WO2009104813A1

WO2009104813A1 - Method of converting solar heat energy

Info

Publication number: WO2009104813A1
Application number: PCT/JP2009/053613
Authority: WO
Inventors: 中村徳彦
Original assignee: トヨタ自動車株式会社
Priority date: 2008-02-22
Filing date: 2009-02-20
Publication date: 2009-08-27
Also published as: CN101946070B; ES2383184A1; IL207473A0; ES2383184B1; JP2009197734A; MA32189B1; CN101946070A; AU2009216073B2; ZA201005525B; AU2009216073A1

Abstract

Provided is a method of converting a solar heat energy obtained in a first region to a driving energy to be utilized in a second region having less solar radiation than the first region. The method includes: a step in which in the first region, the solar heat energy obtained is used as the only energy source to synthesize ammonia from air and water; a step in which the ammonia is transferred from the first region to the second region; and a step in which in the second region, the ammonia is burned so as to generate nitrogen and water to thereby obtain a driving energy.

Description

9 053613

Solar thermal energy conversion method

Technical field

In recent years, global warming has developed into a more serious situation, and even the future survival of humankind may be threatened. The main cause was apparent in the 20th century

It is thought to be atmospheric carbon dioxide (C 0 ₂ fields) released from fossil fuels that have been used in large quantities as a source of incoming energy. Therefore, in the near future, it will not be allowed to continue writing on fossil fuels. On the other hand, with the increase in energy demand accompanying soaring economic growth in so-called developing countries such as China, India, Brazil, etc., oil and natural gas, which had been thought to be inexhaustible in the past, are now being used up. It has become real.

In this situation, it can be fully inferred from the recent rapid increase in oil prices that fossil fuels such as oil and natural gas cannot be used as an inexpensive energy source in 20-30 years. Therefore, in order to achieve a sustainable society, there is a need to search for new energy sources and fuels that do not release carbon dioxide and do not depend on limited fossil fuels.

Background art

Currently, coal energy, biomass energy, nuclear energy, and natural energy such as wind energy and solar energy are being considered as alternative energy alternatives to fossil fuel energy such as oil and natural gas.

When using coal energy as an alternative energy, JP2009 / 053613 It is considered that a large amount of carbon dioxide is released by firing. For this, it has been proposed to capture carbon dioxide during combustion and store it underground, and many studies have been carried out, but there is still uncertainty about long-term stable storage. There are also uneven locations suitable for storage. In addition, it may be a problem that a lot of cost is required to collect, transport, and throw carbon dioxide into the ground. Furthermore, the combustion of coal, sulfur oxides (so _x), also considered to be a problem that is likely to cause environmental problems due to occurrence of such smoke.

Biofuels as alternative energy, especially biofuels, mainly ethanol, have been in the spotlight in recent years. However, enormous energy is required for the production and concentration of ethanol from plants, which may be disadvantageous in terms of energy efficiency. Furthermore, when corn, soybeans, sugar millet, etc. are used as raw materials for biofuels, these will naturally also be used as food and feed, which will increase the price of food and feed. . Therefore, biomass energy cannot be considered as a substantial energy source outside of special regions such as Brazil.

The use of nuclear energy as an alternative energy has not been found to be a sufficient solution for the treatment of radioactive waste from nuclear power plants, and there are also many dissents based on fear of proliferation. From that, we can not expect great progress globally. Rather, the use of nuclear energy as an alternative energy is expected to decrease over the long term due to an increase in the number of decommissioned nuclear reactors.

As mentioned above, none of coal energy, biomass energy, or nuclear energy has solved the problem of carbon dioxide generation that leads to sustainability and global warming. So ideal energy PT / JP2009 / 053613 As a source, natural energy such as wind energy and solar energy is inevitably considered.

With regard to the use of wind energy as an alternative energy, wind power generation is spreading around the world in recent years. However, there are limited places where the wind blows stably, does not match the damage of typhoons, hurricanes, lightning strikes, etc., and the noise generated by the windmills is not a problem. Therefore, wind energy is a strong alternative energy candidate, but it is not enough.

Solar energy is considered to be the most stable and abundant natural energy as alternative energy. In particular, near the equator, which is called the world's sambel ridge, a vast desert spreads out and the solar energy that falls here can be said to be inexhaustible. In this regard, it is believed that if only a few percent of the desert that extends to the southwestern United States is used, energy of as much as 7,00 GW can be obtained. It is also believed that using only a few percent of the Arabian Peninsula and the deserts of North Africa can cover all the energy used by all mankind.

Thus, although solar energy is a very powerful alternative energy, in order to utilize it in social activities, (1) the energy density of solar energy is low, and (2) Difficulties in storing and transferring energy may be problematic.

On the other hand, it has been proposed to solve the problem of low solar energy density by collecting solar energy with a huge concentrator. However, storage and transport of solar energy is very difficult, especially when the transport distance of energy is long and large.

In general, solar energy is directly generated by solar cells, or 2009/053613 It is converted into electric power as secondary energy indirectly by a steam turbine, etc., and it is made convenient for its use and transportation. In the case of converting solar energy into electric power, the energy transfer problem can be solved in principle because electric energy can be transferred through the transmission line. However, when a plant that obtains electric energy from solar energy is installed in a desert area rich in solar energy, it is necessary to construct and maintain a new high-capacity transmission line, which is difficult. Many. Furthermore, for example, it is considered extremely difficult to send large amounts of power energy obtained from solar energy at plants in desert areas to other continents and island countries across the sea.

