Food miles have become a useful concept for assessing the environmental impact of food production. The concept of food miles can be defined as the environmental impacts of transporting food from producers to consumers. A recent study used the concept to show that 19% of the total emissions produced by food systems are caused by transportation. Naturally, it seems intuitive to think that the options with the fewest food miles are the best ones. However, even the academic who coined the term, Tim Lang, argues “a local greenhouse grown tomato in mid winter is more energy inefficient than bringing a sun ripened one a long-distance. There are trade-offs.” So, is it or is it not sustainable to bring food production into cities? The CITYFOOD project provides an answer by showing that aquaponic systems can meet Berlin’s food demand in a way that is both environmentally and economically sustainable. Its results include a systems analysis showing how scaling-up aquaponics in Berlin impacts its food, water, and energy systems; a cost-benefit analysis showing the profitability of using aquaponics to meet the city’s food demand; and a definition of aquaponics that can help avoid legal and administrative challenges. Gösta Baganz, one of the project’s key researchers, tells us about each result in detail.
The project successfully identified if upscaling aquaponics in Berlin to meet the city’s food demand was a sustainable proposition. Its findings show that by using approximately 370 aquaponic facilities covering 224 hectares, Berlin’s demand for freshwater fish, tomatoes and lettuce could be met whilst saving two million m3 of water. Producing these figures required a detailed analysis of how an aquaponic system impacts a city’s food, water, and energy systems. This was achieved by first identifying the variables within an aquaponics system (shown in the green and blue boxes in Figure 1 below) and then showing how they increase or decrease the demand for food, water and energy. Importantly, the project also identified ambiguous causal relations which cannot be determined by a general model, either because they are too complex or because they need to be analysed on a case-by-case basis (represented by the dashed brown lines in Figure 1). Knowing which causal relationships are ambiguous allows policy-makers at the city-level to know what kind of things can generally be assumed and what kind of things require context-specific knowledge.
CITYFOOD’s work in Berlin shows that specific production conditions in food systems must be valued alongside food miles. Gösta offers two specific reflections from the Berlin case study: firstly, the Netherlands produces 60% of Berlin’s tomatoes, and sustainably replacing this supply would require Berlin’s aquaponics systems to replicate the more efficient greenhouse designs and cultivation practises of the Dutch. Secondly, Almeria in Spain produces about 25% of Berlin’s tomatoes, replacing these tomatoes with ones grown in Berlin requires a sober understanding of regional and global climate conditions. Even though Berlin has a lower level of water stress than Almeria, climate change is already undermining this benefit. Increasingly, Germany is facing the risk of drought in the summer, so conserving Berlin’s water supply may take precedence over localising food production.
CITYFOOD’s work in Berlin shows that specific production conditions in food systems must be valued alongside food miles.
CITYFOOD proposes strategies which optimise production for climate zone advantages be investigated. In this case, a seasonal split in tomato production between Berlin and Almeria might be optimal. Keeping production in Spain in the winter could be mutually beneficial for both regions as it would relieve pressure on their water and energy systems when they are most stressed. Using this seasonal strategy would decrease Almeria’s water stress in the hotter and drier summer months and decrease energy demand for heating in Berlin’s colder winter months.
The last key output of the project was a cost-benefit analysis showing that professional aquaponics in Berlin can be profitable. This analysis identified a scenario which could recover initial investments and start-up costs within twelve years by using about 2,000 m2 of the city’s space for aquaponics facilities. The model case can be made economically viable provided favourable credit conditions are given, direct sales are facilitated, and no major production outages take place. Furthermore, the analysis also identified that there is room for further optimisation by paying attention to fish stock choices, labour conditions, and disease prevention. In terms of implementation, location and how aquaponic facilities are implemented are key factors for success. Additionally, decision-makers being sensitive to market prices and doing research on consumer behaviour and their perceptions of aquaponics were also identified as key issues. Perhaps, one of the most important considerations is that it takes seven years for this option to break even, making endurance a key prerequisite for successfully implementing this model.
It takes seven years for this option to break even, making endurance a key prerequisite for successfully implementing this model.
CITYFOOD’s technically precise definition of aquaponics is likely to make it more viable by clearing up potential legal disputes and technical misunderstandings. CITYFOOD’s definition states that “Aquaponics is a technology that couples tank-based animal aquaculture with hydroponics—involving Microbiological processes -using water from aquaculture for plant nutrition and irrigation.” This definition was useful for sharpening their own assessments and can aid decision-makers in avoiding complications around the labelling of food produced in an aquaponic system. Gösta explains that according to E.U.’s current legislation, food labelled as organic must be grown in a soil-based system. Since aquaponics use hydroponics instead of soil, vegetables produced using it cannot be labelled as organic. On the other hand, some soil-based systems have been labelled as aquaponic systems because they take advantage of what is known as the aquaponic principle: using aquaculture (fish farming) to produce nutrient-rich water for plant cultivation. This creates a dilemma for policy-makers about whether aquaponic systems produce food that can be legally labelled as organic. CITYFOOD offers a definitional distinction that avoids this conundrum by classifying systems that use the aquaponic principle but go beyond aquaponics distinct features of using a tank-based system and nutrient-enriched water as the direct medium for plant growth as trans-aquaponic systems. CITYFOOD’s definitions for aquaponics and trans-aquaponics have already found academic acceptance and have been included in COST Action Circular City’s framework for nature-based solutions. This framework will be widely disseminated, and it will likely see significant use.
Gösta concludes that CITYFOOD’s main achievement was answering the question, should you bring food production into cities? Clearly, the project’s work points to yes being the answer, but it also shows the importance of boundary conditions: the advantages of a production system and its regional climate. In terms of further research, Gösta argues it would be natural to follow up on CITYFOOD’s work by assessing scenarios where tomatoes grown in Spain during the wintertime are used to make highly-concentrated products. This might make sustainable models that use seasonal splits in production more economically viable. After reflecting on this idea, Gösta finishes the interview by reminding us why food miles are still conceptually useful, “transporting [just] Spanish tomatoes to Berlin is basically the same thing as transporting Spanish water to Berlin, Tomatoes are more than 90% water!”