"Jornal do Brasil" Jan. 2008 Article on Reservoir Emissions

Translated extracts from article "Energy Policy: Hydropower and Global Warming" published in Jornal do Brasil, 27 January 2008. For full article in Portuguese click on: http://quest1.jb.com.br/editorias/cienciaetecnologia/papel/2008/01/27/ci...

Alexandre Kemenes, Programa LBA (INPA)
Bruce Forsberg, Instituto Nacional de Pesquisas da Amazônia (INPA)
John Melack, University of California, USA

Brazil is committed to producing inventories of all its greenhouse gas emissions. The first inventory of emissions from hydropower compared the emissions from tropical Brazilian reservoirs with thermal power plants and concluded that, in the majority of cases, hydropower was cleaner. However this inventory considered only emissions upstream of dams, while other studies show that downstream emissions are significant. Gwenaël Abril, of the University of Bordeaux 1 in France, for example, found that downstream emissions represent 48% of the total emissions of the Petit-Saut Dam in French Guiana. Kemenes (one of the authors of this article) has shown that 15% of the total emissions of Balbina Dam in Brazilian Amazonia occur downstream . . .

Up to the present, the total emissions of five hydropower plants from the humid tropics (Balbina, Tucuruí, Curuá-Una, Samuel and Petit-Saut) have been estimated from measurements and mathematical calculations. The calculations indicate that the emissions are for each of these projects worse than those from thermal power, including coal, the most polluting fossil fuel. For Balbina, which has one of the worst “energy densities” (the relationship between area flooded and power generation capacity), the emissions are around 10 times worse per megawatt-hour generated than a coal plant. Even Tucuruí, with one of the better energy densities in Brazil, generates nearly twice as many greenhouse gases per MWh than a coal plant . . .

In the case of existing dams, new technologies could help to reduce their emissions. Methane in reservoirs could be collected and then burned to generate electricity. Estimates suggest that using this technology at Balbina could increase its power generation capacity by up to 75% and reduce its methane emissions by 65% . . .