Also, storage of electricity can be a problem. The development of batteries for storing electric power has long been a major theme around the world. However, even state-of-the-art lithium-ion batteries are not sufficient for high-power storage, and especially for high-power batteries, further safety development is required. In addition, a plant that obtains electric energy from solar energy needs a huge heat storage device and auxiliary boiler in addition to the battery in preparation for situations where power generation becomes difficult due to bad weather, etc., which increases the construction cost. It ’s a good thing.

In addition, conversion of solar energy, which is primary energy, to hydrogen as secondary energy, and synthesis of ammonia, methane, etc. using hydrogen obtained in this way as a raw material are also being studied ( Japanese Patent Laid-Open No. 20 0 6-3 1 9 2 9 1).

Although hydrogen is attracting attention as a clean energy, storage is a major issue as with electricity. In recent years, a lot of research on hydrogen storage has been conducted for supplying fuel cells, but it is becoming clear that its practical application is not easy. In addition, the hydrogen transfer In particular, the construction of a hydrogen pipeline is more difficult than the construction of a transmission line, especially the construction of a hydrogen pipeline infrastructure such as a mesh for supply to users. In addition, it is necessary to store liquid hydrogen at 1 25 3, and therefore, this is not considered to be applied at any other time than for special purposes such as space development. Disclosure of the invention

As described above, efforts are being made around the world to convert solar energy, which is a sustainable energy of salient poles, into electric power, hydrogen, etc. as secondary energy. There are major problems with transport. If this storage and transport problem is not solved, it will be difficult to distribute it all over the world and to use it for moving objects such as cars, aircraft and ships.

The present invention solves the problems related to the storage and transfer of solar energy, thereby making it possible to use solar energy all over the world, and to solve the problem of the generation of carbon dioxide, a greenhouse gas, and the problem of drought of oil. It is intended to be resolved.

The first set of methods intended to solve the above problem is as described in (A 1) to (A 2 0) below:

(A 1) A method for converting solar thermal energy obtained in a first area into driving energy used in a second area where the amount of solar radiation is lower than that in the first area.

In the first area, ammonia is synthesized from air and water using only the acquired solar thermal energy as an energy source,

The ammonia is transferred from the first area to the second area, and the ammonia is generated in the second area so as to generate nitrogen and water. 2009/053613 A method characterized by having a process of obtaining driving energy by burning.

(A 2) The method according to (A 1), wherein the transfer step uses the ammonia as a fuel to obtain at least a part of electric power and Z or power necessary for the transfer.

(A 3) The method according to (A 1) or (A 2), wherein nitrogen and water generated by the combustion are released into the atmosphere and can be recycled as ammonia in the synthesis step.

(A4) The method according to any one of (A1) to (A3), wherein the drive energy is acquired using an internal combustion engine.

(A5) The step of synthesizing the ammonia includes

(1) Using a part of the acquired solar thermal energy, causing a reaction to generate hydrogen from water,

(2) Utilizing another part of the acquired solar thermal energy, causing a reaction to synthesize ammonia from nitrogen and hydrogen obtained in step (1),

The method according to any one of (A 1) to (A 4), comprising:

(A 6) Any one of the above items (A 1) to (A 5) is used to obtain at least a part of electric power and / or motive power necessary for performing the synthesis process by using the acquired solar thermal energy. The method of crab.

(A7) The synthesized ammonia is used as a fuel to obtain at least a part of the electric power, power and Z or heat necessary for carrying out the synthesis step, (A1) to (A6) The method in any one of.

(A 8) In the step (1), any one of the above (A 5) to (A 7), wherein the obtained solar thermal energy is directly used as a heat source to cause a reaction to generate hydrogen from water. The method described.

(A 9) The solar heat energy used as a heat source in step (1) The method according to (A 8), wherein at least a part of the lug is obtained by a parabolic dish type concentrator and / or a solar tower type concentrator.

(A 10) The method according to (A 6) or (A 7), wherein in step (1), the electric power is used as a heat source to cause a reaction to generate hydrogen from water.

(A l l) The method according to (A 6) or (A 7), wherein in step (1), water is electrolyzed with the electric power to cause a reaction to generate hydrogen from water.

(A 1 2) The method according to any one of (A 1 0) or (A l 1), wherein the solar thermal energy is acquired by a parabolic trough concentrator.

(A 1 3) In the step (2), ammonia is synthesized from nitrogen and hydrogen using the obtained solar thermal energy directly as a heat source and Z or as a power source, (A 5) to (A 1 2) The method described in any one of the items.

(A 14) The method according to (A 13), wherein the solar heat energy used as a heat source in the step (2) is obtained by a parapoly trough concentrator.

(A 15) In step (1), the obtained solar thermal energy is directly used as a heat source to cause a reaction to generate hydrogen from water; the solar thermal energy used as a heat source in step (1) is reduced In part (2), the obtained solar thermal energy is directly used as a heat source and / or as a power source in the step (2). A reaction of synthesizing ammonia from nitrogen and hydrogen; and the solar thermal energy used as a heat source in step (2) 9 053613

The method according to any one of (A 5) to (A 7), which is obtained by using a parapolic trough concentrator.

