blade construction and generator design allow today’s wind turbines to
operate quietly and reliably in a wide variety of environmental conditions.
Before deciding on a specific type of wind system, it is important to
know the potential of your site. Ample wind is a prerequisite for successfully siting a wind turbine, and generally speaking, the more the better.
There are many factors that affect the performance of a wind turbine,
including wind speed and density, obstructions, and tower height. The
power that can be generated from a wind turbine is directly related to the
force of the wind and the size of the portion of the turbine that interacts
with the wind, usually a blade of some sort. Properly siting a wind turbine
is essential to the performance of the wind system.
The amount of power available in the wind is affected by several factors.
The two most important of these factors are the speed of the wind and the windswept area of the turbine’s blades. Simply stated, the larger the blades and the stronger the wind, the more power the turbine can generate. But other factors come into play which can affect the power available in the wind, including air density. Air density is affected by temperature and altitude, but turbulence is by far the biggest factor in reducing the available power and must be reduced or eliminated for a wind turbine to function efficiently.
Reducing turbulence means siting the turbine at least 40 feet above
any obstruction within 400 feet of the turbine. Understanding the characteristics of the wind at a particular site is also of great importance in
properly siting a wind turbine. The low air density associated with
swirling wind and wind that constantly changes direction will rob up to
90% of the available power of the wind. A wind turbine that continually
hunts in an attempt to stay “in the wind” will invariably lead to disappointing performance.
Wind systems fall into three basic categories: grid-connected electrical
power generation, stand-alone battery charging systems, and water
pumping systems. The simplest and most cost effective system is the gridtied
wind system. In the grid-tied system the wind generator sends electricity
to an inverter which conditions the power to match the electrical
grid power. Some turbines incorporate the inverter right into the turbine
housing, making the connection as simple as running a wire to your
existing load center.
The grid-tied wind system is connected through an agreement with
your local power company and the energy is net-metered. In the net-metered energy system, your electric meter will spin backward whenever
you are generating more power than you are using and forward when you
are using more power than you are generating. Your electrical usage is
billed at the net difference between what you make and what you use.
Frequently asked questions about wind energy systems:
- How does the presence of numerous hills impact the effectiveness of wind energy systems?
- What is the life expectancy of a windmill?
- Are windmills harmful to birds?
- Do windmills make a lot of noise?
- How much maintenance is involved?