KR20190054711A - System and method for complex grid of heat and electricity using electrolysis and fuel cell - Google Patents

Abstract

The present invention relates to a complex grid system of heat and electricity using water electrolysis and a fuel cell. The system comprises: an electricity supply unit for supplying stored electricity or produced electricity; a water electrolysis device for receiving the electricity from the electricity supply unit and electrolyzing the water; a hydrogen tank for storing hydrogen electrolyzed from the water electrolysis device; and a fuel cell for generating heat and electricity by using hydrogen in the hydrogen tank and air in the atmosphere. When a fuel cell starts driving at the time of power failure or a peak load, the start-up time can be shortened and the response time to load variation can be shortened.

Description

TECHNICAL FIELD [0001] The present invention relates to a grid system and a method for operating the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a grid system for thermal electricity using fuel cells and a fuel cell, and more particularly, And to a thermoelectric composite grid system using a fuel cell.

Hydrogen energy is attracting attention as a unique alternative to solving potential environmental and energy problems, while global warming and demand for research and development of energy due to exhaustion of fossil fuels are steadily increasing.

When hydrogen is used as a fuel, it can solve the environmental pollution problem of fossil energy because no pollutant is generated except a very small amount of NO _x when it is burned. In addition, since it can be produced with an unlimited amount of water as a raw material, it is attracting attention as an ultimate alternative to depletion of fossil energy in the future.

Currently, the most widely used hydrogen production technology is to reform fossil fuels. However, the issue of resource depletion can not be solved in that it still uses fossil fuels. Hydrogen is produced from non-fossil fuels by far the most known technology, and water electrolysis is the only practical technology.

Thus, the importance of hydrogen energy technology has already been well known to the international community. Advanced countries, including the United States, Japan, and Germany, have been devoting themselves to the study of hydrogen energy technology as the only alternative to solve 21st century energy problems and environmental problems at the same time.

On the other hand, renewable energy sources such as solar power and wind power, which are currently being commercialized, are non-continuous energy sources that can be produced only when the sun is shining or when the wind is blowing. . Therefore, hydrogen production by water electrolysis is regarded as the most preferable power storage means.

One of the methods of electrolysis by water electrolysis is a method of using a solid polymer electrolyte membrane as an electrolyte (Polymer Electrolyte Membrane Electrolysis, PEME). The membrane used in this method separates the generated gas, such as the diaphragm of alkaline water electrolysis, and also acts as an ion exchanger to transport hydrogen ions from the anode to the cathode. On the other hand, the reaction at each electrode is as follows.

Cathode: 4H ⁺ + 4e ^- ? 2H ₂

Anode: 2H ₂ O → 4H ⁺ + 4e ^- + O ₂

This method is free of corrosive electrolytes because the electrolyte is stable, the cell structure is simple, and pure water is used. Compared with alkaline water electrolysis, it is possible to operate at high current density and the efficiency of the device is high.

Polymer electrolysis can be designed for operating temperatures up to hundreds of bar, and both mobile and stationary systems are possible. However, there are disadvantages of installation cost and low capacity. In addition, there is a disadvantage of low efficiency and short life span. Therefore, the solid electrolytic water electrolysis method is not developed as much as the alkaline water electrolysis method.

Finally, high temperature electrolysis (HTE) using high temperature steam is a method utilizing the phenomenon that the theoretical decomposition voltage corresponding to electric energy among the energy required for water decomposition is lowered at high temperature. Because electrolysis occurs at high temperature (over 700 ℃), it can decompose water with high efficiency by using less electric energy. In addition, since the electrolyte is solid, unlike alkaline water electrolysis, it is unnecessary to replenish the electrolytic solution, and maintenance is easy because there is no corrosion problem. It is the reverse reaction of solid oxide fuel cell (SOFC) and can be used as the basic technology of SOFC. However, it is necessary to develop a solid electrolyte which can be used at high temperature, and it is still in the basic research stage.

The fuel cell stack consists of a membrane electrode assembly (MEA) with a catalyst electrode layer on both sides of the solid polymer electrolyte membrane on which hydrogen ions migrate and an electrochemical reaction takes place, and distributes the generated electrical energy evenly And a gasket for maintaining the airtightness of the reactor and the cooling water are laminated on the both sides of the unit cell, An end plate for supporting and fixing is coupled while maintaining a predetermined surface pressure by a fastening mechanism, and typically about 100 to 300 unit cells are arranged between end plates.

