The Promises—and Perils—of Ocean Desalination

upstart writes:

As the world gets drier, do we need to turn to the ocean?

Sean Bothwell can understand why people think desalination is a silver bullet. When he was a kid living in California's Orange County, the ocean was always close by. It didn't make sense to him that all the water near him wasn't usable.

"I grew up thinking, like, why the heck aren't we desalinating?" said Bothwell, who is now executive director of the California Coastkeeper Alliance. "Why are people always saying that we need to save water and conserve?"

[...] For his part, after doing his graduate school thesis on desalination as an adaptation mechanism for climate change, Bothwell's mind began to change on the process of ocean desalination, and he finally understood its problems and limitations.

"I realized all the things that people don't understand about desal-of all the issues we work on, [the efficacy] is the toughest thing to communicate to people," he said. "Everyone thinks it's a good idea."

[...] It's not just what gets sucked into plants that poses a problem for the ocean. The potable water produced by desal plants has an evil cousin: the super-salty discharge that remains, a substance known as brine, which is roughly twice as salty as the original seawater. Brine is heavier than seawater and can sink to the bottom of the ocean, where it creates a deoxygenated dead zone. [...]

"Our ocean is already under a ton of different pressures: nutrient runoff, ocean acidification, climate change," said Bothwell. "You add desal on top of it, and it creates a dead zone."

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