For millennia, humans have sought to make seawater drinkable. Ancient mariners tried distillation by boiling the oceans in which they sailed, and in more recent times, engineers have experimented with filters and chemicals. As the climate warms, populations surge and droughts intensify, there is a growing need to make the sea drinkable. … But creating drinking water from the sea is not without environmental impacts. These depend on how plants process seawater, whether they run on fossil fuels or renewable energy and where they are built.