Say it ain’t so! It appears that hydroelectric power may not be quite as clean as once thought. In a post to Ars Technica today, we discover that there is actually quite a bit about this type of power that was never considered.

People are familiar with the idea that fossil fuels are considered to be responsible for anthropogenic climate change, and as such the demand for renewable energy supplies has seen the development of nuclear, wind, wave, solar, geothermal and hydroelectric power. The last of these, hydroelectric, has been a favorite of both governments, with their supplies of rivers, and environmentalists, who like the absence of fumes.

Unfortunately, new research suggests that this power source is far from clean. Organic matter from plants decomposes in the new lakes and forms methane, which is then released into the atmosphere when the dam water is used to drive the turbines. Worse yet, the seasonal variations in water levels provide a steady supply of decomposing plant material. Methane, it should be noted, has a much stronger effect on climate than CO2, compounding the problem.