About 200 scientists from the ecological and wildlife communities called on the government to review certain crops that may be used for biofuels production. A letter sent to the White House said some of crops under consideration are viewed as invasive species.
"These invasive species already cost billions of dollars a year in the United States and are one of the primary threats to North America's native species and ecosystems," the letter states.
The United Nations last year warned that the increase use of biofuels could strain agriculture systems normally used for food. The Union of Concerned Scientists, in a 12-page report last week, found that biofuels produced from non-food crops, farm residues and waste products could become a major source of renewable energy, however.
The U.S. government is reviewing the potential for two grass types -- Arundo donax and napier grass -- used for biofuel production elsewhere in the world.
Notable deaths of 2014 [PHOTOS]