Renewable Wind

The three-bladed wind turbine is the most common modern design today because it minimizes forces related to fatigue.

Wind power is the conversion of wind energy into a useful form, such as electricity, using wind turbines. Although wind produces only about 1.5% of worldwide electricity use, it is growing rapidly, having doubled in the three years between 2005 and 2008.

The principal application of wind power today is the generation of electricity. Wind power, along with solar power, is non-dispatchable, meaning that for economic operation all of the available output must be taken when it is available.

Large scale wind farms are typically connected to the local electric power transmission network, with smaller turbines being used to provide electricity to isolated locations.

The construction of wind farms is not universally welcomed though, due to their visual impact and other effects on the environment.

The strength of wind varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there.

To assess the frequency of wind speeds at a particular location, a probability distribution function is often fit to the observed data.

Different locations will have different wind speed distributions. Because so much power is generated by higher wind speed, much of the energy comes in short bursts.

The consequence is that wind energy from a particular turbine or wind farm does not have as consistent an output as fuel-fired power plants.

Making wind power more consistent requires that various existing technologies and methods be extended.

Electricity generated by a wind farm is normally fed into the national electric power transmission network.

The surplus power produced by domestic microgenerators can, in some jurisdictions, be fed back into the network and sold back to the utility company, producing a retail credit for the consumer to offset their energy costs

Pumped-storage hydroelectricity or other forms of grid energy storage can store energy developed by high-wind periods and release it when needed.

Stored energy increases the economic value of wind energy since it can be shifted to displace higher cost generation during peak demand periods.

 In particular geographic regions, peak wind speeds may not coincide with peak demand for electrical power.

In California and Texas, for example, hot days in summer may have low wind speed and high electrical demand due to air conditioning. Some utilities subsidize the purchase of geothermal heat pumps by their customers, to reduce electricity demand during the summer months.

Wind power forecasting methods are used, but predictability of wind plant output remains low for short-term operation.

A good selection of a wind turbine site is critical to economic development of wind power.

Aside from the availability of wind itself, other factors include the availability of transmission lines, value of energy to be produced, cost of land acquisition, land use considerations, and environmental impact of construction and operations.

Off-shore locations may offset their higher construction cost with higher annual load factors, thereby reducing cost of energy produced. Wind farm designers use specialized wind energy software applications to evaluate the impact of these issues on a given wind farm design.

Europe leads the world in development of offshore wind power, due to strong wind resources and shallow water in the North Sea and the Baltic Sea.

Continued on page two