Ecological sanitation, or 'ecosan,' can provide both improved hygiene and an income for the majority of the world, where just getting a sip of clean water can be a challenge.
Hydropower will never be the complete answer to emissions-free energy production in the U.S., but a strong case can be made for it becoming a useful part of the answer.
Looking at the untapped potential for hydropower to supply the U.S. with carbon-free electricity, Lea-Rachel Kosnik finds ample opportunities for expanding hydro.