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Combustion is a violent chemical reaction with both exothermic and luminous effects. Exothermia, luminescence and generation of new substances (such as carbon dioxide and water, leaving carbon and ash) are the three characteristics of combustion phenomenon. Combustion is an oxidation reaction, in which oxygen is the most common oxidant, but the oxidant is not limited to oxygen, and oxidation is not limited to combining with oxygen. The heat released by fuel combustion is still the main energy source of people, and its purpose is not to prepare products, but to obtain energy. Studying the conditions and methods of fuel full combustion is not only very important for saving energy and improving fuel utilization rate, but also of great significance for reducing the atmospheric pollution caused by harmful gases such as CO and soot produced by incomplete combustion. Generally speaking, the combustion of fuel in air is a redox reaction between fuel and oxygen in the air. In order to fully oxidize the fuel, we should ensure that there is enough air. At the same time, in order to ensure the full combustion of solid and liquid fuels, it is also an effective measure to increase the contact surface between fuel and air (solid fuel crushing, liquid fuel spraying in mist, etc.). ).

Combustion conditions: 1. Combustible (whether solid, liquid or gas, anything that can react violently with oxygen or other oxidants in the air is generally combustible, such as wood, paper, gasoline, alcohol, gas, etc. ) 2. Sufficient oxygen.

3. Reach the ignition point of matter

Basic principles and methods of fire fighting: combustion must meet three conditions at the same time, and measures should be taken to destroy at least one of them in order to put out the fire. There are three basic ways to put out a fire: (1) cold.

Solution: put out the burning substance by cooling, such as putting out the wood with water when it is on fire; (2) Asphyxiation method: the combustion-supporting substances are diluted and suffocated until they cannot be burned, such as nitrogen and carbon dioxide.

Wait for inert gas to extinguish the fire. (3) Isolation method: cut off the source of combustible gas, remove combustible substances, apply flame retardant, and cut off flame retardant substances, such as foam extinguisher for oil fire.

Common fuels in the world today: coal, oil and natural gas are the three most important fossil fuels in the world today, and they are also extremely important raw materials in the chemical industry. They are subdivided into (1) solid fuels: firewood and cigarettes.

Coal, bare coal, anthracite, charcoal, coke, pulverized coal, etc. ; (2) Liquid fuel; Gasoline, kerosene, diesel, heavy oil, etc. ; (3) Gaseous fuels: natural gas, artificial gas and liquid.

Liquefied petroleum gas and so on.

Clean fuels: liquid ammonia, alcohol, liquid hydrogen (the cleanest fuel, the combustion product is water), methanol, etc.

Exploitation and utilization of marine resources and marine environment

Types of marine resources

Marine resources are abundant. Nowadays, the contradiction between the shortage of global food, resources and energy supply and the rapid population growth is increasingly prominent, and the development and utilization of rich marine resources is an inevitable trend of historical development. At present, the marine resources developed and utilized by human beings mainly include marine chemical resources, marine biological resources, seabed mineral resources and marine energy.

Seawater can be directly used as industrial cooling water source and inexhaustible seawater desalination water source. Developing seawater desalination technology and obtaining fresh water from the ocean is one of the important ways to solve the shortage of fresh water in the world.

More than 80 chemical elements have been found in seawater. At present, the development of marine chemical resources has reached industrial scale, including salt, magnesium, bromine and fresh water. With the development of science and technology, rich marine chemical resources will benefit mankind widely.

There are more than 200,000 species of life in the ocean, including 6,543,800 species of animals and 6,543,800 species of fish. In ancient times, humans began to catch and collect seafood. Now, human marine fishing activities have expanded from offshore to various sea areas in the world. The improvement of fishing gear, fishing boat and fish exploration technology has greatly improved the marine fishing ability of human beings. Marine biological resources are composed of fish, shrimp, shellfish and algae, which can be directly fished for food and medicine, and can also be continuously utilized through cultivation and proliferation.

