Although dams often have big environmental
and social impacts, the World Wide Fund for
Nature (WWF) estimates that another 370
Gigawatts (GW) of large, medium, or small
hydroelectric capacity could be developed
"without unacceptable impacts" by 2050.
The 1-2 percent annual global growth rates
for large hydropower is significantly slower
than growth in other renewable sectors, such
as wind (over 20 percent) and solar (over 30
Scientists are developing other ways of
generating energy from the world's water
resources, though none are yet significant
producers of energy. There are still only a
handful of wave and tidal power projects,
but researchers see a much bigger potential
if investment grows.
Ocean thermal energy conversion, also mostly
experimental, would generate energy by
utilizing the differences between surface
and deep-sea ocean temperatures,
particularly in tropical climates.