There are many nature's power, such as wind energy, ocean energy, solar energy, etc. These nature's power will solve the problem of energy shortage in the future, so we should use these nature's power reasonably, so that they can benefit human beings.
The use of wind energy
The wind is due to the sun's exposure to the Earth's surface at various places heated differently, resulting in a temperature difference caused by the atmospheric movement formed. Although only 2% of the solar energy that reaches the earth is converted into wind energy, the total amount is very considerable. The global wind energy can be actually utilized for 2X1O'MW, which is 10 times larger than the total amount of water energy that can be developed and utilized on the earth.
At present, the use of wind energy is mainly power generation, wind power in the new energy and renewable energy industry, the fastest growing, an annual increase of up to 35%,
The United States, Italy and Germany's annual growth is as high as 50% or more. German wind power has accounted for 3% of the total power generation, Denmark wind power has more than 10% of the total power generation. The global installed capacity of wind power has reached more than 25000MW, can meet 15 million families, that is, 38 million people's electricity needs. Although Europe accounts for more than 70% of the world's total installed capacity of wind power, but other countries are also actively opening up the market, there are more than 50 countries are actively promoting the development of wind energy. Due to the relative maturity of wind power generation technology, many countries have invested more, faster development, so that the price of wind power continues to decline, the current cost of wind power generation 0.4-0.7/KWH, if you consider the environmental protection and geographic factors, coupled with the government's tax incentives and related support, in some areas have been able to compete with the thermal power and other energy sources. Globally, wind power has formed an annual output value of more than 5 billion U.S. dollars
Industry. The main investment in building wind farms is wind turbine equipment, which accounts for more than 80% of the total investment. Wind turbine from 100w-1MW, there are many kinds of specifications. Small and medium-sized wind turbines more off-grid independent operation, medium and large units more wind farms or wind fields and grid-connected power generation. At present, grid-connected power generation is dominated by 500KW-750KW units, and there are also a small number of 12MW units in operation. The largest trial run unit capacity has reached 2.5.3MW, of course, there are people in the development of SMW wind turbines. Now, not only the wind farms built inland, islands and coasts, the United Kingdom, the Netherlands and other European countries experience shows that the wind farms built in the sea, the economic benefits, environmental benefits and social benefits are more obvious.
According to the World Energy Organization in 1999, the development of the "wind energy 100" report, revised in 2002 into the "wind energy 12 report, after scientific measurement
calculated that the future of wind power generation in the annual growth of more than 30%, and predicted that by 2020, the world's total capacity of wind power installed capacity will reach 1,260GW, the annual power generation will be up to the world's total demand for electricity 12%.
China's wind energy resources, reserves of 3.2 billion kilowatts, can be developed by the installed capacity of about 25.3 billion kilowatts, ranking first in the world, and can be developed with the installed capacity of hydroelectricity 3.8 billion kilowatts of the same magnitude, with the potential for commercialization, large-scale development. China's government attaches great importance to the wind power industry, 1996 on the development of the "wind plan", aimed at encouraging the improvement of medium and large-scale wind turbine manufacturing technology and localization rate, "Tenth Five-Year Plan" period of the original plan to invest 1.5 billion yuan in the wind power industry. Because of certain business opportunities and market prospects, some local governments and private individuals are also actively involved in the wind power business. At present, the country's cumulative installation of small wind turbines nearly 200,000 units, as a solution to the western region without electricity, farmers and herdsmen play an important role in the production and use of electricity. In Guangdong, Fujian, Zhejiang, Liaoning, Inner Mongolia, Xinjiang and other places have built 26 wind farms, stand-alone capacity from 200 kilowatts to 1300 kilowatts of various specifications, with a total installed capacity of nearly 400,000 kilowatts. In terms of equipment, China has developed from 100 watts l kilowatts of more than 10 kinds of small wind turbine capacity, independent development of 200-300 kilowatts of wind turbine localization rate of more than 90%, 600 kilowatts of prototype unit localization degree has reached 80%. China's near-term goal is to 2005, the installed capacity of grid-connected wind power generation to reach 1.2 million kilowatts. Although China's wind power generation in recent years has been growing rapidly, the annual growth of about 50%, but both the level of equipment manufacturing, or the total installed capacity and Europe and the United States compared to a number of developed countries there is still a large gap with neighboring India there is also a significant gap. China's installed capacity of wind power generation accounted for only 0.11% of the national installed power, visible in China's wind power generation potential how huge! Guangdong is extremely rich in wind power resources, has built up the Shantou Nanao Island wind farms. Shenzhen has the conditions should also take a solid step in the wind power generation.