There are abundant mineral resources such as oil, natural gas, coal, sulfur and phosphorus buried in the shallow sea bottom of the continental shelf. The coastal placer in the nearshore zone is rich in building materials and metal minerals such as sand and shells. Deep-sea manganese nodules are widely distributed in most ocean basins and are the most potential metal mineral resources in the future (Figure 3. 14 Deep-sea manganese nodules).

Seawater movement contains huge energy, which belongs to renewable energy and has no pollution. However, these energy densities are very small, and special energy conversion devices must be adopted to develop and utilize them. At present, tidal power generation and wave power generation have commercial development value, but the project investment is large and the benefit is not high.

Marine fishery production

Marine fishery resources are mainly concentrated in the coastal continental shelf, that is, the part of the continental seabed extending from the coast to about 200 meters underwater. Here, the sunshine is concentrated, the photosynthesis of organisms is vigorous, and the rivers entering the sea bring rich nutrients, so plankton is flourishing (Figure 3. 15 Schematic Diagram of Continental Shelf Profile). These plankton are the bait of fish, and their distribution in the ocean is very uneven, usually in temperate waters.

The seasons in temperate regions vary greatly. When surface seawater and bottom seawater are exchanged in winter, the submerged bottom seawater is rich in nutrients, which come from decaying biological debris in the ocean. At the intersection of warm current and cold current, or where there is cold seawater flooding, the bait is rich. These places are usually fishing grounds (Figure 3. 16 Distribution of major fishing areas in the world). Therefore, although the continental shelf waters only account for 7.5% of the total ocean area, the catch accounts for more than 90% of the total ocean catch in the world.

The main fishing countries in the world are located in temperate regions, where the consumption of fish products is high and the market demand is large. China and Japan are countries with a large amount of marine fishing in the world. China has made full use of offshore fishing grounds (Figure 3. 17 "Zhoushan Fishing Ground and shenjiamen Fishing Port") and shallow beaches to vigorously develop marine fishing and mariculture, while offshore fishing has also made great progress. Japan has limited arable land and high population density, so seafood accounts for a large proportion in the food structure.

Offshore oil and gas development

The development of submarine oil and gas began in the early 20th century. Its development has gone through the process from offshore to offshore and from shallow sea to deep sea. Limited by technical conditions, only oil and gas deposits extending directly from the coast to the shallow sea can be mined at first. Since the 1980s, stimulated by the energy crisis and technological progress, offshore oil exploration and development have developed rapidly, and offshore oil development has rapidly advanced to the continental shelf, gradually forming a brand-new offshore oil industry sector.

Geologists and geophysicists usually use seismic wave method to find submarine oil and gas deposits, and then estimate the types and distribution of mineral deposits through offshore drilling to analyze whether they have commercial development value.

Offshore drilling platform (Figure 3. 18 "Offshore Drilling Platform") is the working base for offshore oil and gas exploration and development, which indicates the level of offshore oil and gas development technology. The transportation of personnel and materials between the platform and the land is generally completed by helicopters. Oil and gas fields are generally far away from refineries, and oil and gas should be shipped to their destinations through oil loading stations or directly transported to the coast by submarine pipelines.

The exploration and development of submarine oil and gas is a project with high investment, high technical difficulty and high risk, and international cooperation and project bidding are one of the feasible ways.

Marine space utilization

With the rapid growth of the world's population, land space has become more and more crowded, and the development and utilization of marine space has been paid more and more attention. The available space of the ocean includes three parts: the ocean, the middle of the ocean and the seabed. With the gradual advance of mankind to the ocean, the ocean will become a vast space for human activities (Figure 3. 19).

The marine environment is different from the land, and its environmental and ecological conditions are complex and special. Human activities are at the seaside and on the surface of the ocean, which need to resist the changeable meteorological conditions and the movement of seawater; Deep-sea activities should be able to adapt to the dark, high pressure, low temperature and anoxic environment; Seawater is corrosive and sea ice is destructive, so there are strict requirements for materials and structures of engineering equipment. Therefore, the development of marine space resources is highly dependent on science and technology and capital investment, which is technically difficult and risky.

