Wind energy

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Wind energy is collected from the kinetic energy of naturally occurring wind and converted into mechanical energy or electricity. The primary form of wind energy involves the use of wind turbine blades that rotate and power a generator to create electricity. Wind energy can be utility scale to generate 100 kilowatts of electricity or more or small scale to provide mechanical energy or electricity for homes, farms, and businesses.

Background

A combination of unevenness in the Earth's surface, the Earth's rotation along its axis, and the irregular heating of Earth's atmosphere by the sun causes wind. Wind patterns also depend on bodies of water, vegetation, and the terrain of a given area. Windmills are able to generate mechanical energy though not electricity, while wind turbines are able to use the kinetic energy of wind to produce mechanical energy for electricity generation. Larger turbines are generally built at least 100 feet above the ground to utilize faster, less turbulent wind flow. Propeller-like blades around a rotor are first moved by the air. The rotor, which is connected to the main shaft, then spins a generator to produce an electric current. Wind turbines can also be connected to the electric grid to distribute electricity to utilities or power systems. Wind farms, which are comprised of several large turbines built near each other, are used for utility-scale electricity generation. Smaller, stand-alone wind turbines are generally used for smaller tasks, such as grain grinding or water pumping, at a home, farm, or business, though these turbines can also be used to generate electricity.

Types of wind energy

According to the American Wind Energy Association, the three major types of wind energy include the following:

• Utility-scale wind includes turbines that generate more than 100 kilowatts of electricity. These turbines are also capable of delivering electricity to a power grid for distribution to utilities and power system administrators.
• Distributed wind generate less than 100 kilowatts of electricity. These smaller turbines are used for mechanical energy or to generate and deliver electricity to homes, farms, or businesses.
• Offshore wind includes turbines found in bodies of water.

Policies

In 1992, Congress passed the Energy Policy Act, which enacted a production tax credit of 1.5 cents per kilowatt hour for companies that generate electricity from wind. As part of the Consolidated Appropriations Act of 2016 passed by Congress in late 2015, the tax credit for wind facilities began its phase-down on January 1, 2017. For wind facilities that begin construction in 2017, the credit is reduced to 1.2 cents per kilowatt hour. For facilities that begin construction in 2018, the credit is reduced to 0.9 cents per credit. For facilities that begin in 2019, the credit is reduced to 0.6 cents per credit.

As of March 2017, 29 states had an enforceable Renewable Portfolio Standard (RPS) and eight states had a voluntary renewable standard or target. An enforceable RPS is a state-level mandate to electric utilities to generate a minimum amount of electricity from eligible renewable energy sources, which can include wind energy (depending on the state).

Generation by state

The map below shows wind generation by state in 2015 (in terawatt hours) and the percentage change in generation from 2014 (click to enlarge).

Wind generation by state in 2015 (data was collected by the U.S. Energy Information Administration)

Use in electricity generation

According to the U.S. Energy Information Administration, utility-scale wind power accounted for 22.6 million kilowatt hours of electricity in 2016. In total, the United States produced 4.07 billion kilowatts of electricity in 2016 of which wind energy accounted for 5.6 percent.

The table below shows net generation of electricity from renewable sources, including wind energy, from 2005 to 2015.

Net generation from renewable sources, 2005-2015
Year	Wind	Solar photovoltaic	Solar thermal	Wood and wood-derived fuel	Landfill gas	Biogenic solid waste	Other biomass	Geothermal	Conventional hydroelectric	Total*
2005	17,811	16	535	38,856	5,142	8,330	1,948	14,692	270,321	357,651
2006	26,589	15	493	38,762	5,677	8,478	1,944	14,568	289,246	385,772
2007	34,450	16	596	39,014	6,158	8,304	2,063	14,637	247,510	352,747
2008	55,363	76	788	37,300	7,156	8,097	2,481	14,840	254,831	380,932
2009	73,886	157	735	36,050	7,924	8,058	2,461	15,009	273,445	417,724
2010	94,652	423	789	37,172	8,377	7,927	2,613	15,219	260,203	427,376
2011	120,177	1,012	806	37,449	9,044	7,354	2,824	15,316	319,355	513,336
2012	140,822	3,451	876	37,799	9,803	7,320	2,700	15,562	276,240	494,573
2013	167,840	8,121	915	40,028	10,658	7,186	2,986	15,775	268,565	522,073
2014	181,655	15,250	2,441	42,340	11,220	7,228	3,202	15,877	259,367	538,579
2015	190,719	21,666	3,227	41,929	11,291	7,211	3,201	15,918	249,080	544,241
*Total refers to all utility-scale renewable electricity generation. Source: U.S. Energy Information Administration, "Table 3.1.B. Net Generation from Renewable Sources: Total (All Sectors), 2005 - 2015"

Economic impact

A wind farm in Idaho.

