Have you ever thought about where the electricity you use everyday comes from? When you turn on your hair dryer or your computer, you use electricity to power those appliances. From what natural resource is it made? Well, if you look at electricity usage nationwide, it is more than likely the source was coal, or perhaps nuclear power. It also could have come from natural gas or even a renewable resource.

According to U.S. Department of Energy data, in 2003 about 51 percent of electricity was produced using coal and about 20 percent came from nuclear power. Nationally, natural gas generated about 16 percent of electricity, and renewables produced about 9 percent. Petroleum contributed 3 percent. For more information about the past, present and predicted future energy needs and sources for the United States, go to the U.S. DOE's Energy Information Administration's Energy Outlook web site. You can also visit AEP's Learning from Light web site to figure out which natural resources are used in your state for electricity generation.

How does wind power fit into the energy puzzle? Wind is considered renewable energy -- a natural resource that is constantly replenished and never runs out. Most renewable energy comes either directly or indirectly from the sun. In contrast, nonrenewable fuels -- such as coal, natural gas, uranium (fuel for nuclear power), or petroleum -- can run out because there are finite amounts.

In 2003, a small portion of renewablable generation came from wind. Just about 4,850 megawatts (MW, or million watts) or 5 percent, comes from wind power. However, that number is expected to grow as more utilities and individuals use wind to generate electricity and better wind turbine technology makes wind power even more competitive.

The Pacific Northwest Laboratory has studied and mapped the available wind resources nationwide in the Wind Energy Resource Atlas of the United States . If you browse the atlas, you'll notice that most states have at least some wind resources that are rated at 2 and many have land areas rated 3 or higher, indicating better wind generation potential. To use wind resources effectively, the right size wind turbine is required to economically harness the available energy.

When it comes to generating electricity from wind, you need wind turbines. Wind turbines are the modern equivalent of the windmills used during the past century and a half to power farms and their rural homes. All wind turbines have a few basic components. Most are horizontal-axis (some are vertical-axis) propeller type systems consisting of a rotor and propeller. The propeller is the blade(s) that actually rotate in the wind and capture the kinetic energy of wind. The propeller converts the wind’s kinetic energy into rotary motion that turns the rotor, or electrical generator, which uses magnets and wire windings to create electricity. Each turbine is placed on a tower to ensure that it is high enough to avoid the turbulent wind usually found close to the ground and to avoid wind shadows from trees, buildings and hills. The turbine needs to be high enough to catch the faster winds.

The largest machine has propellers that span more than the length of a football field and stands 20 stories high, producing enough electricity to power 1,400 homes in the United States. Groups of these large turbines are usually located in higher wind class areas such as California, Texas or on mountain tops. On the other hand, a small turbine for home or small business use would have rotors between eight and 25 feet in diameter and stand about 80 feet high. The small turbine would supply enough power to meet some or all of the needs of a home or small business, depending upon when the wind was blowing and when the electricity was needed for heating, cooling, lighting or other energy needs.

Since 1992, the U.S. Department of Energy has worked with the wind turbine industry to develop low-cost wind power technologies. Central and South West Corp., an electric utility company in Texas that has since merged with AEP, worked with DOE to install 12 commercial 500-kilowatt (kW) wind turbines in Fort Davis, Texas. Building the wind farm provided CSW with extensive experience in siting, installing and monitoring wind power.

AEP also built the Trent Mesa wind generation project, a 150-megawatt development completed in 2001 that generates enough power to serve about 30,000 homes.

TXU purchases the electricity from Trent Mesa for its customers.

AEP also owns the Desert Sky Wind Wind Project, a 160-megawatt wind farm in Texas completed in 2001. Electricity from Desert Sky is sold to City Public Service of San Antonio.

One important consideration in the design and installation of any wind turbine is lightning, which strikes tall objects including turbines on towers. To avoid damage and down time needed for repairs, turbine manufacturers are incorporating features to protect internal electrical components and specifying careful grounding methods for towers.

Wind turbines are designed to generate specific amounts of electricity using as much of the energy in wind as possible. The turbine's electrical output rating (1000 kW, 10 kW, etc.) is the maximum amount of power it produces at a high wind speed. It produces less electricity at lower wind speeds. Power curves like this one show the wind speed the turbine needs to begin generating power (8 miles per hour in this case) and the wind speed when maximum amount of electricity is generated (about 36 mph). In this case, if a homeowner needs 8 kW to heat his or her home -- which is the average peak amount for AEP customers -- the wind must blow at more than 28 mph to produce the power he or she needs. If not, additional sources of electricity would be needed.

Large turbines can be used to generate lots of electricity and some utility companies are planning to add them to their system. AEP's Texas wind farms use large turbines that can generate up to 1.5 MW (1,500 kW) of power.

Small turbines, about 10 kW, are gaining in popularity as owners of homes and small businesses consider how to meet their electricity needs. AEP purchased small turbines for our research project from Bergey Windpower Co.