In general, fuel cells have disadvantages in that fuel cells have a disadvantage in that they have a slow reaction rate in case of power failure or peak load. In particular, when the load fluctuation width is large, power overshoot can occur, and when overshoot occurs, the anode membrane is dried to increase the membrane resistance, which causes performance degradation, and a decrease in cathode dilution / starvation performance There is a problem.

[Prior Art Literature]

[Patent Literature]

Korean Registered Patent No. 10-1592926 (Registered on February 02, 2016)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell system which can shorten a start-up time and shorten a response time to a load variation when the fuel cell starts driving at the time of power failure or peak load The present invention provides a grid system for a thermal electricity using a water electrolysis solution and a fuel cell.

The present invention relates to a grid system for a thermoelectric composite using a water electrolysis solution and a fuel cell, comprising: an electricity supply unit for supplying stored electricity or produced electricity; A water electrolytic apparatus for receiving electricity from the electricity supply unit and electrolyzing water; A hydrogen tank for storing the electrolyzed hydrogen from the water electrolysis apparatus; And a fuel cell that generates heat and electricity by using hydrogen in the hydrogen tank and air in the atmosphere.

The electricity supply unit may be a renewable energy device that generates electricity from a renewable energy source, or a battery or a system that stores electricity.

The water electrolytic apparatus further includes a heat exchanger for controlling the temperature of the water discharged from the fuel cell.

Next, a method for controlling a grid system of a thermoelectric composite using an electrolytic solution and a fuel cell according to the present invention comprises the steps of: supplying electricity to a production or electricity water electrolyzer from an electricity supplier; Electrolyzing water using electricity supplied to the water electrolytic apparatus; Storing hydrogen generated by electrolysis in a hydrogen tank; Producing electricity and heat using hydrogen stored in the hydrogen tank and air in the atmosphere in the fuel cell; And a control unit.

In addition, when the water electrolytic apparatus is shut down, electricity generated by the electricity supply unit is supplied to a use place.

As described above, according to the embodiment of the present invention, when the fuel cell starts driving at the time of power failure or peak load, the start-up time can be shortened and the response time to the load variation can be shortened.

FIG. 1 is a schematic diagram of a thermal electricity composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention. FIG.
FIG. 2 is a graph showing a temperature change of a polymer electrolytic device in a thermoelectric composite grid system using a water electrolytic solution and a fuel cell according to a preferred embodiment of the present invention.
FIG. 3 is a graph showing a change in temperature of a polymer fuel cell in a thermoelectric composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention
4 is a diagram illustrating a network environment utilizing a LoRa in a heat and electric power composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention
5 and 6 are diagrams for a load response test of a grid system for thermal power using a fuel cell and a water electrolysis solution according to a preferred embodiment of the present invention
7 is a graph showing the battery and the total output of the A company PEMFC system
8 is a graph showing a PEMFC, a battery, and a total output of a heat and electric power composite grid system using a fuel cell and a water electrolysis solution according to a preferred embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention.

The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, a heat and electric power composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention will be described with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a heat and electric power composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention; FIG.

Referring to FIG. 1, a heat and electric power composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention includes an electricity supply unit, a water electrolysis device, a hydrogen tank, and a fuel cell device.

The electricity supply unit supplies the stored electricity or the produced electricity to the water electrolytic unit. The electricity supply unit may be a renewable energy device that generates electricity from a renewable energy source, or a battery or a system that stores electricity. The renewable energy source may be renewable energy such as sunlight, wind power, hydro power, and geothermal energy.

The water electrolytic apparatus can use the most advanced alkaline water electrolytic apparatus or a PEMWE (Polymer Electrolyte Membrane Water Electrolyzer).

The water electrolytic apparatus receives electricity from the electricity supply unit and electrolyses the water. At this time, water is electrolytically decomposed into hydrogen and oxygen, and electricity and heat are generated. The hydrogen is transferred to a hydrogen tank and stored, and the oxygen is evaporated into the atmosphere.

The electrolytic apparatus may use an electrolyte as KOH. At this time, the KOH may be used in a range of 20 to 25%.

In addition, it is preferable to use DI water in which impurities are removed from the water (water) used in the water electrolysis apparatus.

Also, the hydrogen production capacity of the water electrolysis apparatus can be 3.5 to 4.3 Nm < 2 > / h when the supplied water is supplied with a capacity of 3,205 liter per hour.

FIG. 2 is a graph illustrating a temperature change of a polymer electrolytic apparatus in a thermoelectric composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention.

The water electrolytic apparatus may be provided with a temperature sensor. The temperature sensor measures the temperature of the supplied water supplied to the water electrolytic apparatus. For example, as shown in FIG. 2, when the feed water is supplied at a temperature of 20 to 50 ° C., the upper water electrolytic apparatus shows the highest efficiency at the temperature of the feed water at 50 ° C. In addition, when the water electrolytic apparatus uses water supplied at 50 ° C or higher, system overheating may occur. Therefore, it is most preferable that the water electrolytic apparatus use water supplied at 50 캜 or lower.

FIG. 3 is a graph showing a power-receiving reaction according to a voltage in a thermoelectric composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention.

The graph of FIG. 3 is a graph of I-V polarization curves measured under PEMFC driving conditions by activating the MEA by supplying hydrogen to the anode and air to the cathode in the state that the MEA is tightly coupled after the electrolysis for 1 minute at each voltage. As shown in FIG. 3, when the water electrolytic solution was reacted at 1.8 V, there was no difference from the MEA performance before the electrolysis, but at 1.9 V and 2.0 V, it decreased to about 1/2 of the initial performance. (In the graph, 1.9v, 2.0v seem to increase the current density.

FIG. 4 is a graph showing hydrogen permeability according to voltage in a thermoelectric composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention. 4 is a graph showing hydrogen permeability measured by LSV in order to confirm deterioration of the polymer electrolyte membrane. As can be seen from FIG. 4, the hydrogen permeation current density did not increase at 1.8 V, but increased to 1.9 mA / cm ² when the electrolysis reaction occurred at 1.9 V and 2.0 V, which was about twice that of the initial membrane have.

Therefore, hydrogen is generated due to the Faraday current, which is the current to be used for the hydrogen reaction in the water electrolytic apparatus. At this time, the voltage is preferably 1.9 to 2.0V. That is, as the voltage of the water electrolytic device increases, the current value increases and the ferrode current increases, thereby increasing the hydrogen generation rate. As a result, the water electrolysis apparatus increases the hydrogen yield as the voltage increases.

The fuel cell generates electricity and heat by using hydrogen stored in the hydrogen tank and air (oxygen) in the atmosphere, and transfers it to the place of use (building). At this time, the fuel cell is combined with hydrogen and oxygen to produce water. The water (effluent) is discharged from the fuel cell and then transferred to the feed water of the water electrolysis apparatus.

The fuel cell may be a PEMFC (Polymer Electrolyte Membrane Fuel Cell), and the durability may be reduced by deterioration of the polymer membrane and deterioration of the electrode.

The fuel cell effluent is used as the feed water for the water electrolysis device. At this time, the temperature of the discharged water is high. The effluent water having a high temperature has a disadvantage in that the efficiency is low for use in the water electrolytic apparatus. The water electrolytic apparatus may further include a heat exchanger for controlling the temperature of the water discharged from the fuel cell.

More specifically, the polymer electrolyte membrane according to the present invention has a low enthalpy (ΔH) value when the LHV is low, so that the efficiency is increased but the enthalpy (ΔH) is increased and the temperature is lowered to deteriorate the performance. In order to solve this problem, a heat exchanger may be installed in the piping moving from the fuel cell to the water electrolysis apparatus. The heat exchanger controls the temperature of the discharge water discharged from the fuel cell.

When the power generation capacity of the fuel cell is 5Kw of electricity and 4kw of heat is produced, the electricity generation efficiency of the fuel cell may be 44% or more. The power consumption of the fuel cell may be 0.5 kWh, the hot water temperature may be 55 to 60 ° C, and the production amount may be 200 liters.

FIG. 5 is a graph showing a change in temperature of a polymer fuel cell in a thermoelectric composite grid system using a water electrolysis solution and a fuel cell according to a preferred embodiment of the present invention.

As shown in FIG. 5, the polymer fuel cell has high performance at a high temperature (50 ° C.) and low performance at a low temperature (20 ° C.). In the polymer fuel cell, the current density decreases as the fuel cell temperature increases. Therefore, as the temperature increases, the mass transfer in the fuel cell increases and the electrical resistance decreases. In addition, the current varies with the mass flow rate of the hydrogen due to the increase of the electrochemical reaction rate.

In polymer electrolyte fuel cells, humidity is important during the driving process. In order to increase the fuel cell efficiency, it is advantageous to adjust the humidification drive with high discharge amount. The purity of the effluent is also important. Further, a driving condition with a high degradation rate can lower the purity of the effluent water.

More specifically, when both the anode and the cathode of the fuel cell have a relative humidity of 100% and a temperature of 70 ° C, they exhibit the highest efficiency.

