There are four basic wind applications:
The size and number of turbines vary in each of these applications. Utility-scale wind power plants typically use turbines larger than 1,000 kW to produce large amounts of wholesale power, accounting for more than 90% of all wind power generated in the United States. A 1,000 kW turbine can supply electricity for about 300 homes. Off-grid and behind-the-meter projects usually employ turbines smaller than 100 kilowatts (kW).
Wind projects range from less than 400 watts (W) to more than 400 megawatts (MW), with much larger projects expected in the future. The utility-scale technology that started in California in the early 1980s revolved around 50- to 100 kW machines, while the standard size of today’s more efficient and reliable turbines ranges from 1,500 kW to 2,500 kW.
Wind power plants consist of a number of individual wind turbines that are generally operated through a common control center. The number can range from a few, to dozens, to hundreds of energy-producing turbines.
Wind projects that are 2,000 megawatts or larger have been proposed. Such large- scale wind projects will bring about new challenges and benefits, requiring (and large enough to justify) dedicated large-scale transmission infrastructure to carry power long distances on land or shorter distances offshore to urban demand centers.
Accelerated growth of wind power in the United States would almost certainly require developing a number of very large-scale projects, considering:
Siting constraints on traditional projects: Installing large numbers of turbines in remote regions minimizes landowner objections to dense turbine siting in populated areas.
Geographic distribution of the wind resource: Most high-quality land-based wind resources in the nation are in mountain and plains states. The 20% Wind Scenario would require significant amounts of these resources to be captured.
Development pace and scale of development: A few very large projects can add as much wind generation capacity as hundreds of traditional 100 MW projects and can be developed and built much more quickly.
Restrictions on land-based deployment: Some energy-constrained coastal areas will depend on offshore wind resources that will require large-scale project development to reduce overall infrastructure costs.
Community stakeholders have started to evaluate wind development as a way to diversify and revitalize rural economies. Schools, universities, farmers, Native American tribes, small businesses, rural electric cooperatives, municipal utilities, and religious centers have installed their own wind projects. Although community wind projects can be of any size, they are usually commercial in scale, with capacities greater than 500 kW, and are connected on either side of the meter. Community wind includes both on-site wind turbines used to offset customer’s loads and wholesale wind generation sold to a third party.
Community wind is likely to advance wind power market growth because it has the following advantages:
Strengthens communities: Locally-owned and -controlled wind development substantially broadens local tax bases and generates new income for farmers, landowners, and entire communities.
Galvanizes support: Local ownership and increased local impacts broaden support for wind energy, engage rural and economic development interests, and build a larger constituency with a direct stake in the industry’s success. Local investments and local impacts produce local advocates.
Small wind (sometimes called “distributed wind energy”) refers to wind turbines that are generally smaller than 100 kW. Residences or businesses can install small wind turbines on-site to meet their local electricity demands, often selling excess electricity sold back to the grid on distribution lines. On-grid behind-the-meter applications, where turbines are connected to distribution lines and supply electricity to partially meet local loads, comprise the primary market for small wind. On-grid installations are currently supported by a variety of state and utility financial incentives, which reduce up-front capital costs to the consumer. Small wind can also include small units for off-grid applications, such as remote homes and livestock watering facilities as well as wind–diesel hybrid systems that are deployed in remote village settings, such as, Alaska.
Small wind has lower wind speed requirements, so more locations can accommodate and harvest wind. The U.S. small wind manufacturing industry dominates today’s world markets, and deploying distributed wind energy in rural or remote parts of the United States can help to build acceptance of future wind power plants. As markets continue to expand and manufacturers increase their volume, the result will be lower cost turbines. An additional benefit, although small wind systems have higher per- kilowatt costs than utility-scale systems, they compete with retail instead of wholesale electricity rates, which are also higher.
Small wind energy market challenges include turbine availability (product gaps exist for 5-, 15-, and greater than 100 kW turbines); economics and lack of financial incentives across all market segments; turbine reliability; utility interconnections; and zoning and permitting.