Wind Farms

Wind farm
Photo courtesy General Electric Company
Raheenleagh wind farm

As in most other areas of power production, when it comes to capturing energy from the wind, efficiency comes in large numbers. Groups of large turbines, called wind farms or wind plants, are the most cost-efficient use of wind-energy capacity. The most common utility-scale wind turbines have power capacities between 700 KW and 1.8 MW, and they're grouped together to get the most electricity out of the wind resources available. They are typically spaced far apart in rural areas with high wind speeds, and the small footprint of HAWTs means that agricultural use of the land in nearly unaffected. Wind farms have capacities ranging anywhere from a few MW to hundreds of MW. The world's largest wind plant is the Raheenleagh Wind Farm located off the coast of Ireland. At full capacity (it's currently operating at partial capacity), it will have 200 turbines, a total power rating of 520 MW and cost nearly $600 million to build.

The cost of utility-scale wind power has come down dramatically in the last two decades due to technological and design advancements in turbine production and installation. In the early 1980s, wind power cost about 30 cents per kWh. In 2006, wind power costs as little as 3 to 5 cents per kWh where wind is especially abundant. The higher the wind speed over time in a given turbine area, the lower the cost of the electricity that turbine produces. On average, the cost of wind power is about 4 to 10 cents per kWh in the United States.

Energy Costs Comparison
Resource Type Average Cost (cents per kWh)
Hydroelectric 2-5
Nuclear 3-4
Coal 4-5
Natural gas 4-5
Wind 4-10
Geothermal 5-8
Biomass 8-12
Hydrogen fuel cell 10-15
Solar 15-32
Sources: American Wind Energy Association, Wind Blog, Stanford School of Earth Sciences

Many large energy companies offer "green pricing" programs that let customers pay more per kWh to use wind energy instead of energy from "system power," which is the pool of all of the electricity produced in the area, renewable and non-renewable. If you choose to purchase wind energy and you live in the general vicinity of a wind farm, the electricity you use in your home might actually be wind-generated; more often, the higher price you pay goes to support the cost of wind energy, but the electricity you use in your home still comes from system power. In states where the energy market has been deregulated, consumers may be able to purchase "green electricity" directly from a renewable-energy provider, in which case the electricity they're using in their homes definitely does come from wind or other renewable sources.

Implementing a small wind turbine system for your own needs is one way to guarantee that the energy you use is clean and renewable. A residential or business turbine setup can cost anywhere from $5,000 to $80,000. A large-scale setup costs a whole lot more. A single, 1.8-MW turbine can run up to $1.5 million installed, and that's not including the land, transmission lines and other infrastructure costs associated with a wind-power system. Overall, wind farms cost in the area of $1,000 per kW of capacity, so a wind farm consisting of seven 1.8-MW turbines runs about $12.6 million. The "payback time" for a large wind turbine -- the time it takes to generate enough electricity to make up for the energy consumed building and installing the turbine -- is about three to eight months, according to the American Wind Energy Association.

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