Wind Basics

Where does the wind come from?
Wind all starts with the sun. As the sun shines, it heats the earth’s surface. Since the earth’s surface is made of very different types of terrain and water mass it absorbs the sun’s heat at different rates. At a certain temperature, because a given volume of hot air is lighter than an equal volume of cooler air that lighter hot air suddenly rises, cooler air flows quickly in to fill the gap the hot air leaves behind. That air rushing in to fill the gap is wind. Variations in temperature cause atmospheric pressures which prompts air to flow. Air is a fluid like any other except that it’s particles are in gas form instead of liquid. When air moves quickly in the form of wind those particles are moving quickly. This Motion known as kinetic energy can be captured. Wind turbine blades are designed to capture the kinetic energy in wind which causes the blades to spin. Predominantly wind comes from the South in spring, summer, fall, and from the North during the winter.

Wind Energy Measurement
The energy generated by wind is typically measured in megawatts (MW), which is 1000 kilowatts.1 kilowatt equals 1000 watts.  A typical household uses 10,000 kilowatt hours for its annual electricity needs. The kilowatt-hour (symbolized kWh) is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 hour) of time. The kilowatt-hour is not a standard unit in any formal system, but it is commonly used in electrical applications. Energy equals power times time. Power is the work input. For a lighting system, the power is the wattage of the system. A 60 watt incandescent lamp uses 60 watts of power to operate. Since utilities measure usage for an entire building, they use kilowatts or thousands of watts. So a utility would measure the 60 watt lamp as .06 kW. Utilities refer to the monthly kW reading as demand.

Utilities factor in the amount of time power is used, typically in hours. So, energy is the measure of power used, measured in kilowatts per hour, or kWh. For example, if the 60-watt lamp operates for ten hours a day, then it will use 60 watts times ten hours divided by 1000 watts/kW or 0.6 kWh per day. Most utilities charge residential and small commercial customers only for the energy, or kWh they use in a month. It pays to be familiar with the specific rate schedules in order to understand energy billing.

Wind Energy History
People have utilized wind energy for thousands of years. Ancient Egyptians were first to use wind for powering the sails of ships. The first windmill structures, built for grinding grain, appeared in Persia during the 6th and 7th centuries, many years later the Dutch improved the windmill design and were able to pump water, grind grain, run sawmills and process other commodities.  In the U.S., wind power had it’s heyday from 1870 until the 1930s. Additional design improvements of adding lighter steel and more efficient shape blades made a viable power source for rural homesteads. Early applications were mostly for pumping water. In 1888 the first windmill to generate electricity was created by Charles Brush in Cleveland, Ohio. This first machine successfully generated electricity for 20 years. Between 1850 and 1970 more than 6 million mostly small mechanical windmill systems were installed in the U.S.

Beginning in the 1930s windmill installations tapered off due to the power grid being extended to rural communities. With the oil shortages of the 1970s, interest in wind energy increased again. In the late 1970s Tax incentives and federal regulation requiring utilities to buy electricity from the private sector encouraged wind development on a much larger scale.  Between 1981 and 1984 California installed 6870 wind turbines clustered together to form wind farms. In 1985 government incentives were dropped and installations slowed down again until the late 1990s when once again oil shortages along with global warming concerns has put wind energy back in the spotlight.