Vertical Farming: Addressing Urban Food Needs While Navigating Environmental Challenges
Cities continue to grow. According to the UN, by 2050, two thirds of the world's predicted population (some 6.7 bn people) will be living in cities.[1]
Doesn't it make sense to produce the food these people require in the cities where they live?
Our food system generates a third of the world’s greenhouse gas (GHG) emissions.[2]
While according to a recent study,[3] the amount of Greenhouse Gases (GHGs) emitted in the course of transporting the food is low compared to other factors in its production it still not negligible.
In a nutshell, buying a local steak is just as bad for the environment as buying an Argentinian one. However, there are other factors contributing to the environmental footprint of food production, such as processing, packaging, and retail.
One way of addressing these issues is vertical farming.
One way of addressing these issues is vertical farming, i.e. the production of food in vertically stacked shelves.
This is, of course, impossible in traditional farming, as the uppermost shelf would cast a shadow on the lower shelves.
In vertical farming this problem is circumvented by artificial lightening, which brings us to a central aspect of vertical farming, namely controlled-environment agriculture (CEA).
CEA is a set of technologies that aim to maximise yields while minimising system inputs. Here, system inputs refer to anything that makes a plant grow and bear fruit: sunlight, water, and nutrients.
Here's a quick overview of some of the technologies used:
Hydroponics [4]
Growing plants in water instead of soil. The nutrients normally provided by the soil are added in the form of aqueous solutions. Physical stability may be provided in the form of inert gravel.
Aeroponics [6]
Growing plants in air, instead of water. The necessary water and nutrients are supplied in the form of sprayed mists. Technically, aeroponics is a sub-form of hydroponics.
Aquaponics [5]
Refers to the farming of aquatic animals such as fish or prawns.
As everything, there are pros as well as cons.
Pros include:
Because these systems are highly optimised it is possible to obtain many times the yield that could be obtained in traditional agriculture. That is in terms of both surface area and mass of soil used. In addition, it is possible to obtain more yields per year than in traditional agriculture. The controlled environment aspect also protects the harvests from pests and/or invasive species.
Another advantage is that it is possible to farm veggies in built up areas, e.g. in disused factories or warehouses. In addition, vertical farming can be done on any scale from warehouses down to a standard shipping container.
A social aspect is the possibility of running smaller scale vertical farming units as neighbourhood projects which may add to social cohesion.
Cons include:
The disadvantages associated with CEA are two-fold. The first set of problems is economic in nature. Vertical farms are both expensive to set up and expensive to run. The second aspect is environmental.
CEA units are somewhat difficult to set up, a task that requires specialist knowledge, and the people skilled in the art know their worth. The reason why CEA units are expensive to run is that while in traditional agriculture sunlight and rain come for free, here their provision requires energy, a) for pumping water, lightening and suchlike, and b) for transporting the necessary seeds and fertilisers to the vertical farm, i.e. from some industrial estate into the cities.
The very aspect that makes CEA a potential winner is also one of its greatest problems, namely that excluded and isolated farms do not provide a habitat for insects an other animals. In these times of mass extinction of insects this is as serious problem.
The absence of insects also causes another problem: Plants which rely on pollination for the production of seeds (and thus fruit) cannot be grown efficiently in CEA units. Plants like lettuce and peppers are suited for growing in CEA, while apples and blueberries are not.
All in all, CEA is still a young technology. As with all technologies this is not a silver bullet (nothing ever is!) but it is worth investigating and using.
If you would like to know more about vertical farming, listen to our podcast (Leaders in sustainability - episode 22): Podcast | Leaders in sustainability | Trianon Scientific Communication (science-by-trianon.com)
01) https://www.weforum.org/agenda/2014/08/six-megatrends-will-shape-future-cities/, last accessed 2023.09.13
02) https://www.nature.com/articles/s43016-021-00225-9/, last accessed 2023.09.13
03) https://ourworldindata.org/food-choice-vs-eating-local/, last accessed 2023.09.13
04) https://en.wikipedia.org/wiki/Hydroponics/, last accessed 2023.09.13
05) https://en.wikipedia.org/wiki/Aeroponics/, last accessed 2023.09.13
06) https://en.wikipedia.org/wiki/Aquaponics/, last accessed 2023.09.13
07) https://en.wikipedia.org/wiki/Aeroponics/, last accessed 2023.09.13
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