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Hydropower a major greenhouse-gas producer, researchers say

Although hydroelectric power is often heralded as a green alternative to fossil fuels like coal, scientists now say that in terms of greenhouse-gas production, hydro projects may be just as damning. Ahem. New research reveals that the initial flooding involved in creating hydroelectric dams releases large amounts of carbon from plants that are killed in the process. Then, leftover plant matter and other plants killed when water levels rise decompose and release methane into the atmosphere. These greenhouse-gas emissions add up -- in the case of one Brazilian dam project studied, emissions released over a year were more than triple what would have been produced by burning oil. The Intergovernmental Panel on Climate Change is considering counting some hydro-related emissions toward countries' allotments, but its proposed new guidelines would not count methane in this group, so some scientists say the proposals don't go far enough.