Israeli Engineer Develops "Gills" For Humans

[calbiterol]

An Israeli engineer, Alon Bodner, has developed a device that allows divers to extract dissolved air from water, replacing conventional scuba tanks and/or rebreathers. It works using the "Henry Law," which states that as the pressure of a liquid is released, the amount of gas able to be dissolved within the liquid decreases. The device uses a centrifuge to lower the pressure of some seawater, thereby liberating dissolved air. Note that this is different from electrolysis and does not result in pure oxygen, but rather in breathable, non-toxic air containing nitrogen, hydrogen, etc in addition to oxygen. It promises to be a revolutionary technology. Bodner hopes to have a fully-functional prototype developed within about 2 years, with a commercial version following soon afterwards.

 

Information sources:

http://www.livescience.com/scienceoffiction/050606_breathe_underwater.html

http://www.isracast.com/tech_news/310505_tech.htm (includes an interview with the inventor)

[Skye]

It seems a very simple idea, it's surprising that it hadn't been made before. The first problem seems to be that there's not that much air in water. Bodner says in the interview that for personal use this would be overcome by have a closed circuit rebreather.

 

I'm not exactly sure how the air will be stored within the device after it has been extracted. Unless it can be pressurised, it will have to be stored at the pressure of the water (in some sort of bag I guess). This seems to me to be a really big problem, and one which he has completely ignored. Air at that pressure occupies a large volume, and this will create buoyancy issues. Even a fair sized reservior will be sucked up in a small time by our lungs. It will also need to be drawn into our lungs by force, rather than having the pressure to push it through a demand valve. Sucking air from a bag, through a valve, is going to be harder than breathing air normally.

 

Another thing is that the compressed air in a conventional SCUBA system is used to fill the buoyancy compensator. I suppose that a small bottle, which could also be used in emergencies, could be used for this. That's likely to mean you still need to refill the bottle after each dive in order to fulfill safety requirements. It could also be a limitation on the length of the dive.

 

With all these components (the motor, batteries, centrifuge, rebreathing system, some sort of reservoir and emergency bottle plus regulator) it's going to cost more than conventional SCUBA or rebreathers. It also has more chances to go wrong, and could be fairly cumbersome. It will require special training, at the least rebreather training. I think it might find a place within professional divers, but the simple SCUBA systems we have now are hard to beat.

[blike]

I suppose you could fill the BC a little bit on the surface, then regulate it by mouth under water (though that would be extremely annoying, especially if you're changing depths a lot).

[LCD]

if the equipment is so bulky it will mean scuba divers will haave to wait a long time, but I imagine the tech could be applied to underwater habitats sooner.

[ed84c]

It has been made before, but it only lasted an hour, i.e. it provided slightly less than enough oxygen, and over the hour he slowly suffocated until he could not stand it anymore.