JPS59231395A - Geothermal energy storage system - Google Patents

Abstract

PURPOSE:To contrive to store simultaneously and effectively the cool-heat and the hot-heat energy by utilizing high heat insulating properties existing originally in the underground, and contrive to utilize timely the stored heat energy by a method wherein a water shut-off wall is provided at suitable location in the underground, a temperature stratification is formed in the geothermal water storage part for obtaining the temperature difference between a lower layer and an upper layer. CONSTITUTION:A water shut-off wall 5 is constructed contacting on a base rock 2, located at the downstream side of a city area 1' for an underground water flow 4 and provided to be high as nearly correspond to the thickness of an underground water containing layer 3. The underground water flow 4 is shut-off by the water shut-off wall 5, the underground dam 6 is constructed under the lower part of the city area 1'. By selecting the injected water temperature and injected location for the underground dam 6, relatively lower temperature water in a lower layer 6a and higher temperature water than said water in an upper layer 6b are stored in a temperature stratification.

Description

[Detailed Description of the Invention] This invention relates to a geothermal energy storage system, and in particular, it stores thermal energy in water at multiple temperature levels simultaneously underground, and uses it on a large scale. The purpose of the present invention is to provide a system that stores the energy over a long period of time and extracts and utilizes the energy at the appropriate time.

One of the purposes of such a geothermal energy storage system is to store cold heat in winter until the entire summer, or heat heat in summer until winter, on a large scale, and extract it in summer and winter for cooling and heating, respectively. I'm trying to use it.

There is considerable interest in the effective use of solar thermal energy, wind energy, or thermal energy derived from various types of agricultural, forestry, and livestock waste, which are generally referred to as local energy, but a serious drawback common to these is that the supply of the energy is discontinuous. In order to eliminate these disadvantages, K is satisfied with the economic efficiency, etc. There is a strong desire to establish a long-term energy storage system.

Conventionally, attempts have been made to utilize underground aquifers as a method for long-term storage of thermal energy in the summer and cold energy in the winter.

In other words, heat is stored by using an underground aquifer with a small flow of groundwater.One specific example is pumping up water from the aquifer in the summer and raising its temperature using high-temperature outside air or active solar heat. This heated water is injected into another aquifer to store thermal energy.

As is well known, aquifers exist in soil with low thermal conductivity.
It can be said to be a heat storage tank surrounded by excellent natural heat insulating material, allowing efficient heat storage with very little heat loss.

Then, such hot water is pumped up at appropriate times, for example in winter, and used for melting snow on roofs and roads in snowy areas, and sometimes heated by heat pumps etc. for hot water supply,
It is used for heating purposes. On the other hand, it is also possible to return the cold water heat-exchanged by the snow melting to another aquifer and store it for use in summer cooling.

However, the existence of the above-mentioned aquifers suitable for storing such thermal energy is usually extremely limited regionally, and furthermore, the existence of the above-mentioned aquifers suitable for storing such thermal energy is generally limited anywhere near the above-mentioned hot energy or cold energy demand areas. The reality is that finding a location is extremely difficult.

The inventors have completed the present invention as a result of extensive studies regarding such a geothermal energy storage system, particularly in order to eliminate the above-mentioned location constraints.

That is, the present invention provides an impermeable wall at a suitable location underground, forms a temperature stratification having a stable temperature difference between the lower layer and the upper layer in the underground water storage part that is dammed by the impermeable wall, and Input/output of the lower layer water and upper layer water in the water storage section A' (r reaches each water layer ↓ is carried out separately with fc pumping and water injection equipment, and the thermal energy stored in the stored water in the above water storage section This geothermal energy storage system is characterized in that both the supply system for water and the consumption system for taking water out of the water storage section and utilizing it are operated in a closed circulation system.

The present invention will be described in detail below with reference to all the drawings. 1st
The figure is a schematic cross-sectional view of the underground water storage part (hereinafter also referred to as underground dam) in the present invention, where 1 is the ground surface, 1' is the urban area built on the ground surface, 2 is the underground bedrock, 3 is the above-mentioned underground aquifer, and 4 is an underground water flow.

In the example shown in FIG. 1B, 5 is an impermeable wall built in contact with the bedrock 2, and is located downstream of the urban area 1' with respect to the underground water flow 4 and close to the underground aquifer 3. The height is approximately equal to the thickness. The above-mentioned underground water flow 4 is blocked by this impermeable wall 5, and an underground dam 6 is formed in the lower part of the city area 1' as shown in the figure. Water at a relatively low temperature is stored in the upper layer 6a, and water with a higher temperature is stored in the upper layer 6b, forming so-called temperature stratification.

In the example shown in FIG. 1C, the impermeable wall 5 is provided without its base touching the bedrock 2, and therefore, in this case, the groundwater always flows away from the bottom of the underground dam.