(A 1 6) The method according to (A 6) or (A 7), wherein the nitrogen is obtained by cryogenic separation of air using the power and Z or power.

(A 17) The nitrogen according to any one of (A 5) to (A 15), wherein the nitrogen is obtained by burning the hydrogen obtained in step (1) and consuming oxygen in the air. Method.

(A 1 8) A method of using solar thermal energy obtained in a first area as driving energy used in a second area where the amount of solar radiation is lower than that in the first area,

In the first region, ammonia is synthesized from air and water using only the acquired solar thermal energy as an energy source,

Transferring the ammonia to the second region to obtain drive energy by burning the ammonia to produce nitrogen and water.

(A 19) A method of using solar thermal energy obtained in a first area as driving energy used in a second area where the amount of solar radiation is lower than that in the first area, In the second area, ammonia synthesized from air and water using only the solar thermal energy acquired in

A method comprising the step of obtaining driving energy by burning the ammonia so as to generate nitrogen and water in the second region.

(A 2 0) Convert solar thermal energy obtained in the first area into driving energy used in the second area, which has less solar radiation than the first area. 3 methods,

The solar thermal energy acquisition means of the first region collects sunlight and acquires solar thermal energy,

Ammonia synthesis means in the first region synthesizes ammonia from air and water using only the acquired solar heat energy as an energy source,

In the ammonia liquefaction means of the first area, the ammonia is liquefied,

An ammonia transfer means for transferring the liquefied ammonia from the first region to the second region;

The driving energy generating means in the second region comprises the step of obtaining the driving energy by burning the ammonia so as to generate nitrogen and water.

The second set of methods intended to solve the above problems are as described in (B 1) to (B 14) below:

(B 1) (a) Obtaining solar thermal energy,

(b) using a part of the acquired solar thermal energy to cause a reaction to generate hydrogen from water; and

(c) using another part of the acquired solar thermal energy to cause a reaction to synthesize ammonia from nitrogen and hydrogen obtained in step (b);

Including a solar thermal energy storage method.

(B 2) Using the solar thermal energy acquired in step (a), obtain at least a part of the electric power and / or power necessary for the implementation of this method.

The method according to item (B 1).

(B 3) Use the synthesized ammonia as fuel to obtain at least part of the power, power and / or heat required to perform this method. 3 The method according to (B 1) or (B 2).

(B4) The method according to any one of (B1) to (B3), wherein only the solar thermal energy obtained in the step (a) is used as an energy source.

(B 5) In the step (b), the solar heat energy obtained in the step (a) is directly used as a heat source to carry out a reaction for generating hydrogen from water (B 1) to (B 4 The method according to any one of the paragraphs).

(B 6) At least a part of the solar heat energy used as a heat source in the step (b) is obtained by a parapoly dish type concentrator and Z or a solar evening type concentrator. 5) The method described in the paragraph.

(B 7) The method according to (B 2) or (B 3), wherein in step (b), a reaction for generating hydrogen from water is performed using the electric power as a heat source.

(B 8) The method according to (B 2) or (B 3), wherein in step (b), water is electrolyzed with the electric power to cause a reaction to generate hydrogen from water.

(B 9) The method according to any one of (B 7) or (B 8), wherein, in step (a), the solar thermal energy is acquired by a parapoly trough-type concentrator.

(B 1 0) In step (c), ammonia is synthesized from nitrogen and hydrogen using the solar heat energy obtained in step (a) directly as a heat source and Z or as a power source. ) To (B 9)

(B 11) The method according to (B 10), wherein the solar energy to be used as a heat source in the step (c) is obtained with a parapoly trough concentrator. PT / JP2009 / 053613

(B 1 2) In step (b), the solar heat energy obtained in step (a) is directly used as a heat source to cause a reaction to generate hydrogen from water; used as a heat source in step (b) At least a part of the solar heat energy is obtained with a parapoly dish type concentrator and a Z or solar tower type concentrator; in step (c), the solar thermal energy obtained in step (a) is directly obtained. And a reaction to synthesize ammonia from nitrogen and hydrogen as a heat source and / or as a power source; and the solar heat energy used as a heat source in step (c) The method according to any one of (B1) to (B4), which is obtained by an apparatus.

(B 1 3) The method according to (B 2) or (B 3), wherein the nitrogen is obtained by cryogenic separation of air using the electric power and / or power.

(B 1 4) The nitrogen according to any one of (B 1) to (B 1 2), wherein the nitrogen is obtained by burning the hydrogen obtained in step (b) and consuming oxygen in the air. Method.

According to the above method, solar thermal energy that can be said to be inexhaustible is converted or stored and used to solve the problems of global warming and oil and natural gas depletion. Brief Description of Drawings

FIG. 1 is a diagram for explaining an example of the conversion system 1.

FIG. 2 is a diagram for explaining an example of the conversion system 2.

FIG. 3 is a diagram for explaining the energy flow of the conversion system 1.

