We just simply don't need that much brine for useful minerals -- it's a huge cost and you'll be left with massive piles of mostly useless salt. On one of my ha

We just simply don't need that much brine for useful minerals -- it's a huge cost and you'll be left with massive piles of mostly useless salt. On one of my hard drives, I've got an engineering / construction plan for a moderately sized intake + discharge for a small RO facility that would've passed muster in Australia, which has pretty reasonable environmental protections. Round numbers - the intake would have cost $25 million and the discharge more like $75 million. You need a massive structure to be able to emit that brine back into the environment in a way that doesn't just nuke the surrounding marine life. Huge pipes + check valves + cascading discharges, all either on the ocean floor if there aren't reefs and other sensitive areas or even worse from a cost perspective, tunneled out to a depth that can handle the amount of salt. Seawater is ~35g/L of TDS - the author is talking about 5 million acre feet of desal - what's that, 20 million tons of salt annually?