The technology for constructing such underground dams is almost established today, and specifically, a large number of injection pooling holes are drilled vertically or diagonally from the ground surface at the location where the underground dam is installed.
Inject all of the cicement bentonite liquid into the hole bottom through the Porin J hole, further suppressing the hydraulic conductivity of the rock mass to a low value,
Furthermore, the water-shielding wall 5 is constructed by injecting a low-viscosity water glass liquid or the like. Due to the installation of the above-mentioned water-shielding wall 5, Fig. 1 B and C
In either case, the groundwater overflows when the water is full or flows underground under the impermeable wall, so it does not significantly change the groundwater flow and prevents occurrences under the ground law etc. due to changes in the groundwater level downstream of the subsurface dam. I almost never feel sad.

Since the water storage section is generally shaped like a gravel pit, convection due to temperature differences in the stored water is difficult to occur, and the above-mentioned temperature stratification is easily formed, which is the purpose of this invention to simultaneously preserve multiple energies as described below. It becomes eminently suitable for

Next, 10' of wells are installed from the ground surface to reach the upper and lower layers of the underground dam as shown in the figure, and these wells 10 are connected to a water pumping and water injection device 11.

In this case, in the example shown in Figure 1B, the upper layer flows out due to overflow of groundwater, so it is suitable for storing low-temperature water.
In this example, groundwater constantly flows out at the bottom, making it suitable for storing high-temperature water. However, in either case, it is necessary to take in and out the stored water separately through wells that reach each layer directly, and to avoid mistaken inflow and outflow of groundwater that would disturb the mutual stratification. Must have.

All of these water pumping and water injection devices 11 are provided with conventional means to operate in a closed circulation system.

Next, a case will be described in which an example of a system for storing thermal energy in an underground dam constructed as described above is used for winter snow melting and summer cooling in snowy areas.

In FIG. 2, l'a is a building on the ground, 10a.

10b is a well installed to reach the lower and upper layers of the underground dam 6, and 12 is a snow melting pipe placed on the roof of the building 1'a.

When it snows this winter, a pump (not shown) pumps relatively high temperature water from the upper layer of the underground dam 6 through the well 10b and passes it through the snow melting finned pipe 12 to melt snow on the roof.
And here, the cold water which is cooled by heat exchange n2 is sent to the well 1.
An underground dam 6 is connected to an injection pump (not shown) through 0a'r.
is reduced to the lower layer.

Next, in the summer, the cold water from the lower layer is pumped up through the well 10a and converted into heat by the coil 13a of the air conditioner 13 installed indoors to cool the indoor area and raise the temperature. water well 1
It returns to the upper layer of the underground dam 6 via 0b'.

The cold water returned to the lower layer of the underground dam 6 in the winter and the hot water returned to the upper layer in the summer use the above-mentioned thermal energy because the underground dam 6 is difficult to cause convection and is in a natural insulating atmosphere. will be stored properly for a long period of time, and will be able to adequately respond to snow melting and air conditioning.

Such facilities may be partially omitted from the wells, piping, and various other facilities so that they are suitable for use only in the winter or summer season due to the purpose of use, especially regional considerations; however, in this case, the underground dam 6 It is necessary to provide separate heat conversion equipment for the water to be reduced.

In addition, such rapid pumping of groundwater tends to lead to unexpected defects under the ground law, so it is desirable to determine the amount of pumping or reinjection in advance to anticipate these problems.

In order to reduce the heat loss during pumping and injection, it is advisable to install the above equipment as close as possible to the place where the energy is used, and to make the circulation system a closed system, so as to reduce the heat loss during the pumping and injection. It is particularly preferable that water can be replenished directly, since clogging of the extraction or injection well, changes in water quality, etc., can be prevented, in addition to the various problems that may occur.

When the system shown in Figure 2 above is operated at full capacity, water from the upper layer is pumped up and water is injected into the lower layer in the winter, and vice versa in the summer. Although it fluctuates, the overall water volume remains balanced.

It is particularly preferable to introduce such a system for the entire region and increase the capacity of the above-mentioned underground dams. Equipment can be installed, or water intake and water injection can be distributed to each district within a single large-scale dam, thereby allowing stored energy to be distributed and used individually throughout the area.

The above system example has a single purpose of snow melting in the winter and cooling in the summer, and it is assumed that a certain balance can be achieved in the heat balance, but in general, the energy for melting snow in snow-covered areas is ) usually occupies a large proportion of the population.

From the perspective of such energy balance, it is necessary to comprehensively judge and systemize energy use in the entire region. An example of supplementing the energy balance for this purpose is shown in FIG.

In the figure, 22 is a cold warehouse for storing agricultural products such as rice, 23 is a cultivation factory for the purpose of relatively low-temperature cultivation of enoki mushrooms, etc., and 24 is a garbage incinerator, all of which are connected to the lower layer of underground dam 6. It is possible to take in all of the cold water, convert it into heat, and return hot water to the upper layer, and by incorporating these into the system, it is possible to balance the energy balance of the heat storage system.

In the figure, 24' is an incineration plant chimney, 25 is each heat converter, 26 is a central water intake pipe, and 27 is each water injection pipe.

Next, in municipal waste incineration plants, steam is sometimes generated by the heat generated from waste incineration and used for turbine power generation, and the above-mentioned cold water can be used as condenser cooling water for the steam turbine. An example of this is shown in FIG.

