The vast majority of hydro power dams in the Mekong Delta in Southeast Asia have a similar climate footprint as wind power, solar power, and other renewable power sources, scientists conclude in a newly published study in the peer-reviewed Environmental Research Letters. The findings are particularly powerful because the Mekong Delta dams are likely to emit more methane than dams built and maintained in the United States and much of the rest of the world.

Wind and solar advocates have attempted to attack the climate benefits of emissions-free hydro power by arguing the lakes created by hydro power dams emit large amounts of methane that negate the carbon-free electricity the dams produce. A team of scientists analyzed the methane impacts of more than 100 hydro power dams in the Mekong delta and found the vast majority have a similar greenhouse gas footprint as wind and solar power.

According to the scientists, 82% of the 111 hydro power dams had similar greenhouse gas footprints as other renewable power sources. Analyzing the individual dams, they found that dams built in areas of lush tropical foliage had a larger methane footprint than other dams. The reason for the difference is foliage and vegetation submerged in the lakes are the primary source of methane emissions from the lakes. Dam reservoirs that submerged large amounts of existing vegetation and dam reservoirs that tended to collect more vegetation transported from upstream resulted in more methane emissions from the lakes.

The scientists’ finding supports prior studies finding that dams built closer to the equator and in lush tropical forests result in greater methane emissions than other dams.

The Mekong Delta, an area of lush tropical vegetation at approximately 15 degrees north latitude, is at a latitude similar to Guatemala and Nicaragua in Central America. This results in disadvantages regarding methane emissions from these dams in comparison to dams built in the United States, China, and most other global regions. Nevertheless, fewer than 20% of the Mekong dams resulted in greater net greenhouse gas emissions than other renewable power sources.

Hydro power dams built and maintained in the United States encounter few of the greenhouse gas challenges of Mekong Delta hydro power reservoirs. Moreover, the scientists found that methane emissions from hydro power dams can be further reduced by clearing out existing foliage before dam construction and situating dams in locations where the resulting reservoirs would create deeper lakes with less surface area relative to the amount of water impounded.

In short, the peer-reviewed study contradicts claims by the environmental left that new hydro power dams and existing hydro power dams in the United States and Canada are not effective at reducing net greenhouse gas emissions.


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