FIG. 4 is a diagram showing an outline of a parapoly dish type condensing device. FIG. 5 is a diagram showing an outline of a solar tower type condensing device. FIG. 6 is a diagram showing an outline of a parapoly trough-type concentrating device. FIG. 7 is a diagram showing an example of equipment for implementing a solar thermal energy storage method. BEST MODE FOR CARRYING OUT THE INVENTION

Regarding the storage and transfer of solar energy, the following three substances are considered as candidates for liquid fuels that can be produced from water, air and solar thermal energy and are easy to store and transfer:

(1) Hydrogen peroxide (H ₂ 0 ₂ )

(2) Hydrazine (NH ₂ NH ₂ )

(3) Ammonia (NH ₃ )

Among these, considering the ease of handling of substances, ammonia is considered to be a useful candidate. Ammonia is a strongly irritating gas, and it is a deleterious substance that damages the respiratory system when inhaling high-concentration gas, but due to its strong odor, the lethal dose is less than 1/1, 0 0 0 or less Humans can detect leaks from around 5 ppm, and there are very few accidents in the actual market. For example, ammonia is used as a refrigerant for refrigeration equipment such as fish boats along with chlorofluorocarbons. A fatal accident at the time of leakage of ammonia is 1/1 0 Degree. Explosive disasters during the transfer of ammonia are less than 1/5 of gasoline and liquefied petroleum gas (LPG).

The world's current ammonia production is about 150 million tons per year, which is mainly used for fertilizers in large quantities. In view of the fact that it is used in large quantities in the market in this way, ammonia is considered to be sufficiently socially acceptable. T / JP2009 / 053613 The physical properties of ammonia are close to those of LPG, easily liquefy at about 8 atmospheres at room temperature, and have a sufficient track record for storage and transfer, and are not a particular problem. In addition, ammonia is defined as a non-flammable substance, and it is difficult to ignite, and even if ignited, the burning rate is slow and the flammable range is narrow, so its handling is not considered to be a particular problem.

The energy density of ammonia is about half that of gasoline and almost the same as methanol, but the calorific value in theoretical mixing is higher than that of gasoline, and it can be applied to a moving body as a fuel. Furthermore, it can be sent to a thermal power plant in a remote area by a tanker or the like and burned instead of natural gas or coal. In this case, the efficiency is theoretically considered to exceed that of natural gas or coal.

In the combustion of ammonia, a combustion reaction as shown by the following formula A can be performed:

2 N H 3 + 3/2 O 2 →

N ₂ + 3 H ₂ O + (Exotherm) (Formula A) In other words, in the combustion of ammonia, carbon dioxide is not generated, and therefore there is no problem with respect to global warming.

Note that the power obtained by burning ammonia as described above is described in, for example, Japanese Patent Laid-Open No. 5-3 3 2 1 5 2.

Energy conversion method>

With reference to Fig. 1, a conversion system 1 that converts solar thermal energy into drive energy will be described.

The conversion system 1 condenses sunlight 20 0 to produce solar thermal energy, solar thermal energy acquisition means 10, and ammonia synthesis means 20 0 to synthesize ammonia from water and air using solar thermal energy For details, see Solar Energy Storage Method below. A) an ammonia transfer means 30; and a drive energy generation means 40 which burns ammonia to generate drive energy.

The solar heat acquisition means 10 and the ammonia synthesis means 20 are arranged in the first area 3, and the drive energy generation means 40 is arranged in the second area 5 that is geographically different from the first area 3. .

As described later, the ammonia synthesis reaction from air and water is an endothermic reaction as a whole. Therefore, the ammonia synthesis means 20 uses solar heat energy as reaction heat and converts ammonia (NH ₃ ) and oxygen (〇 ₂ ) from nitrogen (N ₂ ) and water (H ₂ 0) contained in the air. Generate. The produced ammonia is optionally liquefied and transferred from the first region 3 to the second region 5 as fuel by the ammonia transfer means 30. In the second region 5, ammonia is burned by the driving energy generation means 4 0 so as to generate nitrogen and water, and driving energy 1 2 40 and thermal energy 2 5 0 are generated.

Nitrogen and water are non-polluting substances that are abundant in the atmosphere. Therefore, nitrogen and water generated by combustion are released into the atmosphere and circulate according to convection existing in nature, and can be used again as raw materials for ammonia synthesis means 20 in the first region 3. become.

The conversion system 1 has an energy balance of driving energy 2 4 0 and thermal energy 2 5 0 with sunlight 2 0 0 as input, while nitrogen + water-ammonia + oxygen (ammonia synthesis), It has a material balance of the circulation loop of ammonia + oxygen-nitrogen + water (ammonia combustion). And all the processes of the conversion system 1 do not require chemical substances containing carbon atoms, and therefore do not emit any carbon dioxide (C 0 ₂ ).

As described above, the conversion system 1 uses the ammonia generated using air and water as a solar thermal energy transfer material. Solar thermal energy acquired in Region 3 in 1 can be used as driving energy in Region 5 in the second. In addition, since the conversion system 1 converts energy by circulating chemical substances that do not contain carbon atoms (water, nitrogen in the air, ammonia), it does not emit carbon dioxide at any step in the system.

The solar heat acquisition means 10 is preferably located in an area with a large amount of sunlight, so the first area should have a higher solar radiation than the second area that uses drive energy. . The ammonia synthesizing means 20 also discharges oxygen. Oxygen is a valuable substance for the manufacture of chemical products, so oxygen utilization facilities may be established in the first area.

An example of the conversion system 2 will be described with reference to FIG.

