As one of the first technologies used to generate electricity, hydroelectric power has historically provided the largest share of renewable electricity generation in the United States. However, this year EIA expects wind power to surpass hydroelectricity, based on forecasts in the latest Short-Term Energy Outlook. Different factors lead to uncertainty about the forecast level of electricity generation from each energy source.
Because few new hydro plants are expected to come online in the next two years, hydroelectric generation in 2018 and 2019 will largely depend on precipitation and water runoff. Although changes in weather patterns also affect wind generation, the forecast for wind power output is more dependent on the capacity and timing of new wind turbines coming online.
