If it weren't for the nuclear leakage caused by the tsunami, Japan might not give up its plan of pure electric vehicles. The closure of all nuclear power plants in Japan has made all car companies realize that the dream of charging with surplus electricity at night cannot be realized. In the face of rising fossil fuel prices, Japan has more and more energy loopholes, and Japan has begun to look for real alternative energy sources. This energy source may be temporarily unclean and costly, but it must be hopeful and truly mastered.
It is not that Japan has not considered natural gas, nor that methane fuel cells have too many shortcomings. One of the real reasons for Japan to give up natural gas is that most of the standards of this energy source are not in Japan's hands. This means that if natural gas energy is used in the future, a large amount of patent fees will still be paid overseas. This is not the case with hydrogen. At present, Japan's patents on hydrogen energy are far ahead. The scale of hydrogen energy in China may not be the largest in the world, but the utilization rate is the highest. In addition, CSS carbon dioxide capture technology and hydride transportation method developed by Kawasaki Heavy Industries and Chiyoda Chemical Industry have made the Japanese Hydrogen Society see clearly.
NEDO released a white paper on hydrogen energy, which positioned hydrogen energy as the third pillar of domestic power generation, and hydrogen energy was paid more and more attention. The lack of domestic resources and energy crisis in Japan forced Japan to pay attention to ultra-energy-saving technology. If we take a path on hydrogen energy, the energy problem that Japan has been troubled for many years will be completely solved. At least it seems that way.
At present, Japan lacks allies in the development of hydrogen energy. Shale gas in the United States and natural gas in Europe seem to be concentrated in the United States and China. In addition, Toyota's newly listed hydrogen fuel cell vehicle has received a lot of subsidies in Japan, which also makes everyone regard hydrogen energy as an island syndrome. Most experts believe that hydrogen energy can only take off in Japan and cannot be developed in other countries. In fact, I don't see any plans to develop hydrogen energy outside the United States and China.
Hydrogen exists not only as an energy source, but also as an energy medium. The purpose of developing hydrogen energy in Japan is very simple, mainly through purchasing or cooperating to develop some inefficient petrochemical resources, and even purchasing excess electricity from Siberia to electrolyze water to produce hydrogen. In the process of implementing hydrogen energy, transportation is the primary problem.
The natural density of hydrogen is low, so how to realize high-density transportation mode has become the main topic in Japan. Under this topic, there are three main ways in Japan: high-pressure hydrogen, liquid hydrogen, organic matter, and of course, pipeline transportation of hydrogen. Different transportation modes of hydrogen vary according to the actual situation such as distance and location.
1
High pressure hydrogen
This mode of transportation is generally suitable for short-distance transportation of onshore hydrogen production stations or hydrogen bases. Generally, it is compressed under the pressure of 20MPa and transported by traditional transport vehicles. The current technology can reach the transportation volume of 2300-3000 cubic meters per vehicle. The advantage is low cost, but the disadvantage is not conducive to long-distance transportation.
Kawasaki Heavy Industries pointed out in "Discussion on Water Transportation Technology in Refineries" that at present, three kinds of pressure transportation can be realized according to container materials and transportation methods, namely 14.7 45MPa- 19.
High-pressure hydrogen is almost ubiquitous in any industry. High-pressure hydrogen can supply hydrogen for household fuel cells, and in the popularization stage of hydrogen fuel cell vehicles, it can supply hydrogen for hydrogen refueling stations, and it can be pressed into accumulators through compressors to provide fuel for FCV. In addition, it can also be used in semiconductors, liquid crystals, smelting and power generation.
2
Transport of liquefied hydrogen
Liquefied hydrogen is suitable for large-scale long-distance transportation of hydrogen. Liquefying hydrogen at -253℃ can reduce the volume by more than 800 times and improve the efficiency by more than 12 times, which is the most efficient way at present. Due to the high cost of maintaining the high temperature of -253℃ and not conducive to long-term preservation, this technology was originally an aviation technology research and development, but at present Japanese enterprises have increased the practical progress.
Transportable small liquid hydrogen filling usually adopts double-layer vacuum design, similar to our common thermos container. In addition, some reflective coatings are added to prevent external heat from entering. Liquefied hydrogen is usually transported in containers, but there are also liquefied hydrogen mobile workstations.
Iwatani Industry uses the theory of crushing thermal expansion to produce liquefied hydrogen with a purity of 99.9999%. Because the liquefaction of hydrogen is about -253℃, other impurities can be continuously removed. As for controlling the temperature at -253℃, Iwatani industry uses the basic principle of thermal expansion and cold contraction. This common principle is similar to bicycle tire heating in summer. With the increase of air temperature in the tire, the pressure in the tire increases, while the external air temperature decreases. In Iwatani industry, hydrogen is compressed by liquid nitrogen expansion, and nitrogen liquefied at about-190℃ is used to achieve the goal of -253℃ through a series of other equipment.
The manufacturing cost of liquid nitrogen is quite high, and it is constantly developing around the practical application of this technology, and because of ultra-high pressure liquid hydrogen, the requirements for containers are very strict. Usually, the strength of metal decreases below -253℃, and liquid hydrogen is also facing the problem of excessive leakage. At present, Kawasaki Heavy Industries has made great achievements in the long-distance transportation of liquid hydrogen, and adopted a liquid hydrogen carrier to transport the hydrogen produced by Australian lignite mining. The transport ship adopts extremely low-temperature pressure storage equipment which can hold 2500 cubic meters of liquid hydrogen, and the leakage of hydrogen charging is also controlled at about 0.09%.
three
Organic matter transportation
The transport of organic matter to hydrogen is mainly the process of hydrogen synthesis and escape, which requires special catalysts. At present, Chiyoda Chemistry has been carrying out such experiments. The volume can be reduced by more than 500 times through the reaction of hydrogen with organic substances. However, due to the use of aromatic organic compounds, benzene, naphthalene, toluene and decalin are extremely stable and highly toxic, and catalysts have become the most important. The transportation of organic matter is convenient, the requirements for equipment are not high, and the transportation efficiency is at least five times higher than that of traditional land high-pressure transportation. This technology has also attracted the attention of Japanese companies.
At present, the synthesis of organic compounds is mainly concentrated between benzene and cyclohexane, naphthalene and decalin, and methylcyclohexane and toluene. Different reactions also have different advantages and disadvantages, some are solid and some are liquid at normal temperature and pressure. The main transportation mode is to react with toluene in the place where hydrogen is produced, then transport it in the form of organic matter, and finally dehydrogenate it. Among them, the catalyst can be recycled, and if exothermic and endothermic reactions are considered, it can also be completely used for household heating.
In addition to using organic substances, HyGrid also considers converting hydrogen into chemical fuels, such as ammonia, for transportation. Ammonia can be directly electrolyzed to produce hydrogen, but this is not the focus of Japanese enterprises. They think that ammonia is more convenient to transport than hydrogen. Overseas cooperative energy development can produce oxygen and ammonia through the reaction of water and nitrogen to store excess heat and electricity. After ammonia is made, it is shipped to China, and hydrogen is produced by heavier methods such as electrolysis.
It can be said that there are already practical cases and enterprises in Japan to transport hydrogen. As far as the current hydrogen transportation mode is concerned, the technologies of organic matter, ammonia and liquefied hydrogen developed in China are mainly aimed at the utilization and development of foreign energy sources. This may reflect the enormous pressure Japan is facing on fossil fuels. Whether it is hydrogen transportation or hydrogen production, the main problem in Japan at present is to reduce the cost of hydrogen fuel.
Figure? | From the Internet
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.