Renewable Electricity Futures Study Union of Concerned Scientists some experts claim some experts claim 80% of the US' needs hope that the growth continues essa matéria Renewable Electricity Futures Study study hope that the growth continues 80 percent study help the United States become less dependent on fossil fuels study The National Renewable Energy Laboratory some experts claim study by 2050 80% of the US' needs 2012 NREL study hope that the growth continues study Department of Energy 2012 NREL study Union of Concerned Scientists