What Are the Advantages of Wind Energy Production?

Wind energy The kinetic energy generated by air movement. A converted form of solar energy. Due to the uneven heating of parts of the earth's surface caused by solar radiation, the pressure distribution in the atmosphere is unbalanced. Under the effect of the horizontal pressure gradient, the air moves in the horizontal direction to form wind. The total reserves of wind energy resources are very huge. The technically developable energy in a year is about 5.3 × 10 ^ 13 kWh. Wind energy is a renewable and clean energy source with large reserves and wide distribution, but its energy density is low (only 1/800 of water energy) and unstable. Under certain technical conditions, wind energy can be developed and used as an important energy source. The utilization of wind energy is a comprehensive engineering technology. The kinetic energy of the wind is converted into mechanical energy, electrical energy and thermal energy by a wind turbine. ^[1]

Wind energy resources are determined by wind energy density and the cumulative hours of wind energy available annually. Wind energy density is the wind power available per unit of windward area, which is directly proportional to the cube of wind speed and air density.

Chinese name: Wind energy
Foreign name: wind energy

Classification: non-renewable energy
Generate energy: Mechanical energy

Basic overview of wind energy

Introduction to Wind Energy

Wind energy (wind energy) is a kind of available energy provided to human beings due to the work of air flow. It belongs to renewable energy (including water energy, biological energy, etc.). The kinetic energy of air flow is called wind energy. The higher the air velocity, the greater the kinetic energy. People can use the windmill to convert the kinetic energy of the wind into a rotating motion to push the generator to generate electricity,

Wind energy The method is to transmit the rotating power of the rotor (composed of aerodynamically driven blades) to the generator through the transmission shaft. As of 2008, wind power generated around 94.1 million kilowatts in the world, and the power supplied has exceeded 1% of the world's consumption. Although wind energy is not the main energy source for most countries, it has more than quadrupled between 1999 and 2005.

Modern turbine blades are used to convert the mechanical energy of airflow into electrical energy and become a generator. In medieval and ancient times, windmills used the collected mechanical energy to grind grains and pump water.

Wind is used in large-scale wind farms and some isolated places where electricity is supplied, making a huge contribution to local life and development.

Wind energy characteristics

Wind energy is abundant, nearly endless, widely distributed, clean and mitigates the greenhouse effect. Exists within a certain range of the earth's surface. After long-term measurement, survey and statistics, the average wind energy density profile is called the basis for utilization within this range, and is usually marked on the map with energy density lines.

Wind energy history

Wind energy The history of human use of wind energy can be traced back to BC, but for thousands of years, wind energy technology has developed slowly and has not attracted enough attention. However, since the world oil crisis in 1973, under the dual pressure of the exigencies of conventional energy sources and the deterioration of the global ecological environment, wind energy as a part of new energy sources has regained considerable development. Wind energy has great potential for development as a pollution-free and renewable new energy source, especially for coastal islands, remote mountainous areas with inconvenient transportation, sparsely populated pastures, and rural areas that are far away from the power grid and are difficult to reach in the near future Frontiers, as a reliable way to solve production and living energy, have very important significance. Even in developed countries, wind energy is gaining increasing attention as an efficient and clean new energy source. For example, the US Department of Energy has investigated that the wind density in Texas and South Dakota alone is sufficient to supply the entire United States. energy used.

Wind energy source

Wind energy Wind is a natural phenomenon on the earth, and it is caused by solar radiant heat. The sun shines on the earth's surface, and the earth's surface is heated differently, creating a temperature difference, which causes the convection of the atmosphere to form wind. Wind energy is the kinetic energy of air. The magnitude of wind energy depends on the wind speed and the density of the air. The global wind energy is about 2.74X109MW, of which the available wind energy is 2X107MW, which is 10 times larger than the total amount of water energy that can be developed and used on the earth. The kinetic energy created by air movement and wind energy. Wind energy is a form of conversion of solar energy. The solar radiation causes uneven heating of the earth's surface, causing uneven pressure distribution in the atmosphere, and the air moves in the horizontal direction to form wind. The formation of wind is the result of air movement.

Overview of Wind Energy Utilization

It is estimated that although only about 2% of the solar energy reaching the earth is converted into wind energy, the total amount is still considerable. The global wind energy is about 130 billion kilowatts, which is 10 times larger than the total amount of water energy that can be developed and used on earth.

