Is Vertical Farming Really the Future of Agriculture?

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.

Everything you said is right. It’s still more efficient to use the suns energy and then distribute the leds than to directly try to use the suns light. Modern hydroponic grow led controllers can adjust the wavelengths as the plants grow

For instance, it may be cheaper to grow tomatoes in Florida rather than in Manhattan, but in order to get a Florida tomato to Manhattan, the tomato itself has to be a bruise-resistant variety with predictable shape and size, harvested while green, and artificially ripened with ethylene gas. The tomato grown in Manhattan and eaten in Manhattan can be one of those bulbous, deeply-pigmented heirloom varieties, harvested while ripe, and eaten within hours, bursting with actual tomato flavor.

The tomato grown in Florida must be grown during the tomato-growing season for Florida. The vertical farm tomato can be grown as easily in the local regular season or for harvest in mid-February.

Rather than solar panels and LEDs, the rooftop could support advanced deck prisms that pipe natural sunlight through optical fibers. That alone is likely insufficient to meet the lighting needs of the plants, but it would be more efficient, and a watt of natural sunlight is a watt that you don't have to pump through the LEDs. The true advantage of LEDs is not in energy efficiency, but in wavelength tuning. The farming LEDs don't even produce the green light that is usually reflected by plants. Also, the red-blue balance can be altered to produce different effects on the plants. Blue light produces growth, and red light influences the plant hormones for germination, rooting, etiolation, and flowering. Tinkering with the red-blue schedule could allow the farmer to grow larger heads of lettuce or cabbage without bolting.

And, as you mentioned, hydroponics and aeroponics are more water-efficient.

Vertical farming will never entirely replace land-surface farming, but it will complement it. And it will allow farming underground, and in non-terrestrial habitats.