Will ocean energy be harnessed in the future?

Seawater DC cooling technology has a history of nearly 100 years of development, and the relevant anti-corrosion and anti-marine organism attachment technology has been basically mature. At present, China's seawater cooling water consumption does not exceed 14.1 billion cubic meters per year, while Japan is about 300 billion cubic meters per year, and the United States is about 100 billion cubic meters per year, which is a big gap. Seawater circulating cooling technology began in the 70s of the 20th century, and has been widely applied in the United States and other countries, which is one of the main development directions of seawater cooling technology.

Our country has passed"Eighty-five""Ninety-five"Scientific and technological research, completed the 100-ton industrial test, and made major breakthroughs in key technologies such as seawater corrosion inhibitors, scale inhibitors and dispersants, fungal and algae biocides, and seawater cooling towers. "Fifteen"During this period, through the implementation of major national scientific and technological research projects, 1,000-ton and 10,000-ton seawater circulating cooling demonstration projects are being established. <>

Desalination refers to the technology and process of obtaining fresh water from seawater. In the 30s of the 20th century, the seawater desalination method mainly used the multi-effect evaporation method; From the 50s of the 20th century to the mid-80s of the 20th century, the multi-stage flash evaporation method (MSF) was mainly used, and the desalination of water still accounted for a considerable proportion of the method. In the mid-50s of the 20th century, electrodialysis (ED in the 70s of the century) reverse osmosis (RO) and low-temperature multi-effect evaporation (LT-MED) gradually developed, especially reverse osmosis (RO) desalination has become the fastest developing technology at present. According to the statistics of the International Desalination Association, by the end of 2001, the daily production of seawater desalination water in the world had reached 32.5 million cubic meters, which solved the water supply problem of more than 100 million people.

These desalination waters can also be used as high-quality boiler make-up water or high-quality production process water, which can provide stable and reliable fresh water for coastal areas. The water sales of international desalination have dropped from more than US$2 in the 60s and 70s of the 20th century to less than US$10 at present, which is close to or lower than the tap water of some cities in the world**. As the costs of technological progress are further reduced, the economic justification of desalination will become more apparent and will attract increasing attention from the international community as a means of sustainable development of freshwater resources.

Ocean energy includes tidal energy, wave energy, ocean current energy, seawater temperature difference energy and salinity difference energy. Except for tidal energy, which comes from the gravitational pull of the moon and the sun, all other energy is converted by solar radiation, which is a permanent clean renewable energy source.

Tidal energy refers to the energy produced when the tide rises and falls in the sea. The people of the ancient coastal areas knew how to use the tides as the power of the mill. Since the 50s of the 20th century, many countries in the world have begun to build dams in bays or river estuaries with large tidal ranges, and use the water level difference inside and outside the dam to drive hydro turbines to generate electricity, which is called tidal power stations.

The largest tidal power station is located at the mouth of the Lens River near Saint-Malo, France, with an annual power generation capacity of 100 million kWh. China is one of the countries with the most tidal power stations in the world.

Wave energy is the energy possessed by waves on the surface of the sea caused by the action of the wind. In the early 60s of the 20th century, Japan was the first to successfully develop a wave power generation device for navigation lights. Since then, Norway, the United Kingdom, the United States, Portugal, China and other countries have also built experimental wave power stations and wave power plants for navigation lights.

Current energy refers to the kinetic energy of seawater flow, mainly including the relatively stable flow in submarine waterways and straits, as well as the regular tidal currents caused by tides, and the energy is very considerable. For example, the current energy in many places along the coast of Liaoning, Shandong, Zhejiang, Fujian and Taiwan in China is very high, and the tidal current near the Zhoushan Islands changes its size and direction twice a day with the rise and fall of the tide, and the maximum flow speed is 3m s. The principle of ocean current power generation is similar to that of wind power, except that the turbine is placed on the bottom of the seabed or suspended from the bottom of a pontoon.

At present, the United States, the United Kingdom, Canada, Japan, Italy and China have all built demonstration ocean current power stations.

Seawater thermodynamic refers to the heat energy generated by using the temperature difference between the surface and deep seawater of the ocean. For example, in the South China Sea, the surface sea water is warmed by the strong irradiation of the sun, with an annual average of more than 26, and the depth is affected by the cold sea water flowing from the polar region to the equator, and the water temperature at a depth of 800 meters is perennial 5, and the temperature difference between the upper and lower levels is at least 21. This difference in seawater temperature can be used to generate electricity in a thermal cycle by pumping the surface warm seawater into a vacuum flash evaporator, boiling it and evaporating it into steam, which drives the turbine generator.

The exhaust steam enters the condenser, where it is cooled by the pumped deep icy seawater, re-condensed and discharged into the sea. At present, France, the United States, Japan and other countries have built several experimental marine temperature difference power stations.

