Sustainable city

As described in my previous posts, the terrifying disasters caused by human ambition (ranging from petroleum production to over population) and their impact on natural resources such as water, air and agricultural areas causes huge risk to the survival of the human population due to famine. Whilst bioremediation is one of the alternatives to decontaminate part of the damage caused in natural environments, hydroponics are a method of crop production which neither use pesticides nor soil as a substrate.


Before talking about this innovative system that is already underway and increasingly developing more and more, we should know that this project was already used by different ancient civilizations, some of which we are already aware of, we just never considered them as examples of hydroponics. The most well known would probably be the Hanging Gardens of Babylon or that the floating gardens of the Aztecs in Xochimilco. So when these civilisations were confronted with natural disasters such as floods, their crop yield was able to withstand these pressures and supplied the populations with necessary food, however flooding was not to the scale that we now face as a result of climate change. Ultimately it was the Ancient Greeks who defined hydroponics as aquatic work.

Hidro” (water) + “pono” (work) = water work

In 1865 and 1895 the German Von Sachs and Knop discovered that plants need certain nutritional elements to develop without the need for soil; this was supported by the American Gericke during World War II, who was able to supply fresh vegetables using hydroponic systems.

In my previous posts I mentioned about the reduction of land which is fit to be used for agricultural purpose as a product of pollution, mainly due to fossil fuel production. In the same way, the uncontrolled spread of urban areas has also decreased the amount of fertile land available to dedicate to food production registered as arable or agricultural land. According to the FAO, in 2050 the world population will increase to 10 billion of which 70% of people will live in urban areas. Whilst clearly land cannot be preserved over a need for housing a growing population, the CO2 and waste generated in these urban areas can be used to cultivate plants using the hydroponic method.

First, the substrate depends on the species to be developed and what vegetal material is sown (seeds, stakes, tubers, etc.), as well as the irrigation program and plant size.

The sutrates to choose are within two large groups:

Substrates with high cation exchange capacity (CIC) are more stable in the face of variations in the hydric potential (pH) and the electrical conductivity of the nutritive solution (EC), for example peat, coconut fibre, vermiculite.

The low capacity cation exchange (CIC) substrates are very sensitive to changes in pH and EC, among the most used are perlite, sand, rock wool.

Benefits of this floorless system:

Food yield would increase from 3 to 10 times in a space reduced to arable soil, and with a growth rate that would double the development of a plant in soil, therefore harvest time is reduced and the final product has an increased nutritional value. Since no soil is needed they can be developed in a controlled environment such as in interiors of buildings where the weather would not be a determining factor in the rate of food production, water can be used up to 90% more efficiently in a well-managed hydroponic system, no weed or pest control chemicals are needed.

Hydroponics is a solution that will take advantage of CO2 emissions and waste from large cities to turn them into where each building turns into vertical farms and high rise food factories.

This achievement will require a lot of collaboration of knowledge of technology, architecture, engineering, agriculture, water, waste, science, among others. An excellent example of this is the Swedish company Plantagon which initiated a project in Linköping in 2009 and still developing their hydroponic infrastructure to build the first city which holds a symbiotic system combining municipal infrastructure such as cooling, heating, bio-gas, waste, water and energy with food production.

Plantagon design

This company, apart from producing food in buildings, promises that it will turn its buildings into the lungs of the cities, (the Amazon’s current purpose,) by making use of CO2 emanating from the city to include food growth and returning pure air to its inhabitants.

Plantagon design

The Plantagon company has specialised in the infrastructure of vertical vegetable agriculture in urban areas. With the help of several partners such as Sweco, Plantagon plans to develop solutions for the benefit of energy waste, excess heat, CO2, waste and water. With this greenhouse of the future, Plantagon would be able to create an International Center of Excellence for Urban Agriculture in Linköping and provide food for its population not just by making use of the land (as this is dedicated to buildings), but literally making use of the buildings.

Plantagon intends to produce 500 tonnes of crops every year in each building façade which reaches 60 meters high.

Their idea is fascinating and proposes a marvellous solution, but it will take years to create. It is necessary to find or develop such a solution at a similar rate to which fertilised land is disappearing if food is not to be scarce. Hydroponics proposes a solution to the centuries of problems as sung by John Lenon, “imagine no possessions (…) no need for greed or hunger”. Thanks to the leading example of Plantagon, it is in the hands of the world’s leaders.

Imagine a world full of sustainable cities where they make use of all their waste and can grow food in an intelligent way in relation to resources, making use of the city’s infrastructure.

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