Due to the global population explosion, land is no longer enough for people to live in. Therefore, people turned their attention to the ocean and built cities in it. In a marine city, people travel freely in the ocean by a new type of high-tech machine, which is called "Passepartout". Passepartout looks like a submarine, and its streamlined appearance allows it to shuttle freely in the sea. "Passepartout" has an automatic seawater purification system, which can not only make the seriously polluted seawater clear for direct drinking, but also filter fresh air from the seawater for the people on board to breathe. This machine is driven by seawater, so it won't cause any pollution to the ocean. This submarine is powerful. He can not only walk freely in the sea, but also drive at high speed at sea and even walk freely on land. In this way, cars, ships and submarines are replaced, which greatly saves space.
In marine cities, people live in the "Crystal Palace"-"SJG" made of special materials. The "Crystal Palace" is so big that fifty people will not feel crowded when they live together. Because it is made of special materials, it is comfortable to live in it, which is warm in winter and cool in summer. And because this material is transparent, you can watch TV while lying in bed, enjoying colorful fish and colorful corals in the past, which is very comfortable!
By the way, Ocean City also has a garbage treatment plant, which can decompose and recycle garbage into various decorations.
In a word, in marine cities, there are all kinds of living facilities, even more complete than those on land. In a marine city, people will live more happily and comfortably than on land.
However, if you want to make this a reality, you can't just think about it. We must cherish and protect the ocean. Only in this way can we live in peace with the ocean.
Comment: No matter how attractive the future marine cities are, I think marine life is absolutely unwilling to be rounded up by us. Why can't we humans design a bright future for birds, fish and insects?
Offshore oil and gas development
Oil and natural gas resources According to the estimation of 1995, the world's proven offshore oil resources reserves are 37.9 billion tons and natural gas reserves are 39 trillion cubic meters. According to incomplete statistics, submarine oil and gas resources account for about 1/3 of global oil and gas reserves. It is predicted that in this century, submarine oil and gas development will extend from the shallow continental shelf to the sea area with water depth of 1000 meters.
Most offshore oil in the world exists on the continental shelf. According to estimates, the area of the world continental shelf is about 30 million square kilometers, accounting for 8% of the world's ocean area. With regard to the reserves of offshore oil, due to the limitation of exploration data and calculation methods, the conclusions are not the same. An estimate by the French Petroleum Research Institute is that the limited reserves of global oil resources are 654.38+0 trillion tons, and the recoverable reserves are 300 billion tons. Among them, offshore oil reserves account for about 45%, and recoverable reserves13.5 billion tons.
Semi-bottom platform (for deep water mining)
Oil production on the continental shelf of the Persian Gulf entered large-scale exploitation earlier, and together with offshore oil production on nearby land, it supplied more than half of the world oil demand after the war. Beihai, located in the northwest of Europe, is the second largest offshore oil producing area after Persian Gulf. The Gulf of Mexico between the United States and Mexico and the offshore of China, including the Nansha Islands, are recognized as the areas with the richest offshore oil in the world.
It is much more difficult to explore and exploit oil and gas in the ocean than on land. Some special technologies different from land are needed, such as platform technology, drilling technology and oil and gas transportation technology.
The working platform includes fixed platform and mobile drilling platform. The invention overcomes the defect that the fixed platform and firewood can not be reused, and greatly increases the working depth. Mobile offshore oil drilling equipment has its own buoyancy structure and can be towed by tugboats. Some also bring their own power equipment and can sail by themselves. Mobile offshore drilling equipment includes: pedestal platform, jack-up platform, semi-submersible platform and drilling ship. Among them, semi-submersible platform is an advanced platform suitable for deep water operation at present, which can not only overcome the instability of drilling ships, but also work in deep water.
In order to enter the development of deepwater oil, cheap deepwater platforms and deepwater gravity platforms have been studied and stabilized. The jacking platform fastens the steel cable, and the working water depth is 600-900 meters. The latter two platforms are fixed platforms that stand upright from the seabed to the sea surface. Their main feature is to reduce the cost by reducing the cross-sectional area, and the working depth can reach 500-600 meters.
