, the interior of the housing 141, is provided with a first stick 144 and a second stick 145. The sticks 144 and 145 are rod-shaped protrusions from the inner surface of the housing 141, and as an example, they are rod-shaped members that connect to the opposite side.

[0036] The first stick 144 is positioned at the lowest end of the cathode holder 13 connected to the insertion member 14, or at a lower position. The position T2 indicated by the first stick 144 is a marker used when injecting the drained water 30 into the water reservoir 142, and is used as a marker to indicate when the drained water 30 should be injected up to position T2.

[0037] The second stick 145 is positioned above the anode electrode A attached to the anode holder 12. The position T1 indicated by the second stick 145 is a marker indicating when the amount of drainage in the reservoir 142 decreases and when it is time to add more drainage. When the amount of drainage reaches position T1, it is used as a marker to inject the drainage. This ensures that the level of the drainage is maintained above position T1, and the front surface of the anode electrode A remains in contact with the drainage. As a result, the power generation efficiency can be improved.

[0038] The insertion member 14 has a tapered convex portion 14A that gradually narrows in width in the direction of arrow R. The direction of arrow R is downward with respect to the front view. This makes it easier to insert the power generation device 100 downward into the soil S.

[0039] The anode holder 12 is provided on the insertion member 14. Preferably, the anode holder 12 is provided on the protruding portion 14A. This makes it easier for the anode electrode A attached to the anode holder 12 to come into contact with the soil S.

[0040] Preferably, the insertion member 14 has multiple protrusions 14A, and an anode holder 12 is provided on each of the multiple protrusions 14A. In the illustrated power generation device 100, the insertion member 14 has two protrusions 14A, and an anode holder 12 is provided on each of the two protrusions 14A. This makes it possible to attach multiple anode electrodes A to the power generation device 100. In addition, in the power generation device 100, multiple anode electrodes A can be inserted into the soil S, and more contact of the anode electrodes A with the soil S can be obtained.

[0041] An insertion slit 121 is formed in the protruding portion 14A. Preferably, the insertion slit 121 is provided vertically in each protruding portion 14A. The upper and lower ends of the front insertion slit 121 and the rear insertion slit 121 are connected inside the housing 141 at the lower edge portion 123 and the upper edge portion 124, respectively.

[0042] The lower edge 123 and upper edge 124 support the anode electrode A, which is inserted through the insertion slit 121, from below and above, respectively. This attaches the anode electrode A to the anode holder 12. By attaching the anode electrode A to the water reservoir 142 inside the housing 141, the anode electrode A can be brought into contact with the drainage water stored in the water reservoir 142.

[0043] A drain port 122 is provided on the side of the protruding portion 14A. As a result, the wastewater stored in the water reservoir 142 is drained out of the housing 141 through the drain port 122 and supplied to the microorganisms 20 in the soil S when the power generation device 100 is inserted into the soil S. At this time, if the anode electrode A is attached to the anode holder 12, the wastewater is supplied to the microorganisms 20 in the soil S by passing through the anode electrode A. In addition, the anode electrode A attached to the anode holder 12 can be brought into contact with the microorganisms 20 in the soil S.

[0044] A connecting opening 143 is provided at the top of the housing 141 for inserting a connecting member 134 of the cathode holder 13, which will be described later. By inserting the connecting member 134 into the connecting opening 143, the cathode holder 13 is connected to the insertion member 14.

[0045] The connecting port 143 has a mechanism for connecting the cathode holder 13 to the insertion member 14 with a variable relative position. One example of the connecting mechanism is to make the length of the connecting port 143 in the height direction longer than the thickness of the connecting member 134. This makes the position of the connecting port 143 of the connecting member 134 variable in the height direction, and as a result, the cathode holder 13 can be positioned with a variable relative position to the insertion member 14.

[0046] The anode electrode A, attached to the anode holder 12, is electrically connected to the cathode electrode C, attached to the cathode holder 13. Therefore, the insertion member 14 has a wiring section 146 for wiring the conductor LA connected to the anode electrode A from the anode holder 12 to the cathode holder 13. For example, the wiring section 146 is arranged continuously inside the housing 141 from the anode holder 12 to the cathode holder 13 and has an internal cavity 146A. By placing the conductor LA in the internal cavity 146A, the conductor LA can be wired from the anode holder 12 to the cathode holder 13.

[0047] The cathode holder 13 has a frame portion 132 that holds the edge of the cathode electrode C, and an insertion slit 131 is formed on its front side. This allows the cathode electrode C to be inserted into the inside of the frame portion 132.