In August 2016, the U.S. Department of Energy issued an analysis of the wind energy market for 2015. The department used price data from Lawrence Berkeley National Laboratory (a federal research lab) for 121 U.S. wind turbine transactions from 1997 to 2015. From 2002 to 2008, average wind turbine prices increased from approximately $750 per kilowatt hour of electricity (kW) to approximately $1,500 per kW. From 2008 to 2016, average wind turbine prices fell to a range between $850 per kW to $1,250 per kW.

Proponents of wind energy argue that the industry supports thousands of jobs. The American Wind Energy Association, a wind power advocacy group, argued that "wind energy supported over 100,000 well-paying American jobs in 2016, including 25,000 manufacturing jobs." Additionally, the group argued that the industry helped produce additional economic activity through income and jobs in rural areas, which the group claimed contained 71 percent of nearly all U.S. wind farms. Additionally, the group argued that wind projects provided landowners at least $245 million in lease payments in 2016 and that taxes collected by local governments on these payments paid for services in rural areas, including public education and roads.

Authors of an August 2015 study published by Lawrence Berkeley National Laboratory (a federal research lab) argued that wind energy became more affordable in 2014, which in turn increased demand for wind power. Specifically, the authors argued, "Wind energy prices have reached all-time lows, improving the economic competitiveness of wind." The authors credited lower wind turbine prices, lower installed project costs, and increased capacity for the increased affordability of wind energy. The study's authors found that the average levelized long-term price from wind power sales agreements in 2014 was 2.35 cents per kilowatt hour (kWh) of electricity, a decrease of 66 percent of 7 cents per kWh in 2009. The full study can be accessed here

Opponents of policies favoring wind energy argue that federal grants and subsidies obscure the actual cost and price of wind power. Specifically, these opponents argue that U.S. taxpayers pay more in federal taxes than wind energy companies receive in subsidies. A November 2015 study published by the Institute for Energy Research, a research group that supports free market energy policies argued, "Taxpayers in 30 states and the District of Columbia paid more in taxes to the federal government over the past 10 years [2005 to 2014] to support wind subsidies than wind producers who own wind facilities in those states received in subsidy allocations." The study's authors argued that the top-five states that saw a net loss from 2005 to 2014 (California, New York, Florida, New Jersey, and Ohio) paid approximately $4.81 billion more in taxes ($6.26 billion total) than wind companies in the five states received in subsidies ($1.45 billion total). The full study can be accessed here.

Other opponents of policies favoring wind energy argue that federal wind subsidies and credits benefit large wind companies, including foreign-based companies. Randy Simmons, a professor of economics at Utah State University, argued in 2015, "More generally, the beneficiaries of federal renewable energy policies tend to be large companies, not individual taxpayers or small businesses." Simmons emphasized that the top five recipients of federal credits and grants for renewable energy from 2000 to 2014 were Iberdrola, NextEra Energy, NRG Energy, Southern Company, and Summit Power. Additionally, Simmons cited a 2010 study by the Investigative Reporting Workshop at American University, which found that 84 percent of all federal renewable energy grants as of 2009 went to foreign-based wind energy companies. The 2010 study can be accessed here.

Environmental impact

Wind energy does not produce air pollutants or water pollution. Additionally, wind power does not produce carbon dioxide (CO₂) or other greenhouse gasses. Proponents of wind energy argue that greater use of wind could reduce CO2 emissions that may be linked to human-caused climate change and global warming. Environment America, an environmental advocacy group, argued in December 2014 that if wind energy accounts for 30 percent of U.S. electricity generation in the year 2030, the United States would see CO₂ emissions decline by 40 percent from 2005 levels in the form of fewer coal-fired power plants. The full study can be accessed here.

According to the Union of Concerned Scientists, a nonprofit organization that supports increased use of renewable energy, wind energy does not use water to generate electricity, unlike facilities that use coal, natural gas, and nuclear power, and that large-scale utilization of wind energy could address water scarcity issues. The organization also cited the potentially harmful environmental effects of wind energy, such as its impact on wildlife. The group argued, "The impact of wind turbines on wildlife, most notably on birds and bats, has been widely document and studied." Authors of a 2010 study published by the National Wind Coordinating Committee found that birds and bats die after colliding with wind turbines. These collisions are caused by air pressure changes made by operating wind turbines. However, the study's authors concluded that "these impacts are relatively low and do not pose a threat to species populations," according to the Union of Concerned Scientists.

Wind energy may also produce mechanical noise that is irritating to local residents, though sound levels vary depending on the turbine and wind speeds. According to the U.S. Department of Energy, "Although wind power plants have relatively little impact on the environment and communities compared to conventional power plants, concern exists over the sound sometimes produced by the turbine blades and visual impacts to the landscape." Additionally, nearby residents may find that wind turbines obstruct scenic views of the natural landscape.

See also

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  Ethanol

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  Hydroelectric power

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  Solar energy

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  Glossary of energy terms