The history of human use of wind energy goes back to BC. Ancient Egypt, China, and Babylon were among the first countries in the world to use wind energy. B.C. used wind to lift water, irrigate, polish, and millet rice, and use sails to propel ships forward. Due to the shortage of oil, modern sailing ships have received great attention in modern times. In the Song Dynasty, it was the heyday of the application of windmills in China. At that time, the popular vertical axis windmills were still in use today. In foreign countries, in the 2nd century BC, the ancient Persians used vertical axis windmills to mill rice. In the 10th century, windmills were used by Islamics to lift water. In the 11th century, windmills have been widely used in the Middle East. The windmills spread to Europe in the 13th century, and in the 14th century have become an indispensable prime mover for Europe. In the Netherlands windmills were first used to draw water from lakes and low-humid lands in the Rhine Delta, and later used for oil extraction and sawmilling. It was only because of the advent of steam engines that the number of windmills in Europe dropped sharply.

For thousands of years, wind energy technology has developed slowly and has not attracted enough attention. However, since the world oil crisis in 1973, under the dual pressure of the exigencies of conventional energy sources and the deterioration of the global ecological environment, wind energy has made great progress again as a part of new energy sources. Wind energy has great potential for development as a pollution-free and renewable new energy source, especially for coastal islands, remote mountainous areas with inconvenient transportation, sparsely populated pastures, and rural areas that are far away from the power grid and are difficult to reach in the near future Frontiers, as a reliable way to solve production and living energy, have very important significance. Even in developed countries, wind energy is gaining increasing attention as an efficient and clean new energy source.

The United States began a federal wind energy program as early as 1974. Its contents are mainly: assessing the country's wind energy resources; studying social and environmental issues in the development of wind energy; improving the performance of wind turbines and reducing their costs; mainly researching wind turbines less than 100kw for agricultural and other users; for power companies and industry User designed megawatt wind turbines. The United States has successfully developed 100, 200, 2000,

Wind energy street light 6 types of wind turbines of 2500, 6200 and 7200kw. At present, the United States has become the country with the largest installed capacity of wind turbines in the world, exceeding 2X104MW, and growing at a rate of 10% each year.

Now the world's largest new wind turbine has been built and operated on the island of Hawaii. Its wind turbine blade diameter is 97.5m and weight is 144t. The adjustment of the windward angle of the wind turbine and the operation of the unit are controlled by the computer. · H. According to US Department of Energy statistics, by 1990 US wind power had accounted for 1% of total power generation. In Sweden, the Netherlands, the United Kingdom, Denmark, Germany, Japan, and Spain, corresponding wind power generation plans have been formulated according to the conditions of their respective countries. For example, in Sweden in 1990, the installed capacity of wind turbines reached 350MW and the annual power generation was 1 billion kw · h.

Denmark completed the Jutland Wind Power Station in 1978, with an installed capacity of 2,000 kW, a sweep diameter of three blades of 54 m, and a concrete tower height of 58 m. It is estimated that 10% of the electricity demand in 2005 will come from wind energy. Germany built a wind power station at the mouth of the Elbe in 1980, with an installed capacity of 3000kw. By the end of this century, wind power will also account for 8% of total power generation. The United Kingdom and the British Isles are bordered by the ocean, and the wind energy is very rich. The government also attaches great importance to wind energy development. By 1990, wind power generation had accounted for 2% of the total electricity generation in the United Kingdom.

In Japan, in October 1991, Japan's largest wind power station in Aomori Prefecture of the Kazutsu Strait was put into operation, and five wind turbines could provide electricity to 700 households. China is located in the southeast of the Asian continent and borders the western coast of the Pacific Ocean. The monsoon is strong. Monsoon is a basic feature of China's climate. For example, the winter monsoon lasts 6 months in North China and 7 months in Northeast China. The southeast monsoon extends across the eastern half of China. According to the estimation of the National Meteorological Administration, the total national wind resource reserves are 1.6 billion kw per year, and approximately 160 million kw can be developed in the near future. / s has more than 200 days.

The development of wind turbines in China in the late 1950s was a canopy windmill with various wooden structures. In 1959, there were more than 200,000 wooden windmills in Jiangsu Province alone. By the mid-1960s, wind turbines were mainly developed. After the mid-1970s, the development and utilization of wind energy was included in the Sixth Five-Year Plan national key project, and it has developed rapidly. Since the mid-1980s, China has introduced a number of medium and large wind turbines from Denmark, Belgium, Sweden, the United States, and Germany. Eight demonstration wind farms have been established in Xinjiang, Inner Mongolia's Fengkou and the islands of Shandong, Zhejiang, Fujian, and Guangdong. The installed capacity reached 8MW in 1992. The installed capacity of the wind farm in Dabancheng, Xinjiang has reached 3300kw, which is currently the largest wind farm in the country. By the end of 1990, the irrigated area of wind-lifted water had reached 25,800 mu. In 1997, 100,000 kw of wind power was added. At present, China has developed more than 100 different types and different capacity wind turbines, and has initially formed the wind turbine industry. Nevertheless, compared with developed countries, the development and utilization of wind energy in China is still quite backward. Not only is the development speed slow and the technology is backward, it is far from being formed. In the 21st century, China should increase investment in the development and utilization of wind energy, so that efficient and clean wind energy occupies its place in China's energy structure.