[0048] A groove 132B is formed on the inner side of the frame portion 132 where the insertion slit 131 is not formed. The cathode electrode C inserted through the insertion slit 131 is held in place by the frame portion 132 by fitting into the groove 132B. Because the cathode electrode C is held in place by the frame portion 132, the portions of the upper and lower surfaces of the cathode electrode C that are not held in place by the frame portion 132 can be exposed to the outside from the cathode holder 13. Therefore, as will be described later, the upper surface can be brought into contact with air and the lower surface can be brought into contact with drainage.

[0049] The frame portion 132 is connected to the connecting member 134. Preferably, the cathode holder 13 has two frame portions 132, and the connecting member 134 connects them. This allows two cathode electrodes C to be attached to the power generation device 100. As a result, the power generation efficiency can be improved.

[0050] The frame portion 132 has an outlet 132A formed at the boundary with the connecting member 134. The outlet 132A is a portion for drawing out the conductor LC connected to the cathode electrode C held in the frame portion 132 from the frame portion 132, and is, for example, a notch. This allows the connected conductor LC to be drawn out from the cathode electrode C held in the frame portion 132 to the outside of the frame portion 132.

[0051] When the connecting member 134 is inserted into the connecting opening 143 of the insertion member 14, both frame portions 132 protrude to the left and right from the insertion member 14 and are provided outside the water storage portion 142.

[0052] Preferably, the connecting member 134 has a restricting member that restricts the movement of the cathode holder 13. The restricting member is provided, for example, on the surface of the connecting member 134 that is in contact with the connecting opening 143, and is a member that increases friction between the connecting opening 143 and the connecting member. The restricting member is, for example, a rubber member 134A. As a result, after the connecting member 134 is inserted into the connecting opening 143, its movement is restricted by the frictional force generated between the rubber member 134A and the connecting opening 143.

[0053] The cathode electrode C attached to the cathode holder 13 is electrically connected to the anode electrode A attached to the anode holder 12. Therefore, the cathode holder 13 has a wiring section 135 for connecting the conductor LC connected to the cathode electrode C to the conductor LA wired from the anode holder 12.

[0054] The wiring section 135 has an internal cavity and has insertion openings 135A into the internal cavity on the surfaces facing each of the frame sections 132 connected to the left and right. The conductors LC drawn out from the outlets 132A of each of the left and right frame sections 132 are inserted into the internal cavity of the wiring section 135 through the insertion openings 135A.

[0055] The wiring section 135 has an insertion opening 135B on its front side that leads into the interior cavity. The conductor LA, which is wired into the interior cavity 146A of the wiring section 146 and pulled out from the upper end, is inserted into the interior cavity of the wiring section 135 through the insertion opening 135B.

[0056] The wiring section 135 has an outlet 135C on its upper surface. Conductors LA and LC are connected within the cavity of the wiring section 135, and conductor LS is pulled upward from the outlet 135C.

[0057] The wiring section 135 also functions as a support member for the device that supplies the generated power. For example, the wiring section 135 is configured so that the device that supplies the generated power can be fixed to its upper surface. Fixing can be done, for example, with a clip. The device that supplies the generated power is, for example, an LED (Light Emitting Diode) light bulb.

[0058] By drawing the conductor LS upward from the outlet 135C, the conductor LS can be easily connected to the equipment that supplies the generated power, which is supported by the wiring section 135. This allows for easy supply of the generated power.

[0059] The anode electrode A is an electrode body that collects electrons released by microorganisms 20 in the soil S when they take in organic matter in the wastewater 30. The cathode electrode C can be any electrode body made of a conductive material such as carbon.

[0060] The anode electrode A and cathode electrode C are, for example, electrode sheets made of activated carbon sheets, and are formed from, for example, carbon nanotube (CNT) composite paper. CNT composite paper is made by dispersing CNTs in pulp fibers, which are components of paper.

[0061] Preferably, the anode electrode A and the cathode electrode C are electrode sheets formed by laminating the ends of plate-shaped wires LA and LC with CNT composite paper. The ends of the plate-shaped wires LA and LC are, for example, stainless steel mesh. The anode electrode A and the cathode electrode C consist of two layers of activated carbon sheets with stainless steel mesh sandwiched in between. By using plate-shaped members such as stainless steel mesh as the ends of the wires LA and LC, it becomes easier to sandwich the ends of the wires LA and LC between the layered electrodes. By sandwiching the ends of the wires LA and LC between the layered electrodes, the connection of the wires LA and LC to the electrodes is facilitated.

[0062] Anode electrode A and cathode electrode C are produced, for example, by immersing a stainless steel mesh in a 6% by weight multilayer CNT solution to bond it, and then drying it in a flat container. A 6% by weight multilayer CNT solution can be produced, for example, by adding 0.5 g of carbon fiber, 0.5 g of activated carbon powder, and 0.5 g of cellulose fiber to 6 ml of a 6% multilayer CNT solution and operating a stirrer such as a magnetic stirrer at 600 rpm for 20 hours. Drying is carried out, for example, at 40°C for about 20 hours.