The utilization of marine space has expanded from traditional transportation to many fields such as production, communication, power transmission, storage, culture and entertainment. Traffic includes seaports, ships, waterways, undersea tunnels, bridges, airports and pipelines. The production space includes offshore power station, industrial artificial island, offshore oil city, land reclamation, marine pasture, etc. Communication and power transmission space is mainly submarine cables. As far as storage space is concerned, there are submarine freight yards, submarine warehouses, offshore oil depots and marine waste treatment plants. Cultural and recreational facilities include marine parks, bathing beaches and marine sports areas.

Marine transportation and port construction

The ocean used to be a natural barrier for human beings to engage in transportation. For a long time, mankind has been trying to turn the marine barrier into a smooth road at sea. At first, people used manpower, wind or ocean currents as power to drive wooden boats in offshore areas. With the arrival of Europeans on the American continent, the world's ocean transportation changed from offshore to ocean. After that, important waterways of the world's oceans were opened one after another. At the beginning of the 20th century, the navigation channels to the South Pole and the North Pole were opened, and the Panama Canal and Suez Canal were opened one after another. Now, humans can sail ships to any sea area in the world (Figure 3.20: main shipping routes in the world).

In 1960s, the world oil production and transportation increased, and large oil tankers were developed. The rise of container ships has brought a revolution to the transportation of goods by sea. Today, million-ton container ships and giant oil tankers shuttle through the vast ocean. These ships not only have modern instruments and equipment such as radio navigation and global positioning technology, but also can choose the best route service, saving energy and navigation time and reducing danger.

Coastal ports are places where marine transport ships stop, transit and load and unload goods, and also the main places for people to develop and utilize marine space. Generally, a port has a service area, that is, the hinterland, through which the goods and goods in this area spread outward. In order to complete the transportation task, the port should have supporting facilities, such as docks, loading and unloading equipment and efficient operation services. In the process of port development, affected by internal and external factors, the scale, service function and scope of the port may change. For example, in order to attract ships to transit through their ports, some governments have implemented special policies to turn ports into free trade zones and free ports with little or no payment.

Rotterdam, the Netherlands, has long been a world trade center. After that, the port of Rotterdam continued to develop by digging a canal connecting the North Sea to improve the water transport conditions. Rotterdam has developed agriculture, mineral products processing industry and shipbuilding industry by using the transshipment function of bulk goods (Figure 3.2438+0 Land use of Rotterdam Port). Relay trade has also promoted the rapid development of modern industries in the mainland. After World War II, the economies of western European countries recovered, Rotterdam became the gateway of the European Union, with perfect harbor and aviation facilities, and the port's transit function became more prominent. Now, Rotterdam is one of the largest ports in the world, and its hinterland covers half of the countries in the European Union.

Reclamation project

The intensification of the contradiction between man and land in coastal areas has made people look to the sea. The Dutch began to reclaim land from the sea in the13rd century. At present, 1/5 of the land in the Netherlands is surrounded by the sea. Land reclamation is an important way to alleviate the tension between population and land, but it needs full scientific demonstration, especially the supporting construction centered on water conservancy projects.

Land is built with sand, gravel, mud and waste in shallow coastal areas, and is connected with the coast through seawalls, trestles or subsea tunnels. This new land is called an artificial island. Some developed coastal countries in the world, such as Japan, the United States, France and the Netherlands, have built artificial islands. Among them, Sea City (Figure 3.22 Artificial Island in Kobe, Japan) has the largest scale and the most complete functions. The construction of marine cities needs huge projects and costs, and needs to be built on the basis of strong national strength.

Macao has a large population and little land, and the limited land is not enough to meet the needs of residential development, greening, transportation and industrial and commercial construction. There are many shoals along the coast of Macao, some of which can be exposed to the water at low tide, and Macao people regard them as good reserve land resources. In the past 100 years, Macao people have expanded the land area by 1 times through reclamation (Table 3.2 Historical changes of land area in Macao and Figure 3.23 Historical reclamation scope in Macao).

