Why do turbines always spin at the same speed no matter how hard the wind is blowing?
It has been found that consistent speeds are the most effective means of extracting energy from the wind, according to Jeff Cook-Coyle, vice president of development for Nature Energies.
"Electric motors work best at a constant speed and generators are the same way," he said. "As the wind blows harder, it puts more torque on the generator shaft which then translates into a larger amount of power delivered to the generator, but the speeds stays approximately the same."
Is wind energy just a passing fad?
"There is no doubt that electricity generation developers run in packs; they run in herds," Cook-Coyle said. "Forty years ago, nuclear was the big thing; 15 years ago it was a natural gas; today, it's wind. But there are still a lot of operating nuclear plants; there are still a lot of operating natural gas plants, and 15 years from now there will still be a lot of operating wind farms."
What happens when a turbine gets struck by lightning?
Garwin McNeilus has 56 turbines near Dodge Center, and he says they get struck by lightning all the time.
"My turbines get struck by lightning probably 50 to 60 times a year," he said. "They are fully protected from lightning with the proper equipment and grounding. When you come out here in a lightning storm you can just see the lightning bouncing off of them. It doesn't hurt them."
How do they handle the Minnesota cold?
Nathan Svoboda, Grand Meadow Wind Farm plant manager, says the turbines' minimum operating temperature is -30 C (-22 F).
"As long as they stay running, we don't see too much of an issue," he said.
The cold's effect on the turbines is probably most noticeable on the grease.
"What happens in the real cold is all those blades are on bearings with grease in it, and the grease is getting pretty cold, grumpy, doesn't want to turn quite right," said Kurt Christensen, enXco operations manager for the Grand Meadow and Wapsipinicon Wind Farms.
So a little extra attention is needed to make sure the grease stays unctuous. That is easily done, Christensen said, by manually moving the blades a few times so the grease loosens up.
Why is Minnesota so windy?
Wind is closely related to elevation. The higher the area, the windier it usually is. In southeastern Minnesota, there are notable high spots, which allows for good wind production here.
Are there other kinds of turbines besides the three-blade horizontal axis turbines that we have here in Minnesota?
While the most common turbines are three-blade horizontal axis turbines such as the ones we have here, there are several other models out there: turbines that look like whisks, double helixes, cones, Darrieus machines -- which is the shape of a football sitting on its end. The reason the three-blade horizontal axis is the most widely used is because it most efficiently converts the linear motion of the wind into rotational energy.
How big is the biggest turbine in the world?
The largest turbine in the world is a whopping 7.5 megawatts. The Enercon E-126 has a rotor diameter of 413 feet and generates enough electricity to power nearly 2,000 American homes with one turbine. The turbine is installed in Emden, Germany. A 6-megawatt offshore turbine was just installed in northern Germany by REpower.
In the United States, the largest onshore turbine is a 3-megawatt Vestas V90 turbine in Cloud County, Kan. Sixty-seven of the turbines were installed just this year. The turbines stand 262 feet high, with a rotor 295 feet in diameter.
Do the turbines throw ice?
Years ago, back when turbines were being developed, their blades were stationary. That means their pitch couldn't be rotated and ice could build up on the blades. Nowadays, with updated blade designs and engineering, the blades are able to change pitch, and the blades can be rotated to break up ice that has built up. When they rotate, the ice falls straight down underneath the turbine.
What impact has the American Recovery and Reinvestment Act (ARRA) of 2009 had on wind energy?
The American Wind Energy Association recently released a summary of ways the ARRA will help the wind industry.
Some of the most noticeable benefits include a three-year extension of production tax credits, appropriation to the loan guarantee program, and nearly $8 billion to construct transmission lines. For a full list of benefits visit www.awea.org.
Wind doesn't blow all the time, so why don't we save some of the energy generated by wind for another time?
According to Dan Hayes of the Southern Minnesota Municipal Power Agency, that would be ideal. But "storage is a problem," he said. As of right now, there are only 850 megawatts of storage available in the whole world. The state of Minnesota has nearly double that in installed capacity.
What will the current economic situation do to wind energy development?
This is hard to predict, but Dan Juhl, who installed the first wind farm in Minnesota, has a positive outlook.
"The economic times will affect a lot of things," he said. "Wind, I am sure, will be a little effected, but you have to remember we need clean energy and we haven't built hardly any power plants in the last 20 years, but the demand keeps going up and up and the cost keeps going up and up."
