One word: corrosion.

I honestly don't think this idea is too far fetched, though it's going to need subsidies to get going. If it all works out, then it would be pretty revolutionary.

Sure, but's got to be much cheaper to scrape off and shovel out the salt than to separate it by reverse osmosis, etc. Besides, to save on the scraping, might line the relevant areas with some tough, flexible plastic and, then, periodically shut down, remove the plastic, flex it to break off the salt, reinstall, and continue.