TEXAS

10,085 MW 3,675 MW

IOWA

3,177 MW

COAL: 459,803 MW

NATURAL GAS: 338,723 MW

NUCLEAR: 106,618 MW 1 MW =

1,000 U.S. HOMES

HYDRO: 77,910 MW

WIND: 34,683 MW*

CALIFORNIA

MINNESOTA2,104 MW

WASHINGTON & OREGON

2,192 MW

20| ej spring 2011 ejmagazine.com ej | 21

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IN THE WINDBy harnessing an abundant, clean and free resource, wind power has become a viable source of energy for homes, farms and businesses. Despite setbacks such as large start-up costs and the remote locations of wind farms, it remains one of the fastest growing forms of alternative energy on the planet.

SAY YES! TO WIND ENERGY!

WORKING WITH WIND BREEZY NUMBERSStates with the highest installed megawatt capacity for wind

Megawatt capacity for other forms of U.S. energy in 2009

A breath of fresh wind facts

TURN OFF THE WIND TURBINES!

Wind is one of the cleanest forms of energy on earth. It’s a sustainable resource that can be converted to energy without emitting fossil fuels and has few negative impacts on the environment, making it a popular choice for renewable energy resources.

Because it is a form of solar energy wind resources will never be depleted. Wind exists due to uneven heating of the earth by the sun. As hot air rises, cool air moves in to take its place, resulting in the creation of wind.

Compared with coal and natural-gas power plants, it takes less time to construct wind farms. A 50-megawatt wind farm is typically built in 18 to 24 months, and the payback energy period is only three to six months.

Small-scale wind turbines allow homeowners, farms, small businesses and public facilities to generate their own on-site energy. Small-scale turbines are defined as having capacities of producing 100 kilowatts or less. Average small wind turbines stand from 35 to 140 feet tall. Small turbines may serve as a way to break free from the reliance of fossil fuels for powering homes and businesses, but they don’t come cheap. For a 10 kilowatt machine, which is the size needed to power an average home, the price tag ranges from $35,000 to $50,000.

By being built in rural regions away from cities, large scale wind farms are able to harness the powerful winds in their isolated areas. Texas is home to the six largest winds farms in the U.S. with the Roscoe Wind Farm in Roscoe, Texas tipping the wind energy scales at a capacity of 781.5 MW. The 100,000-acre West Texas farm houses 627 wind turbines, ranging from 350 to 415 feet tall. The land was primarily used for cotton before being converted to a wind farm in 2007. Roscoe Wind Farm can generate electricity for more than 230,000 homes.

The biggest advantage of offshore wind farms is their ability to capture the strong, afternoon breezes produced at sea, which occurs at a time of peak energy consumption. While there currently are no offshore wind farms in the U.S. (pending the Cape Wind Project), the largest offshore project is the Thanet Offshore Wind Farm, approximately seven miles off the coast of England. The wind farm boasts 100 turbines with a total capacity of 300 MW, which is enough to power 200,000 British homes.

The growth in wind energy has led to the creation of more engineering and manufacturing jobs in wind energy technologies. The U.S. increased its wind power capacity by more than 5,000 megawatts (MW) in 2010 to its current capactiy of 40,180 MW.

The average cost of wind turbines in 2007 ranged from $1.2 million to $2.6 million per MW of nameplate capacity, the maximum rated output of a wind generator. Most commercial-scale turbines produce 2 MW of power.

Because of the high wind speeds, some of the best places to harvest wind are in remote locations, often hundreds of miles away from major cities. Building transmission lines from these desolate wind farms can be expensive.

Wind isn’t always constant. This increases the need to have power plants store the energy or the use of a battery system to help even out erratic flows. Turbines must be shut off in winds greater than 55 miles per hour to prevent damage to the machine.

Wind turbines aren’t the most aesthetically appealing structures. Some opponents cite that wind turbines are an eye sore, cause noise pollution and pose as life-threatening obstacles to both birds and bats.

Winds blow over the blades of the turbine, causing them to rotate. Turbines generally don’t operate unless winds speeds blow greater than 8 miles per hour. Turbines are able to generate the most electricity when winds are blowing at 22-to-55 mph.

The area covered by the rotating rotors, also known as the swept area, plays a role in how much electricity the turbines can produce. The larger the swept area, the greater the electricity yield will be.

WIND SPEED

SWEPT AREA

GENERATORTURBINE SIZE

Larger turbines take advantage of the more powerful winds at altitude and are less subjected to turbulence. Offshore wind turbines are able to harvest the dense, heavy air at sea level, which is able to produce more electricity by exerting more lift on the blades.

Most small-scale turbines are 100 feet tall with a rotor diameter of 23 feet. The largest wind turbines stand as tall as 230 feet with a rotor diameter spanning 231 feet.

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The spinning blades turn a drive shaft, which powers the gearbox within the turbine. The gearbox rotates at 1,200-1,800 rpm, which is the speed required by most generators to produce electricity. The gear box moves the high-speed shaft which in turn fuels the generator.

The electrical output of the generator is connected to a larger electrical grid, which supplies power to homes, offices and other businesses.

THREE OF A KIND: THE PRIMARY WAYS TO PRODUCE WIND POWER

*The 2010 MW capacity for wind energy was reported at 40,180 by the American Wind Energy Association.

20 percent of the nation’s electricity that will be supported by wind energy in 2030, according to an U.S. Department of Energy estimate.

100,000-300,000 estimated number of birds killed per year by wind turbines.

39 million estimated number of birds killed per year by rural cats.

SOURCES: AMERICAN WIND ENERGY ASSOCIATION, MSNBC.COM, NATIONALGEOGRAPHIC.COM, NATURAL RESOURCES DEFENSE COUNCIL, NPR.ORG, POLITIFACT.COM, POWERNATURALLY.ORG, POWER-TECHNOLOGY.COM, SUSTAINABLEBUSINESS.COM, THE NEW YORK TIMES, U.S. DEPARTMENT OF ENERGY, U.S. DEPARTMENT OF THE INTERIOR, U.S. ENERGY INFORMATION ADMINISTRATION, WINDUSTRY.ORG