Geothermal energy use
Humans began to use geothermal energy a long time ago, such as the use of hot springs, bathing, medical treatment, the use of underground hot water heating, the construction of crop greenhouses, aquaculture and drying grains and so on. However, the real understanding of geothermal resources and larger-scale development and utilization began in the mid-20th century. The use of geothermal energy can be divided into geothermal power generation and direct use of two categories, and for different temperatures of geothermal fluid may be used in the following ranges:
1, 2O0 ~ 400 ° C direct power generation and comprehensive utilization;
2, 150 ~ 200 ° C double-cycle power generation, refrigeration, industrial drying, industrial thermal processing;
3, 10O ~ 15O ° C double-cycle power generation, heating, refrigeration, industrial drying
3, 10O ~ 15O ℃ double-cycle power generation, heating, refrigeration, industrial drying, dehydration processing, recycling of salts, canned food;
4, 50 ~ 100 ℃ heating, greenhouses, hot water for domestic use, industrial drying;
5, 20 ~ 50 ℃ bathing, aquaculture, livestock rearing, soil heating, dehydration processing;
Many countries are now in order to increase the utilization of geothermal heat and use of terraced development and Comprehensive utilization of methods, such as cogeneration cogeneration, cogeneration of heat and power cold three, first after the breeding of heating and so on.
In recent years, foreign non-power utilization of geothermal energy, that is, the direct use, attaches great importance. Because of geothermal power generation, low thermal efficiency and high temperature requirements. The so-called thermal efficiency is low. That is, due to the different types of geothermal, the different types of turbines used, the thermal efficiency is generally only 6.4 ~ 18.6%, most of the heat consumed in vain. The so-called high temperature requirements, that is to say, the use of geothermal energy to generate electricity, the temperature requirements of underground hot water or steam, generally have to be above 150 ℃; otherwise, it will seriously affect its economy. The direct use of geothermal energy, not only the loss of energy is much smaller, and the temperature requirements of the underground hot water is much lower, from 15 to 180 ℃ such a wide range of temperatures can be used. In all the geothermal resources, this kind of medium and low temperature geothermal resources is very rich, much larger than the high temperature geothermal resources. However, the direct use of geothermal energy also has its limitations, due to the heat-carrying medium - hot water transport distance constraints, in general, the heat source should not be too far away from the towns and cities with heat or settlements; otherwise, more investment, loss of large, poor economy, is not good.
At present, the direct use of geothermal energy development is very rapid, has been widely used in industrial processing, civil heating and air conditioning, bathing, medical, agricultural greenhouses, agricultural irrigation, soil heating, aquaculture, livestock and poultry rearing, and other aspects, received a good economic and technical benefits, saving energy. The direct utilization of geothermal energy, technical requirements are lower, and the required equipment is simpler. In the direct use of geothermal systems, although sometimes due to the geothermal heat flow in the salt and sediment content is very low and can be directly utilized for geothermal, but usually with a pump will be pumped up the geothermal heat flow, through the heat exchanger into the hot gas and hot liquid and then use. These systems are the simplest of all, using conventional off-the-shelf components.
Most of the heat source temperatures used in the direct utilization of geothermal energy are above 40 degrees Celsius. A hydrothermal source with a temperature of 20°C or less can also be used as a heat source if heat pump technology is utilized (as is the practice in the United States, Canada, France, Sweden and other countries). A heat pump works on the same principle as a domestic refrigerator, except that while a refrigerator is actually a one-way heat pump, a geothermal heat pump can deliver heat in both directions. In the winter, it extracts heat from the earth and provides it to the home or building (heating mode); in the summer, it extracts heat from the home or building and provides it back to the earth for storage (air conditioning mode). In either cycle, the water is heated and stored, performing all or part of the function of a stand-alone hot water heater. Since electric current can only be used to transfer heat, not to produce it, a geothermal heat pump will be able to provide three to four times more energy than it consumes on its own. It can be used over a wide range of earth temperatures. In the U.S., geothermal heat pump systems are growing at a rate of 20% per year and will continue to grow at a good double-digit rate in the future. The U.S. Energy Information Administration predicts that geothermal heat pumps will provide up to 68 Mt oil equivalent of energy for heating, cooling and water heating by 2030.
