CN105308317A - Large-capacity electric power storage system using thermal energy/chemical potential - Google Patents

Abstract

The present invention relates to a large-capacity power storage system using salt water, which is capable of separating salt water into high-concentration salt water and fresh water and storing them using excess power during low loads, and when power consumption increases rapidly (such as at peak loads) Period) to generate electricity using the concentration difference between high-concentration salt water and fresh water. The ultra-large-capacity power storage system using brine includes: a concentration device for concentrating/separating brine and supplying concentrated brine and fresh water; a concentrated brine storage device and a fresh water storage device for respectively storing the concentrated brine and fresh water supplied by the concentration device; a salinity difference power generation device connected to a concentrated brine storage device and a fresh water storage device to generate electricity using the concentration difference between the concentrated brine and fresh water; and a brine storage device for storing The brine that has passed through the salinity difference power plant is supplied to the concentration plant.

Description

Large-capacity power storage system using thermal energy/chemical potential

technical field

The present invention relates to a large-capacity power storage system using thermal energy and chemical potential, and more particularly, to a large-capacity power storage system using brine capable of separating brine into high-concentration using excess power during periods of low load salt water and fresh water to store it, and use the difference in concentration between highly concentrated brine and fresh water during peak loads (during which there is a rapidly growing power consumption) to generate electricity, and use waste heat to raise The temperature of salt water and fresh water to raise the chemical potential in conventional equipment.

Background technique

In centralized power generation such as thermal power generation or nuclear power generation, there is a disadvantage that in order to meet peak power demand, a large-scale backup power should usually be prepared in advance even if the operating rate of the equipment will be reduced.

In addition, new renewable energy using wind power generation, solar photovoltaic power generation, and the like is not suitable for reliable power supply because the amount of power fluctuates greatly depending on the climate.

Therefore, for centralized power generation, for the purpose of preparing for peak power demand and in order to solve the problem of unstable power supply caused by environmental factors in power generation using new renewable energy, a large-capacity power storage is required system.

For example, the currently used large-capacity power storage systems include batteries (lead batteries, network-attached storage (NaS), lithium-ion batteries, metal-air batteries, redox flow batteries, etc.), pumping power generation, and compressed air energy storage (CAES). , ultra-large capacity, flywheels and superconducting magnetic energy storage (SMES), etc.

Except for pumping power generation and CAES, the large-capacity power storage systems described above require high initial investment costs and have limitations in storage capacity (less than 1GW), so it is difficult to use GW-level large-capacity power Storage System.

In addition, pumping type power generation with low initial investment cost poses a problem that its own construction is difficult because of restrictions on site selection and risk of disturbing the ecosystem (Korean Patent Registration No. 10-102056).

In addition, CAES has limitations in use because it is necessary to find a sufficiently solid ground to store compressed air (Korean Patent Laid-Open Publication No. 10-2011-7026187).

Contents of the invention

technical problem

Considering the problems mentioned above, it is an object of the present invention to provide a large-capacity power storage system that stores thermal energy by simultaneously utilizing waste heat from a power station, exhaust gas from a diesel generator, or other heating media so that the efficiency of the chemical potential storage system Maximized, the bulk power storage system is capable of addressing unstable power demand and supply in centralized power generation and power generation using new renewable energy, unlike conventional bulk in the field using brine at room temperature power storage system.

Technical solutions

In order to achieve the above objects, there is provided an ultra-large-capacity power storage system using brine, including: a concentration device configured to concentrate brine and separate the brine into concentrated brine and fresh water to supply the concentrated brine and the fresh water; a concentrated brine storage device and a fresh water storage device configured to respectively store concentrated brine and fresh water supplied from the concentration device; a salinity difference power generation device, the salinity difference power generation device connected to a concentrated brine storage device and a fresh water storage device to generate electricity using a difference in concentration between the concentrated brine and fresh water; and a brine storage device configured to store brine passing through the salinity difference power generation device , and the brine is supplied to the concentrating device, wherein at least one of the concentrated brine, the brine, and the fresh water is heated by a heat exchange circuit.

