Think Hydropower Is Green? Scientists Believe It Might Emit More Greenhouse Gas Than They Thought

While the natural gas industry and cows get a bad reputation for emitting methane — a greenhouse gas that scientists say contributes to global warming — a form of renewable energy touted as a green alternative might actually be producing more of this potent gas than previous thought.

Hydroelectric power and reservoirs, which were thought to account for about 20 percent of all man-made methane emissions, could be producing even more, according to the blog Climate Central.

The U.S. Environmental Protection Agency considers methane to be the second most abundant greenhouse gas from human activities in the U.S. There are natural sources and sinks of methane as well. Though its "lifetime" is shorter than that of carbon dioxide, another greenhouse gas, methane has a 20 times greater impact on climate change than CO2 per pound, the EPA says.

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While the EPA reports that the air emissions of hydropower is "negligible because no fuels are burned," it acknowledged that plants around a reservoir can create decay in the lake, resulting in methane emissions.

Climate Central reported that scientists are beginning to think, based on recent research, that reservoirs might be more of a methane source, but they don't know how much more due to a lack of data.

"[It's] still a big question mark," John Harrison with Washington State University, Vancouver's School of the Environment told Climate Central.

With that, he added that he doesn't think "we really know what the relative greenhouse gas effect of reservoirs is compared to other sources of energy in the U.S."

“We’re still in the very early days here of understanding how these systems work with respect to greenhouse gas production,” Harrison told Climate Central.

The EPA is beginning a study that will measure the emissions at 25 reservoirs from Indiana to Georgia. Data from this study will allow the agency to better estimate the contribution reservoirs have on methane emissions from man-made sources.

(H/T: Scientific American)

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