A review on scale and siting of wind farms in China

Authors


Abstract

Using a wind power information system, which is based on the geographic information system (GIS), this paper presents a statistical analysis of built and approved wind farms to the end of 2008. The average capacity of wind turbine generators (WTGs) and the scale of wind farms are investigated. The geographical distribution of wind farms and the main factors affecting wind farm siting are analysed. The results show: (i) The average capacity of WTGs is increasing; MW scale WTGs have become the mainstream product in the China market. (ii) Because of the national wind project approval policy, most of the wind farms have installed capacities of just under 50 MW. (iii) When siting a wind farm, wind resource is still the predominant factor being considered, while grid connection is still the main constraint in this stage. (iv) Concerning land use, among the wind farms built by 2008, 40% use grasslands, 31% use agricultural land, 17% use desert or bare lands, while 12% use farmlands. (v) Statistics show 88.6% of the built wind farms have elevation change of less than 300 m, and 90% of the built wind farms have GIS slopes of less than 10°. (vi) The geographical distribution of wind farms reveals a highly concentrated deployment tendency, 58.7% of all the newly built wind farms in 2008 are within 10 km of existing wind farms. Copyright © 2010 John Wiley & Sons, Ltd.

1. Introduction

With the development of wind energy technologies and the decrease of wind power production cost, wind power has rapidly developed around the world in recent years. In China (except Hong Kong, Macao and Taiwan regions, the same below), since 2006, the cumulative wind power capacity has increased by more than 100% annually, with more than 11,600 units of total installed wind turbine generators (WTGs) and 12,000 MW cumulative wind power installed capacity by 2008.1

With the heavy dependence on local wind energy resource and grid connection, it is of decisive importance for a feasible wind power project to choose a reasonable project scale and a suitable location. At the same time, wind farm siting usually needs to go through a complicated process, which includes the comprehensive evaluation of many related factors,2–4 such as wind energy policy, economical feasibility, wind resources, etc. In order to facilitate wind farm siting, some decision support systems based on geographic information system (GIS) have been developed elsewhere,5,6 but in China, these types of systems are still developing.

Under the support of the National High-Tech R&D Program (863 Program), Sun Yat-sen University (SYSU) is developing a suit of software for wind farm siting. As a part of the research work, a GIS-based wind power information system is established. It incorporates the latest development of wind energy in China7 and includes the databases of wind energy resources, wind farms, and wind power related information, such as land use and transportation conditions. Some information comes from published reports, and some comes from relevant research, such as wind energy resource, which is derived from MM5 (The Fifth-Generation NCAR/Penn State Mesoscale Model)8 numerical modeling. The databases contain information on annual electricity output of some wind farms, but don't contain any grid-related information. The information system will be shared with the registered users.

Based on the information system, this paper presents a statistical analysis of the already built and approved wind power projects by 2008, with the focus on wind farm siting and wind power project scale. The average capacity of installed WTGs and the scale of individual wind farms are investigated. Geographical distribution of wind farms is displayed and the factors in wind farm siting are discussed. Also, the paper analyses the tendency of wind farm siting.

2. Average capacity of WTGs

Generally speaking, if conditions permit, a wind power project with large scale WTGs not only saves land, but also effectively reduces the cost of per unit KW installation, increasing the economic benefits of wind power project.

Table I shows the average capacity of WTGs for built wind farms in recent years. The average capacity of newly installed WTGs is 1.05 MW in 2007 and it reached 1.21 MW in 2008. Furthermore, for the recently approved 199 wind power projects in 2008, with 11,638 MW total capacity and 8637 units of WTGs, the average capacity of WTGs is up to 1.34 MW. Statistics show that the average capacity of WTGs in China is increasing year by year; MW scale WTGs have become the mainstream product in the market.

Table I.  Average capacity of WTGs for built wind farms.
Year200620072008
  1. WTGs = wind turbine generators.