[0063] An air cathode is used for the cathode electrode C. An air cathode utilizes oxygen from the air. Therefore, the cathode electrode C is attached to the cathode holder 13 so as to be in contact with both drainage and outside air. Specifically, as shown in Figure 10, the power generation device 100 is inserted into the soil S up to the position of the cathode holder 13, and drainage 30 is injected into the water reservoir 142 to a height that does not exceed the position of the cathode holder 13. As a result, the lower surface of the cathode electrode C attached to the cathode holder 13 comes into contact with the drainage 30, and the upper surface comes into contact with the air. Consequently, the cathode electrode C functions as an air cathode.

[0064] The power generation device 100 is used and generates electricity as shown in Figure 10. Specifically, referring to Figure 10, the anode electrode A is attached to the anode holder 12, the cathode electrode C is attached to the cathode holder 13, and the insertion member 14 is inserted into the soil S where the microorganisms 20 are present. The cathode holder 13 is connected to the insertion member 14 so that the cathode electrode C is aligned with the upper surface of the soil S, and its position is fixed.

[0065] Drainage water 30 is injected into the water reservoir 142 of the power generation device 100, which is inserted into the soil S, up to position T2. ​​The drainage water 30 injected into the water reservoir 142 passes through the anode electrode A and is drained out of the housing 141 from the drain port 122, as shown by arrow T in Figure 10, and is supplied to the microorganisms 20 in the soil S.

[0066] Microorganisms 20 decompose organic matter 31 contained in wastewater 30. Electrons e- generated when organic matter 31 is decomposed by microorganisms 20 are recovered at anode electrode A. The recovered electrons e- are moved from anode electrode A to cathode electrode C via wire LA. Protons (H+) are generated at anode electrode A. The protons react with the electrons e- that have moved from anode electrode A to cathode electrode C, and with oxygen, to produce water.

[0067] In the power generation device 100, a current is generated from the cathode electrode C to the anode electrode A in the opposite direction to the movement of electrons e-. By converting this current into a digital voltage signal, the power generation device 100 can obtain electrical energy.

[0068] The inventors conducted demonstration experiments to prove the power generation capacity of the power generation device 100. In the first experiment, the open circuit voltage (OCV) and power density were measured while the injected wastewater 30 was kept at 30-31°C in an incubator under the following first and second conditions. The open circuit voltage was measured over time. The power density was measured by varying the external resistance in the range of 10Ω to 0.15kΩ. Condition 1: After inserting into soil S, tap water was added 24 hours later. Subsequently, 20 ml of tap water was added every 72 hours. Second condition: After inserting into soil S, rice washing wastewater was added 24 hours later. Subsequently, 20 ml of rice washing wastewater was added every 72 hours.

[0069] Soil S was collected from a drainage channel near a paddy field, and its parameters were pH: 4.5, electrical conductivity (EC): 1.36 dS / m, and total carbon content (TC): 85,200 mg / kg.

[0070] The results shown in Figures 11 and 12 were obtained from the first experiment. Figure 11 shows the time variation of the measured open-circuit voltage (OCV). Figure 12 shows the time variation of the maximum power density under the first and second conditions, respectively.

[0071] As shown in Figure 11, the maximum open-circuit voltage obtained when tap water was used as wastewater 30 (Condition 1) was 0.57V, and the maximum open-circuit voltage obtained when rice washing wastewater was used (Condition 2) was 0.83V. From the results in Figure 11, it was found that the open-circuit voltage was generally higher when rice washing wastewater was used as wastewater 30 (Condition 2) than when tap water was used (Condition 1), and that the voltage decreased less over time.

[0072] As shown in Figure 12, when tap water was used as wastewater 30 (Condition 1), the maximum power density gradually increased from immediately after the start and leveled off after about 240 hours. In contrast, when rice washing wastewater was used as wastewater 30 (Condition 2), the maximum open-circuit voltage increased significantly from immediately after the start, and the maximum power density decreased after about 190 hours. The maximum power density when rice washing wastewater was used (Condition 2) was 490 mW / m². 2 To some extent, it was obtained.

[0073] The results of the first experiment showed that in the power generation device 100, using rice washing wastewater as the wastewater 30 resulted in higher power generation efficiency than using tap water. This is thought to be because rice washing wastewater contains more organic matter 31 than tap water.

[0074] Even when rice washing wastewater was used as the wastewater 30, it was found that continuous power generation was only possible for about 190 hours after the start. This suggests that the pH on the surface of the anode electrode A increases due to the fermentation of organic matter 31, which in turn reduces the activity of microorganisms 20.