The development of the global wind energy industry has gone through several cycles of prosperity and decline and finally turned around. It will usher in a new round of upsurge.

2013 will undoubtedly be a blow to the global wind energy industry, but there are also some great points.

In the United States, the most prosperous wind energy industry is Texas, which already has an installed capacity of 12,400 megawatts of wind power. The contribution of wind energy to the state's power grid is also increasing.

In 2010, China has surpassed the United States' wind power capacity and became the world's largest wind energy producer. China also plans to add 39 MW of offshore wind power development scale.

In addition, wind power projects are in full swing in other parts of Asia. For example, in Pakistan, the total installed capacity of wind power in 2013 doubled from 2012 to 100 MW. With the implementation of two 50 MW wind energy projects launched in 2014, the total installed capacity will double again. Similarly, Thailand doubled its total installed wind power capacity to 220 MW in 2013. The seven projects completed in the Philippines in 2014 expanded the country's installed wind power capacity to 450 MW, an increase of 13 times.

It can be seen that after the dormancy in 2013 and the storage capacity in 2014, the global wind energy industry will once again usher in a boom of development, and even set a new record. ^[2]

Wind energy utilization form

Wind energy is mainly used to convert the kinetic energy of the atmosphere into other forms of energy. Wind is air that moves horizontally. The movement of air is mainly caused by the different intensity of solar radiation received at various latitudes on the earth. In the equator and low latitudes, the sun has a high angle of altitude, long sunshine hours, strong solar radiation, and the ground and the atmosphere receive more heat and higher temperatures. In high latitudes, the sun has a smaller angle of altitude, shorter sunshine times, and the ground and the atmosphere. The heat is small and the temperature is low. This temperature difference between high latitudes and low latitudes creates a pressure gradient between North and South China, which makes the air move horizontally.

Wind energy monsoon

Theoretically, the wind should blow in the direction of the horizontal pressure gradient, that is, the vertical and isobar lines blow from high pressure to low pressure, but the force of the earth's rotation that deflects the horizontal movement of the air is called the geostrophic deflection force. This force causes the northern hemisphere airflow to Right deflection, the southern hemisphere is deflected to the left, so in addition to the pressure gradient force, the earth's atmospheric motion is also affected by the deflection force of the earth's turn. The true motion of the atmosphere is the combined force of these two forces. In fact, the surface wind is not only dominated by these two forces, but is also greatly affected by the ocean and terrain. Mountains and straits can change the direction of airflow and increase the wind speed. Hills and mountains Friction Ambassador reduced wind speed, but isolated mountain peaks increased wind speed due to high altitude. Therefore, the spatial and temporal distribution of wind direction and wind speed is more complicated. For example, the effect of sea-land differences on airflow movements. In winter, the continent is colder than the ocean, the continental air pressure is higher than the ocean, and the wind blows from the mainland to the ocean. On the contrary, the continent is hotter than the ocean in the summer, and the wind blows from the ocean to the inland. The wind that changes with the seasons is called the monsoon.

Wind energy sea land wind

The so-called sea and land breeze is also daytime. The air current on the continent is heated to expand and rise to the ocean at high altitude. It cools and sinks above the ocean. The air current on the near-surface ocean blows to the mainland to compensate for the continental upwelling. The low-level wind blows from the ocean to Sea breeze

Wind energy At night (winter), the situation is the opposite. Low-level winds blow from the mainland to the ocean, called land winds. In the mountain area due to thermal reasons, the valley is blown to the plain or hillside during the day, and the plain or hillside is blown to the valley bottom at night. The former is called valley wind and the latter is called mountain wind. This is due to the rapid heating of the hillside during the day, the temperature is higher than the temperature of the air at the same height above the valley, the warm air on the slope flows from the hillside to the top of the valley, and the air in the valley along the hillside replenishes the lost air. The wind on the hillside is called valley wind. At night, the mountain slope is cooled by radiation, and its temperature is faster than the air at the same height. The cold air flows down the slope into the valley, which is called mountain wind.