Number of WTGsAdded144230905236
Cumulative3312640211638
Installed capacity (MW)Added1328.753254.206320.85
Cumulative2599.165853.3612174.21
Average capacity of WTGs (MW)Added0.921.051.21
Cumulative0.780.911.05

At the same time, the average capacity of WTGs also differs from one region to another. Table II lists the average capacity of WTGs for 11 regions with total installed wind power capacity of more than 300 MW by the end of 2008. It shows that in some northern parts of China, such as Inner Mongolia Autonomous Region, the average capacity of WTGs is larger due to abundant wind resources and relatively flat terrain; while in some southern parts, such as in the province of Guangdong, the average capacity of WTGs is relatively small mainly because of the complex terrain. In addition, in the Xinjiang Autonomous Region, where wind power has been developed for a long time, the average total capacity of all installed WTGs is relatively small. This is because the scale of WTGs has been increasing over time.

Table II.  Average capacity of WTGs for typical regions.
RegionNumber of WTGsInstalled capacity (MW)Average capacity of WTGs (MW)
  1. WTGs = wind turbine generators.

Inner Mongolia35053761.491.07
Liaoning11551189.161.03
Jilin10201157.911.14
Hebei10741101.551.03
Heilongjiang 772833.51.08
Jiangsu 455646.751.42
Xinjiang 778635.110.82
Gansu 657607.60.92
Shandong 489579.951.19
Ningxia 411393.20.96
Guangdong 532349.940.66

3. Scale of wind farm

The scale of a single wind farm, i.e. the installation capacity, should be determined by many factors, including available funds from the investment enterprise, available land lots for construction, local wind energy resources, etc. Generally speaking, in order to achieve the economies of scale, wind power projects with larger capacities are preferable.

Considering the built and approved wind farms by the end of 2008, Table III shows the statistics of the installed capacity. The statistics show that the majority of wind farms in China have installed capacities of less than 50 MW, a large part of which are between 49 and 50 MW. For newly approved wind power projects, the proportions are as high as 91.5 and 74.9%, respectively. This phenomenon is related to wind project approval policy, which stipulates that wind projects with a capacity greater than 50 MW must be approved by the state government, while the rest only need to obtain the approval of the local provincial government. Obtaining the approval of the state government is much more complicated and does not have any advantage in wind farm construction, including integrating into the grid. So, under such policy, investment enterprises always search for the largest possible project capacity with the most convenient approval process.

Table III.  Distribution of wind farm capacity.
Capacity (C) (MW)Built wind farmsApproved wind farms
NumberPercentage (%)NumberPercentage (%)
C < 4912552.3 3316.6
49 ≤ C < 50 4619.214974.9
50 ≤ C < 100 4117.2 1 0.5
100 ≤ C < 200 2410.0 10 5.0
C ≥ 200 3 1.3 6 3.0

In addition, the proportion of large-scale wind power projects with capacities of 200 MW and above is increasing. For the newly approved projects in 2008, 3% are large-scale wind farms. It is the result of both the wind power concession policy and the national development plan of large-scale wind power plants.

4. Wind farm siting

4.1. Wind resource

Wind farm siting should consider many factors, such as wind energy resource, land use, grid connection and, etc. Obviously, wind energy resource, which determines the final electric power generation, is the top priority for consideration. According to the guidelines9,10 for wind resource assessment, a suitable wind farm site should have wind power density of 150–200 W m−2 or average annual wind speed of 5.6 m s−1 at a height of 10 m above ground.

Research11 shows wind energy resource in China is rich in two strip-shaped regions with annual wind power density of above 200 W m−2 at 10 m above ground: one goes along the southeast coast and nearby islands, and includes a 10-km width coastal area of the provinces of Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong, Guangxi and Hainan; another is the ‘three-north’ region (i.e. northeast China, north China and northwest China), and includes a 200-km wide area of the provinces of Heilongjiang, Liaoning, Jilin, Hebei, Shanxi, Shannxi, Gansu, Qinghai, and the Autonomous Regions of Ningxia, Inner Mongolia, Tibet and Xinjiang.

Figures 1 and 2 are the geographical distribution maps of built and approved wind farms, respectively, by 2008. From the figures, we can see that wind farms in China are concentrated in those two regions with rich wind resource, especially the ‘three-north’ region.

Figure 1.

Geographical distribution of built wind farms.

Figure 2.

Geographical distribution of proved wind farms.

