Hardly a new idea. The Aztecs were already doing this in what is now Mexico City, when the Conquistadores arrived. Floating garden beds. Still in use today.

I would hope that the "8 tons (7.3 tonnes) of vegetables and 1.7 tons (1.5 tonnes) of fish per year" would be per acre (or less) and does not indicate the production from the entire 2.2 Million sq ft (Approx. 51 acres).

Solar panels to power grow lights. really?

This could be significant, as long as the veggies aren't Monsantified and the fish don't have the undesirable effects of "fish farming syndrome". A self-sustaining operation that can be localized close to population centers means less transport too. I wonder how it will fare in freezing temperatures.

@owlbeyou, is "fish farming syndrome" any less imaginary than wind-turbine syndrome?

Ahhh, the other comments are more comprehensive and worthwhile than mine. But yes they surely could help food supply. I don't know where they get the 80 percent of arable land is used up - is that land taxed as farms with twenty percent not productive atm? I see land all over that could be planted, brown watered (if taxes did something other than service the retirements of public employees ) and used to produce something other than grass.

Floating gardens may not be an especially new idea but the violent storm action of mega storms like as Super Storm Sandy are new and are likely to increase in intensity and frequency. Any offshore system has to be capable of tolerating a gigantic amount of wind & wave action. The cute drawings of a calmly floating barge shown here does not look capable of taking any real sea action. This does not mean this is a bad idea at all, but as shown will not survive the first violent storm. None the less, good luck.

15-foot seas. Toast.

Not sure what you mean CliffG, but personally, I don't care for produce from fish farms. Even if the pens are moved around, I have noticed a kind of rough and worn condition in the fish that I don't find appetizing. I have a problem with treating animals like plants, chickens included.
As for wind turbines, there is a kill rate for birds that bugs me also.
So lets get one of these floating farms built off the coast of Louisiana! :)

It is a great idea !
I have interest to know about the investment amount !
Thank you!