When solar radiation passes through the earth s atmosphere, the atmosphere absorbs about 2 * 10 ^ 16W of energy, a small portion of which is converted into the kinetic energy of the air. Because the tropical subtropical region absorbs more solar radiant energy, it produces atmospheric pressure differences that cause air movement and wind. As for local areas, for example, in high mountains and deep valleys, during the day, the air on the top of the high mountains is heated by sunlight and rises, and the cold air in the deep valleys replaces them. Therefore, the wind blows from the deep valleys to the high mountains. At night, the air on the high mountains dissipates heat quickly, so Blowing from high mountains to deep valleys. Another example is, for example, in coastal areas, the sea breeze is blown to the land due to the temperature difference between the land and the sea during the day; otherwise, it is blown from the land to the sea at night.

Wind energy wind energy

1% to 3% of the solar energy absorbed by the earth is converted into wind energy, the total amount is equivalent to 50 to 100 times that all plants on the earth absorb solar energy into chemical energy through photosynthesis. Wind power can be found at high altitudes, where strong winds sometimes exceed 160 km (100 miles, 160 km / h 100 mph). The energy of these winds is finally released in various thermal energy modes due to friction between the ground and the atmosphere.

Causes of wind: the surface is not heated due to the unevenness of the polar and equatorial rays of the sun; the surface temperature is faster than the sea surface; the effect of the stratosphere in the atmosphere like the ceiling accelerates the convection of the gas; the season / change; the Coriolis effect ; The reflection ratio of the moon formed the wind.

Wind energy can be extracted by a windmill. When the wind blows the wind wheel, the wind drives the wind wheel to rotate around the shaft, so that the wind energy is converted into mechanical energy. The amount of wind energy conversion is directly proportional to the air density, the area swept by the wind wheel, and the square of the wind speed. Air mass flow across the area swept by the wind wheel varies with wind speed and air density. For example, on cool days at 15 ° C (59 ° F), sea-level air density is 1.22 kg per cubic meter (air density decreases when humidity increases). When wind blows through a 100-meter-diameter runner at 8 meters per second, 1,000,000,000 kilograms of air per second can pass through the area swept by the rotor.

The kinetic energy of a given mass is proportional to the square of its velocity. Because the mass flow and the wind speed increase linearly, the effective wind energy for the wind wheel will be proportional to the cube of the wind speed; in this example, the power of the wind blowing wind wheel is about 2.5 million watts.

Because the wind turbine extracts energy, the air slows down, causing it to spread and contain it to some extent near the wind turbine. The German physicist, Albert Betz, determined in 1919 that a wind turbine could extract at most 59% of the energy that would otherwise flow through the cross section of the turbine. Regardless of the design of the turbine, Betz Extreme applies. Recent work is around a theoretical limit of about 30% for propeller type turbines. Actual efficiency ranges from 1% to 20% for propeller type turbines, and is as high as 35% for 3D vertical axis turbines like Darrieus or Gorlov turbines.

2002 at Lee Ranch facility in Colorado Wind changes and the average value for a measured location alone does not indicate that a wind turbine can cause a significant amount of energy there. To estimate wind speed and geology in a particular location, the probability distribution effect is often adapted to the observed data. Different locations will have different wind speed releases. The most frequently used distribution model to shape wind speed and geology is the two-parameter Weibull distribution because it can follow a variety of distribution shapes, from Gauss to exponential. Rayleigh shapes, examples, where plots on the right against actual measured data sets, are a specific form of shape parameter aggregate 2 Weibull effect and reflect the actual distribution of wind speeds in many locations very closely in many locations. Since much electrical energy is generated by high wind speeds, most of the available energy comes from instantaneous high wind speeds. More than half of the available energy is only 15% of the operating time. Therefore, it cannot be like a thermal power plant using fuel, which can adjust the power generation according to the demand for electricity. Because the wind speed is not constant, the power generation of wind power generation throughout the year is not the indicated power generation rate multiplied by all the operating hours (within one year). The actual value and the theoretical value (maximum value) are called capacity factors. A well-installed wind turbine has a capacity factor of 35%. Compared with the turbines of power plants that generally use fuel, a wind turbine marked with 1000kW can generate up to 350kW per year. Short-term output power is difficult Forecast, but the change in annual power generation should be within a few percent. When it comes to storage, such as pumping hydroelectric storage, or other forms of generation being used to "shape" wind power (by guaranteeing continuous delivery credibility), commercial delivery represents an approximately 25% cost increase, Submissive and dynamic business performance.

