| | The development of wind energy is being supported by the Chilean government through wind potential analyses, among others. Despite of the large existing project pipeline, such support is of very high importance, due to the fact that numerous projects have been planned at sites, which under current framework conditions hardly allow for profitable operation. Even the existing wind farms (with exception of small projects in the south of the country) have so far only reached capacity factors between 17 and 24 % in 2010. A tool that stands out is the so-called „Explorador Eólico y Solar“, which is a map of wind- and solar potential with a resolution of 1 km<sup>2</sup>, covering Chile from the extreme North to south of Puerto Montt. This map was elaborated using the Weather Research and Forecasting Model (WRF) and uses meteorological data from global weather models as input-parameters. The „Explorador“ is publicly available on the internet-pages of the Chilean Energy Ministry (www.minenergia.cl) and can also be downloaded for use with Google Earth. Comparisons with actual measurements show that the simulation has a slight tendency to underestimate the absolute wind potential, but it represents very well the differences in wind potential between different sites, and hence, can be used as a reliable tool when searching for locations for wind project development.<br/>In fact, the “Explorador” served as the basis for an ongoing cooperation-project between the Chilean government and the German International Cooperation – GIZ (formerly German Technical Cooperation – GTZ), which is being financed by the International Climate Initiative of Germany´s Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. The project´s aim is to identify state-owned lands which are suitable for wind power development, and to make these available for private investors. The search for suitable lands focuses on the Atacama Desert in the Antofagasta-Region in northern Chile where a large share of the land is owned by the state, and due to the numerous copper-mines, excellent transport- and electricity-infrastructure is available. And there is lots of wind.<br/>Using the wind-potential map 20 locations were identified where since August 2009 wind measurements are being carried out using 20m-towers <span style="color: rgb(255, 0, 0)">(Picture 1). </span>Some interesting findings have been made so far:<br/>The wind roses usually have two clearly pronounced main wind directions, which alternate during the course of the day (<span style="color: rgb(255, 0, 0)">Picture 2</span>). This behavior is also reflected in the wind speed frequency distributions, which usually have two peaks, and therefore cannot be represented by a regular Weibull-Distribution (<span style="color: rgb(255, 0, 0)">Picture 3</span>). At some locations these wind characteristics are so extreme, that the average wind speed as a criterion for a site´s quality looses meaning. A good example comes from the measurements carried out at a location near the city of Antofagasta where the average wind speed is rather low with 6,64 m/s at 20 m height, putting this location in the lower half of all 20 sites. But in terms of power in the wind, this location achieves the second-highest value of all 20 sites with 660 W/m<sup>2</sup>. This can be explained by looking at the frequency distribution (<span style="color: rgb(255, 0, 0)">Picture 4</span>): more than 50 % of the measured values lie below 4 m/s, strongly reducing the average wind speed. But more than 30 % of the remaining measurement values are clearly above 10 m/s (the second maximum of the distribution lies at 17 m/s). Since wind speed enters the calculation of power with the cube, these high wind speeds very strongly increase the average power in the wind. Unfortunately, due to the limitation of power output at high wind speeds, a wind farm at this site would achieve a capacity factor of „only“ about 30 %.<br/><span style="color: rgb(255, 0, 0)">Table 2</span> summarizes the measurement results for the period between November 2009 and October 2010 for 14 measurement masts (6 masts have been relocated, no simultaneous year of data is yet available), and compares wind speeds, power in the wind and estimated capacity factors. The calculation of the capacity factors is done using an IEA class I turbine with 2 MW of installed capacity. In lack of further information about wind speeds at greater height for all sites, it was assumed that the wind speed at hub-height is equal to the wind speed at 20 m above ground. Furthermore, a total of 14,3 % losses were assumed (non-availability of the turbines, wake-effects, etc.).<br/>Based on the results of these wind measurements, as well as taking into account other criteria (topography, grid-proximity, accessibility, mining activities, etc.) the two most promising areas were identified, and measurement towers with a height of 80 m were installed. These are the sites B3.1 (Sierra Gorda) and D5 (Taltal). <span style="color: rgb(255, 0, 0)">Tables 3 and 4</span> show the wind speeds registered in the six months of operation from May to October 2010 and the estimated yearly values deduced by MCP-analysis with the data from the nearby 20m-towers. One can observe that the average wind speed at Sierra Gorda does not continuously increase with height, but actually reaches its maximum value at about 40 m above ground, and decreases further up (<span style="color: rgb(255, 0, 0)">Picture 5</span>). This inversion of the vertical wind profile can only be observed with the nightly katabatic winds. At daytime the vertical wind profile is positive. However, since the night-time winds are clearly stronger, this pattern can also be observed in the overall average values. The vertical wind profile will surely influence the selection of size and type of wind turbine to be installed, in order to maximize energy yield at this location. | | The