Vertical Farming in Time

The people at Time have made the vertical farming system of Valcent the 16th best invention of 2009.

Now the writeup says: "pioneering a hydroponic-farming system that grows plants in rotating rows, one on top of another. The rotation gives the plants the precise amount of light and nutrients they need, while the vertical stacking enables the use of far less water than conventional farming."

The picture seems to show 6 racks of lettuce growing, though I don't see the mechanism to rotate them.  But assume it's there--then if you rotate the 6 racks through the 24 hours of the day, each rack gets 4 hours of direct sunlight.  I find it conceivable that lettuce could grow with that much sun--greens usually require less than vegetables.  What I do find inconceivable is that there's any place on this green earth where the sun shines overhead for 24 hours in the day.

Now I may be misunderstanding, instead of a vertical rotation they may be talking about a horizontal rotation. Again, I don't see the mechanism in the photo, but if you rotated the whole stand then each plant would get 1/4th of the available sunlight.  Again, I've my doubts.

Looking at the data on the company, I observe the stock price of Valcent, which is publicly traded, is much lower than in the past--not the profile of a promising company. Nor do the various releases cite any real concrete achievements, just a bunch of golden futures to come.