[0075] In the second experiment, sandy soil was used as the soil S, and the injected drainage 30 was set to the first and second conditions below, while all other conditions were the same as in the first experiment. The open circuit voltage (OCV) and power density were then measured. Condition 1: Tap water was added 48 hours after insertion into soil S. Subsequently, tap water was added after each power density measurement. Second condition: After insertion into soil S, rice washing wastewater was added 48 hours later. Subsequently, rice washing wastewater was added after each power density measurement.

[0076] The results shown in Figures 13 and 14 were obtained from the second experiment. Figure 13 shows the time variation of the measured open-circuit voltage. Figure 14 shows the time variation of the maximum power density under the first and second conditions, respectively.

[0077] As shown in Figure 13, the maximum open-circuit voltage obtained when tap water was used as wastewater 30 (Condition 1) was -0.1V, and the maximum open-circuit voltage obtained when rice washing wastewater was used (Condition 2) was 0.62V. As shown in Figure 13, when tap water was used as wastewater 30 (Condition 1), the maximum open-circuit voltage remained almost constant around 0V, whereas when rice washing wastewater was used (Condition 2), it rose after about 48 hours from the start and maintained a high voltage.

[0078] As shown in Figure 14, when tap water was used as wastewater 30 (Condition 1), the maximum force density remained almost constant around 0V, whereas when rice washing wastewater was used (Condition 2), it increased after about 70 hours from the start and gradually decreased after about 240 hours. The maximum force density when rice washing wastewater was used (Condition 2) was 110 mW / m². 2 To some extent, it was obtained.

[0079] Comparing the results of the first and second experiments, it was found that using soil collected from drainage channels near paddy fields resulted in higher power generation efficiency than using sandy soil as soil S. This is thought to be because the soil collected from drainage channels near paddy fields contains more microorganisms 20 in soil S than sandy soil.

[0080] The housing 141 of the power generation device 100 has a protruding portion 14A, making it easy to insert into the soil S. Furthermore, the anode electrode A and cathode electrode C are easily attached to their respective holders, and the conductors LA and LC are easily wired, making it easy to transport. Therefore, for example, it can be easily carried to drainage channels near rice paddies and used by inserting it into the soil.

[0081] In the power generation device 100, the anode electrode A is detachably attached to the anode holder 12. Therefore, even if the power generation efficiency decreases as shown in the experimental results in Figure 12, the anode electrode A can be easily replaced. As a result, high power generation efficiency can be easily maintained.

[0082] In the power generation device 100, rice washing wastewater is suitable as the wastewater 30. Similarly, kitchen wastewater is also considered suitable. Therefore, it becomes possible to recycle wastewater such as rice washing wastewater, which can reduce the environmental impact. In addition, the costs associated with power generation can be reduced.

[0083] [Second Embodiment]

[0084] Figure 15 is a schematic perspective view of the power generation device 300 according to the second embodiment, taken from diagonally above. Figure 16 is a schematic perspective view showing how the anode electrode A and cathode electrode C are attached to the power generation device 300 of Figure 15. Figure 17 is a schematic perspective view showing the power generation device 300 of Figure 15 with the anode electrode A and cathode electrode C attached.

[0085] Figure 18 is a plan view of the power generation device 300. Figure 19 is a plan view of the power generation device 300 with the wires LA and LC from the anode electrode A and cathode electrode C, respectively, wired. Figure 20 is a side view of the power generation device 300. Figure 21 is a front view of the power generation device 300. Figure 22 is a cross-sectional view of CC of Figure 18, showing only the anode holder 34 portion of the power generation device 300.

[0086] Figure 23 is a diagram illustrating how the power generation device 300 is used. The power generation device 300 is a so-called microbial electrolysis device that generates electricity by utilizing the metabolic reaction in which microorganisms 20 decompose organic fuel, and uses soil S as an electrolyte (biofuel).

[0087] The power generator 300 includes an anode holder 32 to which an anode electrode A can be attached, and a cathode holder 33 to which a cathode electrode C can be attached. The anode holder 32 and the cathode holder 33 are detachable from the anode electrode A and the cathode electrode C, respectively, and the anode holder 32 has an insertion slit 321 for inserting the anode electrode A. The anode electrode A is attached to the anode holder 32 by being inserted through the insertion slit 321 and removed by being pulled out through the insertion slit 321.

[0088] The power generation device 300 is used by inserting it into an environment where microorganisms 20 are present, as shown in Figure 23. An example of an environment where microorganisms 20 are present is soil S in which microorganisms are present. That is, the power generation device 300 is used by inserting it into the soil S in the direction of arrow R in Figures 15 to 17. Therefore, the power generation device 300 is further provided with an insertion member 34 for inserting the power generation device 300 into an environment where microorganisms 20 are present. Arrow R indicates the direction in which the power generation device 300 is inserted into the soil S.

