JP2010062192A - Liquefaction and storage of natural energy utilizing dimethylether (dme) - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convert power based on largely varying natural energy obtained by solar power generation or wind power generation to easy-to-use power. <P>SOLUTION: Water is electrolyzed using the power obtained by a natural energy recovery means to generate hydrogen and oxygen, the generated hydrogen is made to react with carbon monoxide or carbon dioxide using a catalyst to synthesize dimethylether (DME), and the synthesized DME is liquefied and stored. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for storing electric power by liquefying electric power with a large fluctuation obtained by solar power generation or wind power generation, and converting the electric power into electric power with little fluctuation and easy to use.

  Electric power obtained by solar power generation, wind power generation, and the like varies greatly, and as it is, it is extremely difficult to use it as normal power. For this reason, a method is currently used in which this electric power is once supplied to the electric power company and mixed into the electric power company's large-capacity electric power to absorb fluctuations. For this reason, it cannot be used without backup from the power company.

  However, as the power generation capacity of solar power generation, wind power generation, etc. increases, there is a limit to the capacity that can be accepted by electric power companies, and acceptance will be refused, inevitably becoming a self-contained system. It is becoming.

  In order to eliminate fluctuations in power, it is best to store the power once in some way, and if this can be done, all will be solved. However, if it has a small capacity, it can be stored as it is using secondary batteries, capacitors, etc., but if it has a large capacity, it is extremely difficult to store as it is technically and economically. It is impossible as a matter of fact. Therefore, instead of storing electric power as it is, it is possible to replace it with another substance that can be easily restored to the original electric power and to store it in large quantities. Therefore, a method for regenerating power again is provided.

  Hydrogen itself is a substance that can be produced relatively easily with energy and water. Electricity is generated by using electricity generated by using natural energy such as solar power generation or wind power generation as energy, and water is electrolyzed to generate hydrogen and oxygen, and energy is stored using hydrogen. Storage.

However, since hydrogen is a very difficult material to handle, it cannot be used as it is, so one of the following methods must be taken.
1. A method of compressing and storing in a high-pressure cylinder as a gas.
2. Method of absorbing metal as metal hydride.
3. A method of storing as liquid hydrogen.
4. Chemical hydride, liquefied and stored.

  If it is packed in a high-pressure cylinder as it is in a gas state, it can be compressed to a maximum of 25 MPa in accordance with Japanese safety standards and reduced to 1/250. However, high compression with a gas body requires a thick high-compression container, which increases the weight of the container. Currently, measures such as reinforcing the periphery of an aluminum tank with carbon fiber are being taken as a countermeasure. Yes. However, hydrogen storage is still only a few percent of the tank weight. Therefore, it is not suitable for storing large-capacity hydrogen and is at most about the fuel tank of a fuel cell vehicle.

  If the metal hydride is used, the volume can be reduced to about 1/1000. In this case, however, the weight of the metal is increased, and the target is to set the hydrogen content to 5.5 percent of the metal content. At present, it is only 3.5%, and it is not easy to take out hydrogen, which is not suitable for storing a large volume of hydrogen.

  If liquid hydrogen is used, the energy density can be several times higher than that of highly compressed hydrogen. However, it is necessary to use an extremely low temperature of minus 253 ° C., and about 30 to 40 percent of the energy of hydrogen in the liquefaction process. Since it is consumed and leaks very easily, the loss during supply is as large as 10 to 20 percent, and it is currently used only for special purposes such as rocket fuel.

  From the viewpoint of a large amount of storage and ease of handling, the most practical and excellent method is to use chemical hydride and liquefy. That is, it is a method of synthesizing and storing methanol or DME (dimethyl ether).

  According to the present invention, it is possible to dramatically improve the total energy efficiency by effectively recovering natural energy, and it can be used as an extremely effective ecological measure. Furthermore, if an urban distributed generation system is formed, an efficient natural energy utilization society can be constructed.

The chemical formula of DME used as a hydrogen reservoir is represented by the following formula.
CH ₃ —O—CH ₃

As for the physical properties, it is a colorless gas with a boiling point of -25 · 1 ° C and is chemically stable. The saturated vapor pressure at 25 ° C is as low as 0.6 MPa. ing. Low calorific value gaseous higher than methane 8600Kcal / Nm ³ in 14,200Kcal / Nm ^3, less than propane 21,800Kcal / Nm ^3.

  Recently, it has attracted attention as an environmentally friendly fuel and is expected to be a non-petroleum fuel. It is an artificial synthetic fuel that is extremely low in toxicity and has recently been used as a propellant as a substitute for Freon and does not exist in nature.

There are two methods for producing DME: a “methanol dehydration method” and a “direct synthesis method” in which carbon monoxide is directly synthesized. The “direct synthesis method” can be synthesized with hydrogen and carbon, so it is synthesized from natural gas and coal. Also the catalyst can be synthesized from the utilizing carbon dioxide (CO _2), and is greatly expected future absorption means of CO ₂ is currently a problem, and as active usage.

