All About Wind Energy
The History of Wind Power
Wind power has been used for centuries. The earliest documented use of wind power is the sailboat, which gave rise to the use of sail-type windmills. The first windmills were used for grinding grain and pumping water in ancient Persia. These had a vertical axis with "sails" made of wood or bundles of reeds. These types of windmills were also used in China during the same era and there is some confusion as to the exact origin of these earliest windmills.
When windmills were introduced to Western Europe around the 12th century, they appeared with a horizontal-axis and were also used as water wheels. Grain grinding was another common function of windmills in Europe and the design we commonly think of (the Dutch windmill, or the Don Quixote-ish windmill) was developed to house the grain milling equipment, this design actually appeared somewhat earlier in the Mediterranean.
Because these windmills had no way to orient themselves to the wind, the blades had to be oriented manually by pushing a large lever at the back of the mill. During the following centuries, improvements were made to windmills sails that increased efficiency. These became the predecessors to modern wind turbine blades.
Over time, steam engines began to take the place of windmills for water moving, grain grinding and other processing functions. But windmills would still serve a purpose on the American farm and growing industries. These windmills usually had paddle-like wooden blades and tails for wind orientation. Some were speed controlled with hinged blades so that they could fold back in high winds. The wood blades were eventually replaced with steel blades, which were light and could be worked into more efficient shapes.
By 1970 several million small windmills had been installed in the U.S. alone. These windmills were 1 horsepower or less, and were used for water pumping on farms. Larger windmills could be used to pump water for steam railroad trains.
How Does Modern Wind Power Work?
The huge modern wind turbines that we see on wind farms work just like the old-fashioned windmills do. The wind turns the blades, and this kinetic energy is turned into electricity. Wind turbines normally have three blades, which are connected to a rotor, which in turn drives the generator. Blowing wind causes pockets of low pressure to form on the downside of the blade, causing it to move and to turn the rotor.
The rotor is connected to a large generator, which is housed in the nacelle (the thing that looks like a long capsule behind the rotor). The electricity produced by the generator passes through cables from the generator, down through the tower and then to a transformer. The electricity ends up on the electricity grid for use by consumers.
Electricity is generated when wind speeds reach a little over 13 feet per second. Wind turbines will cut out when wind speeds reach storm force (about 82 feet per second), so that the turbine doesn't get damaged.
How Much Electricity Does a Wind Turbine Generate?
An average one megawatt turbine produces enough energy to power about 350 average households. Energy produced will vary depending upon the size of the turbine and the average wind speeds in the area where it is placed.
Modern turbines typically range from 660 kilowatts to over 3 megawatts in size. Most wind turbines run at between 30 to 40 percent of capacity. This means a one-megawatt wind turbine could produce about 3 million-kilowatt hours of electricity in one year.
Is the Electricity Produced by Wind Turbines Completely Clean?
Once the wind turbine is built and placed, the energy it produces is clean. There is no CO2 emission related to wind produced electricity. Nor is sulfur dioxide, mercury or any other type of pollution produced as with fossil fuel energy production. The production process of the wind turbine uses resources such as steel, aluminum, and concrete, and there are costs related to the transportation and set-up of the turbine. The period of "pay back" is usually only a matter of months though.
Fossil fuel plants are used as back up for wind power when the turbines are not producing enough energy to satisfy consumer needs. Even though this is true, wind energy reduces the consumption of fossil fuel, thus leading to a reduction in emissions.
Wind turbines do not use water for the generation of electricity unlike nuclear power plants and fossil fuel plants, which both use water for cooling.
Why Do People Complain About Having a Wind Farm Near Them?
Some people are sensitive to the noise produced by wind farms. Modern turbines produce a whooshing or swishing sound as the blades turn. The sound in terms of decibels is about equal to the sound of a normal conversation (about 45 dB), if you are standing at the foot of the turbine tower.
Other people seem disturbed by the view. The look of tens or hundreds of wind turbines all turning is unsettling for some. Also, taller wind turbines are required to have aircraft warning lights, which constantly blink on and off. Some fine this troublesome.
How Much Land Does a Wind Turbine Take Up?
Typically, the actual space occupied by a wind turbine is small – less than 100 square feet. There may be accompanying enclosures for monitoring equipment, transformers and the like, though, which can take up additional space.
Farmers commonly lease land to energy producers who are building wind farms. The land leased is used for the turbine structure itself, access roads and necessary small buildings or enclosures. The surrounding land can still be used for grazing and farming. It is very uncommon to see wind turbines in urban areas.