[0089] The insert member 34 has a structure 341. The structure 341 is, for example, a lattice shape formed by a combination of vertical and horizontal rod-shaped members. More specifically, the structure 341 has a plurality of frames 341A, 341B, 341C having openings 322 in the lateral direction, and connecting members 341D connecting them at the top. In this example, the structure 341 has three frames 341A, 341B, 341C. The structure 341 is formed from a polymer, for example, using a 3D printer. This allows for the easy formation of complex shapes.

[0090] Preferably, the structure 341 is formed from a biodegradable polymer. The biodegradable polymer is, for example, polylactide. This allows it to be decomposed by microorganisms, and even when the power generation device 300 is installed in the external environment, the impact on the external environment can be minimized.

[0091] Each frame 341A, 341B, and 341C has a tapered convex portion 34A that gradually narrows in the direction of arrow R. The direction of arrow R is downward relative to the front view. This makes it easier to insert the power generation device 300 downward into the soil S.

[0092] The anode holder 32 is provided on the insertion member 34. Preferably, the anode holder 32 is provided on the protruding portion 34A of each frame 341A, 341B, 341C. This makes it easier for the anode electrode A attached to the anode holder 32 to come into contact with the soil S.

[0093] Furthermore, since anode holders 32 are provided on the protruding portion 34A of each frame 341A, 341B, and 341C, it becomes possible to attach multiple anode electrodes A to the power generation device 300. In addition, in the power generation device 300, multiple anode electrodes A can be inserted into the soil S, and more contact between the anode electrodes A and the soil S can be obtained.

[0094] An insertion slit 321 is formed in the protruding portion 34A of each frame 341A, 341B, and 341C. Preferably, the insertion slit 321 is provided vertically in each protruding portion 34A. The insertion slit 321 on the front side and the insertion slit 321 on the back side are connected at their lower ends by a lower edge portion 323. A groove 323A is formed in the lower edge portion 323. As a result, the anode electrode A is held in each frame 341A, 341B, and 341C on the front and back sides, fixing it in the left-right and up-down directions, while at the opening 322, the lower edge portion 323 prevents it from falling downwards, and the groove 323A fixes it in the left-right direction.

[0095] Since openings 322 are formed on the sides of the protruding portion 34A of each frame 341A, 341B, and 341C, when the anode electrode A is attached to the anode holder 32 and the power generation device 300 is inserted into the soil S, the anode electrode A attached to the anode holder 32 can be brought into contact with the microorganisms 20 in the soil S.

[0096] The anode electrode A, attached to the anode holder 32, is electrically connected to the cathode electrode C, attached to the cathode holder 33. Therefore, each frame 341A, 341B, and 341C of the insertion member 34 is formed with a wiring groove 342 for routing the conductor LA connected to the anode electrode A from the anode holder 32 to the cathode holder 33, and a lead hole 343 for pulling out the conductor LA from the anode electrode A.

[0097] The lead-out hole 343 is an opening on the front side of each frame 341A, 341B, and 341C, and is in communication with the opening 322. The wiring groove 342 is a groove provided on the front side of each frame 341A, 341B, and 341C, continuously from the lead-out hole 343 to the cathode holder 13. As a result, the conductor LA is drawn out from the anode electrode A attached to the anode holder 32 through the lead-out hole 343 to each frame 341A, 341B, and 341C. The drawn-out conductor LA is then placed in the wiring groove 342 from the lead-out hole 343 to the cathode holder 13.

[0098] The cathode holder 33 has a plurality of legs 331 that hold the cathode electrode C around it, and an upper plate portion 332 to which the upper ends of the plurality of legs 331 are connected. The lower ends of the plurality of legs 331 are not connected. Therefore, the cathode electrode C can be inserted inward from the lower end side of the plurality of legs 331.

[0099] At least one of the multiple leg portions 331 is provided with a connecting portion 337 for connecting to a connecting member 341D of the insertion member 34. The connecting portion 337 is, for example, a claw, and by hooking the connecting member 341D onto the connecting member 341D, the cathode holder 33 can be attached to and detached from the insertion member 34. Because the cathode holder 33 can be attached to and detached from the insertion member 34, the cathode electrode C can be attached to and detached from the cathode holder 33.

[0100] A wiring groove 333 is formed on the front surface of at least the front-facing leg portion 331 of the multiple leg portions 331, extending from the lower end to the upper end. The wiring groove 333 is positioned to be continuous with the wiring groove 342 formed in the insertion member 34 when the cathode holder 33 is attached to the insertion member 34. As a result, the conductor LA from the anode electrode A is placed in the wiring groove 342 and reaches the cathode holder 33, and then placed in the wiring groove 333 and reaches the upper end of the leg portion 331.

