Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in
vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«.
35
The potential of aquaponics for food production in the
cities of the future
Ranka Junge and Andreas Graber
ZHAW Zurich University of Applied Sciences, Institute for Natural Resource Sciences
Gruental, CH-8820 Waedenswil, Switzerland (ranka.junge@zhaw.ch)
Abstract
Urban farming is becoming a buzzword nowadays. It started as a grassroots movement, and
entered the political agenda since early 2000. To establish urban farming on a sustainable scale
beyond the pilot projects that seem to flourish in nearly every city with some self-respect, several
components are necessary: social, economic, ecological. Visionary and provocative schemes such
as Vertical farms (Despommier, 2009, 2010) and utopian renders by architects like Callebaut (DD
14 New Worlds, 2005) are widely disseminated and evidence public interest, but do not provide
practical tools to address the situation with the technologies that are available now.
While recent accentuations seem to focus on social aspects, the scientific base for these
endeavours should be strengthened as well. If food is to be grown in the city, it should be of high
quality, not loaded with pollutants of both urban and agricultural origins. Innovations are required
that simplify successful operations in urban gardening and enable cost-effective urban farming,
while making these products safe for human consumption: new planting techniques, new varieties
of produce, biological pest control, irrigation techniques, and integration with existing building
infrastructures. Aquaponics has the potential to contribute to all these aspects.
Key words: Urban farming, Building integrated agriculture, Aquaponics, Zero Emission
Buildings
1
Introduction
Human society in the 21st century faces many challenges. Growing urbanization and a growing
population lead to increasing resource consumption. Between 2011 and 2050, the world
population is expected to increase from 7.0 billion to 9.3 billion. At the same time, the population
living in urban areas is projected to gain 2.6 billion, and by 2050 70% will live in the cities. Thus,
urban areas worldwide are expected to absorb all the population growth expected over the next
four decades, and continue to draw in rural population (United Nations 2012). Climate change is
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in
vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«.
36
predicted to cause more environmental stressors in the future, while food production needs to be
intensified. The required transition will require an increased flexibility of the urban environment,
more sustainable use and re-use of natural resources as well as the adaptation of new infrastructure
systems (Schuetze & Thomas, 2011).
In order to assure human health and wellbeing, the resilience of our food supply systems to cope
with future hazards has to be strengthened. To build a nexus between water, energy and food we
will need cooperation between different sectors, e.g. sanitation, drinking water supply, urban
design, architecture, agriculture, and provisioning of energy.
Cities receive inputs, which accumulate and grow, are cycled, attenuated and transformed within
the system, and produce outputs (Figure 1). The urban metabolism can be linear, cyclic or in
between (Rogers 1997, Daigger, 2009). To enhance the resilience of cities, the flow-through
economy should be changed to cycling systems, wherever possible.
2
Integration of food production into the cities
(Re-)integration of food production into the city is a necessary element to achieve the circular
metabolism. While urban agriculture cannot supply all of cities’ needs, there is inherent
environmental logic and resilience within recognised historic models incorporating urban food
growing such as those by Johann von Thünen (1826, cited in van der Schans & Wiskerke 2012)
and Howard (1902).
Food grown in the vicinity of the consumers will also reduce the dependency on transport of
goods (“Food Miles”, Paxton 1994), energy and consumables. It will contribute to improved
health (Rex & Blair, 2003). Plants provide ecosystem services for the city (enabling nutrient
recycling, mitigating urban heat island effect, reduce storm water runoff and food transport needs)
and enhance its living quality. Sustainable city farming can produce excellent quality food, thus
contributing to public health. The water and nutrient demand can partly be met by source-
separation of domestic greywater, treated on-site and reused for irrigation, and by rainwater
harvesting.