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Bottom-up modelling of urban food-systems and their environmental impacts

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posted on 09.10.2020 by Data Steward
The current food-system is highly unsustainable as it is responsible for up to 50% of all anthropogenic environmental pressure. Therefore, there is a need to transform the current food-system, in particular the demand-side. Cities form the agglomeration of food consumption with limited capacity for food production. Addressing urban consumption and the inherent environmental impacts are considered key factors for climate change mitigation. In order to develop sustainability strategies for a city, a baseline assessment of urban food consumption and environmental impacts is required. A bottom-up approach is suggested to be suitable for consumption-based accounting of urban food-systems. However, there is no consensus on this approach nor the implementation of it due to a lack of modelling experience and data on urban food-consumption.

The aim of this thesis was to explore the bottom-up modelling approach for consumption-based accounting of urban food consumption. Almere was used as a case-study to explore how a robust bottom-up model can be designed. Hereby, the study aimed to contribute to the debate on suitable modelling approach and the otherwise lack of urban food-systems studies. Lastly, it aimed to provide recommendations for Almere to develop sustainability strategies.

The hybrid UM-LCA method was used to develop a bottom-up model for Almere. Dietary data was used as a basis to model the annual consumption of the city and therefrom the associated food-system was modelled. Primary data acquisition on the food purchasing behaviour of the citizens of Almere was done by means of a survey (N=663).

The annual consumption of Almere is estimated at 156 k tons of food per year. This includes food that is eaten and wasted by retail, food-services and households. The environmental impacts on air, water and land were modelled for the food-system of Almere by using three indicators. The Global Warming Potential (GWP) was estimated between 351 - 411 k tons CO 2 eq. emissions per year. Freshwater Eutrophication Potential (FEP) was estimated between 153 - 169 tons P eq. deposition and the Agricultural Land Occupation (ALO) between 174 - 189 km 2 per year. However, further research is recommended for both the FEP and ALO to increase reliability. Production and processing of the food were responsible for the largest share of environmental impact for each indicator (≥86%). The food categories with the highest impact were meat, dairy and beverages. Therefore, it is recommended to encourage dietary shifting in Almere. Besides production and processing, a considerable share of environmental impact was generated by the distribution of food to suppliers (15% of the GWP). In particular, air freight had a significant contribution and therefore it would be recommended to avoid this mode of transport. Additionally, grocery shopping had a considerable impact as the majority of travel was done by motorized modes, mainly cars. It is recommended to decrease this by encouraging modal shifting to bike and walking. Currently, only 0.85% of the consumed food is purchased directly at the farmer. Further research into the flows of regionally produce through other retailers is needed to determine the total share of regional production of Almere's consumption.

In general, it is relevant to explore the opportunities to receive consumption data from retailers, as dietary data is considered an essential element in bottom-up modelling of urban food-systems. It can be concluded that bottom-up modelling of food-systems is challenging but provides much-needed insights to start the transformation towards a sustainable food-system.



TU Delft, Wageningen U&R

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Prof. Dr. Ir. Eveline van Leeuwen

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Dr. Ir. Ellen Slegers