Marine environmental protection

Marine environmental problems include two aspects: first, marine pollution, that is, pollutants enter the ocean, which exceeds the self-purification ability of the ocean; The second is the destruction of marine ecology, that is, under the influence of various human and natural factors, the marine ecological environment is destroyed.

(a) marine pollution

Most marine pollutants are produced on land. Coastal activities such as waste dumping and port engineering construction also discharge pollutants into coastal waters. Pollutants enter the ocean, polluting the marine environment, endangering marine life and even endangering human health.

Waste discharged from industrial production is the main source of marine pollutants, which is concentrated near large ports and industrial cities. 1953- 1970 mercury pollution occurred in Minamata Bay, Kyushu Island, Japan, because the factory discharged mercury-containing waste during the production of organic products. These harmful substances are gradually enriched in fish and shellfish after flowing into the ocean. Finally 100 people were seriously poisoned and died one after another.

The cooling water discharged from nuclear power plants and factories, with high water temperature, often affects marine life when it flows into estuaries or the sea. Pesticides applied to farmland flow into rivers with rainwater, or deposit near estuaries with soil particles, and finally enter the ocean. Occasionally, accidents occur on offshore oil platforms and oil tankers, resulting in oil leakage and overflow, resulting in marine pollution.

(2) marine ecological destruction

In addition to marine pollution, human production activities, such as engineering construction and fisheries (reclamation and overfishing, etc. ), as well as changes in the natural environment such as global warming and sea level rise, will destroy and change the marine ecological environment. Over-fishing of some marine organisms by human beings has led to a decline in the quantity and quality of marine biological resources, and some species are on the verge of extinction. Some coastal engineering construction and reclamation lack scientific demonstration, which destroys the coastal environment and coastal ecosystem. At present, marine development activities still lack comprehensive and long-term planning, and the comprehensive benefits are poor.

Oil pollution and its monitoring and prevention

Ships in coastal industrial production and shipping routes are the main sources of oil pollution. Therefore, oil pollution areas are concentrated in coastal waters and along sea lanes. Accidental oil spill has attracted public attention because of obvious pollution signs, concentrated pollutants and serious harm, and is also the focus of pollution control at present.

In order to reduce accidents, many countries are experimenting with new crude oil loading methods. Some countries are equipped with cleaning boats to remove garbage and dirty oil from the port surface.

Maritime rights and interests and the United Nations Convention on the Law of the Sea

Since the 1960s, there has been an upsurge of developing the ocean in the world. The rapid development of marine science and technology has become one of the important fields of contemporary new technological revolution. In order to adapt to the new situation of international marine development, protection and management, after more than 20 years' efforts, the international community adopted the United Nations Convention on the Law of the Sea, which came into effect on June 5438+0994165438+10/0/6, 2006. The birth of the Convention on the Law of the Sea has brought great changes to the international maritime legal system. For example, the long-standing dispute over the width of the territorial sea has been resolved; The international seabed and its resources have been identified as the common heritage of mankind.

According to the United Nations Convention on the Law of the Sea, 144 coastal countries in the world have the territorial sea right of 12 nautical mile, and the sea area under their jurisdiction can be extended to 200 nautical miles. As their exclusive economic zones, they have the sovereignty to explore, develop, utilize, protect and manage the natural resources of the overlying waters and subsoil of the seabed. The sea area under the jurisdiction of China is 4.73 million square kilometers, which is about half of the land area of China. Therefore, it is increasingly important to strengthen integrated marine management.