For geothermal power, if the geothermal resource is hot enough, a good way to utilize it is to generate electricity. The electricity generated can either feed the public **** grid or power local industrial processes. Normally, it is used for base-load power generation, and only under special circumstances is it used for peak-load power generation. The reasons for this are, firstly, the difficulty of controlling peak loads, and then the problems of scaling and corrosion of the vessel, once the liquid inside the vessel and the turbine is not full and air is allowed to enter.
To summarize the above, geothermal energy utilization plays an important role in the following four areas.
1. Geothermal power generation
Geothermal power generation is the most important way of geothermal utilization. High-temperature geothermal fluids should first be applied to power generation. Geothermal power generation and thermal power generation is the same principle, are the use of steam heat energy in the turbine into mechanical energy, and then drive the generator to generate electricity. The difference is that geothermal power generation does not need a huge boiler like thermal power generation, nor does it need to consume fuel, the energy it uses is geothermal energy. The process of geothermal power generation is to transform the underground thermal energy into mechanical energy first, and then transform the mechanical energy into electrical energy. In order to utilize the underground thermal energy, first of all, there needs to be a "heat carrier" to bring the underground thermal energy to the ground. At present, the heat carriers that can be utilized by geothermal power plants are mainly natural steam and hot water underground. According to the type of heat carrier, temperature, pressure and other characteristics of the different ways of geothermal power generation can be divided into steam-type geothermal power generation and hot water-type geothermal power generation two categories.
(1) steam-type geothermal power generation
Steam-type geothermal power generation is the steam field in the dry steam directly lead to the turbine generator set power generation, but in the lead generator set before the steam contained in the rock debris and water droplets should be separated out. This type of power generation is the simplest, but the dry steam geothermal resources are very limited, and most of them are stored in deeper strata, and the extraction technology is difficult, so the development is restricted (refer to the relevant articles in the "Resources" column). There are mainly back-pressure and condensing two power generation systems.
(2) Hot water geothermal power generation
Hot water geothermal power generation is the main way of geothermal power generation. At present, there are two kinds of circulation system in hot water type geothermal power station: a. Flash vaporization system. When the high-pressure hot water from the hot water wells pumped to the ground, in the pressure reduction part of the hot water will boil and "flash" into steam, steam sent to the turbine to do work; and after the separation of the hot water can continue to use the discharge, of course, it is best to inject back into the stratum. b. Double circulation system. Geothermal water first flows through the heat exchanger, and transfers the geothermal energy to another working fluid with low boiling point, so that it boils and produces steam. The steam enters the turbine to do work and then enters the condenser, and then passes through the heat exchanger to complete the power generation cycle. The geothermal water is injected back into the ground from the heat exchanger. This system is particularly suitable for geothermal resources with high salt content, high corrosivity and high non-condensable gas content. The key technology for the development of dual-cycle systems is the development of highly efficient heat exchangers.
The future of geothermal power generation depends on how to develop and utilize dry-heat-rock resources with large geothermal reserves. The key technology is the ability to drill deep wells into hot rock formations. Visionary tests of such a system are being conducted at the Los Alamos Science Laboratory in New Mexico, USA.
2. Geothermal heating
Geothermal energy is directly used for heating, heating and hot water is second only to geothermal power generation of geothermal utilization. Because of this way of utilization is simple, good economy, doubly valued by the countries, especially located in the alpine region of the western countries, of which Iceland development and utilization of the best. The country as early as 1928 in the capital city of Reykjavik built the world's first geothermal heating system, now this heating system has been developed very well, every hour from the ground to extract 7740t80 ℃ of hot water for the city's 110,000 residents to use. With no towering chimneys, Iceland's capital has been described as "the world's cleanest and smokeless city". In addition to the use of geothermal heating to the factory, such as used as a heat source for drying grains and food, used as a heat source for diatomaceous earth production, timber, paper, tannery, textiles, brewing, sugar and other production processes is also promising. At present, the world's two largest geothermal application plant is Iceland's diatomaceous earth plant and New Zealand's paper paddle processing plant. China's use of geothermal heating and hot water development is also very rapid, in the Beijing-Tianjin area has become the most common way of geothermal utilization.
