Hydropower is supposed to be "clean," as it doesn't rely on the burning of fossil fuels. But this form of renewable energy is controversial for several reasons.
From displacing human settlements to inundating biodiverse landscapes, the construction of dams and hydropower facilities presents numerous environmental and social problems. Yet hydropower is a source of renewable energy - and if done with proper planning, can truly be green.
The Nile River has been the life line for East Africa for thousands of years. A mythical river, drinking water, irrigation, hydropower - the Nile feeds many needs in the countries it traverses. But now tensions increase over the water usage. Anna Osius and Linda Staude met people who depend on the river's water, from its southermost source in Burundi down to the Nile delta in Egypt.
While the Brazilian government praises hydropower as a motor for economic development, local people fear environmental and social impacts. A new dam project on the Tapajos river was recently stopped, people there are preparing to cope with future projects. (Report: Zoe Sullivan) Reporting for this story was supported by the environmental news site Mongabay.com