  Since DME is easily reformed to extract hydrogen, it is a valuable fuel as a hydrogen storage body and carrier. Compared to liquefying hydrogen into liquid hydrogen, it is much easier to handle and costs less. .

  Making hydrogen from natural energy and water and synthesizing liquid fuels such as DME in this way means liquefying natural energy, which means that the earth will spend solar energy over tens of millions of years and hundreds of millions of years. Is the same as having been recycled into liquid fuel such as oil. If natural energy can be liquefied in this way, great benefits can be expected. For example, a solar power plant with a hydrogen and DME manufacturing plant will be built in the Sahara Desert, and a hydroelectric power plant will be built in the Himalayas, where DME will be synthesized and transported by tank trucks and tankers like oil.

  Natural energy power plants are often installed in remote areas such as deserts and mountainous areas, so the benefits of converting generated power to DME are immeasurable. Since no transmission line is required, it can be installed in a remote location far away from the consumption area.

  By the way, if solar cells are packed in 5% of the world's deserts, and if the water flowing from the Himalayas can be used effectively for hydroelectric power generation, it is possible to cover all the energy required by the world in any case. There is also a trial calculation.

  As another use method, it is possible to use it as a load fluctuation adjustment mechanism if a nuclear power plant that dislikes load fluctuations, or if a hydrogen and DME manufacturing plant is installed in a hydroelectric power station, the same as for a pumped storage power plant. The effect can be expected.

  Furthermore, the construction of a new energy society will be visible. In other words, it is an energy measure by distributed cogeneration power generation.

  The current large-scale thermal power plants and nuclear power plants are far away from the demand areas, so the enormous amount of waste heat generated by power generation cannot be used effectively. Disrupting the ecosystem. Moreover, although this abandoned “heat” is low pressure, it is the most valuable “latent heat” as steam, and therefore, enormous energy is wasted. For that reason, when the infrared image is taken from the artificial satellite, it can be confirmed that the color of the sea around the power plant has changed. Therefore, even the latest thermal power plants have only exceeded 40 percent overall energy efficiency. The majority of the energy that fuel has is abandoned involuntarily in the sea or in the air.

  For example, as shown in FIG. 1, the roof 1 of each household is covered with solar cells to form a roof 1 that is covered with solar cells, and the generated power is transmitted as it is to the energy center in the area to generate water electrolysis hydrogen. Hydrogen is generated by electrolyzing water collectively using the apparatus 2. Next, DME is synthesized by reacting with carbon monoxide or oxygen dioxide using a catalyst in the DME synthesizer 3 using hydrogen generated by this electrolysis. The synthesized DME is stored in a DME storage tank. Thereafter, the synthesized DME is re-delivered to each home and office through a pipeline and decomposed to generate hydrogen, which is used as fuel for the stationary fuel cell 6. The carbon monoxide or oxygen dioxide produced again is reused as a raw material for DME synthesis in the next cycle. In addition, the generated DME is generated along with power generation by, for example, transferring to a predetermined storage location of the generated DME using a tank lorry (for transporting DME), and performing cogeneration with a microturbine system at any appropriate location. Heat can be effectively used. The generated electric power can be supplied to a general household and used to operate electric equipment such as an air conditioner 8, a television 9, and a refrigerator 10, for example. Further, if the cogeneration power generation by DME is performed in each home, the heat generated by the power generation can be directly used for, for example, the home sink 11, shower 12, bath 13, etc., and the total energy efficiency is Improve dramatically. In FIG. 1, a solid line indicates a power line, a dotted line indicates a hot water line, a broken line indicates a DME transfer line, and a double solid line indicates a hydrogen transfer line.

Diagram of natural energy liquefaction process (DME synthesis) and power regeneration from DME. 1 is a diagram illustrating an urban distributed cogeneration power generation system.

Explanation of symbols

1. Solar cell-fired roof 2, water electrolysis hydrogen generator 3, DME synthesizer 4, DME storage tank 5, hydrogen reformer 6, fuel cell 7, tank truck (for DME transportation)
8, Aircon 9, TV 10, Refrigerator 11, Sink 12, Shower 13, Bath

Claims (3)

Electrolyzing water using power obtained by natural energy recovery means including at least one power generation device of solar power generation and wind power generation to generate hydrogen and oxygen;
Reacting the generated hydrogen with carbon monoxide or carbon dioxide using a catalyst to synthesize (DME);
Liquefying and storing the synthesized dimethyl ether.
A natural energy storage method using dimethyl ether as a storage body of hydrogen generated by the electrolysis.   The method of claim 1, further comprising: removing hydrogen from the dimethyl ether using a catalyst and regenerating power by using the hydrogen as fuel for a fuel cell.   The method further comprises the step of recovering the natural energy by driving driving means including at least one of a diesel engine and a micro turbine using the dimethyl ether as a direct fuel. Method.

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