Discussions on “What is Green?” Can Be Complicated, Illogical
Here’s a discussion on the ecological pros and cons (mainly cons) of hydro-electric dams, which serves as an excellent example of how complex our discussions on “what is green?” can be. The author, not content to point out the usual eco-liabilities in terms of migrating fish, etc., claims that dams cause climate change. The number one reason? Methane emissions. He writes:
Organic material—vegetation, sediment and soil—flows from rivers into reservoirs and decomposes emitting methane and carbon dioxide into the water and then the air throughout the hydro-electric generation cycle. Studies indicate that where organic material is the highest (in the tropics or in high sediment areas) hydro-electric dams can actually emit more greenhouse gases than coal-fired powerplants…..Brazil’s National Institute of Space Research estimates that “dams are the largest single [human-caused] source of methane, being responsible for 23 percent of all methane emissions due to human activities.”
He then goes into the use of concrete in these dams, and all the energy consumed and CO2 emitted for that purpose. The fact that concrete has a large energy/carbon footprint is unarguable, but how large is it? We all know that there is no free lunch. The process of building, installing, and decommissioning a wind turbine has a footprint too–one that is somewhere between 1/15th and 1/30th of the total energy it will produce in its lifetime. For the author’s argument to mean anything, he needs to offer a similar analysis here.
The real lulu, however, is the author’s first point. Yes, the organic material flowed into the reservoir, where it decomposed. But wouldn’t it have decomposed somewhere else? He’s contending that the Earth is worse off because it happened in one place? Give me a break. Apparently, a passing grade in logic isn’t a prerequisite for a writing gig at EcoWatch.
For what it’s worth, I’m not a fan of dams either; I favor run-of-river hydro projects like this one.
The advantage a dam has over a run of the river is a much better scale on the power conversion equipment. I am building a much smaller turbine to turn high pressure water into energy than something that passively sits at intervals in a river. Not saying one is absolutely right, but there is a tradeoff and we tend to build more dams.
Run of river hydro equipment doesn’t just sit passively in the river. Having said that, let’s talk. Please see my email. Thanks, Craig