4.2. Grid connection

Grid connection is very important for the operation of a wind farm. At the present stage, grid connection is still the main constraint for wind power development. There are two main reasons: (i) Due to the rapid development of wind power, grid construction lags behind in some provinces, especially in north China, such as in the Inner Mongolia Autonomous Regions. (ii) Wind power is not the preferred choice for grid operating companies for both economical and technological reasons.

Report from Xinhuanet (the online service of the Xinhua News Agency)12 revealed that by the end of 2008, among 10,000 MW wind power installations ready for grid connection, only 8000 MW installations were on grid; about 2000 MW of capacity was lost mainly because there was no grid connection. At the same time, grid availability is also a problem in some areas due to the low electrical load. The recent survey report of wind power development in China13 says that during the spring festival of 2009, in order to ensure the heat supply for residents, all wind farms in the Inner Mongolia Autonomous Regions and some wind farms in the Jilin province were required to stop running simply because local electrical load is low and many power plants are combined heat and power (CHP) plants.

Fortunately, the situation is becoming better. According to the published data of the China Electricity Council,14 installed wind power capacity being incorporated into the grid has reached 16,130 MW, accounting for 76% of the total installed and ready for grid connection wind power capacity by 2009, which is a notable increase compared with 58% by 2008. It is believed that two reasons contribute to the increase.

  • National Development and Reform Commission issued ‘Notice for improving wind electricity price policy’ in July 2009. The notice points out that according to wind energy resources and engineering construction conditions, the country can be divided into four wind energy resource areas with the corresponding benchmark electricity price of 0.51, 0.54, 0.58 and 0.61 Chinese Yuan per kWh, respectively. Under such price policy, grid corporations become more active in purchasing power from wind farms. This price is still high compared with the sale price of bulk electricity, which is about 0.61 Chinese Yuan in Guangzhou, for example.

  • Also, in July 2009, the State Grid Corporation of China issued the revised version of technical requirements for wind power connection. It includes many technical requirements such as low voltage ride through of wind turbines. With the ongoing improvement of grid connection requirements, more and more wind power will be connected to grid.

4.3. Land use

A piece of available land is the precondition for wind farm construction. The mandatory governmental regulation15 requires that wind farm construction should be in line with conservation principles and the intensive use of land, to make use of unused land, and use as little arable land as possible. Also obviously, in order to be approved by the government, wind farm siting should avoid the dedicated areas such as natural reserves, exclusive economic zones, places of historical interests, etc.

The statistics of 238 built wind farm made by SYSU shows that according to the current land use classification,16 40% of the wind farms use grasslands, 31% of the wind farms use agricultural land, 17% of the wind farms use desert or bare lands, while 12% of the wind farms use arable lands.

Table IV shows the land use of some typical areas for wind farm construction. From the table, we can see that in the Inner Mongolia Autonomous Regions, 80% of the wind farms use grasslands, while in the Guangdong province, 70% of the wind farms use agricultural land, especially in the coastal areas where most of the wind farms are constructed in scrublands.

Table IV.  Land uses of wind farms for typical regions.
Land useRegion (%)
Inner MongoliaLiaoningHebeiGuangdong
Desert or bare land143.55.515
Agricultural land1.5655.570
Grassland833.57215
Arable land1.52817 0

4.4. Terrain complexity

The effects of terrain condition on wind farm siting are complex and many. Terrain condition can affect wind energy resource, ease of construction and economic benefits of wind power project. Complex terrain condition will bring difficulties for equipment transportation, site construction and will inevitably increase the project investment. At the same time, complex terrain condition will limit the scale of wind power project, which will make the project lose economies of scale.

There are some descriptive guidelines17 concerning terrain condition in wind farm siting. For example, the terrain condition for wind farm sites should be simple, facilitating the transportation, installation and management of equipments.

Usually, terrain condition can be represented by relief amplitude and GIS slope (slope calculated by GIS software). According to the statistics made by SYSU, relief amplitudes and slopes of the built wind farms in China are shown in Tables V and VI. From the tables, we can see that 88.6% of the wind farms have relief amplitudes of less than 300 m and 90% of the wind farms have GIS slopes of less than 10°.