[0101] A support portion 336 is formed on the upper surface of the upper plate portion 332 to support the equipment that supplies the generated power. The support portion 336 is, for example, a recess provided on the upper surface of the upper plate portion 332, in which the equipment is set and used.

[0102] Near the upper end of the wiring groove 333, an outlet 334 is provided that penetrates from the front surface of the leg portion 331 to the upper surface of the top plate portion 332. As a result, the conductor LA that has been routed to the upper end of the wiring groove 333 is pulled out from the outlet 334 to the upper surface of the top plate portion 332.

[0103] At least one of the multiple legs 331 is provided with an outlet 335 that penetrates from the inside to the upper surface of the upper plate 332. As a result, the wire LC from the cathode electrode C attached to the cathode holder 33 is drawn out from the outlet 335 to the upper surface of the upper plate 332.

[0104] By bringing the conductors LA and LC out onto the upper surface of the upper plate portion 332, the conductors LA and LC can be easily connected to the equipment set on the support portion 336. This allows the generated power to be easily supplied to the equipment set on the support portion 336.

[0105] The anode electrode A has the same multilayer structure of electrode sheets as the power generation device 100 according to the first embodiment. For example, the anode electrode A may have a structure consisting of two electrode sheets attached with 6 ml of a 6% multilayer CNT solution. The conductor LA may be a copper wire.

[0106] An air cathode is used for the cathode electrode C. The cathode electrode C also has the same multilayer structure of electrode sheets as the power generation device 100 according to the first embodiment. Furthermore, the cathode electrode C includes an ion exchange membrane. For example, the cathode electrode C may have a structure consisting of three electrode sheets attached with a mixture of 1.5 ml of 6% multilayer CNT solution and 10% Nafion (registered trademark) in a 2:1 ratio. The conductor wire LC may be a stainless steel mesh, similar to the electrode used in the first embodiment, and may be sandwiched between the three electrode sheets.

[0107] The cathode electrode C is further used laminated onto the float member F. For example, the cathode electrode C is attached to the underside of the float member F. The float member F is a member that floats on water and is made of, for example, polyethylene foam.

[0108] When the cathode electrode C attached to the float member F is mounted to the cathode holder 33 and the power generation device 300 is used as shown in Figure 23, the cathode electrode C floats to the water surface due to the buoyancy generated by the float member F. Therefore, the cathode holder 33 can be used to mount the cathode electrode C in a variable relative position to the insertion member 34.

[0109] When the cathode electrode C floats to the water surface due to the buoyancy generated by the float member F and reaches the upper plate portion 332, further floating is restricted by the upper plate portion 332. Therefore, the upper plate portion 332 of the cathode holder 33 functions as a restricting member that restricts the movement of the cathode electrode C.

[0110] When the cathode electrode C moves laterally due to the water flow acting on the float member F and reaches one of the multiple legs 331 that hold the cathode electrode C around, further lateral movement is restricted by the legs 331. Therefore, the multiple legs 331 of the cathode holder 33 also function as restricting members that restrict the movement of the cathode electrode C. This prevents the position of the cathode electrode C from becoming inappropriate due to water flow or volume.

[0111] The power generation device 300 is used and generates electricity as shown in Figure 23. Specifically, referring to Figure 23, the anode electrode A is attached to the anode holder 32, the cathode electrode C is attached to the cathode holder 33, and the insertion member 34 is inserted into the moist soil S where microorganisms 20 are present. The insertion member 34 is inserted into the soil S to a position where the anode electrode A attached to the anode holder 32 is completely buried in the soil S, and the water level of the water 30A in the soil S does not exceed the upper plate portion 332 of the cathode holder 33. This allows the anode electrode A to come into contact with the soil S more, improving the power generation efficiency. In addition, the water 30A in the soil S causes the float member F to float to the water surface, allowing the cathode electrode C to come into contact with the air.

[0112] When organic matter 31 is attached to the surface of anode electrode A, microorganisms 20 in soil S decompose the organic matter 31. The electrons e- generated during decomposition are recovered at anode electrode A. The recovered electrons e- are moved from anode electrode A to cathode electrode C via the wire LA. Protons (H+) are generated at anode electrode A. The protons react with the electrons e- that have moved from anode electrode A to cathode electrode C, and with oxygen, to produce water.

[0113] In the power generation device 300, a current is generated from the cathode electrode C to the anode electrode A in the opposite direction to the movement of electrons e-. By converting this current into a digital voltage signal, electrical energy is obtained in the power generation device 100.