The brine supplied to the concentrating device may be supplied from a brine storage device or a brine supply source.

The fresh water supplied to the salinity differential power plant may be supplied from a fresh water storage facility or a fresh water supply source.

The power generation device may include one or more power generation elements, and the power generation elements may include: an anode path through which the electrode solution flows; a cathode path through which the electrode solution flows and the cathode path is disposed facing the anode path, spaced apart from the anode path; and a fresh water path through which the fresh water flows, and a salt water path through which the salt water flows, the fresh water path and the salt water path The brine paths are alternately placed from the anode paths between the anode paths and the cathode paths adjoining the brine paths, wherein the anode paths and the cathode paths may form a closed loop so that the electrode cleaning solution circulates therein, when the fresh water paths and the brine When the paths are placed in this order based on the direction from the anode path to the cathode path, the cation exchange membrane can be placed between the anode path and the fresh water path, and the cathode path and the salt water path, and the anion exchange membrane can be placed between the fresh water path and the salt water path between the paths, and when the salt water path and the fresh water path are placed in this order based on the direction from the anode path to the cathode path, the cation exchange membrane can be placed between the salt water path and the fresh water path, and the cations of the electrode solution and the cations of the salt water can be the same as each other.

The anode path and the cathode path may include electrode active material therein.

Beneficial effect

According to the present invention, a closed loop in which brine circulates as an energy storage medium can be formed by the storage of electricity by separating the brine and the generation of electricity by concentrating the separated A mixture of salt water and fresh water. In addition, when the temperature of the introduced salt water and fresh water is raised by heat exchange with waste heat of a power station, the activity of ions contained in the aqueous solution is enhanced, whereby the effect of heat storage becomes an increase in chemical potential.

Furthermore, the power storage system can be used for the purpose of collecting useful resources (salt and minerals) from the concentrated brine, the purpose of using it as drinking water, etc., whereby by-products can also be utilized, if necessary.

Furthermore, the power storage system according to the present invention can use brine to reduce initial investment costs. Furthermore, storing energy by using highly concentrated salt can provide a competitive power storage system due to higher energy density and smaller capacity of storage banks compared to hydroelectric power systems.

Description of drawings

FIG. 1 is a schematic diagram of a large-capacity power storage system using salt water according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a power generation unit of a salinity difference power generation device used in the large-capacity power storage system of FIG. 1 .

FIG. 3 is a graph of power generation output in consideration of temperature variable factors in the power generation unit of FIG. 2 .

detailed description

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Referring to the drawings, like reference numerals indicate like or corresponding parts throughout the several views. In the embodiments of the present invention, well-known functions and constructions which are considered to unnecessarily obscure the intention of the present invention will not be described in detail.

A large-capacity power storage system using brine 100 according to an embodiment of the present invention generally includes a power storage unit 102 and a power generation unit 104 based on functional division. In the present invention, salt water is used as a comprehensive concept including brackish water.

The power storage unit 102 includes a concentration device 106 and the power generation unit 104 includes a salinity difference power generation device 114 . Here, the power storage unit 102 and the power generation unit 104 share a brine storage device 112 for storing brine, a concentrated brine storage device 110 for storing concentrated brine, and a fresh water storage device 108 for storing fresh water.

Therefore, fresh water and highly concentrated brine are stored in the fresh water storage device 108 and the concentrated brine storage device 110, respectively, which are separated using excess power during a low load period in thermal power generation, nuclear power generation, etc., Alternatively, the fresh water and highly concentrated salt water are separated using electric power with large fluctuations due to wind power generation or solar photovoltaic power generation.

