Rio De Janeiro

A confrontation between the insatiable appetite for energy and the enduring need for habitability is under way in Brazil as it moves aggressively to harness the power of its rivers with plans for dozens of hydroelectric dams.

Such projects are engineering and aesthetic marvels that provide hydroelectric power and can also control floods and direct water for irrigation. But they also divert rivers, destroy animal habitat, displace entire communities and drown vast amounts of land beneath reservoirs.

One project has galvanized the anti-dam movement in Brazil — the Belo Monte dam on the Xingu River, a tributary of the Amazon in Pará State. At a cost of roughly $16 billion, it is one of 30 large dams that have been announced for Brazil’s Amazon region.

At last month’s United Nations Conference on Sustainable Development here, it was hard to miss the irony of delegates gathering to promote a “cleaner, greener and more prosperous world for all” as opponents of Belo Monte protested in the streets of Rio and Indians occupied the dam site.