Building dams has always been controversial, both in Africa and around the world.
A conventional hydropower project, in which a dam is constructed across a river and a valley is flooded to create a reservoir, can generate a huge amount of electricity. But these projects also tend to cause large-scale disruption.
As a valley is flooded, anyone living on the site of the new reservoir will be forced to leave their home. The largest projects have been known to displace massive numbers of people. Over one million people had to make way for the Three Gorges Dam in China, the world's largest hydro scheme.