Right now the world's largest vertical farm is in Japan. But that will change this year as a new facility comes to completion in Newark, New Jersey. AeroFarms will be nearly 3x bigger than the one in Japan.
"[It] is on track to produce 2 million pounds of food per year in its 70,000-square-foot facility in Newark, under construction less than an hour outside of Manhattan.
"Their efficient operation, based on previous experience at similar but smaller facilities, can accomplish this astonishing output “while using 95% less water than field farmed-food and with yields 75 times higher per square foot annually.”
"“We use aeroponics to mist the roots of our greens with nutrients, water, and oxygen.,” explains AeroFarms. “Our aeroponic system is a closed loop system, using 95% less water than field farming, 40% less than hydroponics, and zero pesticides.”
(from https://weburbanist.com/2016/06/05/worlds-biggest-indoor-vertical-farm-near-nyc-to-use-95-less-water/)