Imagine the modern cities of London, New York and Hong Kong. They’re sleek, polished and impossibly tall. Their skyscrapers dominate the landscapes around them, piercing the gloom of night and sheltering thousands of people and businesses as our urban populations continue to swell with no sign of stopping.
Skyscraper building is an obvious answer to a growing problem. When space becomes scarce, we simply build up, creating the infamous and glamorous high-rise buildings that epitomise contemporary living.
By the year 2050, the world population is set to have increased to nearly 9 billion people, with 80% of them living in urban areas. With a population set to become so big and so dense, one question is becoming more and more important. How are we meant to feed them all?
The answer to that question could in fact be held within those very same skyscrapers. Growing and raising enough food for the current world population takes up time, resources and ultimately, a space as large as the South American continent. In order to grow the adequate amount of food for the estimated extra 2 billion people by 2050, extra land the size of Brazil will have to be found somewhere.
Does the new land have to be spread out flat on one level though? Perhaps not, according to Dickson Despommier, an ecologist for Columbia University in New York.
Since the late nineties, Despommier has been championing the idea of vertical farming – growing crops all year round in multi-storey urban buildings, making use of the skies above us.
In his book, The Vertical Farm: Feeding the World in the 21st Century, Despommier envisions modern cities that are a blend of glass and green. As a New Yorker, he himself has seen the amount of waste produced by just one city and the vermin that it entices. But with the right thinking, he argues that cities like New York could cut down on the reliance of food imports as well as recycle and reuse the food waste that it produces.
How would it work?
Vertical farming would have to include numerous complex systems including water purification, energy production, waste disposal and environmental controls. It would not be an easy system, but Despommier and other fans argue that they are necessary and in the longer term, are better for the planet.
What it wouldn’t necessarily have to rely on, however, is the use of soil, which over time can lose nutrients if improperly handled, requiring the use of fertilisers that can damage water supplies. They could instead, make use of hydroponics or even aeroponics.
These growing techniques do away with soils entirely; plants are instead grown in nutrient rich waters. The vitamins and minerals that are normally found in soil are instead put into water. With hydroponics, the plant roots are suspended in the liquid, and with aeroponics, the nutrient rich water is continuously sprayed in a fine mist over the roots.
Soilless crops sound like the brainchild of science fiction, but it has actually been carried out several times in human history. The beautiful and fertile Hanging Gardens of Babylon, one of the ancient wonders of the world, are believed to have used a form of hydroponic farming in order to cope with the dry, arid landscape. There are also records of the Aztecs and Chinese using similar methods in the 12th and 13th centuries, respectively.
Despommier suggests that by treating and reusing the wastewater that is produced by a city, hydroponic and aeroponic crops can be continuously grown, meaning that seasonal produce becomes less of a problem.
The issue of pests and diseases could also be managed in the vertical farming environment. The introduction of a pest can blight entire crops, driving up food prices and ruining the work of farmers. Highly valuable or vulnerable crops would be controlled and sealed off from the outside world in order to reduce the exposure to outside pests and problems. The result of this rigorous system would be multi-beneficial, providing food that is free of pesticides for the population and also reducing the ecological damage that can be caused by the overuse of chemicals.
Critics of vertical farming have questioned how plants can be adequately exposed to the UV rays of the Sun in order to grow, as the energy is necessary for their photosynthesis. In order to tackle this problem, the plants could either be rotated upwards so that they all get an equal time in the sun, or they could be kept entirely indoors under the constant light of UV bulbs, which would maintain the appropriate light levels for all the crops.
This method, along with other systems within the buildings, however, would require an extraordinary amount of energy, especially as UV bulbs are still not considered to be energy efficient at this point in time. This raises doubts about the sources of energy for the farms, as well as the cost of all the required systems.
Has anyone actually tried vertical farming?
Singapore is one of the most urbanised countries in the world, and has to import over 90% of all its food. This makes it a prime location to trial out vertical farming in order to feed its 5 million inhabitants. A company called SkyGreens has set itself up in the heart of Singapore, creating what it calls ‘A-Go-Gro’, a vertical growing system where plates of Chinese greens are stacked and slowly rotate upwards via a conveyor belt, ensuring that all the plants receive equal amounts of light.
A Japanese company, Nuvege (pronounced ‘new veggie’), operates an indoor farm in Kyoto. Instead of rotating plants towards the sun, this windowless facility uses LED lights that are tuned to the chlorophyll molecules within each plant. This method however, fuels criticism about electricity bills, though the farm itself successfully produces 6 million lettuces every year, selling the produce on to Disneyland Tokyo and Subway.
Meanwhile in America, another company called Green Spirit Farms have opened the world’s largest vertical farm. It’s only one story high, but the 3.25 hectares of space in the former industrial unit will be able to house over 17 million plants, separated into high yielding crops including spinach, tomatoes, kale and strawberries.
In London, one of the world’s most populous cities, vertical farming is also taking off, making use of aquaponic technology. The company, GrowUp Urban Farms, designed the GrowUp box, a crowd funded ex-shipping container, growing over 300 salad plants in a greenhouse on the top, whilst conversely farming fish underneath in the shipping container. This method, using the omnivorous tilapia fish, means that the waste from the fish is used to feed the plants, before it is recycled and pumped back down to the fish, who are fed a small number of the plants, as well as plant waste from other areas such as the brewing industry. Although it is a small example, being nowhere near the scale of the American vertical farm, it is showing promise, having been showcased at the Chelsea Fringe festival.
Feeding a much more populated world is going to prove a challenge in the upcoming decades, but with the right level of work and technological advancement, the agricultural future could have a radically different face by the mid 21st century. Vertical farming, while seen by some as a miracle answer to crop growing, will not be without its problems, particularly when it comes to costs and the use of energy to power the farms themselves.
It seems therefore, that as farming becomes more and more advanced, so do the problems. From what we have seen though, vertical farms are indeed growing and are showing good levels of success. So the dream of Dickson Despommier, the cities of glass engulfed in greenery, may become a more common sight within the next generation.