A quiet revolution is underway in the world of hydropower. An emerging non-dam based hydro industry holds the promise of economically viable technologies that do not deplete resources or warm the planet, and do not wipe out species, ecosystems and cultures. With supportive policies from governments, non-dam hydro could become a key part of the world's energy mix over the coming decades, and could, as wind power already has, overtake big-dam hydro in terms of its share of new capacity additions.