The birth of the United Nations Convention on the Law of the Sea has taken an important step towards establishing a new international legal order. However, because the United Nations Convention on the Law of the Sea should take into account the interests and requirements of all countries, there are still many imperfections and ambiguities. Therefore, in the process of implementation, some new contradictions and problems will inevitably appear. For example, in a closed and semi-closed sea area, the 200-nautical-mile exclusive economic zone advocated by neighboring countries may overlap, and some issues such as island sovereignty disputes and fishery resource allocation may become new factors of tension between neighboring countries and even lead to international conflicts. Therefore, the delimitation of maritime areas and maritime rights and interests under the jurisdiction of neighboring countries needs to be resolved fairly and reasonably by the countries concerned in the spirit of friendly consultation.

General situation of seawater chemical resources

Marine chemical resources refer to various chemical elements contained in seawater that can be used by human beings. The composition of seawater is very complicated. The global ocean contains 500 million tons of salt and a lot of very rare elements, such as 5 million tons of gold and 4.2 billion tons of uranium, so the ocean is the largest mineral resource pool on the earth. The sustainable utilization of marine resources is an important prerequisite for human survival and development. At present, more than 2 billion tons of fresh water, 50 million tons of salt, 2.6 million tons of magnesium and magnesium oxide and 200,000 tons of bromine are extracted from the ocean every year, with a total output value of more than 600 million US dollars. Water is the source of life, and there are more and more water-deficient areas in the world. Seawater desalination has become an important way to obtain fresh water resources, which are all to be studied in marine chemistry.

Marine living resources

1, estimation of marine living resources. The ocean is a treasure house of biological resources. According to the statistics of biologists, there are about 200,000 species of organisms in the ocean, including about10.9 million species of known fish and about 20,000 species of crustaceans. Many marine life has the value of development and utilization, providing abundant food and other resources for human beings. The global marine phytoplankton production is 500 billion tons, which translates into an annual fish production of about 600 million tons. If 50% of the resources are taken as the allowable catch, the global marine fish catch is about 300 million tons.

2. Present situation of marine living resources development. The main industry to develop marine biological resources is marine fishery, and there are also a few marine medicinal biological resources. From 65438 to 0989, the world marine fishery output was about 85.75 million tons. 1990 (not reported by official statistics) The total world fishery output is estimated to be1100,000 tons, among which the marine fishery output is also higher than 1989. Among them, the fishery output of the world's oceans is 54 million tons in the Pacific Ocean, 24 million tons in the Atlantic Ocean and 60 million tons in the Indian Ocean.

The development level of marine fisheries varies greatly among countries. For a long time, Japan and the former Soviet Union are both big fishing countries with fishery output exceeding 6.5438+million tons. China's fishery has developed rapidly, with the fishery output reaching more than 1990 tons, making it the largest fishery country. Some countries in the United States, Canada and Europe, as well as some countries in South Korea and Southeast Asia, have relatively developed fisheries.

3. The development potential of marine living resources. The development potential of marine living resources in the world is great. According to the estimation of experts from various countries, the total catch of global marine fishery resources is between 200-300 million tons, and the actual catch at present is less than 654.38+ 1 100 million tons. In addition, medicinal and other biological resources also have great development potential. In recent years, Japan and other countries are exploring the development of biological resources in deep-sea areas, first of all, investigating resources and developing new fishing techniques. It is reported that the deep-water area of the ocean, once considered as a desert in the ocean, contains a large number of pelagic fish resources, of which the biomass of bottle fish alone reaches 900 million tons and the annual catch can reach 500 million tons. The annual catch of krill resources in the Southern Ocean can reach 0.5? Billions of tons. Besides, the water depth is 200? There are many other economic fish within the range of 000 meters, such as long-tailed cod, deep-sea cod, flat-headed fish, golden-eyed snapper, sole and so on. , can catch about 30 million tons.

Overview of marine mineral resources

It is more accurate to describe marine resources with "cornucopia". As far as her mineral resources are concerned, its types and richness are amazing. More than 80 kinds of 100 elements found on the earth exist in the ocean, of which more than 60 kinds can be extracted. These rich mineral resources exist in the ocean in different forms: "liquid sediments" in seawater; Solid sediments enriched on the seabed; Oil and natural gas resources are rolling in from the bottom of the sea.

