I can't let one paragraph of the "A rather balanced view from Energy Biz.com
email" go without comment. The author cites a New Scientist story that
claims:  
  > contrary to popular belief, hydropower can cause serious damage to the
  > environment. It says that hydroelectric dams produce significant levels
>of carbon dioxide and methane because up to 28 percent of all artificial
  > greenhouse gas emissions could be from rotting vegetation in dams. "

Rotting vegetation could of course produce significant amounts of CO2, but
not if the vegetation was largely removed before the impoundment was filled
with water. Once the lake is established, photosynthesis could result in an
amount of plant matter which may later decay and produce CO2 in low light or
cold seasons, but the net effect is zero change in annual CO2 to the
environment. Methane produced if anaerobic conditions prevail may be a more
legitimate concern.
 The quoted story goes on to say:

  >"...Philip Fearnside of Brazil's National Institute for Research in the
  >Amazon, who estimates that the greenhouse effect from one Brazilian dam
>was 3.5 times what would have been produced if oil had been burned."

 I wonder if such a statement was (irresponsibly) made simply to encourage
opposition to dam building?
As I said above, the possibly of high CO2 and CH4 could have been true in
the first year, but would not hold true for the long run.

Friends of hydropower, correct me if I am wrong.

Chris






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