The Earth’s wind is responsible for accomplishing many tasks. Wind spreads seeds, keeps the Earth cool, and could even meet 20% of the US electricity demand by 2030, according to the Department of Energy. Wind energy can produce electricity though generators inside of wind turbines. Wind turbines are slowly popping up across the world and are producing more clean energy every day.

Basics

Wind turbines are rated by their power output. Newer turbines are rated in Megawatts (MW), while older turbines are rated in Kilowatts (KW). Brand new turbines are rated as high as 3.0 MW. Often the limiting factor on making turbines bigger and more powerful is transportation. For example, blades on the new GE 2.5xl wind turbine are almost 160 feet long.

Wind turbines must be spaced out. Wind gets turbulent as it passes through a wind turbine, so the basic rule is that turbines must be placed 5 blade lengths a part from one and other. When taking blade lengths into consideration, this works out to be roughly 1 MW per 100 acres, according to Geronimo Wind Energy of Minnesota.

How it works

First, wind turbines cannot be placed just anywhere. Certain areas of the world produce more wind than others. New Vestas 3 MW wind turbines are designed for an optimal wind of over 26.8 mph. These turbines will not even produce electricity when the wind is blowing less than 6.7 mph.

Secondly, wind turbines need to be placed near transmission lines that connect the turbine to an energy offtake. An energy offtake company is typically an electrical company that has the rights to use the electricity produced by a wind farm (group of turbines). An offtake electrical company purchases electricity produced by a wind farm and then distributes it to consumers. Offtakes pay a premium for large amounts of electricity through long-term contracts.

Wind turbines are fairly simple pieces of equipment. The blades sit atop a high tower connected to the hub, while a gearbox and generator are enclosed behind the blades inside of a nacelle. As wind pushes through the blades, the nacelle will spin around and have the hub face into the wind while the blades turn and spin the main shaft, which spins a large gear inside the gear box. The large gear spins a smaller gear, which spins another shaft inside the generator, creating electricity.

The electricity is then transported down the tower and onto the electrical grid where it will travel to the energy offtake company that has the rights to use the electricity produced by that particular wind turbine.

Problems

Although wind energy is extremely clean, there are a few concerns that go along with it. Noise and visionary pollution are often associated with wind turbines, as well as bird safety. Finally, the mobility of electricity produced by wind energy is regularly the biggest issue when planning for a wind turbine.

Noise and visual pollution

A wind farm typically takes 18-24 months to create. It takes 12-18 months to get the proper zoning and permits for a wind farm.  During these first 12-18 months, local land owner concerns are taken into consideration and solutions are found. The last 6 months is roughly how long it takes for the actual wind farm to be built, according to the American Wind Energy Association (AWEA).

People who live around wind farms have complained about low frequency noise pollution being emitted from wind turbines. A common solution to this nuisance is to build wind farms in areas with low population density. When standing 1,000 feet away from a wind farm, it shouldn’t sound any louder than a refrigerator according to the AWEA.

Others have stressed that wind turbines are ugly and can ruin landscapes. While some people may think this, many citizens believe that wind turbines are a part of the overall energy crisis solution and see wind turbine as a clean energy solution.

Bird deaths

Another concern about wind farms is the ecological stress they may cause on birds. Concerns were raised when a 2008 study on a wind farm at Altamont Pass, California revealed that 80 golden eagles were killed by turbines as well as nearly 10,000 other birds annually. Since then, researchers have looked into these problems further and found that Altamont Pass is a unique case.

In 1986, it was observed that 69 million birds flew through the San Gorgorio Pass. Only 38 bird deaths were reported by turbines during the 1986 observation, according to the AWEA. In the US, on average, 1.83 avians are killed each year by turbines, while .006 raptors are killed each year by turbines as noted by The National Wind Coordinating Collaborative (NWCC).

In comparison to other manmade structures, wind turbines do not do as much harm. A TV tower was observed in Eau Claire, Wisconsin for many years because there was speculation that birds were flying into it and dying. A study found that 121,000 birds died over a 37 year span from the one tower, including one night where 30,000 died according to Wendy Weisensel of the Wisconsin Department of Natural Resources.

Wind turbines kill 10,000 to 40,000 birds annually according to the American Bird Conservancy. Power lines kill 130 to 174 million birds per year according to the AWEA, while 60 to 80 million annual bird deaths can be attributed to automobiles.

