Does hydro power hurt the environment?

Answer 1

Contrary to popular belief, hydroelectric power can seriously damage the climate. Hydroelectric dams produce significant amounts of carbon dioxide and methane, and in some cases produce more of these greenhouse gases than power plants running on fossil fuels. Carbon emissions vary from dam to dam. in 1990 the greenhouse effect of emissions from the Curuá-Una dam in Pará, Brazil, was more than three-and-a-half times what would have been produced by generating the same amount of electricity from oil. This is because large amounts of carbon tied up in trees and other plants are released when the reservoir is initially flooded and the plants rot. Then after this first pulse of decay, plant matter settling on the reservoir's bottom decomposes without oxygen, resulting in a build-up of dissolved methane. This is released into the atmosphere when water passes through the dam's turbines. In effect man-made reservoirs convert carbon dioxide in the atmosphere into methane. This is significant because methane's effect on global warming is 21 times stronger than carbon dioxide's. With the proposed IPCC guidelines, tropical countries that rely heavily on hydroelectricity, such as Brazil, could see their national greenhouse emissions inventories increased by as much as 7%. Colder countries are less affected, because cold conditions will be less favourable for producing greenhouse gases. ................................................... But it doesn't make sense to me cuz If a tree falls in the woods, and there is no hydro dam for it to fall into, it's still going to rot and produce greenhouse gases. I'm sure that it produces different proportions of gases depending on what conditions it decays under, but it's not possible for rotting vegetation to put out more carbon/greenhouse gases into the air than it originally filtered out when it grew. So many clean technologies get marked as dirty because they are subject to unfair analysis. This seems to be happening all the time. We now find out that the Toyota Prius is actually quite bad for the environment because of the batteries and the extended manufacturing process.

We can never just be satisfied with what we assume is true about a power source or "green" product, we must always dig deeper to see what is really going on.