For the concentrating device 106, any conventional technique known in the art may be used. For example, for the enrichment unit 106, various technologies can be used such as distillation (multi-stage flash (MSF), multiple-effect distillation (MED), vapor compression (VC)), ion exchange, membrane processes (electrodialysis reverse (EDR) ), reverse osmosis (RO), nanofiltration (NF), membrane distillation (MD)), capacitive deionization, freeze desalination, geothermal desalination, solar desalination (solar humidification and dehumidification (HDH), multi-effect humidification (MEH)), Methane hydrate crystallization, high-quality water reuse, seawater greenhouses, etc., but not limited to the above technologies in the present invention.

For the salinity difference power plant 114, various processes can be used, such as pressure retarded osmosis, reverse electrodialysis, capacitive methods, absorption refrigeration cycle, solar (energy) pool, etc., but are not limited in the present invention the above process.

The large-capacity power storage system 100 according to the present invention can store in the form of chemical potential using highly concentrated salt, and also store thermal energy by raising the temperature of salt water and fresh water. Thermal energy can be used for direct heating using exhaust air, hot water or excess electricity from multiple processes.

More specifically, the efficiency of the configuration system can be improved as the temperature of fresh water and salt water is increased, thereby increasing the efficiency of the separation process, including the power generation process.

In other words, if RED equipment is used in the power generation process, according to the research of E. Brauns, there is a report that when the temperature rises from 20°C to 30°C, the power generation efficiency increases by 25% (see E.Brauns, Desalination (Desalination), 237,378-391), and it can also be seen that when the temperature is raised in the PRO process, the power generation efficiency increases by 46% (see Y.C.Kim and M.Elimelech, J.Member.Sci., 429,330-337 ). In addition, when using a membrane distillation (MD) process as an apparatus for concentrating highly concentrated brine, it is necessary to supply heat of evaporation of moisture. Thereby, process efficiency may be increased when a mixture of brine and fresh water having an increasing temperature is introduced into the separation device. Thus, using the difference in ion concentration to store energy and at the same time maintain thermal energy can achieve further improved results.

In order to add this thermal energy to brine and fresh water, as shown in FIG. 1 , a concentrated brine storage device 110 storing concentrated brine and a fresh water storage device 108 storing fresh water are in contact with a heat exchange line 124 . The heat exchange line 124 is connected to a heat source (not shown) and includes a flowing heating medium therein, thereby transferring heat from the heating medium to concentrated brine or fresh water. In addition, another heat exchange line 126 may be provided to heat fresh water when fresh water is introduced therein from the outside. In addition, a fresh water buffer tank 128 for heat exchange with fresh water may be additionally installed, and heat may be supplied to the fresh water from the fresh water buffer tank 128 for a sufficient time.

FIG. 2 shows a concentration difference power generation element 130 that may be used to form the salinity difference power plant 114 . A plurality of power generation cells 130 may be used by being connected to each other in parallel or in series.

The power generation element 130 includes an anode current collector 131 and a cathode current collector 139 disposed separately from each other, and cation exchange membranes 133 and 137 disposed between the anode current collector 131 and the cathode current collector 139 within the space formed thereby approaching them and being spaced from them. In addition, an anion exchange membrane 135 is placed between the cation exchange membranes 133 and 137 .

Also, when two or more anion exchange membranes are placed between the two cation exchange membranes 133 and 137, the anion exchange membranes and cation exchange membranes may be placed alternately, but the anion exchange membranes should be placed on the outermost side.

According to the arrangement described above, the anode path 132 is formed between the anode current collector 131 and the cation exchange membrane 133 , and the cathode path 138 is formed between the cathode current collector 139 and the cation exchange membrane 137 . Additionally, fresh water paths 134 and salt water paths 136 alternate between anode paths 132 and cathode paths 138 . Spacers may be installed within the fresh water path 134, salt water path 136, anode path 132, and cathode path 138 to prevent the spacing therebetween from being altered.

The electrode solution circulates in the anode path 132 and the cathode path 138 , and the electrode solution has the same cations as the brine flowing in the brine path 136 . Therefore, the electrode solution has sodium ions (Na ⁺ ).