The most common salt in seawater, namely sodium chloride, is one of the earliest minerals extracted from seawater. There is also a kind of magnesium salt, which is the main cause of salty and bitter seawater. In addition to these two kinds, there are dozens of rare elements such as potassium salt, iodine and bromine, as well as boron, rubidium and barium. These elements are generally rare and scattered on land, but they are extremely valuable and useful to human beings.

It is estimated that seawater contains 5.5 million tons of gold, 55 million tons of silver, 2.7 billion tons of barium, 4 billion tons of uranium, 7 billion tons of zinc, 65.438+0.37 billion tons of molybdenum, 247 billion tons of lithium, 56 billion tons of calcium, 65.438+0.767 billion tons of magnesium and so on. Most of these things are necessities for national defense industry, agriculture, production and life. For example, magnesium is a "rising star" in metals, which can be used to make speedboats, rocket fuel and flares. At present, more than half of magnesium in the world comes from seawater.

Sea water is a treasure, and so are sea mines. Marine minerals mainly include coastal minerals and shallow sea minerals. They are all mineral-rich ores with industrial value in beaches and shallow seas with a water depth of less than tens of meters, and are the most convenient mineral deposits for mining. Gold, diamond, diamond, monazite, ilmenite, xenotime, rutile and magnetite can be extracted from these sands. Gold that is more valuable than gold can be extracted. Therefore, marine ore has become one of the biggest potential resources to increase mineral reserves, and it has been more and more used by people.

This kind of ore is mainly distributed in shallow water, and there are many amazing discoveries in that deep seabed: polymetallic nodule manganese nodule is one of the most economically valuable nodules. It was first discovered in the deep seabed of the North Atlantic by a British research ship named "Challenge" on 1872- 1876. These black or brown massive manganese nodule goose eggs, some like potatoes and some like rubber balls, are generally less than 20 cm in diameter, and are highly enriched and distributed on the seabed surface sediments with a water depth of 300-6000 meters.

It is estimated that the reserves of manganese nodules on the whole seabed are about 3 trillion tons. If properly developed, it will be an inexhaustible precious resource in the world. At present, manganese nodule ore has become a hot spot of development in many countries in the world. In this surface mineral, the ocean has a lot of sediments oozing out, which is also a serious mineral, rich in metal elements and plankton debris. For example, seabed laterite covering 1 100 million square kilometers is rich in axis, iron, manganese, zinc, indium, silver and gold, which has great economic value.

In recent years, scientists have discovered 33 "hydrothermal deposits" on the seabed, which are massive sulfide polymetallic oozes and sediments formed by hydrothermal mineralization on the seabed. This kind of hot-dip deposit is mainly formed in the mid-ocean ridge and submarine rift zone. Hydrothermal liquid is discharged from the seabed through hot springs, geysers or water spray holes, and becomes cold when it meets water. In addition, the changes of surrounding environment and pH value make metal sulfides and iron-manganese oxides precipitate in the mineral solution, forming massive substances and accumulating into mine hills. Some are chimney-shaped, some are mound-shaped, and some are carpet-shaped, ranging from several tons to thousands of tons. It is another marine mineral resource with great development prospect.

Oil and natural gas are mineral resources all over the global continental shelf. Oil can be said to be the "darling" of marine mineral resources, also known as "black gold". It is reported that in 1990, the global proven reserves of offshore oil reached 2.970×10/0 ton, and the proven reserves of offshore natural gas reached1.909×10/3m3. The total value of oil and natural gas accounts for more than 70% of the total output value of known marine minerals.

Oil is the "blood of industry". However, at present, the world has exploited 64 billion tons of oil, and the exhaustion of oil is inevitable. From the Gulf War, we can see the value of oil. So people turn to offshore oil resources for help. Natural gas is a colorless and odorless gas, also known as biogas, and its composition is mainly methane. Because of its high carbon content, it is easy to burn and release a lot of heat. 1000 cubic meter of natural gas can be equivalent to the potential of two and a half tons of coal combustion. Therefore, the value of natural gas is second only to oil in the ocean.