In the same figure, 28 μ incineration mailer, 29 is a steam turbine,
30 is a generator, and 31 is a condenser. Specifically, dam 6
The lower layer water can be used for cooling the condenser 31 and hot water can be returned to the upper layer.

Here, if we adopt the example shown in FIG.
Since the lower layer water constantly flows away and the upper layer water is stored relatively quietly, it is particularly suitable for long-term storage of relatively high temperature water.

Applying this to the example system shown in Figure 2 above, cold water is circulated through a finned circulation pipe on the roof for snow melting in the winter, and hot water is generated using solar heat in the summer, when thermal energy sources are abundant, and this water is stored until the winter. Build a system to do this.

Particularly in areas where there is a large amount of snow melting, such a system is also very effective because it can increase the amount of hot water stored and prepare for melting snow not only on roofs but also on roads.

As described in detail above, the present invention actively forms a subterranean dam by installing a water-shielding wall underground, and utilizes the high thermal insulation properties inherent in the underground to efficiently utilize cold and thermal energy at the same time. Since it is a system that stores and utilizes it in a timely manner, it has an excellent effect in that the above-mentioned location constraints are significantly improved.

In addition to the original effects of the present invention, (1) Serious problems under ground laws caused by pumping up groundwater for snow melting, etc., are significantly alleviated.

(11) It is significantly more economical than those that use fuel for producing hot water for snow melting, etc.

(110) Even in urban areas where it is difficult to find a water source in the vicinity, the use of the underground dam becomes possible.

4V) It is also possible to form a completely artificial underground water storage layer, such as by installing an impermeable wall in a place where there is no underground water and injecting and storing cold or hot water there.

It has the following effects, and its range of use is very wide, not only for snow melting and heating, etc., and it ultimately makes it possible to promote the use of local energy, which is a discontinuous energy source, and particularly contributes to the local economy. The industrial effects obtained are truly great.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an underground dam for explaining the system of the present invention, A is a vertical cross-sectional view, B is a cross-sectional view, C is a cross-sectional view of another embodiment, and Figure 2 is a cross-sectional view of the same system. A schematic diagram of an example of the system being used for snow melting and heating; Figure 3 is a schematic diagram of an example in which the same system has been expanded to other fields of use; Figure 4 shows the thermal energy of turbine-generated cooling water, especially from the heat generated during garbage incineration. It is a schematic diagram showing an example of use in a reduction system. 1...Ground surface, 1'...Urban buildings, 2...Underground bedrock, 3...Underground aquifer, 4...Groundwater flow, 5...
° Waterproof wall, 6... Underground dam (water storage part), 6a, 6b.
... Upper layer, lower layer (temperature stratification), 10a, 10b... Well, 11... Pumping water, water injection device, 12... Pipe with fins for snow melting, 13... Nitrogen regulator, 25... Heat exchanger,
26.27... Central piping, 29... Steam turbine,
3o... Generator, 31... Condenser. Patent Applicant Agent Figure 1 (8) Figure 3 Figure 4 Continuation of page 1 [Phase] Inventor Kei Yukimura Hitachi Plant Construction Co., Ltd. Research Center, 537 Funatsuki, Kamihongo, Matsudo City ■Applicant Furukawa Electric Kogyo Co., Ltd. 2-6 Marunouchi, Chiyoda-ku, Tokyo ■Applicant Ishikawajima Harima Heavy Industries Co., Ltd. 2-2 Otemachi, Chiyoda-ku, Tokyo ■Applicant Ebara Corporation 11-1 Haneda Asahi-cho, Ota-ku, Tokyo ■ Applicant: Sumitomo Metal Industries, Ltd. 5-15 Kitahama, Higashi-ku, Osaka @Applicant: Hazama Co., Ltd. 2-5-8 Kita-Aoyama, Minato-ku, Tokyo ■Applicant: Hitachi Zosen Corporation 1-6-14 Edobori, Nishi-ku, Osaka ■ Applicant: Hitachi Plant Construction Co., Ltd. 1-1- Uchikanda, Chiyoda-ku, Tokyo

Claims (1)

[Claims] (1) An impermeable wall is provided in a suitable location underground, and a temperature stratification having a temperature difference between the lower layer and the upper layer is formed in the underground water storage part that is dammed by the impermeable wall, and the lower layer water of the water storage part is The upper layer water is taken in and taken out separately by pumping and water injection devices installed to reach each water layer, and a supply system for thermal energy stored in the water stored in the water storage section and a system for extracting it from the water storage section. A geothermal energy storage system characterized in that all of the consumption systems used are operated in a closed circulation system. 2) The impermeable wall in item (1) above was installed on an impermeable bedrock, and low-temperature water (as well as normal groundwater) was stored in the lower layer of the water storage fc4? The geothermal energy storage system described in the preceding paragraph (1). <37 The impermeable wall in item (1) above is installed without directly pouring liquid onto the impermeable bedrock, and water with a higher temperature than normal groundwater is stored especially in the upper layer of the water storage area. The geothermal energy storage system described in the preceding item (1), characterized by: