JP2011169171A - Power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation system storing generated heat for a long period of time or for a long period, and responding to fluctuation in electric demand. <P>SOLUTION: The power generation system includes a heat generation means 10, a heat transmission means 20, a heat accumulation means 30, a heat recovery means 40, and a power generation means 50. The heat generation means 10 generates heat to heat a heat medium. The heat transmission means 20 transmits the heat of the heat medium heated by the heat generation means 10 into the ground. The heat accumulation means 30 accumulates the heat transmitted by the heat transmission means 20 into the ground. The heat recovery means 40 takes out and recovers the heat accumulated by the heat accumulation means 30. The power generation means 50 generates power by the heat recovered by the heat recovery means 40. The heat generation means 10 makes the heater generate heat by electricity generated by a wind turbine generator to heat the heat medium. The ground 31 is utilized as the heat accumulation means 30 as it is. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power generation system that stores generated heat in the ground and generates electricity by taking out the stored heat.

Conventionally, a nuclear power generation system has been used as a main power source. In recent years, power generation systems using natural energy (renewable energy) such as solar heat, wind power, and geothermal heat have attracted attention from the viewpoints of CO ₂ reduction and effective use of new energy resources.

  For example, Non-Patent Document 1 describes a technique related to solar thermal power generation. Solar thermal power generation condenses solar heat into thermal energy, generates steam with the thermal energy, and rotates a turbine to drive a generator to generate electricity. That is, solar energy is converted into thermal energy and extracted as electrical energy. As a solar thermal power generation system, for example, a tower type has been put into practical use. This is by concentrating sunlight on a heat collector installed at the top of the tower (tower), sending steam generated by the heat to the turbine provided at the bottom of the tower, and rotating the turbine. This is a method of generating power by driving a generator (see FIG. 3 of Non-Patent Document 1).

  In solar thermal power generation, the power generation output (power generation amount) fluctuates depending on the weather and time. Therefore, in order to perform stable power generation, heat is stored in the regenerator and at the same time the heat necessary for power generation is extracted from the regenerator It is done to install a heat storage system that can be used in a solar power generation system.

  Next, for example, Non-Patent Documents 2 to 4 describe technologies related to wind power generation. Wind power generation is to generate electricity by rotating a windmill with wind and driving a generator. That is, wind energy is converted into rotational energy and extracted as electrical energy. A wind power generation system generally has a structure in which a nacelle is installed at the top of a tower, and a horizontal axis wind turbine (a wind turbine whose rotation axis is substantially parallel to the wind direction) is attached to the nacelle. The nacelle stores a speed increaser that increases the rotational speed of the shaft of the windmill and outputs it, and a generator that is driven by the output of the speed increaser. The speed increaser increases the number of rotations of the wind turbine to the number of rotations of the generator (for example, 1: 100), and a gear box is incorporated.

  Recently, there is also a gearless variable speed type that does not require a gearbox. Many of the causes of failures in wind power generation systems are due to problems with gearboxes, more specifically gearboxes. In the case of gearless, it is possible to avoid gearbox problems because the gearbox is not used, but it is necessary to use a multi-pole power generator. There is a disadvantage that the machine becomes large and heavy.

  Also, in the case of wind power generation, the output fluctuates with the fluctuation of the wind force, so a power storage system is added to the wind power generation system, unstable power is stored in the storage battery, and the output is smoothed. .

  In addition, for example, Non-Patent Document 5 describes a technique related to geothermal power generation. In geothermal power generation, thermal energy generated by magma in the deep underground is extracted in the form of steam, and a turbine is rotated by the steam to drive a generator to generate power. However, a promising area for geothermal resources is the volcanic area, and it has been difficult to construct a new geothermal power plant.

“Solar Thermal Power Generation System (01-05-01-02)”, [online], Nuclear Encyclopedia ATOMICA, [Searched on January 31, 2010], Internet <URL: http://www.rist.or.jp / atomica /> “Wind Power Generation (01-05-01-05)”, [online], Atomic Encyclopedia ATOMICA, [searched on January 31, 2010], Internet <URL: http://www.rist.or.jp/ atomica /> “2000kW large wind power generation system SUBARU80 / 2.0 PROTOTYPE”, [online], Fuji Heavy Industries Ltd., [searched January 31, 2010], Internet <URL: http://www.subaru-windturbine.jp/home/ index.html> “Wind Lecture”, [online], Mitsubishi Heavy Industries, Ltd. [searched on January 31, 2010], Internet <URL: http://www.mhi.co.jp/products/expand/wind_kouza_0101.html> “What is geothermal power generation?”, [Online], Hokkaido Electric Power Co., Inc. [searched on January 31, 2010], Internet <URL: http://www.hepco.co.jp/ato_env_ene/energy/fire_power/ about_geo.html>

  In recent years, with the spread of cooling equipment, etc., the difference in power demand between day and night and between seasons has become a big problem. However, in the conventional power generation system, no effective countermeasure has been found from the viewpoints of efficiency, cost effectiveness, and the like with respect to fluctuations in power demand between day and night and between seasons.

  For example, in the case of a wind power generation system, a power storage system is installed. However, since the power storage system requires components such as a converter in order to store power in a storage battery, the system is complicated and power loss is increased. In particular, a power storage system of a scale that can cover fluctuations in power demand between seasons requires a large amount of storage batteries, which increases the cost of the entire system.

  On the other hand, although a heat storage system is installed in the solar thermal power generation system, the heat storage system is simpler than the power storage system, and the heat storage is also cheaper than the storage battery. However, in order to cover seasonal power demand fluctuations, like the power storage system, a large amount of heat accumulator is required, and a large amount of material and a large installation space are required. That is, the heat storage system (heat accumulator) occupies most of the installation area of the power generation system.

  The present invention has been made in view of the above circumstances, and one of the purposes thereof is a power generation system that can store generated heat for a long period or a long period of time and can respond to fluctuations in power demand. Is to provide.

  The power generation system of the present invention is characterized by comprising a heat generation means, a heat transfer means, a heat storage means, a heat recovery means, and a power generation means. The heat generating means generates heat and heats the heat medium. The heat transfer means transfers the heat of the heat medium heated by the heat generation means to the ground. The heat storage means stores the heat transferred by the heat transfer means in the ground. The heat recovery means takes out and recovers the heat stored in the heat storage means. The power generation means generates power with the heat recovered by the heat recovery means.

  The underground has little temperature change throughout the year, and has a heat insulation function (heat storage function). In the present invention, the heat generated by the heat generating means is transmitted to the ground through the heat medium and stored in the heat storage means in the ground. Then, the heat stored in the heat storage means is taken out and collected, and electricity is generated with the heat. Therefore, by storing the heat in the ground, it is possible to store the excess heat generated by the heating means efficiently and stably over a long period of time such as day and night or during a long period of time. By taking out and generating electricity at a time when demand increases, it is possible to cope with fluctuations in power demand. In addition, by using the underground, the installation space can be effectively utilized.

  In the present invention, examples of the heat medium include water, oil, liquid metals (Na, Pb, etc.), liquids such as molten salts, and gases.

  One form of the power generation system of the present invention is that the heat storage means uses the ground itself.

  According to this configuration, by using the ground itself as it is, it is not necessary to install a large amount of heat accumulator, and it is not necessary to use a large amount of material.

  As one form of the power generation system of the present invention, the heat storage means includes an underground space formed in the ground and a heat storage material filled in the underground space, and the heat stored in the heat transfer means is stored in the heat storage material. Can be stored.

  If the ground itself is used as it is, it is conceivable that the stored heat escapes (is taken away) due to the influence of rainwater that has penetrated into the ground. Therefore, heat can be effectively prevented from being taken away by transferring heat between the earth and the hollow filled with the heat storage material and storing the heat in the heat storage material.

  Artificial underground space and natural underground space can be used as underground space, and also rock salt mining traces, coal mines, and abandoned mine traces of copper mines can be used. In addition, as the heat storage material, for example, solids such as granite and basalt and solids such as concrete, liquids such as water, oil, and molten salt, and gases such as air and carbon dioxide can be used.

  As one form of the power generation system of the present invention, the heat generating means may generate heat by using renewable energy.

  According to this configuration, it is possible to effectively use new energy by using renewable energy.

  The power generation system of the present invention can store heat generated by the heat generation means efficiently and stably over a long period or a long period of time by storing heat underground, and can respond to power demand fluctuations. .

It is a schematic diagram which shows an example of the whole structure of the electric power generation system which concerns on Embodiment 1. FIG. 6 is a schematic diagram illustrating an example of an overall configuration of a power generation system according to Embodiment 2. FIG.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

(Embodiment 1)
The power generation system according to Embodiment 1 shown in FIG. 1 includes a heat generation means 10, a heat transfer means 20, a heat storage means 30, a heat recovery means 40, and a power generation means 50. Hereinafter, the configuration of the power generation system will be described in detail.

  The heat generating means 10 is means for generating heat using renewable energy and heating the heat medium. In this example, a wind power generator installed on the ground is used. More specifically, the electric energy generated by the wind power generator is converted into heat energy to heat the heat medium. Specifically, the heater is heated by electricity, and the heat medium is heated by the heat.