As shown in the figure, the ammonia synthesis means 20 is composed of an ammonia synthesis brand 22, an ammonia liquefaction device 24 that liquefies compressed ammonia with cooling water, and lowers the temperature of the liquefied ammonia by the expanded self-refrigerant. Power generation plant that generates power from steam turbines that use steam generated or gas turbines that use ammonia combustion (including those combined with steam turbines) 25, liquefied ammonia shipping facilities 26, cooling not shown Includes water cooling towers, water treatment equipment that purifies water from well water, seawater, etc. For the ammonia synthesis plant 2 2, the solar thermal energy storage method described later can be referred to. The ammonia transfer means 30 is carried out by a liquefied ammonia ship 3 2 for on-board transfer, or tank lorry 3 4 or pipeline 3 6 for land transfer.

In the second area 5, ammonia is received by the ammonia receiving facility 42, or ammonia is directly transferred to the drive energy generating means 40. Drive energy generating means 4 0 (gas turbine, Automobiles, etc.) use an internal combustion engine to burn ammonia and obtain drive energy.

In this way, the conversion system 2 uses the ammonia generated using air and water as a solar thermal energy transfer material, so that the solar thermal energy acquired in the first region 3 can be driven in the second region 5. It can be used as energy. In addition, since the conversion system 2 converts energy by circulation of chemical substances without carbon atoms (water, nitrogen in the air, ammonia), the solar heat acquisition means 10 and ammonia synthesis means 20 in the first region, Carbon dioxide is not emitted in the driving energy generation means 40 in the second region.

Using Fig. 3, the energy flow of the conversion system 1 is explained. Sunlight 20 0 is converted into solar heat energy 2 10 through solar heat acquisition means 10. Solar thermal energy 2 1 0 is converted to chemical energy 2 2 0 as potential energy of ammonia by ammonia synthesis means 2 0. Here, a part 2 15 of the solar thermal energy 2 10 is used for the ammonia synthesizing means 2 0 as a heat source, a power source and / or a power source.

The chemical energy 220 is transferred from the first region 3 to the second region 5 by the ammonia transfer means 30. In the transfer, the ammonia transfer means 30 is combusted by the internal combustion engine of the ammonia transfer means 30 with a part of chemical energy (that is, a part of the ammonia to be transferred). Power and Z or at least part of power). The chemical energy 2 2 0 is partially consumed by the ammonia transfer means 30, and becomes chemical energy 2 3 0 after being transferred to the second area 5.

The chemical energy 2 3 0 is obtained by combusting ammonia so that the driving energy generating means 40 generates nitrogen and water, and the driving energy 1 2 4 0 The thermal energy 2 50 is output (not shown in the figure, the ammonia synthesizing means 20 and the ammonia transfer means 30 can generate waste heat energy).

In this way, by using the chemical energy of ammonia, sunlight 20 0 input in the first region 3 is transferred as drive energy 2 4 0 and thermal energy 2 5 0 in the second region 5. Is done. The conversion system 1 does not need to use an energy source other than the sunlight 20 0. Therefore, the conversion system 1 enables conversion of solar thermal energy 2 10 to driving energy 2 40 without emitting carbon dioxide at any step in the system.

Methods for storing solar thermal energy include: (a) acquiring solar thermal energy; (b) utilizing a portion of the acquired solar thermal energy, for example, as a heat source, power source and / or power source, particularly directly (C) using other part of the acquired solar thermal energy, for example as a heat source, power source and / or power Use as a source, in particular as a heat source and / or power source, to carry out a reaction to synthesize ammonia from nitrogen and hydrogen obtained in step (b).

According to this energy storage method, solar heat energy can be stored in the form of chemical energy of ammonia by synthesizing ammonia using solar heat energy.

In a preferred embodiment of this method, the solar heat energy obtained in step (a) is used to obtain at least a portion of the power and Z or power required to perform this method. In another preferred embodiment, the synthesized ammonia is used as a fuel to obtain at least a portion of the power, dynamics and / or heat required to perform this method. Also other preferred this way In a new embodiment, only the solar thermal energy acquired in step (a) is used as a source of energy.

Here, examples of the electric power required for carrying out this method include electric power for driving a pump / compressor that flows and compresses a fluid such as a raw material, electric power for further heating of a heat source, and the like. it can. The power necessary for carrying out this method may include power for driving a pump / compressor that causes a fluid such as a raw material to flow and is Z or compressed. In addition, heat necessary for carrying out this method can include heat for further heating of the heat source. Here, supplying a part of the heat energy for the heat source by electric power may be preferable in order to make the temperature of the heat source higher than the temperature obtained directly by the solar heat energy.

According to these aspects, the method can be implemented with reduced, and preferably no, use of conventional fossil fuels such as petroleum.

The total reaction of ammonia synthesis from water and nitrogen is as shown in the following formula B:

N ₂ + 3 H a O →

2 NH 3 + 3/2 O ₂ (endothermic) (Formula B) In the solar thermal energy storage method, water (H ₂ 0) and nitrogen (N ₂ ) are used by using solar thermal energy as an energy source for reaction. Then, ammonia (NH ₃ ) is synthesized through the reaction of hydrogen (H ₂ ) and nitrogen (N ₂ ). The solar thermal energy storage method will be described in detail below.