[0114] The inventors conducted demonstration experiments to verify the power generation capacity of the power generation device 300. In the first experiment, water-saturated soil S was used as the lower first anode electrode A and second anode electrode A, and the open-circuit voltage (OCV) and power density were measured in the same manner as in the first embodiment while maintaining the temperature at 30-33°C in an incubator. First anode electrode A: Anode electrode A coated with 0.5 ml of LB medium and air-dried. Second anode electrode A: Anode electrode A without coating with LB medium

[0115] As an example, a typical LB medium was used, which was prepared by mixing 10 g / l glucose, 10 g / l tryptone, 5 g / l yeast extract, 10 g / l sodium chloride, and 10 g / l sodium hydroxide and adjusting the pH to 7.0. The LB medium corresponds to organic matter 31, with the first anode electrode A having organic matter 31 and the second anode electrode A not having organic matter 31.

[0116] Soil S was collected from a drainage channel near a paddy field, and its parameters were pH: 4.5, electrical conductivity (EC): 1.36 dS / m, and total carbon content (TC): 85,200 mg / kg.

[0117] In the first experiment, the soil S was replaced using the first anode electrode A and the second anode electrode A respectively. Without replacing either the first or second anode electrode A, the open-circuit voltage (OCV) and power density were measured continuously for three cycles (R0, R1, R2), with each cycle defined as 312 hours.

[0118] The results shown in Figures 24-27 were obtained from the first experiment. Figure 24 shows the time evolution of the open-circuit voltage (OCV) measured in each cycle using the first anode electrode A. Figure 25 shows the time evolution of the open-circuit voltage (OCV) measured in each cycle using the second anode electrode A. In Figures 24 and 25, the gray time periods represent periods without discharge, and the white time periods represent periods with discharge. Figure 26 shows the time evolution of the maximum power density measured in each cycle using the first anode electrode A. Figure 27 shows the time evolution of the maximum power density measured in each cycle using the second anode electrode A.

[0119] As shown in Figures 24 and 25, both when using anode electrode A coated with LB medium (first anode electrode A) and when using anode electrode A without LB medium coating (second anode electrode A), the maximum output and stable state of the open-circuit voltage were reached approximately 5 days after the start. This is thought to be because a microbial film is formed on the surface of anode electrode A approximately 5 days after the start.

[0120] As shown in Figure 24, when using anode electrode A coated with LB medium (first anode electrode A), the maximum open-circuit voltage was 0.6V obtained in the first cycle (R0). In contrast, as shown in Figure 25, when using anode electrode A without LB medium coating (second anode electrode A), the maximum open-circuit voltage was 0.48V obtained in the first cycle (R0).

[0121] As shown in Figure 26, when using anode electrode A coated with LB medium (first anode electrode A), the maximum power density was 130 mW / m² one week after the start of the first cycle (R0). 2 This value was obtained and reached its maximum value. Subsequently, in the second cycle (R1) and the third cycle (R2), the maximum value of the maximum power density decreased by approximately 50%.

[0122] In contrast, as shown in Figure 27, when using anode electrode A (second anode electrode A) without LB medium coating, the maximum power density obtained in each cycle was 60-70130 mW / m². 2 The values ​​are generally lower than when using the first anode electrode A. Furthermore, there is no significant change in the maximum power density obtained in each cycle.

[0123] From the first experiment, it was considered that adding organic matter 31, such as coating anode electrode A with LB culture medium, increases power generation efficiency. Furthermore, it was considered effective to replace anode electrode A with added organic matter 31. After the experiment, the surface of anode electrode A was covered with a hard, brown layer, which is thought to be caused by calcium, iron, and other minerals contained in soil S. The decrease in power generation efficiency may be due to deterioration of the electrode surface in addition to a lack of organic matter 31.

[0124] In the power generation device 300, the anode electrode A is detachably attached to the anode holder 32, allowing for easy replacement of the anode electrode A. Therefore, high power generation efficiency can be easily maintained.

[0125] In the second experiment, two cathode electrodes C were used: one attached to the float member F (the first cathode electrode C) and another fixed and not attached to the float member F (the second cathode electrode C). Under the same conditions as the first experiment, power was generated for only one cycle and the open-circuit voltage (OCV) was measured. When the second cathode electrode C was used, the cathode electrode C was submerged below the surface of the soil S and completely submerged.

[0126] The results shown in Figure 28 were obtained in the second experiment. Figure 28 shows the time variation of the open-circuit voltage (OCV) measured using the first cathode electrode C and the second cathode electrode C. In Figure 28, the gray time periods represent periods without discharge, and the white time periods represent periods with discharge.

[0127] Figure 28 shows that the open-circuit voltage is significantly higher when the cathode electrode C is attached to the float member F. This is thought to be because the cathode electrode C is submerged in water, preventing air from being supplied to it.

[0128] In the power generation device 300, it was demonstrated that high power generation efficiency can be obtained because the cathode electrode C is attached to the float member F.