Wind energy classification

The strength of the wind is usually expressed by the wind power level, and the wind power level can be estimated from the situation that the ground or sea surface object is blown by the wind. The current international wind estimation is based on Pufu wind level. Beaufort is a British admiral who first created the wind classification standard in 1805. First used only at sea and later on land, it has been revised many times and has become the universal wind class today. The empirical relationship between actual wind speed and Pufu wind level is:

V = 0.836 * (B ^ (3/2))

B is Pufu wind level, V is wind speed (unit: meter / second)

Generally speaking, when the wind speed of a wind turbine is 2.5 meters / second, when the wind on the face feels and the leaves are shaking, it has already started to generate electricity. When the wind speed reaches 28 ~ 34 meters / second, the fan will detect The test stops running to reduce the damage to the recipient itself.

For more information about wind energy, please refer to the book "Wind Resources and Microsite Selection: Theoretical Basis and Engineering Application" edited by Zhang Huaiquan.

Advantages and disadvantages of wind energy

Wind energy advantages

Wind energy is a clean energy source.

Wind turbines on the grasslands of Inner Mongolia Wind energy facilities are progressing, mass production reduces costs, and wind power generation costs are lower than other generators at appropriate locations.

Wind energy facilities are mostly non-dimensional facilities, which can protect land and ecology. ^[3]

Wind power is a renewable energy source that is environmentally friendly and clean.

Wind power saves energy and protects the environment.

Wind energy disadvantages

The ecological problem of wind power generation is that it may interfere with birds, such as the grouse of Kansas, USA, which has gradually disappeared after the emergence of windmills. The current solution is offshore power generation, which is more expensive but more efficient.

In some areas, the economics of wind power generation are insufficient: In many areas, wind power is intermittent, and worse is the case in places such as Taiwan during summer and daytime when there is a high demand for electricity and less wind; you must wait for compressed air And other energy storage technology developments. ^[4]

Wind power requires a large amount of land to build a wind power plant in order to produce more energy.

When generating wind power, wind turbines make a lot of noise, so find some open space to build.

Wind power is not yet mature, and there is still considerable room for development.

Wind energy restrictions and disadvantages

There are some limitations and disadvantages of using wind energy

1) The wind speed is unstable and the amount of energy generated is unstable;

2) Geographical restrictions on wind energy use;

3) Low conversion efficiency of wind energy;

4) Wind energy is a new type of energy, and the corresponding equipment is not very mature.

5) Wind power is suitable in places where the terrain is relatively open, with few obstacles, or where the terrain is high.

Wind Energy Economic Prospects

Economic value of wind energy

The cost of using wind to generate electricity has been reduced significantly, even without other external costs. The cost of using wind power to generate electricity in many suitable locations is already lower than that of fuel-powered internal combustion engines. The annual growth rate of wind power generation was about 25% in 2002, and it is now growing rapidly at a rate of 38%. The growth of wind power in the United States in 2003 exceeded the average growth rate of all generators. Since 2004, wind power has become the cheapest of all new energy sources. In 2005, the cost of wind energy dropped to one-fifth of what it was in the 1990s, and with the use of large-wattage generators, the downward trend will continue.

Spain

La Muela, located in Aragon, northeast Spain, has a total area of 143.5 square kilometers. Since 1980, the new mayor has been optimistic about the abundant northeast wind resources and vigorously promoted wind power generation. In the past 20 years, 450 wind turbines (rated capacity of 237MW) have been successively built, bringing rich benefits to the locality. The local government also used this well-planned town welfare to attract many people to move here. In just 5 years, the number of residents has increased from 4,000 to 12,000. La Muela has gone from an unknown wilderness town to a well-known destination for sightseeing and relaxation.

France

In addition, Bouin, northwest of France, was originally famous for the seaweed and sea salt produced by Linhai. From July 1, 2004, 8 wind turbines were officially put into operation. These 8 wind turbines and the three items of seaweed and sea salt have become the sightseeing of this town at the same time. With its characteristics, it attracts a large number of tourists from all over the country and brings in abundant tourism income.

Taiwan

Formation of sea and land breeze The Cape of Good Hope, Houlong Town, Miaoli County, Taiwan, is located on the commanding heights of the coastal hills. In the early years, it was a good place to overlook the Taiwan Strait. In recent years, foreign investors have set up 21 wind turbines with a height of 100 meters in the vicinity, forming a beautiful scenery. In 2003, the company saw the strong northeast monsoon in the winter along the coast of Miaoli, and set up wind turbines in Houlong, Zhunan and other places. Among them, Houlong established Dapeng Wind Power Plant, built 21 wind turbines, and had a total power generation capacity. At 42,000 yen, it is currently the largest wind farm in Taiwan. After completion and opening in June 2006, it has become a new tourist attraction, attracting many people to visit. The Cape of Good Hope is located at the top of Bantianyu. You can see 4, 5 wind turbines to the north, and 3 or 4 wind turbines to the south. The Shanghai Railway runs down the mountain and faces the wide Taiwan Strait. The scenery is quite fascinating. Become one of the best spots to appreciate wind turbines.