(A) (Acquisition of solar thermal energy)>

In the solar thermal energy storage method, solar energy is acquired in step (a). T / JP2009 / 053613 In the step (a), any solar concentrator can be used to obtain solar thermal energy. For example, the following solar collectors (1) to (3) are used. be able to :

(1) Parapolic dish type (Par a b o 1 i c d i sh h T y p e)

The parapoly dish type condensing device shown in FIG. 4 has a dish-shaped reflecting portion 1 4 1 that reflects and collects sunlight 20 0 and a light receiving portion 1 4 2 that receives the collected light. The solar receiver 1 4 2 acquires solar thermal energy. Solar thermal energy obtained from the light-receiving unit 1 4 2 can be transferred to the required location using a heat carrier such as a molten alkali metal such as molten metal sodium, molten salt, oil, or water vapor. .

This type of concentrator is suitable for a relatively small plant, and is preferably used as solar heat energy of about 10 1 to several 10 O kw. In general, this type of condensing device has a high condensing degree, which can provide a high-temperature heat source of 2,00 ° C. or higher, but the cost is relatively high.

(2) Solar tower type

The solar tower type concentrator shown in Fig. 5 has a plurality of heliostats (reflectors) 1 5 1 that reflect sunlight 2 0 0 and collects light and a light receiver 1 5 3 that receives the collected light. And the solar light energy is acquired at the light receiving section 15 2. Here, the light receiving portion 1 5 3 is disposed on the upper portion of the light receiving tower 1 5 2. The solar thermal energy obtained by the light-receiving unit 15 3 can be moved to a required location using a heat medium as required.

This type of concentrator is suitable for large plants ranging from 10 MW to several 100 MW. In general, this type of concentrator has a high condensing degree and can provide a high-temperature heat source of several 1,00 0 ° C. 053613 is high, and advanced technology is also required for control of the reflector.

(3) Parapolic trough type

The parapoly trough-type concentrator shown in Fig. 6 has a trough-type reflector 1 6 1 that reflects sunlight 2 0 0 to collect light and a light receiver 1 6 2 that receives the collected light. The solar thermal energy is acquired in this light receiving unit 1 4 2. The solar thermal energy obtained by the light receiving section 16 2 can be moved to a necessary location by optionally circulating the heat medium via the heat medium flow path 16 3.

This type of concentrator is simple in structure and low in cost, and is suitable for large-scale plants. In general, it is suitable for a number of 100 MW, but has a low concentration, and the obtained heat source is a low-temperature heat source of 400 to 500 ° C.

As mentioned above, each concentrator has advantages and disadvantages. Therefore, any of these or a combination of them can be used in the energy storage method. Specifically, solar thermal energy for a high-temperature heat source is obtained by a concentrator with a high degree of concentration (for example, a parapoly dish type concentrator and / or a solar evening-type concentrator), and other solar heat Solar energy for generating energy, for example, a low-temperature heat source, power and / or energy, can be obtained with a concentrator with a low concentration (eg, a parapoly trough concentrator).

For example, solar thermal energy obtained by a concentrating device with a high degree of concentration is less than 1/2 of the total solar thermal energy obtained by a concentrating device with a high degree of condensing and a concentrating device with a low degree of concentrating, It can be in the range of 1 Z 2. Thus, limiting the proportion of light concentrators that are generally high cost and have a high degree of light condensing may be desirable with respect to the cost of the overall light concentrating equipment. '

<One step of solar thermal energy storage method (b) (production of hydrogen)> 3613 In the solar thermal energy storage method, in step (b), a part of the acquired solar thermal energy is used, and in particular, only the acquired solar thermal energy is used as an energy source to cause a reaction to generate hydrogen from water. .

In this step (b), any method can be used to obtain hydrogen from water. Specifically, along with water electrolysis, for example, the following (1) to (3) water splitting methods are known. In these methods, water decomposition is known. The focus is on reducing the reaction temperature required for the reaction: (1) Direct method

It is the most basic method, and it decomposes water into hydrogen and oxygen directly at high temperature by the reaction shown in Equation 1 below:

H ₂ ○ → H ₂ + 1/2 O 2 (2, 0 0 0 ° C or more)

(Equation 1) originally reaction, requires a temperature thousands ¹ C, can be achieved with 2, 0 0 0 ° C before and after the temperature by utilizing a catalyst.

(2) Zn (zinc) method

In order to lower the high temperature required in (1) above, there is a method of decomposing water through the presence of a third substance. A typical example is a method involving zinc, in which the reaction formula is as follows:

Z n + H ₂ 0 → Z n〇 + H ₂ (Approx. 4 0 0 ° C) (Formula 2)

Z n O → Z n + l / 20 ₂ (approx. 15 500 ° C) (Equation 3) All reactions H ₂ 0 → H ₂ + 1/2 O ₂

This method requires two types of heat sources: a high-temperature heat source (approximately 1500 ° C) and a low-temperature heat source (4200 ° C).

(3) I-S (iodine-io) cycle method

As a method for lowering the reaction temperature further than the method (2) above, I 09053613 One s cycle method is known and the reaction is as follows: H 2 SO ₄ → H 2 O + SO ₂ + 1/2 O ₂ (about 9500 ° C)

(Formula 4)

2 H a O + SO 2 + I 2 → H 2 SO ₄ + 2 HI (about 1 3 0 ° C)

(Formula 5)

2 HI → H ₂ + I ₂ (about 4 0 0)

(Equation 6) Total reaction H ₂ 0 → H ₂ + 1 Z ₂ 0 ₂

This method requires two types of heat sources: a high-temperature heat source (950 ° C) and a low-temperature heat source (400 ° C).

