Cultivating plant or animal life within skyscrapers - What is your opinion of vertical farming?

“Vertical farming is a concept that argues that it is economically and environmentally viable to cultivate plant or animal life within skyscrapers.

Many of vertical farming’s benefits are obtained from scaling up hydroponic or aeroponic growing methods. It is estimated that by the year 2050, close to 80% of the world’s population will live in urban areas and the total population of the world will increase by 3 billion people. A very large amount of land may be required depending on the change in yield per hectare. Scientists are concerned that this large amount of required farmland will not be available and that severe damage to the earth will be caused by the added farmland. Vertical farms, if designed properly, may eliminate the need to create additional farmland and help create a cleaner environment.”

http://en.wikipedia.org/wiki/Vertical_farming

How powerful is this concept in your opinion? Can it help save our rain forests?