Palm oil production, under fire from environmentalists concerned about deforestation in the tropics, is also a source of greenhouse gases, U.S. scientists say. Wastewater produced during the processing of palm oil is a significant source of heat-trapping methane in the atmosphere, researchers at the University of Colorado at Boulder reported Thursday. The methane bubbling up from a single palm oil wastewater lagoon during a year is roughly equivalent to the emissions from 22,000 passenger vehicles in the United States, they said, and represents another reason to be concerned about palm oil's environmental impact. "This is a largely overlooked dimension of palm oil's environmental problems," said study lead author Philip Taylor, a postdoctoral researcher at the university's Institute of Arctic and Alpine Research. There is possible solution to the problem, he said; capturing the methane and using it as a renewable energy source to fuel power plants. "The industry has become a poster child for agriculture's downsides, but capturing wastewater methane leaks for energy would be a step in the right direction." This year methane emissions from palm oil wastewater are expected to equal 30 percent of all fossil fuel emissions from Indonesia, the researchers said, where widespread deforestation for palm oil production has endangered orangutans.