Hydropower has always been considered the cleanest form of power generation, but a research paper published in Taiwan yesterday showed that hydropower contributes to global warming.
According to the study conducted across Southeast Asia by the National Sun Yat-sen University and the National Central University, hydropower causes much more global warming than coal or oil-fired power stations.
"Hydropower has always been considered the cleanest form of power generation. But as dams prevent organic matters from flowing down stream, organic matters trapped at the bottom of reservoirs are deprived of the oxygen they need to decompose, thus producing methane and nitrous oxide," Professor Chen Chen-tong (陳鎮東) of the National Sun Yat-sen University said.
Chen said methane and nitrous oxide have different effects on global warming.
"One ton of methane equals 21 tons of carbon dioxide and one ton of nitrous oxide equals 200 tons of carbon dioxide," he said.
Chen warned that China's Three Gorges Dam will produce serious global-warming effects because the dam has blocked 75 percent of the organic matters from flowing downstream.
The Three Gorges Dam built in the middle reaches of the Yangtze River, began operation on May 20.
The dam, the world's largest, is 185m high, 2,309m long and 8m wide at the top, and can produce 18.2kw of electricity each year.
Chen and his team spent three years studying rivers, lakes and reservoirs across Southeast Asia, to evaluate the impact of reservoirs on global warming.
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