As described above, in the reactions (1) to (3) in which hydrogen is generated from water using heat, a heat source having a relatively high temperature is required for at least some of the reactions.

This relatively high temperature heat source can be provided by directly using the solar heat energy acquired in step (a) as a heat source, in which case at least a portion of the required solar heat energy is collected. It can be obtained with a concentrator with a high luminous intensity, such as a parapoly dish type concentrator and a Z or solar tower type concentrator. In addition, this relatively high temperature heat source uses electric power, particularly electric power obtained using solar thermal energy acquired in step (a), or electric power obtained using synthesized ammonia as fuel. be able to. In addition, when hydrogen is obtained without using a relatively high temperature heat source, that is, for example, by electrolysis of water, electric power, in particular, electric power obtained using solar thermal energy acquired in step (a), or synthesized energy Electricity obtained by using monmonas as fuel can be used.

Thus, in the case of providing a relatively high-temperature heat source using electric power, or in the case of electrolyzing water using electric power, in the step (a), JP2009 / 053613 Acquisition of solar thermal energy can be performed by a light collecting device having a low light collecting degree, for example, a parapoly trough type light collecting device. This may be preferable with respect to the overall cost of the light collection equipment.

<One step of solar thermal energy storage method (C) (synthesis of ammonia)

>

In the solar thermal energy storage method, in step (C), a part of the obtained solar thermal energy was used, and in particular, only the obtained solar thermal energy was used as an energy source, and was obtained in nitrogen and step (b). A reaction for synthesizing ammonia from hydrogen is performed.

In this step (c), the synthesis of ammonia from nitrogen and hydrogen can be achieved by any method.

The chemical synthesis of ammonia was the first successful mass production of scientists Herba and Bosch about 100 years ago, contributing to increased food production as a nitrogen fertilizer. The Haber-Bosch synthesis method is an endothermic reaction shown below, and it is simple and relatively efficient, so it is still used basically without modification, and this method should also be used for energy storage. Can:

N ₂ + 3 H ₂ → 2 NH ₃ (approx. 400 ° C) (Equation 8) In other words, this reaction uses a relatively low-temperature (400 ° C) heat source. Conventionally, this reaction has been carried out using an iron catalyst, but recently, the reaction temperature has been further lowered using a ruthenium catalyst. When the reaction temperature is low, the yield of ammonia is high in equilibrium, so research to lower the reaction temperature is still underway.

The relatively low temperature heat source for this reaction and / or the power for this reaction can be provided using the solar thermal energy obtained in step (a), in which case the necessary solar heat Collecting energy PT / JP2009 / 053613 It can be obtained with a condensing device with a low luminous intensity, for example, a parabolic trough concentrating device.

In order to obtain nitrogen for the solar thermal energy storage method, the following methods (1) and (2) are applicable:

(1) Cryogenic separation

In this method, air is cooled and compressed to produce liquid air, and nitrogen is separated from liquid air by utilizing the difference in boiling point between oxygen and nitrogen. This method yields high purity nitrogen, but requires large equipment and a relatively large amount of energy.

Here, for the cryogenic separation of the air, the electric power and Z or power obtained by using the solar thermal energy obtained in the step (a), or the electric power obtained by using the synthesized ammonia as the fuel and Power can be used. In this case, also in this step, the production of carbon dioxide due to the use of the fossil fuel can be suppressed and preferably eliminated.

(2) Removal of oxygen by combustion

In a conventional ammonia plant that uses natural gas, oxygen in the air is consumed in the reforming process to obtain hydrogen, and carbon monoxide and carbon dioxide are absorbed and removed from the remaining mixed gas to remove nitrogen gas. It has gained. This method can also be used as an energy storage method, but in this case, a purification process may be required to reduce the concentration of carbon monoxide and carbon dioxide contained in nitrogen gas to 10 ppm or less. If this is not done, carbon monoxide and carbon dioxide may adsorb on the ammonia synthesis catalyst and accelerate the degradation.

(3) On the other hand, in one embodiment of the energy storage method, as shown in the following formula 7, hydrogen (H ₂ ) produced is burned with air (4 N ₂ +0 ₂ ) Nitrogen can also be consumed by nitrogen 3613 Can produce gas:

2 H 2 + 4 N 2 + O 2 → 4 N 2 + 2 H 2 O (Equation 7) In this case, the combustion product is only water, and the combustion product is not generated as carbon monoxide and carbon dioxide. This reduces or even eliminates the need for carbon monoxide and carbon dioxide removal. Since this reaction is an exothermic reaction, it is possible to use the heat energy generated at this time as necessary to produce the electric power required for the energy storage method.

One example of a solar thermal energy storage method can be implemented using equipment as shown in Figure 7.

In the facility shown in Fig. 7, solar heat energy is acquired by a solar tower type condensing device 15 0 having a relatively high light concentration, and the solar heat energy obtained here is used to distribute a heat medium that is a molten salt 1 7 8 to transfer to reactor 1 7 1. In addition, the parabolic trough-type concentrator with a relatively low concentration is used to obtain solar thermal energy, and the solar thermal energy obtained here is used to circulate a heat medium that is water vapor. Transfer to reactor 1 7 1 by 9.