Exploitation of marine living resources
China sea area is rich in biological species, with more than 20,000 species described and recorded. There are more than 500 species of marine fish/kloc-0, and there are more than 200 species with high yield. The fishing ground covers an area of 2.8 million square kilometers, and the annual output of aquatic products reaches more than 28 million tons, ranking first in the world.
There are many kinds of marine life in China than fresh water. Among the 3802 fish species recorded, the ocean accounts for 30 14 species. In addition, China also has various highly productive marine ecosystems such as mangroves, coral reefs, upwelling, estuaries, bays and islands, which are extremely beneficial to the reproduction and growth of various marine life.
Economists predict that 2 1 century will be the century of the ocean. "Agriculture and animal husbandry of marine aquatic products production", "blue revolution plan" and "seawater agriculture" constitute the main direction of marine agriculture development in the future.
Marine aquaculture
It is to transform the marine environment through human intervention, create good environmental conditions for the growth and development of economic organisms, and at the same time transform the organisms themselves to improve their quality and output. Specifically, it is to establish nursery factories, farms and proliferation stations to carry out artificial nursery, breeding, proliferation and release, so as to make the ocean an agricultural pasture for fish, shrimp, shellfish and algae. China is now the largest mariculture country in the world. With the further development of marine biotechnology in breeding, seedling raising, disease prevention and product development, mariculture will be transformed into a high-tech industry in 2 1 century.
Blue revolution plan
Is to focus on the use of seawater in the depths of the ocean. In the depths of the ocean, the deep water temperature is only 8℃ ~ 9℃, and the nitrogen and phosphorus are 200 times and 15 times that of the surface seawater, respectively, which is extremely rich in nutrition. When deep water is pumped up and there is enough sunshine, a new artificial ecosystem with double output will be formed. The temperature difference can be used to generate electricity or directly used in agricultural production. The United States and Japan have been carrying out this artificial upwelling experiment, which is considered to have triggered a revolution in mariculture, so it is called the "blue revolution".
Seawater agriculture
Refers to the direct irrigation of crops with seawater and the development of coastal saline-alkali land, desert and wasteland. The "Blue Revolution Plan" is to expand mariculture from offshore to ocean. "Seawater agriculture" forces land plants to "go to sea", which is essentially different from land agriculture based on fresh water and soil. In order to obtain seawater-tolerant plants, human beings are making arduous explorations. In addition to screening and cross breeding, they also use cell engineering and genetic engineering breeding. These studies continue. At present, wheat, barley and tomato which can be irrigated by seawater have been obtained by traditional methods such as variety screening and hybridization.
Seawater resources development
Coastal industrial seawater in developed countries has reached more than 90%. If China can also vigorously promote the utilization of seawater, it can greatly alleviate the problem of water shortage in coastal cities.
direct utilization of seawater
The direct utilization of seawater has many aspects and large water consumption, which plays an important role in alleviating the water shortage in coastal cities. In developed countries, seawater cooling is widely used in coastal electric power, metallurgy, chemical industry, petroleum, coal, building materials, textiles, ships, food, medicine and other industrial fields. Japan and Europe are about 300 billion cubic meters per year. At present, China has only 654.38 billion cubic meters. If seawater is actively used as cooling water, washing water, dilution water, etc. In terms of industry, the development of toilet flushing water (about 35% of residents' domestic water consumption) will play an important role in alleviating the water shortage in coastal cities.
The seawater direct utilization technology includes: seawater direct cooling technology, which has been used for 80 years and is the mainstream of industrial application at present; Seawater circulating cooling technology is still in the research stage in China; Seawater washing and other technologies. Important technologies related to the direct utilization of seawater include corrosion-resistant materials, anti-corrosion coatings, cathodic protection, biological adhesion prevention, leakage prevention, sterilization and cooling tower technology.
desalination of sea water
Seawater desalination technology, after more than half a century of development, has matured. The main desalination methods are:
Multistage flash evaporation (MSF). The capacity of a single machine can reach 45-57000 m3/d, and the operating temperature, water production ratio and stage are 120℃, 10 and 40 respectively. Multi-stage flash evaporation not only consumes a certain amount of heating steam, but also consumes 4 ~ 5 kWh/m3 of fresh water for seawater circulation and fluid transportation.
