Maine increased the portion of non-hydroelectric energy production in its energy mix from 20 percent in 2001 to 27 percent last year, the U.S. Energy Department's Energy Information Administration reports. South Dakota and Iowa were close behind, with substantial increases since 2001.
The EIA attributed the increase to renewable portfolio standards, benchmarks for the share of renewable energy in state's overall energy mix. It added that federal tax credits and grants helped boost the renewable energy sector across the board.
The EIA said of all the renewable energy options, wind was making the most substantial gains.
"Wind was the fastest growing source of non-hydroelectric renewable generation, as many operators of wind turbines have benefited from these (federal) programs," the agency said.
U.S. President Barack Obama has called for an "all-of-the-above" domestic energy strategy. The White House had said it aims to generate 80 percent of domestic energy needs from renewable resources by 2035.