Offshore wind farms can be found in many areas of the world, but some complaints have been registered about the negative aesthetic effect. For this reason, most offshore wind farms are located several miles from land.
What About Safety for Animals and People?
Wind turbines do pose some threat to migratory birds and bats, and there have been a few human fatalities directly related to wind turbines in recent years.
It seems that worry over birds is the most heard "safety" issue with wind turbines. Migratory birds and raptors have been known to fly directly into the path of turning blades, but percentage-wise, birds, both migratory and non-migratory are at more risk from other dangers such as traffic and overhead high-voltage power lines.
Some energy companies have taken to painting blades with reflective paint to lessen the possibility of birds flying into them. Modern turbines and farms are now being placed in areas that are not common "flyways". Still an issue, power producers are looking for answers.
Another animal safety issue is bats. For the same reason that concern has been voiced over birds and turbines, bats populations have been found to suffer ill effects from the turning blades. In fact, in the Eastern United States, so many bats have been killed that conservationists are calling for solutions, and energy companies are scrambling to find them.
Other safety issues of concern are the rare, but still serious problems of turbine fires, which don't happen often, but are impossible to put out when they do. These fires must be left to burn themselves out, and in the process, they spew pollutants into the air and burning bits and pieces to the ground, often causing fires to break out at ground-level in surrounding areas.
Human fatalities include a parachutist who collided with a wind turbine, and traffic accidents caused by motorists distracted by the sight of wind turbines. Some workers have lost their lives due to falls, or being caught in machinery while working on the wind turbines. As of early 2006, 32 total human fatalities had been reported (Paul Gipe (2008), Contemporary Mortality (Death) Rates in Wind Energy).
Does Wind Power Really Make an Impact On Electricity Availability?
Yes, and as technology improves, it's impact will become greater. Currently, worldwide production of electricity from wind power is just over 1%, but in some parts of Europe, it is as high as 20%. Because of it's availability, renewability and the fact that it is a clean source of power, wind energy generation is increasing exponentially and is expected to continue to increase.
As a source for roughly 10% of a market's electricity, wind power can be a reliable source of energy. The intermittency of wind would not have a negative effect on the electricity grid at this low penetration and technologies are still being developed to deal with intermittencies in order to ensure more predictable and steady results.
Can Wind Power be Stored?
On a small scale, power from wind turbines can be stored. For example, small turbines can charge batteries that would later be used for powering appliances in a home. On a large scale, this isn't happening yet. The power that is created by a turbine goes directly into the electricity grid now. In the future, if technologies are developed to store excess power generated, this will make wind power a more desirable and effective source of energy.
In Conclusion,
Wind energy is currently the world's fastest growing renewable source for power. Through the kinetic force of the wind, blades turn, activating generators and producing electricity that directly enters the power grid for consumption.
At this time, only a handful of the world's countries produce almost 75% of all the wind power, but wind turbines and wind farms continue to pop up everywhere, even offshore to take advantage of free-flowing sea winds.
Wind farms are large groups of turbines generally varying in numbers from a few to hundreds of turbines. Presently, the largest wind farm in the U.S. is the Stateline Wind Energy Center, which lies along the Oregon-Washington border. It has the capacity to produce enough electricity for about 72.000 average homes, or 300 megawatts of electricity.
While concerns about some loss of wildlife are issues that must be dealt with, wind farms do have distinct environmental advantages. Once manufactured and built, the wind turbines produce no pollutants or emissions in the normal course of producing electricity. And the initial cost in terms of resources and emissions to produce a turbine is recouped usually in less than one year.
Because wind energy is completely dependant on the wind itself, there are concerns over intermittency of power availability. This is a legitimate concern and while technology is being developed to overcome these issues, fossil fuel plants are being used as the back up system. Still, wind power currently takes a bite out of the need for fossil fuels.
Issues surrounding noise and aesthetics aren't likely to go away. While modern wind turbines are actually very quiet, they do produce some noise that may be disturbing to some people. Aircraft warning lights that are required, and the constant turning motion seems to be at issue as well. These are unavoidable and not likely to change. Some people react negatively to having a once pristine land, farm or seascape dotted with huge, towering turbines.
Wind power must however be treated as one of the best candidates for the world's ever increasing power needs as we move further into the 21st century. It is unlikely to be trumped as the cleanest source of renewable energy available as we watch and worry over fossil fuels that are dwindling and polluting.