Low temperature multi-effect (LT-MDE) technology was developed on the basis of multi-effect in 1975, and has made great progress in recent years. A single device can produce 20000 cubic meters of fresh water every day. The evaporation temperature is lower than 800 degrees, and the efficiency is generally around 12. The water yield ratio is greater than 10. Except for heating steam, low-temperature multi-effect conveying fluid consumes electric energy 1.8kwh/m3.
Reverse osmosis (SWRO)RO cornea and module technology has been quite mature. The desalination rate of this module can reach 99.5%, and the energy consumption is 3 ~ 4 kWh/m3 of fresh water. SWRO technology has the advantages of low equipment investment, low energy consumption, high efficiency and mature technology. Accumulated 30 years of experience, the most competitive.
Recently, Sindelayite Company of Japan has developed a new seawater desalination device with low cost and high efficiency. Its outer surface is a porous cylinder made of stainless steel, and a tube made of 1000 stainless steel sheet is installed inside, with an outer diameter of 156 mm and an inner diameter of136 mm. After the tube is twisted slowly, uneven layers will be formed inside and outside due to the displacement of the stainless steel sheet, and nano-scale gaps will appear between the layers. When in use, seawater is first put into a crystallization device, and then high-frequency voltage is applied for "treatment". After a few tens of seconds, sodium ions and chloride ions in seawater will combine to form fine salt crystals, which will gradually grow into particles of about 1 micron. After these particles are agglomerated, they can form salt particles with a diameter of several microns, which can be easily filtered out. Then the seawater is put into a stainless steel cylinder container, and a certain pressure is applied, so that the salt particles will be blocked out of the tube, and the rest of the water immersed in the twisted tube under pressure is the fresh water to be obtained. The salt concentration is about 0.067%, and the content of minerals such as magnesium chloride is half that of normal seawater, which is an ideal drinking water.
The efficiency of the new device is three times that of the submerged membrane method, the utilization rate of seawater is as high as 95%, and the required power and maintenance costs are very low. The company has made a large-scale equipment that can produce 200 liters of fresh water per minute.
The global daily output of seawater desalination has reached 27 million tons, and it is still rising at the rate of 10% ~ 30%. At present, the international market capacity of seawater desalination has reached more than 2 billion US dollars, mainly divided by the United States, Japan and other powerful countries, and it will be nearly 70 billion US dollars in the next 20 years, with huge market potential. At many international conferences on seawater desalination, representatives of third world countries are eager to see China's seawater desalination technology enter the international market and break the current monopoly pattern.
Combined with new energy sources such as nuclear energy, it is the trend of seawater desalination to reduce costs and move towards scale. China National Nuclear Corporation has mastered the new technology of efficient utilization of low-grade nuclear fuel. It is estimated that if all the discarded low-grade nuclear fuel in the world is used, more than 300 low-temperature nuclear heating reactors with a capacity of 200,000 kilowatts can be built (the existing waste in China can be built 10). All this heat is used for seawater desalination, which can produce 24 million cubic meters of high-quality desalinated water every day and feed more than 200 million people. The combination of nuclear energy technology and seawater desalination requires not only the maturity of nuclear technology itself, but also the matching of mature advanced distillation seawater desalination technology, so as to better show its technical and economic advantages. Seawater desalination technology is bound with China's nuclear industry to enter the international market, forming a nuclear desalination industry, which can realize the peaceful use of nuclear energy and benefit mankind. If China can occupy 15 of the nuclear seawater desalination market, the sales output value of nuclear heating equipment will be1500 million yuan, and the sales output value of seawater desalination equipment will be 48 billion yuan, forming an advantageous industry with independent intellectual property rights and international competitiveness in China.
