Source: BBC Online
11 May 2007 | EN | 中文
Dams release greenhouse gases
A method to curb greenhouse gas emissions from large hydroelectric dams has been developed by scientists in Brazil.
The team, from the country's National Space Research Institute (INPE), looked at ways of preventing methane in dam reservoirs from entering the atmosphere.
Methane is produced by bacteria breaking down organic matter in oxygen-poor conditions at the bottom of reservoirs. Hydroelectric turbines are fed this methane-rich water from intake pipes deep in the dam, and the methane is released into the atmosphere.
To prevent methane-rich water entering the turbines, the INPE team's solution is to channel methane-free surface water to the intake pipes.
Meanwhile, deep water is pumped to a rotor at the surface. This creates droplets to liberate the dissolved gas, which is then piped to a plant and burnt to produce electricity, supplementing energy produced by the turbines.
The researchers estimate that their technique ― if applied worldwide ― could prevent more emissions being released than what the United Kingdom creates in a year.
INPE hopes to demonstrate the process later this year with the prototype equipment.
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