Transmission

Transportation of wind electricity has been a problem ever since the first industrial wind turbine was put up. Since electricity must be used immediately, or transported to a power plant, wind turbines must be connected to an electric grid that can offtake the load.

Since wind turbines do not consistently produce electricity because wind is not blowing 26 mph around the clock, commercial and residential areas cannot fully rely on wind power for their electricity needs.

Often times, wind farms are located near an energy offtake, such as an electrical company. While the wind is blowing, wind turbines will produce electricity and it will be transported to the offtake, an electrical company, where the electricity is then purchase from the wind farm and then distributed by the electric company. This way, electricity provided by the electric company is supplemented by clean wind electricity as well. In turn, wind energy is cutting down the need for other electricity production, like coal.

In those first 12-18 months before a wind farm is built, an offtake will sign into a contract with the wind farm to buy electricity for a certain amount of years. This is one of the only ways wind electricity can be consumed; transmission lines must connect a wind farm to the offtake.

Benefits

Landowners can benefit from having a wind farm a part of their property. Ideally on farmland, property owners can sell their wind rights and receive payments per acre. These contracts are created in the very first process of building a wind farm, so land owners get paid prior to any building. When the wind farm is finalized and constructed, land owners will receive fixed and variable payments based on electricity production. Landowners could receive $15,000 per year on a 160 acre parcel, although each wind company’s contract will differ.

Since one wind turbine only requires one acre of land, which includes the service road to it, wind farms do not affect farming practices. Farmland can retain its cropland functionality and can still be leased out for the same price. One acre of cropland is lost, with the possibility of gaining $15,000 per year.

Current wind energy companies have targeted almost every area where transmission of wind electricity is possible within the next five years, and now companies are speculating on transmission. The Green Power Express is a speculative transmission line that would run from the Dakotas, east across the Mississippi River, being built by ITC Holdings Corp of Michigan. The transmission line could be completed by 2020 according to ITC Holdings Corp.

Future

Over the past 20 years, the cost to produce wind electricity has dropped 90% as reported in “The Economics of Wind Energy” by the AWEA. Although wind energy costs are not always as low as conventional power production costs, wind energy costs are continually decreasing.

The US government has helped promote wind energy though subsidies. Through the Production Tax Credit (PTC) and accelerated depreciation, wind projects become more affordable and can yield positive returns. The subsidies help wind energy become cheaper and competitive with other energy sources, like coal, in hopes that clean energy, like wind, can help replace conventional power plants.

The PTC was recently renewed through 2012. The Union of Concerned Scientists explain the PTC as, “Companies that generate wind, solar, geothermal, and ‘closed-loop’ bioenergy (using dedicated energy crops) are eligible for the PTC which provides a 2.1-cent per kilowatt-hour (kWh) benefit for the first ten years of a renewable energy facility's operation.”

The Heartland Institute, a national nonprofit research and education organization, explained the accelerated depreciation benefit to wind energy, “The value of five-year double-declining-balance accelerated depreciation permits wind farm owners to deduct hundreds of millions of dollars from income before they calculate their potential federal and state corporate income tax liability and before deducting the lucrative Production Tax Credit.”

Wind energy production costs are competitive with other sources of energy. Oil can produce electricity for 5.3 cents per kWh, according to Stanford. New geothermal power plant facilities can produce electricity for between 4.5 and 7.3 cents per kWh, according to the California Energy Commission. Wind turbines have a lot of fluctuation when producing electricity. In the Northern Plains, wind electricity can be generated under 5 cents per kWh while in New England it can costs 6 to 7 cents per kWh, according to the AWEA.

Currently wind turbines are 25% to 40% efficient at producing electricity as stated by the AWEA. While many turbines run 65% to 90% of the time, often the wind is not blowing fast so the turbine is not running at 100% efficiency.

Wind energy has evolved fast. Back in 1980, wind turbines produced electricity at 30 cents per kWh, and now we are below 5 cents per kWh in some areas of the world. Although wind electricity cannot be the sole source of electricity in the world, it is one of the cleanest sources available. Wind energy will continue to become more economical over time and slowly take on more of the world’s electricity demand, taking over for fossil fuels.

-Colvin