Seawater desalination plays an important role in promoting seawater utilization. Although the amount of desalinated seawater used by coastal industries is very small, its nature is very important. At present, seawater desalination in China can save about 4 million cubic meters of land water every year, which plays an important role in ensuring the needs of coastal industrial production and residents' domestic water use. At present, the cost of seawater desalination generally ranges from 4 to 5 yuan. If the cost of seawater desalination by cogeneration of thermal power and water can be reduced below that of 4 yuan, if the comprehensive utilization of seawater is further developed and chemical elements are extracted from concentrated seawater, the desalination cost will be reduced. At present, the cost of seawater desalination has been accepted by island fresh water and coastal power plant fresh water and pure water.
Extraction and utilization of seawater chemicals
Extracting chemicals from seawater is a promising new industry. 3.5% minerals dissolved in seawater is a great wealth given to mankind by nature. Many developed countries have gained great benefits in this respect. At present, the chemical elements extracted from seawater in China are potassium, magnesium, bromine, chlorine, sodium and sulfate. However, except that sodium chloride is directly extracted from seawater, other elements are only extracted from underground brine and salt field brine. Moreover, the technological process of comprehensive utilization of resources is backward, and the product quality is far from the international market, so it is urgent to update technology and transform equipment. China is the largest producer of sea salt in the world, with an annual output of nearly 20 million tons; At present, China is still in the transition stage from saline-alkali industry to marine chemical industry. After the "Eighth Five-Year Plan" and "Ninth Five-Year Plan", the industry of directly extracting chemicals from seawater in China is gradually taking shape. There is a huge amount of seawater in the world, with a volume of 65.438+0.37 billion cubic kilometers, or about 65.438+0.37 billion tons. Seawater itself is a treasure house of resources, and more than 80 kinds of metal and nonmetal elements are dissolved in seawater. The elements in seawater are generally divided into two categories: the elements with more than 1 mg per liter of seawater are called constant elements; Elements whose content is below 1 mg are called trace elements. There are more than 60 kinds of trace elements in seawater, such as 250 billion tons of lithium (Li), which is one of the important substances in thermonuclear reaction and the raw material for making special alloys. Rubidium (Rb) has18 billion tons, which can be used to make photovoltaic cells and vacuum tubes. There are 80 billion tons of iodine (I), which can be used in medicine. The commonly used iodine wine is made of iodine.
Comprehensive development of seawater technology
Compared with developed countries, China's comprehensive extraction and utilization technology has a big gap, but it has made great progress since the 1990s, from the traditional "four kinds" of bittern chemicals (potassium chloride, magnesium chloride, sodium sulfate and bromine) to nearly 100 varieties now.
The projects that can be further developed include: developing new technology of bromine extraction, improving bromine utilization rate of existing above-ground brine resources, improving bromine quality, reducing energy consumption and cost, and actively developing efficient brominating agents and new flame retardants; Actively develop the technology of extracting potassium from seawater and brine by inorganic ion exchange. The success of this technology can transform the old salt chemical enterprises and make up for the shortage of land potassium resources in China. Actively develop new magnesium products with high technology content and high added value; Strengthen the research and development of uranium extraction technology from seawater; Strengthen the research and development of directly extracting other chemicals from seawater, and combine water, electricity and heat with comprehensive utilization of seawater.
ocean energy resources
Ocean energy includes temperature difference energy, wave energy, tidal and tidal current energy, ocean current energy, salinity difference energy, offshore wind energy, marine biological energy and marine geothermal energy. These energy sources are renewable energy sources stored at sea, in the sea and under the sea, and belong to the category of new energy sources. The so-called "renewable" means that it can be continuously supplemented and never exhausted. Unlike non-renewable energy sources such as coal and oil, they have limited reserves and less exploitation. People can convert these ocean energies into electric energy, mechanical energy or other forms of energy in various ways for human use. Most of the ocean energy comes from solar radiation energy, and a small part comes from the gravity of celestial bodies (mainly the moon and the sun) in relative motion with the earth. The ocean energy contained in seawater is very huge, and its theoretical reserves are hundreds or even thousands of times of the annual energy consumption of all countries in the world.