Salt difference energy refers to the chemical potential difference energy between seawater and freshwater or between two seawater with different salt concentrations, which mainly exists at the junction of rivers and seas. The principle of salt differential energy power generation is actually the use of the energy released by the diffusion of concentrated solution into dilute solution, and the use of semi-permeable membrane that can only pass through water and cannot pass through salt to form a water level difference between salt water and fresh water, and then directly generate electricity by the hydro generator. At present, experimental studies are being carried out in various countries.

Ocean energy is the use of tides or temperature differences in seawater to generate electricity. Beginning with the oil crisis in the 70s of the 20th century, countries began to shift their attention to the use of local resources and the search for suitable and cheap energy sources. The ocean is the cradle of human beings, and 75% of the earth's area is the ocean, and it has become an inevitable trend for human beings to seek resources from the sea.

Wave power generation is the fastest growing form of marine energy utilization after tidal power generation, so far, Japan, the United Kingdom, Ireland, Norway, Spain, Sweden, Denmark, India, the United States and other countries in the world have established wave power generation devices at sea. Wave energy is the most volatile energy source of renewable energy, and it cannot be produced regularly, and has the characteristics of strong energy but slow speed and periodic changes. The shortcomings of the existing wave power generation technology are the low efficiency of energy harvesting, the instability of the converted secondary energy, and the poor adaptability to the marine environment.

The fluctuating cylinder booster transducer and the fluctuating piston transducer convert the disordered wave energy into a stable secondary energy source that can be directly used at one time. Both technologies can be used directly to generate electricity, set up offshore plants, and apply to desalination, hydrogen production, and manganese nodule extraction.

The most attractive thing about the sea is that it contains an extremely rich amount of natural energy and a huge amount of renewable energy. The rough waves, the rising and falling tides, the endless currents, the temperature difference of the sea at different depths, and the difference in salt content of the water at the intersection of the sea ......All have a huge amount of energy that can be utilized.

The largest tidal power station in the world is the Lens tidal power station in France. In 1991, the United Kingdom built a wave power station. Ocean currents have great impact and potential in the flow, so they can be used to generate electricity, and it is estimated that the total power of the world's ocean energy is about 5 billion kilowatts, which is the largest energy source in the ocean.

Ocean energy is the energy produced by the pressure of ocean waves, tides, or ocean temperature differences. It is estimated that 3 billion kilowatts of electricity can be generated worldwide from tidal energy alone. In 1966, France first built a tidal power station with a power generation capacity of 240,000 kilowatts in the northern Reims region, which now generates 100 million kilowatts of electricity per year.

In 1968, the Soviet Union also built a tidal power station with a power generation capacity of 400,000 kilowatts. The United Nations estimates that by 2020, the world's tidal power generation capacity could reach 60,090 billion kilowatt hours.

The global ocean energy is very renewable. It is estimated that the total amount of ocean energy theoretically renewable is 76.6 billion kilowatts. Among them, the temperature difference energy is 40 billion kilowatts, the salt difference energy is 30 billion kilowatts, the tidal and wave energy is 3 billion kilowatts each, and the ocean current energy is 600 million kilowatts.

However, as mentioned above, it is difficult to extract all of the above-mentioned energy, and it is envisaged that only strong currents, tides, and waves can be used, and the salinity difference in the area of heavy rainfall can be exploited, and the use of temperature difference is limited by the efficiency of the heat engine Carnot. Therefore, it is estimated that the technically allowable power is 6.4 billion kilowatts, of which 3 billion kilowatts can be used for salt difference, 2 billion kilowatts for temperature difference, 1 billion kilowatt for wave energy, 300 million kilowatts for ocean currents, and 100 million kilowatts for tidal energy.

In 1980, a joint study by Japan, the United States, the United Kingdom, Canada, and Ireland showed that large-scale power generation was possible. In 1981, the United States and Japan conducted similar experiments on a large scale. In short, in addition to tidal power generation technology, the technology of ocean energy use in various countries around the world is still in the development and experimental stage of key technologies.

The ocean covers 71% of the surface area, with a total area of about 100 million square kilometers. The vastness of the ocean has contributed a huge treasure of resources to mankind. 80% of the earth's biological resources are in the ocean, and the abundant aquatic resources provide us with high-quality protein; Oil and gas from the bottom of the ocean provide us with energy; Metals on the seabed.

The ocean contains abundant renewable energy, including tidal energy, wave energy, seawater temperature difference energy, ocean current energy, salt difference energy, etc. Scientists estimate that the theoretical reserves of these energy sources are about 150 billion kilowatts, and more than 7 billion kilowatts can be developed and utilized, which is equivalent to more than ten times the current power generation capacity of the world, and is of great significance in the future energy of mankind.

The ocean is rich in resources, and almost all the resources that human beings need can be obtained from the ocean.

Water, because water is the source of life, it is now, and it will be in the future.

The energy source of the ocean for the benefit of mankind in the future is dry ice!