A new study has some worrying news for our planet’s climate: reservoirs formed from man-made dams are emitting far more greenhouse gases than previously believed. As the Washington Post reports, that’s not good news for hydroelectric power:
[A] new paper, slated to be published next week in BioScience, confirms a significant volume of greenhouse gas emissions coming from a little-considered place: Man-made reservoirs, held behind some 1 million dams around the world and created for the purposes of electricity generation, irrigation, and other human needs. In the study, 10 authors from U.S., Canadian, Chinese, Brazilian, and Dutch universities and institutions have synthesized a considerable body of prior research on the subject to conclude that these reservoirs may be emitting just shy of a gigaton, or billion tons, of annual carbon dioxide equivalents. That would mean they contributed 1.3 percent of the global total. […]
“[We] found that the estimates of methane emissions per area of reservoir are about 25 percent higher than previously thought, which we think is significant given the global boom in dam construction, which is currently underway,” [said the study’s lead author and Washington State University researcher Bridget Deemer].
Greens like to imagine that the only thing keeping renewables from powering the entire world is a lack of political will, and that if we could somehow convince our leadership of their value, we’d be able to live in harmony with nature.
It’s not as simple as that, though. Every kind of energy source has its drawbacks. Wind turbines chop up a surprisingly large number of migratory birds. Solar power plants have been known to fry some birds mid-flight—one installation in the Mojave desert was estimated to kill some 28,000 birds annually. Now we’re learning that the reservoirs created by dams used for hydroelectric projects release large amounts of methane, a much more potent greenhouse gas than carbon.
None of these are reasons to stop building wind or solar farms, or to abandon hydroelectricity, but they should serve as a timely reminder that we don’t have any no-risk energy options—whatever greens might try to claim.