Main wind energy technologies

Horizontal axis wind turbine technology. Because the horizontal axis wind turbine has the advantages of high wind energy conversion efficiency and short rotating shaft, it is more economical on large wind turbines, making it a mainstream model for the development of wind power in the world and occupying more than 95% of the market share. The vertical axis wind turbines developed during the same period, due to problems such as long shafts, low wind energy conversion efficiency, and difficulty in starting, stopping, and pitching, have a small market share and a limited number of applications, but due to its full wind direction and wind speed And the generator can be placed under the wind wheel (or the ground) and other advantages. In recent years, relevant international research and development have also continued and made some progress.

The single unit capacity of wind turbines continues to increase, and the utilization efficiency continues to increase. In recent years, the single unit capacity of wind turbines in the world's wind power market has continued to increase. The mainstream models in the world have increased from 500 to 1,000 kilowatts in 2000 to 2 to 3 megawatts in 2004. The largest single unit capacity of wind turbines currently operating in the world It is 5 MW and has started the design and development of 10 MW-class fans.

Offshore wind power technology has become the development direction. At present, the cost division of offshore wind farms is 1.7 to 2 times that of onshore wind farms, and the amount of power generation is 1.4 times that of onshore wind farms, so its economic efficiency is still not as good as that of onshore wind farms. With the continuous development of technology, the cost of offshore wind power Will continue to decline, and its economy will gradually become prominent.

Pitch shifting and power adjustment technologies have been widely adopted. Due to the advantages of smooth, safe and efficient load control, the variable pitch power adjustment method has been widely adopted in large wind turbines this year.

Direct-drive, full-power converter technology has developed rapidly. The straight-through method without gear box can effectively reduce the unit failure caused by the gear box problem, can effectively improve the system's operating reliability and life, and reduce maintenance costs. Therefore, it has been favored by the market and its market share is constantly expanding.

New vertical axis wind turbine. It adopts a completely different design concept and uses new structures and materials to achieve excellent performance such as breeze start, no noise, resistance to typhoons above level 12, and no influence from wind direction. It can be widely used in villas, multi-storey and high-rise buildings, Small and medium applications such as street lamps. The wind-solar complementary power generation system based on it has the advantages of stable power output, high economy, and small impact on the environment. It also solves the impact of solar energy development on the power grid. ^[5]

Wind Energy Encouragement Policy

Since the generation of wind power in the 1980s has attracted attention from European and American countries, the global wind power generation has grown rapidly at an alarming rate of 30% each year. The renewable energy promotion systems of countries around the world can be divided into:

Fixed-price systems: The government sets the preferential purchase price for renewable energy, and the market determines the quantity. Its main methods include:

1.Equipment subsidies: Denmark, Germany, and Spain all adopted equipment subsidies in the early stages of wind power development.

2. Fixed feed-in tariffs: Germany, Denmark and Spain

3. Fixed-premium systems

4. Tax credits: United States

Fixed quantity systems: Also known as renewable-quota system (Renewable Portfolio Standard in the United States), the government regulates the amount of renewable energy generation, and the market determines the price. Its main methods include:

1. Tendering systems: UK, Ireland and France

2. Tradable green certificate systems: UK, Sweden, Belgium, Italy and Japan

The purpose of the two promotion systems is to form a protection market, to make renewable energy more investment-efficient in the electricity market through the power of the government, and its ultimate purpose is to improve technology and reduce costs, so as to ensure that renewable energy can be used in free markets in the future Traditional energy competition.

Growth Trends in Wind Energy Countries

The latest research report released by Deutsche Bank predicts that the global wind power development is entering a stage of rapid expansion, and the wind energy industry will maintain a 20% annual growth rate. By 2015, the total output value of the industry will increase to five times the current level.

From the current technical maturity and economic feasibility, wind energy is the most competitive. In the medium term, the prospects of the global wind energy industry are quite optimistic. The renewable energy encouragement policies issued by governments in various countries will provide rapid progress for the industry in the next few years.

Development of offshore wind energy Development provides great momentum.