  The heat transfer means 20 is means for transferring the heat of the heat medium heated by the heat generation means 10 to the ground. In this example, a heat transfer tube extending from the heat generating means 10 to the ground and through which a heat medium flows is used. More specifically, the forward path part 21 for sending the heat medium heated by the heat generating means 10 to the underground side (heat storage means 30), the heat exchange part 22 for transferring the heat of the heat medium to the heat storage means 30 and exchanging heat, And a return path section 23 for returning the heat medium to the ground side (heat generating means 10), and the heat medium is circulated between the heat generating means 10 and the heat storage means 30.

  The heat storage means 30 is means for storing the heat transferred by the heat transfer means 20 in the ground. In this example, the underground 31 itself is used, and heat is stored in the underground 31 itself. Further, the heat storage means 30 has a heat storage capacity of a scale that can cover fluctuations in power demand between seasons.

  Here, a heat insulating layer may be separately provided so as to surround a space (hereinafter referred to as a heat storage space) serving as a heat storage region of the underground 31, or may not be provided separately. The amount of heat storage that can be stored in the heat storage means is proportional to the volume of the heat storage space, and the amount of heat escaped from the heat storage means (heat radiation amount) is proportional to the surface area. If the heat storage space is assumed to be a sphere, the surface area is proportional to the square of the length (radius), and the volume is proportional to the third power. Therefore, if the heat storage space increases, that is, the scale of the power generation system increases. Indeed, the amount of heat released becomes almost negligible with respect to the amount of heat stored. Therefore, in the case of a small-scale power generation system that responds to long-term fluctuations in power demand such as day and night, it is preferable to provide a heat insulating layer in order to prevent heat from escaping. On the other hand, if it is a large-scale power generation system that responds to long-term fluctuations in power demand such as during the season, it is not necessary to provide a special heat insulation layer, and the construction cost can be kept low despite being large. For example, the heat insulating layer may be formed of concrete. When forming a heat insulation layer with concrete, it is preferable to use lightweight concrete with low thermal conductivity.

  The heat recovery means 40 is a means for taking out and recovering heat stored in the heat storage means 30 (underground 31). In this example, a heat transfer tube that extends from the ground power generation means 50 into the ground and through which a heat medium flows is used. More specifically, the forward path part 41 that sends the heat medium from the power generation means 50 to the underground side (heat storage means 30), the heat exchange part 42 that transfers the heat stored in the heat storage means 30 to the heat medium and exchanges heat, And a return path 43 that returns the heat medium that has received heat to the ground side (power generation means 50), and is configured such that the heat medium circulates between the power generation means 50 and the heat storage means 30. That is, the heat medium flowing through the heat transfer tube of the heat recovery means 40 receives heat from the heat storage means 30, and thereby extracts and recovers the heat stored in the heat storage means 30 (underground 31). For the heat recovery means 40, a known heat pump technique can be used.

  The power generation means 50 generates power with the heat recovered by the heat recovery means 40. More specifically, the power generation means 50 includes a steam generator that generates steam with the heat recovered by the heat recovery means 40, a turbine that rotates with the steam, and a generator that is driven by the turbine. As the power generation means 50, a known geothermal power generation technique can be used.

  The electric power generated by the power generation means 50 is transmitted to the customer side through the power transmission cable 60. As the power transmission cable 60, a superconducting cable can be used.

  According to the power generation system of Embodiment 1, by storing heat in the underground heat storage means, excess heat generated by the heat generation means can be efficiently and stably stored for a long time or a long period of time, By taking out the surplus heat at a time when the power demand becomes large and generating power, it is possible to cope with fluctuations in power demand. In addition, by using the underground, the installation space can be effectively utilized. Furthermore, by utilizing the ground itself as a heat storage means, it is not necessary to install a large amount of heat accumulators, and it is not necessary to use a large amount of materials.

(Embodiment 2)
The power generation system according to the second embodiment shown in FIG. 2 is different from the power generation system according to the first embodiment shown in FIG. 1 in the configuration of the heat storage means, and the difference will be mainly described below.

  The heat storage means 30 of the power generation system according to the second embodiment includes an underground space 32 formed in the ground and a heat storage material 33 filled in the underground space 32, and the heat transferred by the heat transfer means 20 is provided. Store in heat storage material 33. In this example, the underground space 32 is formed in the underground rock, and the heat storage material 33 is filled in the underground space. Therefore, the rock outside the underground space 32 serves as a heat insulating layer. For the heat storage material 33, for example, a molten salt can be used. The outside of the underground space 32 may be formed of, for example, lightweight concrete having a low thermal conductivity, and a heat insulating layer may be formed outside the underground space 32.

  According to the power generation system of the second embodiment, the heat transferred by the heat transfer means is stored in the heat storage material filled in the underground space, thereby effectively preventing the heat from being taken away.

(Modification 1)
In the power generation systems of the first and second embodiments described above, the case where a wind power generator is used as the heat generating means 10 and the heater is heated by the electricity generated by the wind power generator and the heat medium is heated is described as an example. Solar heat can be used as the means. For example, it is conceivable to condense solar heat into heat energy and heat the heat medium with the heat energy. In this case, since the thermal energy of the sun is directly used, the efficiency is better than when a wind power generator is used.

