A renewable, environmentally friendly energyOur energy choices profoundly impact the Earth we inhabit and the lives we lead. Producing electricity from the wind avoids the myriad problems associated with conventional fuels, does not deplete our finite reserves of fossil fuels, and does not consume precious water resources for cooling.
Wind energy is also one of the most environmentally-benign sources of energy in terms of protecting wildlife. The pollution, habitat destruction, and climate change resulting from the production, transportation, and combustion of fossil fuels in conventional power plants can have dire consequences for many species of birds and animals. Conversely, wind energy is 100% clean and renewable and doesn't pollute our air or water, and responsibly-sited wind projects operate in harmony with the natural environment.
|An accepted form of energy
Wind energy is a popular and widely accepted form of renewable energy. Public opinion polling consistently shows a very high rate of acceptance and approval of increased usage of renewable energy resources, particularly wind. People like wind energy because they understand that it makes sense to harness this abundant, renewable, clean source of energy.
Finite fossil fuels and global warming
It is true that fossil fuels - coal, petroleum, and natural gas - have contributed to unprecedented development and prosperity over the last two centuries. However, these resources are not infinite. If the increase in energy consumption continues at the same rate as today, crude oil reserves may be exhausted this century; natural gas and coal reserves will also eventually run out.
Fossil fuels are an important part of our energy mix, providing 85% of the world's energy -- but the global scientific community overwhelmingly agrees that their usage is also the main source of global warming.
|Without drastic and immediate measures, the accumulation of carbon dioxide and other greenhouse gases is likely to have dramatic consequences for the future of mankind. This problem has led the international community to implement a new model of sustainable development based on reducing carbon emissions through improved energy efficiency and development of renewable energies.|
How do wind turbines work?
Image courtesy of Siemens ©
A wind turbine is made up of three main parts: a rotor, a nacelle, and a tower.
The rotor is the part which turns with the wind. It is made up of a hub, a propeller with three blades, and a revolving axis inside the nacelle.
The blades are made of composite materials which are both light and strong: carbon or reinforced polyester glass fiber. The blades are typically 135 to 185 feet in length, making the diameter of the rotor between 270 and 370 feet. The longer the blades, the more power the turbine can produce, because the power generation proportional to the area swept by its blades. By increasing the length of the blades, the swept surface is increased and so is the power of the turbine.
The nacelle contains the equipment used to produce electricity from the rotation of the axis of the rotor, also known as the low-speed shaft. The rotation, powered by the wind, is transmitted by the low-speed shaft to a gear box where the number of revolutions is increased to 1,500 rpm. This mechanical energy is then converted into electricity at 690 volts by a generator. A transformer, located in the nacelle or at the foot of mast, then increases this voltage to 34,500 volts and the electricity is fed into the grid via a substation.
In order to start, a wind turbine needs a minimal wind speed of 6 to 10 miles per hour (the "cut-in" speed), and most turbines will automatically turn parallel to the wind (thereby minimizing aerodynamic resistance) at wind speeds above 50 miles per hour (the "cut-out" speed). Continuing to operate turbines in excessive wind speeds would cause premature wear.
Wind turbines are controlled by a computerized supervision system which makes it possible to direct the turbine rotor and to modify the blade angle in response to the direction of the wind, thereby enabling maximum energy production. This system of supervision and control also makes it possible to stop the turbines quickly and automatically if needed.
The tower supports the nacelle and the rotor and is made up of several metallic sections, fixed to the ground on a concrete foundation which can be up to 70 feet in diameter. However, once construction is finished, only a small portion of the foundation is visible around the base of the tower -- the rest of the foundation is covered with earth, and the area can be used to raise crops or graze animals.
The hub height on modern, powerful wind turbines can be up to 100m tall. Placing the rotors high above the ground allows access to higher wind speeds, which in turn yields more energy. Winds are also more consistent at taller heights due to reduced turbulence from ground-level obstacles such as trees, terrain features, or manmade structures.