It is expected that Asia and the Americas will become the regions with the greatest growth potential in the next few years. China's wind power installed capacity will achieve a rapid growth of 30% per year, and India's wind energy will maintain a growth rate of 23% per year. India encourages large enterprises to invest in wind power and implement preferential policies to encourage wind energy manufacturing bases. India has now become the world's fifth largest wind power producer. In the United States, with the introduction of new energy policies, the wind energy industry will achieve an extraordinary development of 25% each year. In Europe, Germany's wind power development is in a leading position, among which the wind power equipment manufacturing industry has replaced automobile manufacturing and shipbuilding. In the recent long-term wind power development plan formulated by Germany, it is pointed out that by 2025, wind power must achieve 25% of the total power consumption, and by 2050, the goal of 50% of the total power consumption.

The European countries that have been leading in the wind energy sector have slowed down, and are expected to maintain a 15% annual growth rate by 2015. Among the earliest countries that developed wind energy, such as Germany and Denmark, the construction of onshore wind farms is basically saturated, and the main development direction for the next step is offshore wind farms and equipment upgrades. Countries such as Britain and France still have great potential, and the growth rate will be higher than the average level of 15%.

At present, Germany is still the country with the most advanced wind power technology in the world. German wind power installed capacity accounts for 28% of the world's total, while German wind power equipment production accounts for 37% of the global market. With the domestic market becoming saturated, exports have become a major growth point for German wind power equipment companies.

The German government will support the industry to maintain its leading position through technological innovation through price subsidies and other means. This year, Germany will amend the Renewable Energy Law again to increase the subsidy price for offshore wind farms from 9.1 Euro cents per kilowatt hour to 14 Euro cents.

In China, in 2006, eight departments including the National Development and Reform Commission, the Ministry of Science and Technology, and the Ministry of Finance jointly issued the "Opinions on the Implementation of Ten Key Energy-saving Projects during the" Eleventh Five-Year Plan ". According to the standards of ten key energy-saving projects and the government's policy guidance to support environmental protection and energy-saving industries, energy-saving renovation and renovation of industrial equipment, energy conservation in buildings, fuel-saving and oil substitution, and renewable energy will develop rapidly in the future.

At present, according to the industry magazine "Wind Energy World", the hottest renewable energy in the Chinese market, such as wind energy, solar energy and other industries. Wind energy resources are more renewable, inexhaustible, pollution-free, etc., and have high comprehensive social benefits. Moreover, wind power technology development is the most mature and the lowest cost. According to the "11th Five-Year Plan" national wind power development plan, the national wind power installed capacity will reach 5 million kilowatts in 2010, and the national wind power installed capacity will reach 30 million kilowatts in 2020. At the end of 2006, there were about 91 wind farms in the country, with a total installed capacity of only 2.6 million kilowatts. It can be seen that the wind turbine market has attractive prospects and broad development space.

Wind Energy in China

Wind energy reserves and distribution

China is located in the eastern part of the Asian continent, borders the Pacific Ocean, has a strong monsoon, and there are many mountain systems in the inland. The terrain is complicated. In addition, the Qinghai-Tibet Plateau towers over the western part of our country. The winter monsoon comes from inland in middle and high latitudes such as Siberia and Mongolia, where the air is very cold and dry. The cold air accumulates to a certain degree. Under the guidance of favorable high-altitude circulation, the southward wave is commonly known as the cold wave. Under the influence, the formation of cold and dry northwest winds hit all provinces (municipalities and autonomous regions) in northern China. There are always strong cold air that cools down many times each winter in winter, which mainly affects northwest, northeast and north China, and disappears only at the turn of spring and summer the following year. The summer monsoon is the southeast wind from the Pacific Ocean, the Indian Ocean and the South China Sea. The southeast monsoon affects the eastern half of China, while the southwest monsoon affects the southwestern provinces and the southern coast, but the wind speed is far less than that of the southeast monsoon. Tropical storms are air vortices formed on the tropical oceans in the western Pacific and the South China Sea. They are extremely destructive ocean storms. They frequently invade our country every summer and autumn, landing on the coast of the South China Sea and the southeast coast of China. Tropical storms can also be north of Shanghai. Landed, but rarely. ^[6]

Jiuquan City has now built China's first 10-kilowatt-scale super large wind power base, which is the most important wind power base in China.