In this electrode solution, excess electrons or insufficient electrons caused by the inflow and outflow of sodium ions are filled by redox action of specific ions in the electrode solution. For example, when a mixed electrolyte solution of ferrocyanide (Fe(CN) ₆ ) and sodium chloride (NaCl) is used, electrons are charged by conversion between Fe ²⁺ and Fe ³⁺ . In addition, chloride ions (Cl ⁻ ) are contained in brine as anions. Electrolytes such as Na ₂ SO ₄ , FeCl ₂ , EDTA, etc. may be used instead of the above electrolytes.

As shown in FIG. 2, the migration of ions occurs in a fresh water path 134 and a salt water path 136 arranged sequentially between an anode path 132 of an anode electrode and a cathode path 138 of a cathode electrode. That is, cations (such as Na ⁺ ) move through the cation exchange membranes 133 and 137 , and anions (such as Cl ⁻ ) move through the anion exchange membrane 135 . Accordingly, cations of the anode path 132 may move toward the freshwater path 134 and cations of the salt water path 136 may move toward the cathode path 138 . Additionally, anions of the salt water path 136 may move toward the fresh water path 134 . As a result, during the movement of ions from the brine fraction with highly concentrated salt to the freshwater fraction with low salt concentration, cations move towards the right cathode electrode while anions move towards the left anode electrode. Thus, when ionic current flows from right to left, an oxidation reaction occurs in the anode path 132 to obtain electrons from the electrolyte, and a reduction reaction occurs in the cathode path 138 to apply electrons from the electrolyte. In this regard, electrons can flow along external conduction lines to generate an electric current. In this case, the voltage of the generated electricity may be measured by a voltmeter 140 connected to the anode current collector 131 and the cathode current collector 139 .

In this state, the electrode active material is dispersed in the anode path 132 and the cathode path 138, whereby ions can be absorbed more easily through the electrode active material. For such an electrode active material, porous carbon (activated carbon, carbon fiber, carbon aerogel, carbon nanotube, graphene, etc.), graphite powder, metal oxide powder, etc. can be used. The electrode active material loses the concentration difference therebetween after passing through the salinity difference power generation device 114, and is collected by a separate collecting device (for example, a filter) for reuse.

Therefore, it is possible to generate electricity from concentrated brine and fresh water by using the power generation unit 130 through the salinity difference power generation facility 114 . In this case, the generated electricity has the characteristics shown in Fig. 3, and the power density is 0.4 W/m ² at a temperature of 17°C and 0.68 W/m ² at a temperature of 35°C, respectively, the power density varies with remains roughly constant over time.

In addition, the concentrated brine and the fresh water exchange ions with each other while passing through the salinity difference power generation device 114 , thereby obtaining brine with a lower concentration than re-concentrated brine to store in the brine storage device 112 . The brine stored in the brine storage device 112 is supplied again to the concentration device 106 for a cycle of power storage and discharge.

In addition, the concentrated brine separated by the concentration device 106 can be discharged through the concentrated brine discharge valve 118 to be used in the production of useful resource (salt or mineral) salt, and the fresh water can be discharged through the fresh water discharge valve 120 for drinking water. In this regard, when a shortage occurs, concentrated water may be supplied to the concentrating device 106 by using the brine supply valve 116 connected to an external brine supply source, or fresh water may be supplied to the Salinity difference power plant 114.

Specifically, when fresh water is intentionally removed and salt water is further provided, the overall salt amount within the large-capacity power storage system 100 may increase, thereby increasing the salinity of the concentrated salt water. As a result, the concentration difference between fresh water and concentrated brine can be increased, thereby improving power generation efficiency.

