“Green” dams could reduce GHG emissions
“Green” dams could reduce GHG emissions
mongabay.com
May 14, 2007
Scientists in Brazil have developed a way to reduce greenhouse emissions from large hydro-electric dams, according to a report from BBC News.
The technology, developed by researchers at Brazil’s National Space Research Institute (INPE), extracts methane from reservoir water to supplement energy produced by the dam turbines.
The technique could have a significant impact on greenhouse gas emissions. Globally, INPE scientists estimate large dams could be responsible for releasing some 800 million metric tons of carbon dioxide in the atmosphere, an amount greater than annual emissions from the UK.
Lake Balbina, a man-made reservoir created to supply hydroelectric power to the city of Manaus in Brazil. (Photo courtesy of Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC) |
Methane is generally produced by bacteria breaking down organic matter in anaerobic (oxygen-poor) conditions at the bottom of reservoirs. The methane is released when pipes located deep in the dam send methane-rich water through hydroelectric turbines.
“It’s like opening a bottle of soda. A large part of the methane is dissolved in the water bubbles, and it’s released to the atmosphere,” Fernando Ramos, lead scientist of the project, told the BBC. “That’s the reason big hydro-electric dams built in tropical areas are harmful to the environment.”
Historically, hydroelectric projects have flooded vast areas of Amazon rainforest. The Balbina dam in Brazil flooded some 2,400 square kilometers (920 square miles) of rainforest when it was completed. Phillip Fearnside, a leading expert on the Amazon, calculated that in the first three years of its existence, the Balbina Reservoir emitted 23,750,000 tons of carbon dioxide and 140,000 tons of methane, both potent greenhouse gases which contribute to global climate change.
Project aims to extract dam methane
This article is based on a news release from Cornell University