| Wind Energy |
The energy is generated by wind farms in large scales. They are then connected to the electrical grid. Isolated area’s, and farms sometimes have their own wind turbine to create energy, thereby allowing them to be “off the grid”. As wind is a natural, unlimited, source, energy created from the wind is clean and reduces green house gas emissions. It also displaces the more common fossil-fuel derived electricity. Wind energy is most effective when it is used to power a low proportion of total demand, but does present extra costs when used for large fraction of demand. Over time, however, these costs repay themselves.According to statistics, there is an estimated 72 TM of wind energy on tsse Earth, which could potentially be commercially viable to create energy. To assess the potentially of an area for wind farms, you would need to asses the frequency of wind speeds, A probability distribution function is often fit to the observed data. As a lot of the power is generated at higher wind-speed, most of the energy comes in short bursts. The result is that wind energy is not consistent an output as fuel-fired power plants. Utilities need to be put into place, to provide back-up generation for times when the wind is weak. These storage technologies make electricity output more consistent. A wind farms annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Unlike fuelled generated plants, the capacity factor is limited by the inherent properties of wind. Small wind generation systems with capacities of 100 kW or less are usually used to power homes, farms, and small businesses. Isolated communities that otherwise rely on diesel generators may use wind turbines to displace diesel fuel consumption. Wind turbines are often used in conjunction with battery storage. Grid-connected wind turbines use grid energy storage, displacing purchased energy with local production when available. Off-grid systems users either adapt to intermittent power or use batteries, photovoltaic or diesel systems to supplement the wind turbine. Wind power consumes no fuel for continuing operation and has no emissions directly related to electricity production. Operation does no product carbon dioxide, sulphur dioxide, mercury particulates or any other type of air pollution. During manufacturing of wind turbines, it is a different story. Steel, concrete, aluminium and other materials will have to be made and transported using energy-intensive processes. Not to mention the transportation of the finished product, to the usually isolated area of the wind farm. The initial carbon dioxide emissions “pay-back” is within 9 months of operation for off shore turbines. Wind as an energy source is only practical in areas that have strong and steady winds. South Africa has fair wind potential, especially along the coastal areas of Western and Eastern Cape. Currently, the Klipheuwel wind farm is operating near Cape Town and the Darling wind farm is expected to be in operation by early 2007. According to Eksom, South African conditions would enable wind farms to operate at a maximum capacity about 15% to 25%, compared to about 30% in northern Europe.
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