indoor farming is much more efficient

http://weburbanist.com/2015/01/11/worlds-largest-indoor-farm-is-100-times-more-productive/

"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.