"The statistics for this incredibly successful indoor farming endeavor in
Japan are staggering: 25,000 square feet producing 10,000 heads of
lettuce per day (100 times more per square foot than traditional
methods) with 40% less power, 80% less food waste and 99% less water
usage than outdoor fields. But the freshest news from the farm: a new
facility using the same technologies has been announced and is now under
construction in Hong Kong, with Mongolia, Russia and mainland China on
the agenda for subsequent near-future builds."
This is quite amazing and should work for many crops. Of course, things like corn, which grows up to 8 feet tall, would be a bit prohibitive. But still this is great.