While hydroelectric generation has historically been the largest source of renewable electricity generation, the U.S. Energy Information Administration (EIA) expects wind power to surpass hydro and become the largest renewable generation source sometime in the next two years. 2017 was a relatively wet year with hydro providing 7.4% of total utility-scale generation. But with only a handful of new hydro plant slated to come online in the next two years, hydroelectric generation will depend largely on water runoff and precipitation. Currently, the EIA predicts that hydro will be slightly lower in 2018 and 2019, and will produce 6.5% and 6.6% of utility-scale generation respectively. Although weather also greatly affects wind generation, output forecasts from wind are more dependent on capacity and the timing of new facilities coming online.

Wind provided 6.3% of total utility-scale generation in 2017 and with a large number of wind projects expected to come online in the next two years, partially to beat the federal production tax credit that is slated to phase out by 2021, renewable generation from wind projects is likely to become the largest renewable generation source. According to the EIA’s Preliminary Monthly Electric Generator Inventory, wind capacity is expected to increase by 8.3 GW in 2018 and 8.0 GW in 2019. Because of that added generation, EIA expects wind to provide 6.4% and 6.9% of total utility-scale electricity in 2018 and 2019 respectively, making wind the largest generator of renewable electricity. For more information read the full EIA report.