[0129] <3. Addendum> The present invention is not limited to the above embodiments, and various modifications are possible. [Explanation of Symbols]

[0130] 12: Anode holder 13: Cathode holder 14: Insertion part 14A: Convex part 20: Microorganisms 30: Drainage 30A: Water 31:Organic matter 32: Anode holder 33: Cathode holder 34: Insertion part 34A: Convex part 100: Power generation device 121: Insertion slit 122:Drain port 123 :Lower edge 124: Upper edge 131: Insertion slit 132: Frame 132A:Drawer opening 132B: Groove 134: Connecting member 134A: Rubber material 135: Wiring section 135A: Insertion port 135B: Insertion port 135C:Drawer opening 141: Cabinet 142: Water storage section 143: Connection port 144: First Stick 145: Second Stick 146:Wiring section 146A: Inner sky 300: Power generation equipment 321: Insertion slit 322 :Aperture 323 :Lower edge 323A: Groove 331: Legs 332: Upper plate section 333: Wiring groove 334 :Drawer opening 335 :Drawer opening 336: Support part 337 :Connection part 341 :Structure 341A: Frame 341B: Frame 341C: Frame 341D: Connecting member 342: Wiring groove 343 :Drawer hole A: Anode electrode C: Cathode electrode F: Float component LA: Conductor LC: Conductor LS: Conductor R: Arrow S: soil T: Arrow

Claims

1. A power generation device that generates electricity using the metabolic reactions of microorganisms, an anode holder to which an anode electrode can be attached, A cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder, It comprises an insertion member for inserting into soil where microorganisms are present, The anode holder is configured to allow the anode electrode to be detachably attached and is provided on the insertion member. The insertion member is provided with wiring for electrically connecting the anode electrode attached to the anode holder and the cathode electrode attached to the cathode holder. A power generator.

2. The cathode holder allows the cathode electrode to be mounted in a position that is variable relative to the insertion member. The power generation apparatus according to claim 1.

3. The insertion member has a water reservoir inside for storing the liquid supplied to the cathode electrode attached to the cathode holder, The aforementioned liquid is a liquid containing organic matter. The power generation apparatus according to claim 1.

4. The water storage section has a drain port for draining the liquid to the outside by passing it through the anode electrode attached to the anode holder. The cathode holder is provided on the outside of the water reservoir. The power generation device according to claim 3.

5. The water reservoir is provided with a marker based on the position of the cathode holder. The power generation device according to claim 3 or 4.

6. The cathode holder has a float member. The power generation device according to claim 2.

7. The cathode holder further comprises a restricting member that restricts the movement of the cathode electrode attached to the cathode holder. The power generation device according to claim 6.

8. The insertion member has one or more tapered convex portions that gradually narrow in the direction in which it is inserted into the soil. A power generation device according to any one of claims 1 to 7.

9. The insert member has a plurality of the aforementioned protruding portions, Each of the aforementioned multiple protruding portions is provided with the anode holder. The power generation device according to claim 8.

10. The insertion member is provided with a slit for inserting the anode electrode. A power generation device according to any one of claims 1 to 9.

11. The system further includes a support member for supporting the equipment that supplies the generated power. A power generation device according to any one of claims 1 to 10.

12. A power generation device that generates electricity using the metabolic reaction of microorganisms, an anode holder to which an anode electrode can be attached, A cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder, It comprises an insertion member for inserting into soil where microorganisms are present, The anode holder is configured to allow the anode electrode to be detachably attached and is provided on the insertion member. The insertion member has a reservoir inside for storing a liquid containing organic matter that is supplied to the cathode electrode attached to the cathode holder. The water storage section has a drain port for draining the liquid to the outside by passing it through the anode electrode attached to the anode holder. The cathode holder is provided on the outside of the water reservoir. A power generator.

13. A power generation device that generates electricity using the metabolic reaction of microorganisms, an anode holder to which an anode electrode can be attached, A cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder, It comprises an insertion member for inserting into soil where microorganisms are present, The anode holder is configured to allow the anode electrode to be detachably attached and is provided on the insertion member. The insertion member has a reservoir inside for storing a liquid containing organic matter that is supplied to the cathode electrode attached to the cathode holder. The water reservoir is provided with a marker based on the position of the cathode holder. A power generator.

14. A power generation device that generates electricity using the metabolic reaction of microorganisms, an anode holder to which an anode electrode can be attached, A cathode holder to which a cathode electrode can be attached so as to be electrically connected to the anode electrode attached to the anode holder, It comprises an insertion member for inserting into soil where microorganisms are present, The anode holder is configured to allow the anode electrode to be detachably attached and is provided on the insertion member. The cathode holder is capable of mounting the cathode electrode in a manner that allows for variable relative positioning with respect to the insertion member. The cathode holder has a float member. A power generator.

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