Wind power is forecast to surpass hydroelectricity for the first time as the nation’s top source of renewable electricity sometime in the next year, the U.S. Energy Information Administration said Wednesday. The sector is expected to produce 6.4 percent of utility-scale electricity in 2018, and 6.9 percent in 2019, propelled by a construction boom of new turbines across the country.Few new hydropower plants are in the works, so new electricity generation depends on how much rainfall and water runoff pools in existing dams and reservoirs. Hydropower provided 7.4 percent of utility-scale generation in 2017 ― a particularly wet year ― but that figure is projected to fall to about 6.5 percent in 2018 and 6.6 percent in 2019.