3. Geothermal agriculture
Geothermal in agriculture has a wide range of applications. Such as the use of appropriate temperature of the geothermal water irrigation farmland, can make the crops early and increase production; the use of geothermal water for fish farming, in 28 ℃ water temperature can accelerate the fertilization of fish, improve the rate of fish production; the use of geothermal construction of greenhouses, rice seedlings, planting vegetables and flowers; the use of geothermal heating to the biogas digesters to raise the biogas production and so on. The direct use of geothermal energy for agriculture is becoming more and more widespread in China, with geothermal greenhouses of varying sizes being built in Beijing, Tianjin, Tibet and Yunnan. Various places also use geothermal energy to develop aquaculture, such as cultivation of fungus, breeding of African carp, eel, tilapia, tilapia and shrimp.
4. Geothermal medicine
Geothermal application in the medical field has attractive prospects, the current hot mineral water is regarded as a valuable resource, the world are very valuable. As geothermal water is extracted from the deep underground to the ground, in addition to the higher temperature, often contains some special chemical elements, thus making it has certain medical effects. Such as carbonated mineral water for drinking, can regulate stomach acid, balance the body's pH; iron-containing mineral water for drinking, iron deficiency anemia can be treated; hydrogen springs, sulfur water hydrogen spring baths can treat neurasthenia and arthritis, skin diseases and so on. Because of the medical effects of hot springs and the special geological and geomorphological conditions accompanying hot springs, hot springs often become tourist attractions, attracting a lot of healers and tourists. In Japan, there are more than 1,500 hot spring sanatoriums, attracting 100 million people to these sanatoriums every year. China has a long history of using geothermal treatment of disease, containing a variety of mineral elements of the hot springs, so give full play to the role of geothermal medicine, the development of spa treatment industry is promising.
Salt water salt difference power generation
Scientific research has proved that two kinds of seawater with different salt content in the same container, due to the diffusion of salt ions and produce chemical potential difference energy. At the same time, the use of certain conversion methods, you can make this chemical potential difference can be converted into electrical energy. In recent years, the rapid development of the ocean salt difference power generation technology, is the use of this principle of work.
When two different salinity of seawater is a layer of water can only pass through the water and can not pass through the salt of the semi-permeable membrane phase division, the two sides of the seawater will produce a kind of osmotic pressure, prompting the water from the concentration of the low side of the membrane to the concentration of a high one to penetrate, so that the concentration of the high side of the water level rises until to fulfill the two sides of the salt concentration is equal.
Some people through theoretical calculations, the osmotic pressure of seawater at the river into the sea can be equivalent to 240 meters high water level drop. Bit dry in western Asia, the Dead Sea, salinity is higher than the general seawater 7-8 times, the osmotic pressure can reach 500 atmospheric pressure, equivalent to 5000 meters high dam head. In order to explore the effect of seawater salt difference power generation, Israel, a scientist named Loeb in the Dead Sea and the Jordan River confluence of the place to conduct experiments, the use of osmotic pressure principle designed by the pressure delay osmotic energy conversion device, achieved satisfactory results. Scientists at the University of Oregon, the use of osmotic principle, developed a new type of osmotic pressure salt differential energy generation system.
This system installs the generator set in the water depth of 228 meters above the seabed, the river's fresh water from the pipeline to the generator set. A semi-permeable strand installed at the front of the discharge can only pass fresh water, not seawater. If the generator set is installed below 228 meters above sea level, the static pressure of seawater exceeds the osmotic pressure. The opposite process then occurs, with freshwater being transported in the reverse direction. Since the discharged freshwater is less dense than the surrounding seawater, it floats upwards and mixes, while maintaining a stable salinity difference at the bottom. This power generation system is a very promising osmotic pressure type salt differential energy generation system.
Now, people are researching and developing a new type of vapor pressure type salt differential energy generation system. At the same temperature, fresh water evaporates faster than seawater. As a result, the vapor pressure on the seawater side is much lower than on the freshwater side, and so, in the air chamber, water vapor will quickly flow from above the freshwater to above the seawater. As long as a turbine is installed, it can work with salt differential energy. The use of vapor pressure salt differential energy to generate electricity does not require the treatment of seawater, and there is no need to worry about bio-attachment and pollution. In addition to this, mechanical-chemical differential salt energy generation system and seepage differential salt energy generation system have also been used to obtain electricity. After experimentation, all of them also have attractive development prospects.
According to scientists' analysis, the total output power of salt differential energy stored in the world's oceans can reach as much as 3.5 billion kilowatts. Moreover, most of the seawater in the cycle will be constantly renewed and replenished, so how huge is its energy!
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