Wind generation share exceeds 10% in 11 states

Of the 38 states with utility-scale wind farms, 11 states generated 10% of their total electricity from wind in 2015. Only 3 states had this share of wind generation in 2010.

In 2015, Iowa had the largest wind generation share (31.5%). South Dakota (25.9%) and Kansas (24.2%) had wind generation shares in excess of 20%. Two additional states, Texas and New Mexico, are on track to surpass the 10% wind generation share in 2016.

A utility-scale wind farm is one with where the aggregate capacity of the wind turbines is equal to or greater than 1 megawatt (MW).

At the national level, wind's share of total U.S. electricity generation has risen every year since 2001. Wind energy produced 190,927 gigawatt hours (GWh) of electricity in 2015, accounting for 4.7% of net U.S. electric power generation. This level represents a doubling of wind's generation share since 2010, when the share was 2.3%.

The increase of wind power in the U.S has been driven by a variety of factors including the presence of the Federal Production Tax Credit (PTC) and Investment Tax Credit (ITC), state level renewable portfolio standards (RPS), improved wind technology and increased access to transmission capacity. The PTC grants a federal tax credit on wind generation, while the ITC allows for federal tax credits on wind farm investments. State RPS, meanwhile, require that a minimum percentage of electricity generation come from renewable energy.

Two primary factors appear to be driving wind power growth, namely the local wind resource base and the presence of state-level RPS or policies that encourage renewable power generation. The map below illustrates that states with high wind generation shares are located in the Central High Plains and the Rocky Mountains.

States with the highest shares of electricity generation from wind match up with high wind resource areas. The map below shows average wind speeds at 80 meters by region denominated in meters per second (m/s). The three states (Iowa, South Dakota, and Kansas) whose wind's share were 20% or more in 2015 are located in the highest wind resource regions. Four other states (Oklahoma, North Dakota, Minnesota and Colorado) with wind generation shares between 10% and 20% also are located in high-wind areas

State-level RPS, that require a minimum percentage of electricity generation from renewable energy, and other state-level programs have also resulted in rising wind generation. Twenty-nine states and the District of Columbia have RPS policies, and an additional eight states have renewable portfolio goals. Besides RPS, many states provided incentives, such as exemption from property tax, mandated purchases, and additional programs to encourage wind power in their state.

For example, Iowa, the state with the largest share of wind generation at 31.5%, passed one of the country's first renewable generation laws in 1983. The Alternative Energy Law requires Iowa investor-owned utilities (IOUs) to own or contract for at 105 MW of capacity from renewable energy.

South Dakota generated about 26% of its electricity from wind power in 2015. South Dakota set a renewable energy target in 2008 that 10% of all retail electricity sales would be generated from renewable sources by 2015.

Kansas passed an RPS in 2009 requiring certain utilities to generate or purchase 15% of their electricity from renewable resources between 2015 and 2019. In 2015, the Kansas legislature, changed the required standard to a goal of 20% by 2020.

In 2010, Oklahoma enacted a renewable energy goal that 15% of total installed generation capacity would be from operating electric utilities to be renewable sources by 2015.

North Dakota, in 2007, set a voluntary target that by 2015, 10% of all electricity sold in the state would come from renewable sources.

Minnesota passed a renewable energy standard in 2007 that places a 26.5% renewable requirement on IOUs and a 25% requirement on other utilities. Xcel energy has a separate renewable requirement of 31.5% by 2020.

Vermont initially passed a voluntary renewable goal in 2005 that was subsequently changed to a mandatory renewable standard in 2015. The standard requires that 75% of retail sales, by 2032, come from renewable resources. The standard also sets an interim goal of 55% in 2017.

Idaho does not have a RPS, but in 2007, Idaho enacted a bill that restructured the method of taxation for producers of wind energy from a property tax to a tax on production. This restructuring aimed to ease the burden on commercial wind farms in the early years of operation.

Oregon first enacted a RPS in 2007. In 2016, the state legislature increased the state's RPS percentage requirements. The current RPS calls for utilities to meet their sales requirements using 25% renewable sources by 2025, with the percentage requirement increasing to 50% by 2040.

Maine enacted a RPS in 1999 that calls for 40% of electricity generation to come from renewables by 2017. The state also has three wind energy development goals: 2,000 MW of installed capacity by 2015; at least 3,000 MW of installed capacity by 2020, and at least 8,000 MW of installed capacity by 2030.

Principal Contributors:

Joy Liu
(Joy.Liu@eia.gov)

Paul McArdle
(Paul.McArdle@eia.gov)