The electrolyte membrane of the fuel cell has a high degradation rate at high temperature and high voltage. At this time, due to deterioration of the electrolyte membrane, fluorine flows out. At this time, the purity of the effluent water can be estimated by measuring the fluorine outflow rate (FER) under the OCV condition at 90 ° C.

The lower the voltage of the electrolyte membrane of the fuel cell, the lower the fluorine concentration.

In addition, the fuel cell has a higher degradation rate of the polymer membrane than that of the air electrode lower humidification condition under the conditions of low humidification of the anode.

In both RH and humid conditions, the concentration of fluorine ions is low in OCV and the purity of the effluent is 99.9999%, which is high purity. Therefore, the discharge water of the fuel cell is sufficient for use as the water electrolytic raw material water.

Platinum was detected in the condensate (effluent) discharged from the high humidification condition, but the platinum concentration was as low as less than 0.2 ppb as a whole.

The hydrogen-utilizing electrolytic solution of the present invention and the thermoelectric composite grid system using the fuel cell are required to have a short response time since they are driven by power failure or load picking rather than continuous driving. When the fuel cell starts to drive at the time of power failure or peak load, the start-up time should be short and the time to respond to the load fluctuation should be short.

FIGS. 6 and 7 are block diagrams illustrating a load response test of a grid system using a fuel cell and a power grid according to a preferred embodiment of the present invention.

That is, FIG. 6 shows a system in which a battery, a DC / DC, and a load are connected to measure a load response time of the fuel cell.

7 is a configuration diagram of a fuel cell load response test system having two types of DC / DC.

Figures 6 and 7 compensate the output in the stack when the output of the battery drops.

FIG. 8 is a graph showing the battery and the total output of the A company PEMFC system, and FIG. 9 is a graph showing the PEMFC, the battery, and the total output of the grid system of the thermal electricity using fuel cell and the fuel cell according to the preferred embodiment of the present invention Graph.

As shown in FIG. 9, it can be confirmed that the output of the battery is compensated when the output is increased from 0W to 95W.

That is, in the anode fuel cell stack, a system is constructed in which the output is connected through two types of DC / DC to the battery charge and the external output, respectively, and the load responsiveness is tested. Here, the power-receiving solution of the present invention and the thermoelectric composite grid system using the fuel cell can confirm output similar to the PEMFC system of Company A of FIG.

10 is a diagram illustrating a network environment using a LoRa in a thermoelectric composite grid system using a fuel cell and a water electrolysis solution according to a preferred embodiment of the present invention.

Referring to FIG. 10, all the data of the water electrolytic unit and the fuel cell are transmitted to the power management center through the LoRa Node and the gateway, and both wired and wireless networks can be used for real-time monitoring, communication, and control .

As the number of online applications and mobile users increases, the lack of frequency and system stoppage may occur in the smart energy compass. However, using LoRa can reliably use the wireless communication environment regardless of the increase in the number of users .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It is possible to carry out various changes in the present invention.

100:
110: Inverter
200: Water receiving device
210: heat exchanger
300: hydrogen tank
400: Fuel cell

Claims (5)

An electricity supplier for supplying stored electricity or produced electricity;
A water electrolytic apparatus for receiving electricity from the electricity supply unit and electrolyzing water;
A hydrogen tank for storing the electrolyzed hydrogen from the water electrolysis apparatus; And
A fuel cell that generates heat and electricity by using hydrogen in the hydrogen tank and air in the atmosphere;
And a fuel cell, wherein the fuel cell comprises a plurality of fuel cells.
The method according to claim 1,
The electricity supply unit
A new and renewable energy device that generates electricity from a new and renewable energy source, or a battery or a system that stores electricity.
The method according to claim 1,
The water electrolysis apparatus
Further comprising a heat exchanger for controlling the temperature of the discharge water discharged from the fuel cell.
The method of claim 1, further comprising the steps of:
The production or electricity is supplied from the electricity supply to the water electrolysis apparatus;
Electrolyzing water using electricity supplied to the water electrolytic apparatus;
Storing hydrogen generated by electrolysis in a hydrogen tank; And
Producing electricity and heat using hydrogen stored in the hydrogen tank and air in the atmosphere in the fuel cell;
The method comprising the steps of: (a) providing a fuel cell;
6. The method of claim 5,
Wherein the electricity generated by the electricity supplying unit is supplied to a use place when the water electrolytic apparatus is shut down, and the method for operating the thermal electric power combined grid system using the fuel cell.

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