Table V.  Geographic information system (GIS) slopes of built wind farms.
GIS slope (°)Number of wind farmsPercentage (%)
0∼517774.4
5∼10 3715.6
10∼15 13 5.4
15∼20 7 2.9
>20 4 1.7
Table VI.  Relief amplitudes of built wind farms.
Relief amplitudes (m)Number of wind farmsPercentage (%)
0∼10013155.0
100∼200 5723.9
200∼300 23 9.7
300∼400 13 5.5
400∼600 8 3.4
>600 6 2.5

4.5. Transportation and other factors

The sites with abundant wind energy resources are usually in remote areas with poor transportation conditions. Concerning transportation, there are also some descriptive guidelines17 that should be considered for wind farm siting such as transportation accessibility and ease of equipment transportation, which would reduce road investments. In China, transportation is usually not a question for wind farm construction because transportation is rapidly improving in China, providing accessibility to most of the areas. Also, the cost due to transportation is relatively low compared with whole project investment.

In China, environmental constraints should also be considered, and wind power project should have environmental impact assessment before their construction. The emphases are on soil and water conservation assessment and countermeasures. Acoustic and visual intrusions are not considered very seriously in China, mainly because the wind farm sites are usually very far away from residences.

5. Highly concentrated deployment tendency

Siting near the operating wind farm can effectively employ existing data, facilities and other conditions, including observed wind data, actual wind farm operating data, transportation facilities, grid condition, etc. Because many wind farms belong to the same state-owned large-scale corporation, some operating data are shareable to some extent though they may be confidential outside the organization. In addition, in those areas, the local people's awareness and acceptance of wind power is high, and local governments' enthusiasm for investment in wind power is also relatively high.

As the amount of available land with sound development conditions for onshore wind farm has declined rapidly in recent years, wind farm siting has shown a highly concentrated deployment tendency. A similar research result was also reported.18 In the 143 newly built wind farms in 2008, 84 were built within 10 km of existing wind farms, accounting for 58.7% of all the newly built wind farms in that year.

The highly concentrated deployment tendency is particularly obvious in the regions with abundant wind energy resource. Figure 3 shows the distribution of wind farms on Nanao Island of Guangdong province. By the end of 2006, two wind farms (Dalankou, Niutouling) were operating on Nanao Island. In 2007, another two wind farms were established in Xiongzhenguang and Yunxing Village, both of which are within 10 km from the existing wind farms. The same phenomenon also appears in many areas of Inner Mongolia Autonomous Regions.

Figure 3.

The distribution of wind farms on Nanao island.

6. Conclusion

This paper uses statistics of wind farms in China to analyse the features and trends of average capacity of WTGs, scale of wind farms and wind farm siting. The following conclusions have been drawn:

  • Driven by maturing technologies and a rapidly growing market, the average capacity of WTGs is increasing; MW scale WTGs have become the mainstream product. Meanwhile, the average capacity of WTGs exhibits an obvious regional difference.

  • Under the existing wind power project approval policy, the majority of wind farms in China have installed capacities of just under 50 MW. Meanwhile, due to the implementation of wind power concession projects and the construction of large-scale wind power, the number of large-scale wind farms with 200 MW and above is also increasing.

  • Wind energy resource is the predominant condition for wind farm siting. Most of built and approved wind farms are located in regions with rich wind resources. However, in some areas with other limitations, wind power investors should take other conditions into account, such as grid connectivity, which is still the main constraint for wind power development at this time.

  • Concerning land use, among the built wind farms by 2008, 40% use grasslands, 31% use agricultural land, 17% use desert or bare lands, while 12% use farmlands.

  • Statistics show that 88.6% of the built wind farms have relief amplitudes of less than 300 m and 90% of the built wind farms have GIS slopes of less than 10°.

  • As the available land with sound development conditions for onshore wind farms has declined in recent years, wind farm siting shows a highly concentrated deployment tendency. Of all the newly built wind farms in 2008, 58.7% are within 10 km from existing wind farms.

Acknowledgements

The research in this paper is a part of the project ‘wind farm siting and software development’, which has been supported by funding from National High-Tech R&D Program (863 Program), Grant no. 2008AA05Z414.

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