Overview of marine energy

The vast sea is not only rich in mineral resources, but also has inexhaustible marine energy in the true sense. It is not only different from the seabed energy resources such as coal, oil and natural gas stored on the seabed, but also different from the chemical energy resources such as uranium, magnesium, lithium and heavy water dissolved in water. It has its own unique way and form, that is, kinetic energy, potential energy, thermal energy and physical and chemical energy expressed by tide, wave, ocean current, temperature difference and salinity difference. Directly speaking, it is tidal energy, wave energy, seawater temperature difference energy, ocean current energy and salinity difference energy. This is a kind of "renewable energy", which will never be exhausted and will not cause any pollution.

Tidal energy is the energy produced by tidal movement, and it is the earliest marine power resource used by human beings. In the coastal areas of the Tang Dynasty, there appeared a small workshop in China that used tides to push the mill. Later, in the11-12nd century, tidal mills also appeared in France, Britain and other countries. In the twentieth century, the charm of tidal energy reached its peak, and people began to understand how to use the tidal energy of seawater to generate electricity. It is estimated that the global ocean tidal energy is about 2 billion kilowatts, which can generate electricity 12400 trillion kwh every year.

Today, the world's first and largest tidal power station is located at the mouth of the Lanse River in the English Channel of France, with an annual power supply of 544 million kWh. Some experts assert that pollution-free cheap energy is the eternal trend in the future. Other experts pay attention to the ubiquitous waves floating on the global tides.

Wave energy is mainly the energy generated by the periodic movement of seawater along the horizontal direction under the action of wind.

Wave energy is enormous. A huge wave can throw a stone weighing 13 tons to a height of 20 meters. A wave with a wave height of 5 meters and a wavelength of 100 meters has an energy of 3 120 kilowatts on a wave crest piece with a length of one meter. From this we can imagine how amazing the energy of waves in the whole ocean is. According to calculation, the wave energy of the global ocean can reach 70 billion kilowatts, and there are 2-3 billion kilowatts available for development and utilization. The annual power generation can reach 9 trillion kWh.

In addition to tidal energy and wave energy, ocean currents can also contribute. Because the ocean currents are criss-crossing and continuous, they also contain considerable energy. For example, when the Mexican Stream, the largest warm current in the world, flows through northern Europe, it provides heat for the coastline of 1 cm, which is about equivalent to the heat of burning 600 tons of coal. It is estimated that the available ocean current energy in the world is about 50 million kilowatts. Using ocean currents to generate electricity is not complicated. Therefore, contributing to ocean currents is still a profitable business, and it is also a risky business.

The idea of using temperature difference as ocean energy is great. This is ocean temperature difference energy, also called ocean heat energy. Because seawater is a substance with a large heat capacity, the volume of the ocean is so large that the heat contained in seawater is enormous. These heat energy mainly comes from solar radiation, in addition to the heat released from the interior of the earth to seawater; Exothermia of radioactive substances in seawater; The heat generated by ocean current friction and the radiant energy of other celestial bodies, but 99.99% comes from solar radiation. Therefore, the thermal energy of seawater varies greatly with the location of the sea area. Ocean thermal energy is one of the sources of electric energy, which can be converted into 2 billion kilowatts. But in 188 1 year, French scientist Del Songshi boldly put forward the idea of seawater power generation for the first time, which was buried for nearly half a century. It was not until 1926 that his student Claude realized the teacher's long-cherished wish.

In addition, at the mouth of a river, there is a little-known salinity difference between fresh water and seawater. The global available salinity difference energy is about 2.6 billion kilowatts, even greater than the temperature difference energy. The principle of salt differential energy power generation is actually to use the energy released by the diffusion of concentrated solution into dilute solution.

It can be seen that there is huge energy in the ocean. As long as the seawater is not exhausted, its energy will be endless. As a new energy source, ocean energy has attracted more and more people's interest.