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A radical new kind of desalination technology is finally on the cusp of helping to slake the world’s thirst. The pitch: Put desalination plants on the ocean floor.
First proposed in the early 1960s, this deep-sea process would benefit from both the crushing water pressure and relatively pure seawater more than 1,000 feet down. It has been unworkable until now. Only the recent commercialization of enabling innovations—including deep-sea robots from the oil-and-gas industry, and advanced reverse-osmosis filters now standard in terrestrial desalination—make it viable…
Oslo-based Flocean, Netherlands-based Waterise and Bay Area-based OceanWell are among the companies that seized on this idea of desalination—then submerged it to a depth of at least 400 meters.
The principle is easy to grasp: Instead of expending huge amounts of energy to pump seawater onto land, and then pressurize it inside a plant, why not take advantage of the ocean’s extreme natural pressure? At depth, seawater naturally wants to cross a desalination membrane, so long as the fresh water on the other side of it is being pumped to the surface. The result is a net energy savings of up to 40%....
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Only pilot plants have been set up so far. Only time will tell whether this technology will be scaled up to Macro significance.
OK, I started life as a wannabe Mechanical Engineer, but this is one that would never have occurred to me in a thousand years.
In the “on land” version you have to pump the water out of the ocean and then through filters. In the “in the sea version” you pump water through the filters and then up and on land.. I’m not seeing where you get a 40% savings in energy, but maybe that’s just me.
I see some savings, but you’re still pumping water out of the sea, so mayb e you save on putting pressure to force it through the filters. While I can see some savings there, I would thing that “changing the filters” would be a far more difficult process when the machine is hundreds of meters down rather than through, say, a gate saying “change filters here.”
But what do I know? Maybe underwater robotics is that easy nowadays. Which reminds me, I must watch the Netflix doc on the guy who got crushed trying to get.to the Titanic. It’s only the 23rd such “investigation” so far.
I think the difference is that you don’t have to pump/force the water through the filter when it is under the sea. The pressure from the ocean does that work. Of course, you still have to pump the filtered water up to the surface.
Yeah I I get that. It seems a bit disingenuous to claim “40% energy savings” without also noting that “replacing the filters is going to cost 200% more” because it’s 400 meters underwater. Of course perhaps that cost is trivial, I wouldn’t know, but I’d be surprised since it’s one of the things I hear about with desalination technology.
I think you could have two (or more) sets of filters that you can remotely switch between. When a filter is off line you could open valves to blow them out in the reverse direction…i.e. backflushing. This is how submarines clean out seawater cooling for condensers.