- Vertical farming
Vertical farming promises a mini-revolution in agriculture. It is about growing, as the name suggests, crops in the third dimension, thus using less land, up to 10 to 20 times less, by stacking plants on racks, see photo.
This is done in a controlled environment (in a building) which provides the additional advantage of pest control (hence much less use of pesticides) and limited water usage (2 to 4 litres of water per kg of vegetable, much less than what is normally required, that is 50 to 100 times less).
Not everything is suitable for vertical farming (bananas does not lend easily to stack them up…) but many vegetables, from cabbages to peas, tomatoes to salad are perfect. Wheat, as an example is not a good choice. It takes quite a long time to grew wheat and providing illumination over all that period would translate in high cost (some 11$ for a loaf of bread!). On the contrary, plants that grow fast are ok (like salad) where you can generate basically a continuous harvest.
The controlled environment makes possible several harvests per year (like greenhouses). Sensors and computer controlled sprinklers can optimise the use of energy (although this remains higher than growing in an open field where the only energy needed is the one from the Sun).
Clearly vertical farming is not going to replace normal farming but in certain areas, like where there are old buildings – old factories in cities it can make economic sense.
There are several studies aiming at creating affordable economic conditions for vertical farming, e.g. by efficient use of light, since light is an essential component of vertical farming. Using LED light decreases the energy required and LED light can be customised to the need of specific crops by emitting at the right wavelength used by the plants (most of Sun light goes wasted in terms of energy since plants use a subset of the wavelengths of sunlight). Additionally, LED does not generate heat (very very little) and therefore can be placed very close to the leaf, optimising the use of light.
Urban Crop, as an example, is testing ultraviolet light in its completely automated trials of vertical farming. UV has the added advantage of killing certain plants pests.
AeroFarm, is another company that is already in business with what is probably the largest vertical farming complex in the world, producing close to 800 tons of leaf green per year with 22 harvest per year (watch the clip). Both Urban Crop and AeroFarm are using hydroponic systems and they recycle the water to keep consumption at a minimum.