By 2050 the United Nations predicts that 86% of the people in the developed world will live in cities. That makes for pretty crowded cities and an awful lot of people to feed. Will traditional farming practices be able to meet demand in this situation? Is there enough usable, uncontaminated land? Water? How will we adapt to changing weather patterns and the threat of disease? How can we maximize space use, water usage and decrease global movement of food?
One answer may be for all of us to eat and waste less. Almost 50% of the total amount of food thrown away in the UK comes from our homes. We throw away 7 million tonnes of food and drink from our homes every year in the UK, and more than half of this is food and drink we could have eaten (lovefoodhatewaste) – to me this is ridiculous (but that’s for another blog and so is the ‘diet market’ we consume far too much then pay over the odds to consume more products to “help” us lose weight).
A more realistic answer could be hydroponic, aeroponic or aquaponic vertical farming.
The picture below gives a good representation of what it is about and as you can see it involves pretty high tech soil-less systems, where the plant roots are in trays of nutrient enhanced water (hydroponics) or mist (aeroponics). Most of the crops being grown are salads, leafy greens, herbs and fruits such as strawberries. The environment is highly controlled for humidity, water usage, light levels and temperature. Pesticide and herbicides are not required as the biosecurity is closely monitored.
Redundant buildings, such as warehouses are already being used. Could we go ever higher on office roof tops or residential flats?
One example is the Verticrop made by Valcent, a company based in Texas. A hydroponic-farming system grows plants in rotating rows, one on top of another. The rotation gives the plants the precise amount of light and nutrients they need, while the vertical stacking enables the use of far less water than conventional farming.
Not so far from home, Paignton Zoo has gone down the Verticrop route to feed the animals; the zoo will grow a whole range of herbs such as parsley and oregano, as well as leaf vegetables like lettuce and spinach, plus a range of fruits such as cherry tomato and strawberry. The ‘in-mates’ crunch their way through about 800 carrots a day and approximately £8,000-worth of fruit per month.
Other systems rely on all artificial light – using LED’s (to minimize cost and power usage) of different wavelengths, such as infrared. These can mimic different times of the day, sunset, sunrise and can manipulate when the plant goes into the flowering period, required pollination and fruit setting. Plants are being grown faster and with shorter periods to fruit ripening than plants grown outdoors.
Farms also recycle the water, for example, Grow Up Urban Farms in London recycle the water using aquaponics in which fish and plants are farmed interdependently. The fish ‘poo’ provides the nutrients for the water used on the plant, the plants take up the nutrients for growth and in turn effectively filter the water, then the clean water is recycled back to the fish.
But how are plants pollinated? By hand? I heard an interesting fact at the Spring Bee Convention and can’t quite remember the figure but due to the decline of bees the majority of apple flowers in China are pollinated by hand! Pollen is also collected by hand for distribution across China for further hand pollination.
Then there is aeroponics, growing plants in a mist so further reducing water usage. I would like to know the cleaning regimes and the use of water and chemicals in washing? Or do the totally controlled plant husbandry and growing conditions mitigate the need for this? Is all the air filtered and water cleaned? O’Hare airport in Chicago now has such a system in place to provide some of the restaurants on site.
But vertical farming is not just for food production…
The NewScientist reported that Vertical farms are also being used by the US Defense Advanced Research Projects Agency; an 18-storey vertical farm in College Station, Texas, to produce genetically modified plants that make proteins useful in vaccines. Also in Japan, the tsunami has greatly influenced their vertical farming habits as so much of the land is radioactively contaminated (see ‘A new industry born from the distater’ for more information).
Of course this all comes at a power cost, so the use of solar panels and AD plants to digest waste are being used to offset this and generate power and heat. Which crop you grow impacts the waste generated, water use and nutrients. Leafy veg and salads will produce less waste as the whole crop is sold as opposed to a fruiting crop where you will still have the plant to dispose of at some point.
I would like to see an energy mass balance taking in to account all the cleaning stages, what happens to the water is not recycled? But if it is being done commercially it must stack up…..quite literally! Flavour wise – Warm sun-ripened strawberries versus LED ripened strawberries? That said they can’t be much worse than the usual supermarket offerings, picked barely pink and shipped across the globe so we can eat them year round.
Blog post by Jane Yardley