Land is cheap but we're running out of it in a lot of places. We need to stop razing forests to make more farmland, and we need 100% more calories by 2050 to feed the world, and yields are only going up by 2% / year over year, which won't even come close to 100% growth in the next 30 years. https://www.washingtonpost.com/news/wonk/wp/2013/07/01/this-...
All that means that the vast amounts of land required for field production are going to get more expensive. The way I've seen folks pitch vertical farming is as a member of a diverse portfolio of food production investments. It is not going to replace field agriculture, especially of cash crops, but it might free up some field space by moving vegetable and insect production off the land we already have.
> 2) The sun is free and electricity isn't cheap. Putting plants indoors and then buying electricity to create light is going to be expensive compared to using the free sun. (The absurdity of putting solar panels on a roof to make electricity to beam LEDs on plants, losing 90% of the energy along the way, shouldn't be lost on anyone.)
Absurd indeed, but I think the argument that you could just use the sun has the situation backwards. Indoor and vertical farming is about reliable quality that comes from control, and to get that control without spending too much, you need extreme density to keep rent and HVAC costs low. To get extreme density you need to go vertical and stack plants, and sadly, the sun only shines in one direction instead of nicely in each aisle/shelf. You can use something like the Zipgrow tower in greenhouses with the sun only (http://www.zipgrow.com/hydroponic-farming/) , but most people can make more money by going indoors and denser. You spend the extra on electricity, you grow vertically and higher, and you have lower labour costs from less walking about. Solar is also not the only renewable energy source that could power LEDs -- much of the farm land where I grew up is speckled with wind turbines and at night when vertical farm lights are on all my area's energy is provided by nuclear.
> 3) Shipping is cheap. It may make us feel good that a salad's greens were created on a roof-top in Brooklyn, but using some of the most expensive real-estate on Earth to save a few cents on shipping is beyond economically irrational.
Brooklyn rooftops are for amateurs. The successful vertical farms are all in the peri-urban areas right next to the grocery distribution systems where land is pretty darn cheap and transport costs are super minimal. It doesn't make any sense to use the most expensive real estate on earth without a doubt, but the big boys don't.