As the harmful side effects of fossil fuel burning become evermore recognized, the use of clean, renewable technology becomes essential to our health, economy and environment. Petroleum and coal emit harmful pollutants into the atmosphere, contributing to global warming, acid rain and a host of other aliments. Equally concerning is the dependence of the economy on a finite resource such as oil. With world energy consumption rapidly rising, demand is increasing for renewable energy sources that have no significant health impact or environmental degradation. Of all these so called “green” energy sources, wind power has been the most widely used. Wind power is based on the same principals as windmills used for centuries; wind turbines harness air currents to perform work. With modern advances, wind can now be used to power cities, industries and homes. While only currently supplying a minor amount of all US electricity, wind power has the potential to supply a significant amount of energy that will, unlike fossil fuels, never will be depleted or harm the environment.
Wind Power Technology
Wind as Energy
Wind power is actually a secondary form of solar power. The Earth receives about 1.74 x1017 kW/hour from the sun in the form of solar radiation. About 1-2% of that energy is absorbed by the air in the form of heat. Areas of the Earth closer to the sun, like the equator, receive far more sunlight than northern and southern regions, which corresponds to hotter air. The hot air then rises and drifts high into the atmosphere then natural drifts to the poles. As the Earth spins on its axis, the drifting air remains unaffected by the Earth’s movements. This difference in movement pattern is what causes wind; air is actually staying still while the world is moving beneath it. As the air cools, it sinks down into areas of low pressure, and cycles back to the equator, creating convention cells. These cycles of warming and cooling are what create global weather cycles.
Wind Tower Design and Mechanics
The power of wind is captured in wind towers. Modern US wind towers follow a simple design; three propeller blades sit atop a large pool usually 30-50m tall. The center of the propeller is then connected to a turbine rotor. Most US designs typical generate between 50-500 kW of energy, although the larger European designs stand about 135m tall and can produce up to 1.5 MW in a single tower.
Wind energy is captured and converted into energy by lift. The propeller blades are designed to have one side with an arch and the other straight. As wind passes over a blade, air is forced to travel a greater distance over the arch of the blade, creating of low pressure above the curve. This unequal pressure difference forces the blades to rotate in the direction of less pressure. The mechanical force generated by the movement of the propeller is then used to rotate a turbine to generate power.
There is also a design that has propeller blades...