The floating desalination machines powered by the waves

Cool.

Typically land next to the shore is expensive and riddled with people who want to keep it clear of industry. People are loathe to allow even wind turbines on their precious horizon.... How close to the shoreline do these things need to be?

Also, an aside. Waste brine saturation seems to be a laypersons idea of a severe problem, when in actuality it really isn't. See Australia's desalination plants (Perth, Adelaide, others) and their outflows. 100+ Billion gallons a year with no big issues.