Schematic diagram of Lance tidal power station in France
Schematic diagram of Garland Current Power Station
Ocean energy has some characteristics. First, there are huge reserves in the whole ocean water body, but the energy per unit volume, unit area and unit length is very small. In other words, if you want to get great energy, you must get it from a lot of seawater. The second is renewable. Ocean energy comes from solar radiation energy and gravity between celestial bodies. As long as the sun, the moon and other celestial bodies are with the earth, this energy will be regenerated and inexhaustible. Third, ocean energy can be divided into stable energy and unstable energy. The stable ones are temperature difference energy, salinity difference energy and ocean current energy. Unstable energy can be divided into regular energy and irregular energy. There are unstable but regularly changing tidal energy and tidal current energy. According to the changing rules of tides and tidal currents, people compile daily and hourly tidal and tidal current forecasts in various places to predict the tidal magnitude and tidal current intensity at all times in the future. Tidal power stations and tidal power stations can arrange power generation and operation according to the forecast table. What is unstable and irregular is wave energy. Fourth, ocean energy belongs to clean energy, that is, once it is developed, it will have little impact on environmental pollution.
All kinds of ocean energy reserves are huge, estimated at more than 75 billion kilowatts, including wave energy of 70 billion kilowatts, temperature difference energy of 2 billion kilowatts, ocean current energy 1 100 million kilowatts, and salinity difference energy 1 100 million kilowatts. Judging from the situation of various countries, the tidal power generation technology is relatively mature. Using ocean energy such as wave energy, salinity difference energy and temperature difference energy to generate electricity is still immature, and it is currently in the research and experimental stage. There are two main reasons why these ocean energies have not been utilized so far: First, the economic benefits are poor and the cost is high. Second, some technical problems have not passed.
The best substance of nuclear energy for fission reaction is uranium and the best substance for fusion reaction is deuterium. Most of these two substances exist in seawater.
Uranium is a kind of high-energy nuclear fuel, and the available energy of 1 kg uranium is equivalent to 2250 tons of high-quality coal. However, the distribution of uranium deposits on land is extremely uneven, not all countries have uranium deposits, and the total uranium reserves in the world are only about 2× 10 6 tons. However, in the huge sea water, there are abundant uranium resources, the total amount of which exceeds 4× 109 tons, which is about 2000 times of the total land reserves.
Schematic diagram of uranium extraction from seawater by adsorption method
There are many methods to extract uranium from seawater, and adsorption is the most effective method at present. Titanium hydroxide has the characteristic of adsorbing uranium. The adsorber made of this adsorbent can extract uranium from seawater. Now uranium extraction from seawater has shifted from basic research to development and application research. Japan has built a pilot plant with an annual output of 10 kg of uranium, and some coastal countries also plan to build seawater uranium extraction plants with industrial scale of 100 tons or 1000 tons of uranium. If all uranium in seawater can be extracted in the future, its fission energy is equivalent to l× 10 16 tons of high-quality coal, which is 1000 times more than all the proven coal reserves on the earth.
Heavy water is also a moderator and heat transfer medium for atomic energy reactors, and it is also a raw material for making hydrogen bombs. Seawater contains 2× 10 14 tons of heavy water, and deuterium is an isotope of hydrogen. The nucleus of deuterium contains one proton and one neutron more than hydrogen. Deuterium has the same chemical properties as hydrogen, but the weight of a deuterium atom is twice that of hydrogen atom, so it is called "heavy hydrogen". Hydrogen and oxygen combine to form water, and the water synthesized by heavy hydrogen oxidation is called "heavy water". If the controllable thermonuclear fusion research that human beings have been committed to is solved, once heavy water is extracted from seawater on a large scale, the ocean can provide inexhaustible energy for human beings. There are 5 billion tons of deuterium in seawater, which is enough for human use for trillions of years. In fact, that is to say, the energy problem of human sustainable development has been solved once and for all.