The terrain of the Qinghai-Tibet Plateau is high and wide, with southerly winds prevailing in the southeast in winter and northeasterly winds in the northeast, and westerly winds in other areas. In summer, the Tanggula Mountains are bounded by the southeast winds, and the north to east to northeast winds. China has a vast territory, with a total land area of more than 20,000 kilometers and a coastline of more than 18,000 kilometers. There are more than 5,000 islands in the marginal sea and abundant wind energy resources. The annual average wind speed of existing wind farm sites in China has reached more than 6 meters per second. Generally speaking, wind farm wind conditions can be divided into three categories: annual average wind speeds above 6 meters / second are better; 7 meters / second is better; 8 meters / second is better. According to the wind speed frequency curve and the unit power curve, the annual power generation of the unit under the international standard atmospheric state can be estimated. China is equivalent to an area of more than 6 meters per second, and it is limited to a few areas nationwide. In terms of inland, it only accounts for about 1/100 of the country's total area, mainly distributed on the southeast coast and its islands between the Yangtze River and Nan'ao Island. These areas are China's largest wind energy resource areas and areas rich in wind energy resources, including Shandong and Liaodong. Peninsula, the coast of the Yellow Sea, the coast of the South China Sea to the west of Nan'ao Island, Hainan Island and the islands of the South China Sea, Inner Mongolia from the north of the Yinshan Mountains to the north of the Greater Xing'an Mountains, Xinjiang Dabancheng, Alashankou, Hexi Corridor, the lower Songhua River, and the north of Zhangjiakou As well as high mountain passes and peaks.

According to the statistics and calculations of some wind energy data of the National Meteorological Observatory, China's wind energy zoning and the percentage of the country's area are shown in the table below.

index	Rich area	Richer area	Available area	Poor area
Annual effective wind energy density (W / )	> 200	150-200	50-150	<50
Cumulative hours per year 3m / s (h)	> 5000	4000-5000	2000-4000	<2000
Cumulative hours per year 6m / s (h)	> 2200	1500-2200	350-1500	<350
Percentage of national area (%)	8	18	50	twenty four

Table China's Wind Energy Division and Percentage of National Area

About 2% of the solar radiation s energy is converted to wind energy on the earth s surface. Wind energy is a part of the natural energy on the earth. The estimation of China s wind energy potential is as follows: The total amount of wind energy theoretical development (R) is 3.226 billion kilowatts in the country, which can be actually developed. The utilization (R ') is estimated based on 1/10 of the total, taking into account that the actual swept area of the wind wheel is 0.785 times the square area of the calculated airflow. (Square meters)], so the actual developable amount is: R '= 0.785R ÷ 10 = 2.53 (100 million kilowatts).

China is a major energy importer, and the use of renewable energy is a top priority, especially in the vast rural areas where China has abundant wind resources. The Chinese government should increase subsidies for the purchase of wind power equipment, including subsidies for solar panel roofs. Electricity is half self-sufficient, which can save more than 2 billion kWh of electricity each year. It is hoped that the state will increase its efforts in this regard.

Wind Energy Development Potential

^[4]

The total reserves of wind energy resources at a height of 10m in China are 3.226 billion kW, of which the actual wind energy resources that can be developed and utilized are 253 million kW.

The southeast coast and the nearby islands are rich in wind energy resources. The contours of effective wind energy density greater than or equal to 200W / are parallel to the coastline. The effective wind energy density of coastal islands is greater than 300W / , and the annual wind speed is greater than or equal to 3m / s. The number of hours is about 7000-8000h, and the number of hours greater than or equal to 6m / s is 4000h.

Jiuquan City, northern Xinjiang, and Inner Mongolia are also regions with abundant wind energy resources in China. The effective wind energy density is 200-300W / . The annual wind speed is greater than or equal to 3m / s for more than 5000h. The annual wind speed is greater than or equal to 6m /. The hours of s is more than 3000h.

Heilongjiang, eastern Jilin, northern Hebei, and the Liaodong Peninsula also have better wind energy resources. The effective wind energy density is more than 200W / . The annual wind speed is greater than or equal to 3m / s for 5000h, and the annual wind speed is greater than or equal to 6m. The hour of / s is 3000h.

The effective wind energy density in the northern part of the Qinghai-Tibet Plateau is between 150 and 200 W / . The annual number of hours when the wind speed is 3 m / s or more is 4000-5000 h, and the annual number of hours when the wind speed is 6 m / s or more is 3000 h. The altitude is high and the air density is low, so the effective wind energy density is also low.

Yunnan, Guizhou, Sichuan, Gansu (except Jiuquan), southern Shaanxi, Henan, western Hunan, Fujian, Guangdong, Guangxi mountainous regions, Tarim Basin in Xinjiang, and the Yarlung Zangbo River in Tibet are areas with poor wind energy resources, with an effective wind energy density of 50W / Below, the number of hours with a wind speed of 3m / s or more during the year is below 2000h, and the number of hours with a wind speed of 6m / s or more during the year is below 150h, and the wind energy potential is very low. ^[7]