In addition, by installing heat exchangers in brine and/or freshwater storage facilities, when using waste heat from a power station or a single generator to supply thermal energy, as shown in Figure 3, the salinity difference power generation efficiency is greatly improved compared to room temperature. That is, by heating and storing brine and/or fresh water, the output can be maintained at a high level, the size of the storage facility can be reduced, and the size of the power generation facility can also be reduced. In this regard, the storage temperature may be determined in consideration of the vapor pressure according to the temperature, or a device (not shown) for reducing the evaporation amount may be added.

The invention has been described with reference to preferred embodiments, and those skilled in the art will appreciate that various modifications and changes can be made therein without departing from the scope of the invention as defined in the appended claims.

Description of reference signs

100: Large-capacity power storage system

102: Power storage unit

104: Power generation unit

106: Enrichment equipment

108: Freshwater storage device

110: Concentrated brine storage facility

112: Brine Storage Equipment

114: Salinity difference power generation equipment

116: Salt water supply valve

118: concentrated brine discharge valve

120: fresh water discharge valve

122: Fresh water supply valve

124, 126: heat exchange circuit

128: Freshwater buffer tank

130: Concentration difference power generation unit

131: Anode current collector

132: Anode path

133, 137: Cation exchange membrane

134: Freshwater Path

135: Anion exchange membrane

136: Saltwater Path

138: Cathode path

139: Cathode current collector

140: Voltmeter

Claims (5)

1. use a vast capacity power storage system for salt solution, it comprises:

Concentrator, described concentrator is configured to carry out concentrated to salt solution and salt solution be separated into concentrated salt solution and fresh water to supply described concentrated salt solution and described fresh water;

Concentrated salt solution memory device and fresh water memory device, described concentrated salt solution memory device and fresh water memory device are configured to, and store the described concentrated salt solution and described fresh water supplied by described concentrator respectively;

Salinity gradient power generation equipment, described salinity gradient power generation equipment connection, to described concentrated salt solution memory device and described fresh water memory device, produces electric power to use the difference in the concentration between described concentrated salt solution and described fresh water; And

Salt solution memory device, described salt solution memory device is configured to store the described salt solution through described salinity gradient power generation equipment, and described salt solution is supplied to described concentrator,

At least one in wherein said concentrated salt solution, described salt solution and described fresh water is heated by heat exchange circuit.

2. the vast capacity power storage system of use salt solution according to claim 1, is wherein supplied to the described salt solution of described concentrator to be supplied by described salt solution memory device or salt solution supply source.

3. the vast capacity power storage system of use salt solution according to claim 1, is wherein supplied to the described fresh water of described salinity gradient power generation equipment to be supplied by described fresh water memory device or water supply source.

4. the vast capacity power storage system of use salt solution according to claim 1, wherein said power generating equipment comprises one or more generating primitive, and

Described generating primitive comprises:

Anode paths, solution electrode flows through described anode paths;

Negative electrode path, solution electrode is through described negative electrode path flow, and described negative electrode path is arranged to towards described anode paths, spaced apart with described anode paths; And

Fresh water path and salt water route, described fresh water is through described fresh water path flow, described salt solution is through described salt solution path flow, described fresh water path and described salt water route are alternately placed from described anode paths between described anode paths and described negative electrode path, salt water route described in described negative electrode pathway contiguous

Wherein said anode paths and formation closed-loop path, described negative electrode path thus electrode clean solution is circulated wherein,

When described fresh water path and described salt water route are based on when placing from described anode paths to the direction in described negative electrode path with this order, cation-exchange membrane is placed between described anode paths and described fresh water path, and between described negative electrode path and described salt water route, anion-exchange membrane is placed between described fresh water path and described salt water route, and when described salt water route and described fresh water path are based on when placing from described anode paths to the direction in described negative electrode path with this order, cation-exchange membrane is placed between described salt water route and described fresh water path, and

The positive ion of described solution electrode and the positive ion of described salt solution mutually the same.

5. the vast capacity power storage system of use salt solution according to claim 4, wherein said anode paths and described negative electrode path comprise electrode active material wherein.