That demand has to be met somehow and Juhl believes that it will be with wind and other forms of clean energy.
How have turbines improved through the years?
The earliest "modern" turbines that were erected in California were a lot different than those built today. Most of the turbines in California were "small wind," generating 40 kilowatts each. Nowadays, the most common turbines erected are 1.65 megawatts. To increase the energy that can be generated, the size of the turbines also has substantially increased.
The design and look of the turbines has also been upgraded. Older turbines had lattice-style towers, which killed lots of birds who nested in the towers and then flew into the blades when trying to leave or return. Now, the towers are made of tubular steel and bird deaths have sharply dropped.
Blade design has improved. The blades previously were set and couldn't be moved. Now the blades can rotate from 0 to 90 degrees so they can fan out if the wind is blowing too hard.
The blades once used to spin as fast as the wind was blowing; now they spin at one constant slow speed to protect the gears and to allow animals to see them.
How much does the energy produced by a turbine cost per kilowatt-hour?
According to Hayes, the cost of wind per kilowatt-hour has significantly decreased in the last 30 years. He said it was about 40 cents per kilowatt-hour in the 1980s. Today the cost has is about 5-7 cents per kilowatt-hour, Hayes said.
Can I build a turbine?
The short answer to this question is "yes." However, there are several ways to go about it. First, if you are interested in small wind -- 100 kilowatts or less -- your questions can be answered at www.awea.org/smallwind. Another way to go about getting a turbine is to talk with your neighbors and then lease your land to a larger company. If you have a large enough chunk of land in a desirable area, most developers would be interested in conducting business with you. There also is always the possibility of Community-Based Energy Development projects. Visit www.c-bed.org for more information.
When is the best time for the wind to make energy?
One of the anomalies when it comes to wind is that the best time to make wind usually is when it is needed the least. Winter months usually are windier than summer months, and cold air is denser than warm air. In the winter, the denser air pushes harder on the blades, forcing them to turn faster and generate more electricity.
What difference does wind make?
Many are excited about the possibilities of wind not only because of the "clean energy" it produces and the inexhaustible resources we have here, but also because it is "inflation-proof."
"Once a wind plant is built, the cost of energy is known, and is not affected by fuel market price volatility," according to a American Wind Energy Association report.
Also, wind doesn't require imports from unstable countries. According to the AWEA, "Wind energy contributes to our energy security ... it helps reduce our dependence on imports of natural gas, oil and other fuels."
What is considered before putting up a turbine?
Years of studies and research is conducted before before erecting a tower. First and foremost, the wind rating is considered. Once a location is found to have a good wind resource, from there hundreds of other things are considered, such as transmission capability, soil type, archeological sites, wetlands, radio and cell phone towers, migratory paths of birds and land availability.
What kind of schooling does one need to work on a turbine?
People from all backgrounds are currently working in the wind industry, but there is specific training needed. Iowa Lakes Community College offers a two-year program on wind energy and turbine technology, and Riverland Community College is working on developing a wind turbine technician program at its Albert Lea campus as soon as next year.
Courses cover all aspects of the industry. Along with electrical theory and hydraulics, students are taught how to repair and troubleshoot problems with turbines.
Entry-level salaries range from $30,000 to $45,000, according to Iowa Lakes Community College.
Where does the power come from when the wind isn't blowing?
Hayes says that SMMPA uses its coal plant to guarantee that its customers always have power.
What is offshore wind?
Offshore wind comes from turbines in the Great Lakes or ocean. It is a relatively new development, with dozens of proposed projects currently. However, it is a hotly contested topic. For more information visit http://offshorewind.net or www.capewind.org.
I have heard stories about turbines falling apart or starting on fire. What have some of the problems been with turbines?
There have been some problems with certain brands of wind turbines in the past, specifically Suzlon. These turbines have been known to have blades that crack, vibrate excessively, spin out of control and generate only about two-thirds of the expected output. Improvements in technology have recently diminished the problems for Suzlon, according to a spokesperson.
I want to generate power for my furnace. Is there such a thing as a roof-top generator for doing this?
Yes. There are several rooftop wind turbines or generators that are available for purchase and installation. A few can be found at www.swiftwindturbine.com or www.aerotecture.com.