The #1 problem I see is the battery pack.

The methanol fuel cell should fix a lot of that problem.

Here is a bit on a no membrane fuel cell:

Look ma no 'branes

The question is how much energy oxygen extraction will take (for use in the fuel cell) vs energy output. It may be that oxygen extraction is not necessary of course, if the concentration in the water is sufficient. Salt water might require a different fuel cell.

The future is so bright I have to wear shades.

No one mentioned the revolutionary concept of undersea habitats made possible by this type of invention. Present undersea habitats have to be linked by airhose to the surface. With self-regeneration of air supply from water at depth, habitats could be "disconnected" from the surface link.

Likewise submarines would be able to stay under much longer without surfacing, without nuclear powerplants.

Scuba tanks and rebreathers work pretty well for the mobile diver. The problems of decompression and nitrogen narcosis don't go away with this invention. Until the supply time is extended long beyond the one hour mentioned there is no advantage to this approach.

I have seen this in a couple of places now. This is revolutionary!! not just because when it is completed that it will allow a human to breath under water almost unlimited time but that the main problem with Hydrogen Fuel cell tech is getting the hydrogen out of the water storing pure gas hydrogen is dangerous expensive or plain unatainable or all three. This system here if it can pull our oxygen it can pull our the hydrogen gas as-well. H2O beats the hell out of electrolasilisis that requires to much energy.

C-Low, as I understand it, the system just pulls dissolved air from water rather than breaking molecules... so you're no further ahead for hydrogen than you would be if you used the air in your house. Sorry.

As for narcosis and decomression/ the bends, yes those are still there. Thank heaven for dive computers. But the right profile can still give you tons of time, while letting you see what you want. Personally, I find my greatest dive time limit these days (given my breathing and the profiles I select) is "when does the boat have to leave"?

If that wasn't my problem, I could go rebreather - but that's expensive and need specialized support that isn't always present at many dive destinations. This is a better solution (unless I'm diving with whales, and want to kill the "bubbles of distress"), with real benefits.

For instance, I would have a lot more time on the shallow reefs in the 25-45 foot depths. There's always lots and lots to see there. I also wouldn't worry about spending more time at depths of 100 feet or so, where air consumption volume quadruples, because now it doesn't bite into my reserves for shallower waters. This is the best of both worlds... max my deep time, then full time at shallow depths off-gassing.

Outside of my water profile, there are other advantages. One of the biggest is that any boat can become an extended dive boat for multiple dives, without requiring all those extra tank cylinders - or a full certified air compressor plus cooling tank. That will be a truly big deal.

This would certainly be a huge step forward in scuba technology, but it is not without it's problems.

First, water has varying concentrations of dissolved air in it. For example, there are regions of lakes and oceans where there is much less dissolved Oxygen called "dead zones". They are called that for good reason, because fish who swim in these regions will die due to lack of Oxygen. Now consider that humans need much more Oxygen than most fish, because we're warm blooded. Naturally you would expect humans breathing dissolved Oxygen from water to be much more sensitive to the amount of Oxygen in the water and thus more likely to encounter dangerous regions of low Oxygen levels. Consider, for example, that there are no warm blooded animals with gills. Also consider that humans lack a physiological response to low hypoxia. You could stand around in a room of pure Nitrogen gas (with no Oxygen) breathing normally and you wouldn't percieve much of anything wrong until you passed out and died, indeed people have.

Also consider that too much Oxygen at high pressures can be deadly (at ~7-8x surface pressure). If you dive with a higher Oxygen concentration air mixture then you can't dive as deep as you would with normal air, because of Oxygen toxicity. So, if the dissolved Oxygen concentration in the water is higher than normal air, it's possible to run into Oxygen toxicity problems before you expect.

In short, this device needs something along the lines of an Oxygen partial pressure monitor and a reserve tank of pressurized gas which would last at least long enough for emergency surfacing.

It's entirely possible that the actual, experienced conditions for most divers using this device will not encounter any of these issues, but the device needs to be properly tested to make sure that is the case before people trust their lives with it.

Despite all those caveats it is still a very cool innovation, I hope it works out.

Fuel cell output voltage would depend on oxygen concentration. So monitoring that voltage would give an early indication of oxygen concentration.

Eliminating a seperate oxygen sensor.

I have developed near the same project in early 2005. The project was later presented on Moscow's Europian Union Contest For Young Scientest in 2005.
There was a lot of folks from patent office. None of them told me such a project is already under examination.
Have a look
http://water.vizualbod.com/