In this reactor 1 71, a solar collector type concentrator 1 50 having a relatively high concentration is used as a high-temperature heat source, and a parapoly trough type collector having a relatively low concentration is used. Hydrogen is obtained by performing a reaction for generating hydrogen from water using the thermal energy supplied from the optical device 160 as a low-temperature heat source and / or a power source.

Solar thermal energy is acquired by a parabolic trough concentrator 1 60 having a relatively low concentration, and transferred to a reactor 1 7 3 by a pipe 1 7 9 through which a heat medium that is water vapor flows. In the reactor 1 7 3, solar thermal energy is converted into heat source and Z or power source. JP2009 / 053613 is used to synthesize ammonia from nitrogen and hydrogen to obtain ammonia. Here, the nitrogen supplied to the reactor 1 7 3 is obtained by cryogenic separation of air by the air cryogenic separator 1 7 2, and the hydrogen supplied to the reactor 1 7 3 Is obtained with the reaction device 1 7 1.

In other words, in the method of this example, the supply to the system of the facility 700 that performs solar thermal energy is only solar energy 20 0, water (H ₂ 0) and air (A ir), and from these Ammonia (NH 3) is obtained. Therefore, in this example, it does not involve the generation of oxygen dioxide to store solar thermal energy in the form of ammonia chemical energy.

The ammonia obtained in reactor 1 7 3 is optionally liquefied in liquefier 1 7 4 and then stored in storage tank 1 7 5 until shipping. Here, solar energy can also be used as a power source for the liquefaction device.

In the example shown in FIG. 7, instead of the solar tower type condensing device 150, another condensing device having a relatively high condensing degree, for example, a parapoly dish type condensing device can be used. Also, instead of using two types of concentrators, a solar tower type concentrator 150 and a parapoly trough concentrator 1660, only one type of concentrator can be used.

Claims

The scope of the claims

1. A method of converting solar thermal energy obtained in a first area into driving energy used in a second area that has less solar radiation than the first area,

Transferring the ammonia from the first region to the second region, and burning the ammonia to produce nitrogen and water in the second region to obtain drive energy. How to do.

2. The method according to claim 1, wherein the transfer step obtains at least a part of electric power and / or power required for carrying out the transfer using the ammonia as a fuel.

3. The method according to claim 1 or 2, wherein the nitrogen and water generated by the combustion are released into the atmosphere and can be recycled as ammonia in the synthesis step.

4. The method according to any one of claims 1 to 3, wherein the driving energy is acquired using an internal combustion engine.

5. The step of synthesizing the ammonia comprises

(2) Utilizing other part of the acquired solar thermal energy, a reaction for synthesizing ammonia from nitrogen and hydrogen obtained in step (1) is performed.

The method according to claim 1, comprising:

6. The method according to any one of claims 1 to 5, wherein at least a part of electric power and / or power necessary for performing the synthesis step is obtained by using the acquired solar thermal energy.

7. The method according to any one of claims 1 to 6, wherein the synthesized ammonia is used as a fuel to obtain at least a part of electric power, power and Z or heat necessary for carrying out the synthesis step.

8. The method according to any one of claims 5 to 7, wherein in step (1), the obtained solar thermal energy is directly used as a heat source to cause a reaction to generate hydrogen from water.

9. The solar thermal energy used as a heat source in step (1) is obtained by a parapoly dish type concentrator and a Z or solar tower type concentrator. Method.

10. The method according to claim 6 or 7, wherein in step (1), a reaction for generating hydrogen from water is performed using the electric power as a heat source.

1 1. The method according to claim 6 or 7, wherein in step (1), water is electrolyzed with the electric power to cause a reaction to generate hydrogen from water.

1 2. The method according to claim 10, wherein the solar thermal energy is acquired by a parapoly trough-type concentrator.

1 3. In the step (2), ammonia is synthesized from nitrogen and hydrogen by using the acquired solar thermal energy directly as a heat source and / or as a power source. Described method

1 4. The solar heat energy used as a heat source in the step (2) is obtained by a parapolic rough concentrator. the method of.

1 5. In step (1), the obtained solar thermal energy is directly used as a heat source to cause a reaction to generate hydrogen from water; in step (1), the amount of solar thermal energy used as a heat source is reduced. At least a part is obtained by a parapoly dish type concentrator and / or a solar dinner-type concentrator; in step ( ₂₎ , the obtained solar thermal energy is directly used as a heat source and / or A reaction for synthesizing ammonia from nitrogen and hydrogen is performed by using as a power source; and the solar thermal energy used as a heat source in step (2) is obtained by a parabolic trough concentrator. The method described in any of 5-7.

1 6. The method of claim 6 or 7, wherein the nitrogen is obtained by cryogenic separation of air using the power and Z or power.

1 7. The method according to any one of claims 5 to 15, wherein the nitrogen is obtained by combusting the hydrogen obtained in the step (1) and consuming oxygen in the air.

1 8. A method of using solar thermal energy obtained in a first area as driving energy used in a second area with less solar radiation than the first area,

1 9. A method of using solar thermal energy obtained in a first region as driving energy used in a second region with less solar radiation than the first region, Ammonia synthesized from air and water using only solar thermal energy acquired in the first area as an energy source is received in the second area,

2 0. A method of converting solar thermal energy obtained in a first area into driving energy used in a second area that has less solar radiation than the first area,

In the ammonia liquefaction means of the first area, the ammonia is liquefied,