Saturday, May 25, 2013

Deforestation dries up dams threatening hydropower

Maria Elena Hurtado in Deforestation may lead to electricity shortages in tropical rainforest regions that rely heavily on hydropower, as fewer trees mean less rainfall for hydropower generation, a study shows.

For example, if deforestation continues, one of the world's largest dam projects in Brazil will deliver around a third less energy than is currently estimated, according to the research, published in Proceedings of the National Academy of Sciences (PNAS) last week (13 May).

Researchers had presumed that cutting down trees near dams increases the flow of water and hence energy production. This is because crops and pastures that replace trees take less water from the ground and lose less moisture by evaporation.

But trees also release water vapour into the atmosphere, which turns into rain and feeds hydroelectric power stations, and this new research suggests that wider deforestation can reduce overall rainfall and therefore energy production. This should be taken into account when planning hydropower developments in tropical regions, say the authors.

Lead author Claudia Stickler and colleagues looked at the link between trees and power generation at Brazil's Belo Monte hydropower complex, which is being built on the Xingu River, a tributary of the Amazon. It is set to be the third largest hydropower project in the world when it is completed in 2015 and is expected to supply 40 per cent of Brazil's energy needs by 2020.

They found that because of current levels of deforestation in the Amazon region, rainfall is already six to seven per cent lower than it would be with full forest cover....

Fires along the Rio Xingu in Brazil, a NASA shot from the International Space Station

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