development of wind energy is being supported by the Chilean government through wind potential analyses, among others. Despite of the large existing project pipeline, such support is of very high importance, due to the fact that numerous projects have been planned at sites, which under current framework conditions hardly allow for profitable operation. Even the existing wind farms (with exception of small projects in the south of the country) have so far only reached capacity factors between 17 and 24 % in 2010. A tool that stands out is the so-called „Explorador Eólico y Solar“, which is a map of wind- and solar potential with a resolution of 1 km<sup>2</sup>, covering Chile from the extreme North to south of Puerto Montt. This map was elaborated using the Weather Research and Forecasting Model (WRF) and uses meteorological data from global weather models as input-parameters. The „Explorador“ is publicly available on the internet-pages of the Chilean Energy Ministry (www.minenergia.cl) and can also be downloaded for use with Google Earth. Comparisons with actual measurements show that the simulation has a slight tendency to underestimate the absolute wind potential, but it represents very well the differences in wind potential between different sites, and hence, can be used as a reliable tool when searching for locations for wind project development.<br/>In fact, the “Explorador” served as the basis for an ongoing cooperation-project between the Chilean government and the German International Cooperation – GIZ (formerly German Technical Cooperation – GTZ), which is being financed by the International Climate Initiative of Germany´s Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. The project´s aim is to identify state-owned lands which are suitable for wind power development, and to make these available for private investors. The search for suitable lands focuses on the Atacama Desert in the Antofagasta-Region in northern Chile where a large share of the land is owned by the state, and due to the numerous copper-mines, excellent transport- and electricity-infrastructure is available. And there is lots of wind.<br/>Using the wind-potential map 20 locations were identified where since August 2009 wind measurements are being carried out using 20m-towers <span style="color: rgb(255, 0, 0)">(Picture 1). </span>Some interesting findings have been made so far:<br/>The wind roses usually have two clearly pronounced main wind directions, which alternate during the course of the day (<span style="color: rgb(255, 0, 0)">Picture 2</span>). This behavior is also reflected in the wind speed frequency distributions, which usually have two peaks, and therefore cannot be represented by a regular Weibull-Distribution (<span style="color: rgb(255, 0, 0)">Picture 3</span>). At some locations these wind characteristics are so extreme, that the average wind speed as a criterion for a site´s quality looses meaning. A good example comes from the measurements carried out at a location near the city of Antofagasta where the average wind speed is rather low with 6,64 m/s at 20 m height, putting this location in the lower half of all 20 sites. But in terms of power in the wind, this location achieves the second-highest value of all 20 sites with 660 W/m<sup>2</sup>. This can be explained by looking at the frequency distribution (<span style="color: rgb(255, 0, 0)">Picture 4</span>): more than 50 % of the measured values lie below 4 m/s, strongly reducing the average wind speed. But more than 30 % of the remaining measurement values are clearly above 10 m/s (the second maximum of the distribution lies at 17 m/s). Since wind speed enters the calculation of power with the cube, these high wind speeds very strongly increase the average power in the wind. Unfortunately, due to the limitation of power output at high wind speeds, a wind farm at this site would achieve a capacity factor of „only“ about 30 %.<br/><span style="color: rgb(255, 0, 0)">Table 2</span> summarizes the measurement results for the period between November 2009 and October 2010 for 14 measurement masts (6 masts have been relocated, no simultaneous year of data is yet available), and compares wind speeds, power in the wind and estimated capacity factors. The calculation of the capacity factors is done using an IEA class I turbine with 2 MW of installed capacity. In lack of further information about wind speeds at greater height for all sites, it was assumed that the wind speed at hub-height is equal to the wind speed at 20 m above ground. Furthermore, a total of 14,3 % losses were assumed (non-availability of the turbines, wake-effects, etc.).<br/>Based on the results of these wind measurements, as well as taking into account other criteria (topography, grid-proximity, accessibility, mining activities, etc.) the two most promising areas were identified, and measurement towers with a height of 80 m were installed. These are the sites B3.1 (Sierra Gorda) and D5 (Taltal). <span style="color: rgb(255, 0, 0)">Tables 3 and 4</span> show the wind speeds registered in the six months of operation from May to October 2010 and the estimated yearly values deduced by MCP-analysis with the data from the nearby 20m-towers. One can observe that the average wind speed at Sierra Gorda does not continuously increase with height, but actually reaches its maximum value at about 40 m above ground, and decreases further up (<span style="color: rgb(255, 0, 0)">Picture 5</span>). This inversion of the vertical wind profile can only be observed with the nightly katabatic winds. At daytime the vertical wind profile is positive. However, since the night-time winds are clearly stronger, this pattern can also be observed in the overall average values. The vertical wind profile will surely influence the selection of size and type of wind turbine to be installed, in order to maximize energy yield at this location. |