(Modification 2)
In the power generation systems of the first and second embodiments described above, the case where a wind power generator is used as the heat generating means 10 and the heater is heated by the electricity generated by the wind power generator and the heat medium is heated is described as an example. As the means, an energy conversion device that directly converts mechanical energy into heat energy can be used. For example, it is conceivable to rotate a windmill with wind energy, convert the rotational kinetic energy into heat energy, and heat the heat medium with the heat energy. As a method for converting mechanical energy into heat energy, for example, induction heating or compression heat is used. Specific examples of the energy conversion device are shown below.

  As an example of the energy conversion device in the case of using induction heating, a configuration including a magnetic field generation unit, a heating unit at least part of which is made of a conductive material, and a pipe through which a heat medium flows is exemplified. Magnetic flux generated by the magnetic field generation unit passes through the heating unit, and the piping is provided in the heating unit, and the heating unit and the piping are thermally connected. And either one of a magnetic field generation part and a heating part is attached to the rotating shaft of a windmill, and a magnetic field generation part and a heating part rotate relatively by rotation of a windmill. In this energy conversion device, an induction current (eddy current) is generated in the heating unit by the relative rotation of the magnetic field generation unit and the heating unit due to the rotation of the windmill, and the magnetic flux passing through the heating unit changes. The heating unit is induction-heated, receives heat from the heating unit, and heats the heat medium in the pipe.

  In addition, as a magnetic field generation | occurrence | production part, a permanent magnet and a coil (electromagnet) can be used. Specific examples of the coil include a normal conducting coil such as a copper wire and a superconducting coil. Moreover, as a conductive material used for a heating part, metals, such as aluminum, copper, and iron, are mentioned, for example.

  As an example of the energy conversion device in the case of using compression heat, there is a configuration including a cylinder, a piston housed in the cylinder, and a motion transmission mechanism that converts the rotational motion of the windmill into the reciprocating motion of the piston. In this energy conversion device, the piston is reciprocated relative to the cylinder by the rotation of the windmill, and the heat of compression by the piston is transmitted to the heat medium to heat the heat medium. The piston may be either hydraulic or pneumatic. An example of a motion transmission mechanism that converts rotational motion into reciprocating motion is a crank mechanism.

  Since the energy conversion device described above directly converts mechanical energy into thermal energy, it is more efficient than the case where it is once converted into electrical energy. Further, heat can be generated without using a gearbox, and a gearbox trouble can be avoided. Furthermore, the size and weight can be reduced as compared with a multipolar generator, and the nacelle installed in the upper part of the tower can be reduced in size and weight.

(Modification 3)
In the power generation systems of Embodiments 1 and 2 and Modifications 1 and 2 described above, the case where renewable energy is used as an energy source has been described as an example, but nuclear energy can be used as the energy source. In a nuclear power generation system, the output is not fluctuated according to the power demand, and is basically operated at a constant output. Therefore, at night when power demand is low, surplus heat generated in the nuclear reactor is transferred to the ground by heat transfer means and stored in the underground heat storage means. And during the time when power demand increases during the daytime, steam is generated by the heat generated in the reactor, and the turbine generator is rotated by the steam to generate power. The recovered heat is taken out by the heat recovery means and recovered, and the recovered heat is used to generate power by the power generation means. Thereby, the utilization factor of a nuclear power generation system can be improved and it can respond to electric power demand fluctuation.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention.

  The power generation system of the present invention can deal with fluctuations in power demand between day and night and between seasons, and can be suitably used, for example, in the field of power generation using renewable energy.

10 Heating means
20 Heat transfer means
21 Outward part 22 Heat exchange part 23 Return part
30 Heat storage means
31 Underground 32 Underground space 33 Thermal storage material
40 Heat recovery means
41 Outward part 42 Heat exchange part 43 Return part
50 Power generation means
60 Transmission cable

Claims (4)

Heating means for generating heat and heating the heat medium;
Heat transfer means for transferring heat of the heat medium heated by the heat generating means to the ground;
Heat storage means for storing heat transferred by the heat transfer means in the ground;
Heat recovery means for taking out and recovering heat stored in the heat storage means;
A power generation system comprising: power generation means for generating electricity with the heat recovered by the heat recovery means.   The power generation system according to claim 1, wherein the heat storage means uses the ground itself. The heat storage means is
An underground space formed in the ground,
A heat storage material filled in the underground space,
The power generation system according to claim 1, wherein the heat transferred by the heat transfer means is stored in the heat storage material.   The power generation system according to any one of claims 1 to 3, wherein the heat generating unit generates heat using renewable energy.

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