Question# 9:

Site selection for wind turbine requires consideration of a comprehensive set of factors and balancing of multiple objectives in determining the suitability of a particular area for a defined land use. The selection of suitable project areas involves a complex array of critical factors drawing from physical, demographical, economic, policies, and environmental disciplines.

Following shows major factors involved in selecting the sites: Wind ConditionsNaturally, the most important condition for a wind turbine site is the presence of regular and considerable wind current. Wind is an intermittent resource, meaning that wind speeds inevitably change throughout the day and due to different weather conditions, but a good site should have fairly reliable conditions of good wind speed and a nearly constant minimum supply of wind energy. During site selection, wind speeds are usually monitored over long periods of time to measure consistency and at different altitudes to identify the most favorable altitude for a turbine in the area. Wind ObstaclesThe presence of tall or large obstacles on a site, such as buildings, rock formations or trees, can disturb currents from the prevailing wind and dissipate wind energy. As a general rule, an ideal wind site has a significant clearance around it, with few or no obstacles between the prevailing wind direction and the turbine. The effectiveness of coastal wind farms, for instance, is largely based on the complete lack of obstacles for the prevailing wind on the ocean surface. In the case of a site with a few obstacles, the turbine should be placed as far as possible from the obstacles and at a height well over the tallest obstacle to avoid disturbed wind currents.

Grid ConnectionIn general, the longer an electrical link between a power source and its destination, the more energy is lost moving the current. This phenomenon is known as line loss and is another factor for consideration when selecting a wind turbine site. A site can have ideal ground and wind conditions but be so far from the grid or a power load that connecting it would both be quite expensive and involve the loss of considerable amounts of energy in the line. Other FactorsA wind turbine is a large piece of machinery with rapidly moving parts. As such, installing a wind turbine may not be appropriate for every site, no matter how much clean renewable energy it could produce on that site. The scenic and functional quality of areas with historical protection designations or public recreational grounds, for instance, may be diminished by the presence of wind turbines. Areas with large groups of migratory birds or man-made objects flying at the elevation of a wind turbine blade may also raise serious safety concerns. Even in a domestic installation, placing the turbine away from areas that receive a lot of traffic or contain fragile constructions is always a good safety measure.

Based on these factors, The proposed sites for installing wind generation are as follows:

1. On-Shore (Rawdat Ben Habbas Villages).

In this location the annual hourly wind speed is measured at 20, 30, and 40 meters above ground level (AGL). Where other meteorological parameters like ambient temperature, pressure, relative humidity and global solar radiation were measured at 2 meters AGL. The annual mean wind speed at this location was founded 4.6, 5.23 and 5.57 rn/s at 20, 30, 40 meters AGL, respectively which are considered to be an acceptable speeds for economic operation for wind generation[1].

2. Off-Shore (Yanbu).

This city is located at the western coast of Saudi Arabia. From economic point it is worthy to install wind turbines there. The study in [2] concludes installing wind farm with a capacity of 1500, 1000, and 600 kW will reduce the greenhouse effect by 31369, 23601, and 26087 tons in each year respectively. The wind speed at this location has been measured for 14 years at the height of 6 meters above the sea level. Where the average wind speed is found to be 5.1 m/s. The wind power plant capacity factor is obtained as the ratio of the average power produced by the plant over a year to its rated power capacity. The main conclusion depending on the study in [2] is this site economically and environmentally feasible to build off-shore wind power plant. In the reported study many factors have been considered when wind power plant is going to deliver actual power to the main grid such as the effect of various losses like array and wake losses, airfoil soiling/icing losses, downtime losses, and miscellaneous losses.

b) Based on the annual average wind speed of your chosen location, what is the anticipated energy production for one wind turbine in one year at that location (1 page)?

The output power from the wind turbine can be calculated as in follow relation: (1)Where A is the swept area of the turbine as shown in the following figure.

Where (2)Where r is the turbine radius in m, is the air density in (), and represents the wind speed. Air density can be calculated as follow: (3)Where P = the surface pressure (Pa), R = the specific gas constant for air (287 J/kgK); and T = the air temperature in degrees Kelvin (C+273).Depending on the above relations the average power output in (MW) from any wind turbine installed in the selected locations can be calculated as well as the annual energy produced by the installed turbine in (MWh).

In selected locations if the capacity factor for each wind turbine is assumed to equal 33.5% and the rated power output for each wind turbine is 1 MW the annual production from this wind turbine will be equal to:MWh

c) If you now had a 100 turbines what would the capacity factor be for one year (1/2 page)?

The wind power plant capacity factor is obtained as the ratio of the average power produced by the plant over a year to its rated power capacity [2]. Assuming that each turbine is rated at 1 MW, then the power produced by 100 turbines in one year is obtained as

The plant capacity factor can be obtained as

d) Given the various different configurations or topologies of generators, which configuration would you choose and why (2 pages)?

[1]S. Rehman, M. Mahbub Alam, J. P. Meyer, and L. M. Al-Hadhrami, "Feasibility study of a windpvdiesel hybrid power system for a village," Renewable Energy, vol. 38, pp. 258-268, 2012.[2]S. Rehman, "Prospects of wind farm development in Saudi Arabia," Renewable energy, vol. 30, pp. 447-463, 2005.