On 29 March, wind turbines in the Lower 48 states produced 2017 GWh of electricity, making wind the second-largest source of electric generation for the day, only behind natural gas, according to the Energy Information Administration’s ‘Hourly Electric Grid Monitor’. Daily wind-powered electricity had overtaken coal-fired and nuclear electricity generation separately on other days earlier this year but had not previously exceeded both sources on a single day.
Consistent growth in the installed capacity of wind turbines in the USA has led to a strong rise in wind-powered electricity generation. In September 2019, the country’s wind capacity exceeded nuclear capacity, but wind still generated less than nuclear because of differences in the utilisation of those technologies.
The average capacity factor of US wind generators (35% in 2021) is lower than the average capacity factor of nuclear generators (93% in 2021), which are designed to run at or near full output, which they typically do. Wind turbines currently rank as the third-largest source of generating capacity in the United States, behind natural gas-fired generators and coal-fired generators.
In the USA, wind speeds, and therefore wind-powered electricity generation, often peak during the spring. On 29 March the Southwest Power Pool (SPP), which covers parts of Oklahoma, Kansas, Nebraska, North Dakota, South Dakota, and neighbouring states, and the Electric Reliability Council of Texas (ERCOT) both reported new wind penetration records. Wind penetration represents the share of electric demand satisfied by wind generation. SPP reported wind penetration of 88.5% on 29 March, and ERCOT reported 67.2% for the same day.
Because electricity demand tends to be lowest in the spring and autumn months, some generator – including nuclear and coal – reduce their output during these months. Also, on days when weather patterns lead to more wind generation, competing coal-fired and natural gas-fired generators often are called upon to reduce their output so that overall electricity supply matches demand.
Seasonal variations also affect wind output. Wind first ranked as the second-largest source of US electricity for an hour in late March 2021. However on a monthly basis, the US has had less wind generation than natural gas, coal, or nuclear generation. It is not expected that wind will exceed either coal-fired or nuclear generation for any month in 2022 or 2023, based on EIA’s most recent ‘Short Term Energy Outlook’ forecast.