U.S. President Barack Obama has pledged to cut greenhouse gas emissions 14 percent from 2005 levels by 2020 and more than 80 percent from 2005 levels by 2050.
To reach these goals Obama is pushing Congress to pass legislation establishing a system capping carbon emissions and requiring polluters to acquire permits to emit carbon.
Draft cap and trade legislation was unveiled in the House of Representatives with emission reduction targets slightly more stringent than Obama's goals.
"Unfortunately, one year of improved data does not mean that we are on the right path for carbon dioxide reduction from U.S. power plants," Environmental Integrity Project Senior Attorney Ilan Levin said in a statement.
Despite the decline in 2008, carbon emissions from power plants have risen 0.9 percent since 2003 and 4.5 percent since 1998.
Levin said many of the nation's dirtiest power plants will need to be cleaned up or closed for the United States to seriously curb greenhouse gas pollution.
The group based its findings on data from the U.S. Environmental Protection Agency.