Participation at the ISIE conference5 September 2023
11th International Conference on Industrial Ecology (ISIE) Leiden 2023
Dates: 2-5 July 2023
On July 2023, URBAG participated at the International Conference of Industrial Ecology (ISIE) with three presentations. First, Juan David Arosemena presented his research which aims to determine the capacity and environmental impacts of supplying macronutrients such as nitrogen, phosphorus, and potassium from composting organic municipal solid waste. The objective is to meet the urban agricultural nutrient demand of a metropolitan area, considering the environmental benefits of replacing mineral fertilizer while minimizing waste using life cycle assessment. The Metropolitan Area of Barcelona served as the area of study.
Closing the nutrient cycle in urban areas: The use of municipal solid waste compost for peri-urban and urban agriculture
Abstract: Cities need to address food supply and management of organic municipal solid waste (OMSW) amid urban growth. Urban agriculture (UA) has the potential of addressing these issues, by providing local crops fertilized by recovered nutrients from OMSW compost. This research aims to determine the capacity and environmental impacts of supplying nitrogen, phosphorus, and potassium (NPK) from composting OMSW to meet UA nutrient demand, considering the environmental benefits of replacing mineral fertilizer while minimizing waste using life cycle assessment (LCA). The Metropolitan Area of Barcelona (AMB) serves as the area of study, for which official agricultural spatial data and reports from different types of centralized OMSW facilities were analyzed to determine the nutrient demand and the compost supply potential, respectively. The results concluded that the current annual production of 68, 800 tonnes of fresh produce of the AMB requires a yearly total of 769 tonnes of N, 158 tonnes of P, and 592 tonnes of K, currently supplied mostly by mineral fertilizers. Our study indicates that compost from OMSW can potentially supply 7% of the total demand of NPK, given current infrastructures, capacity, and waste collection practices, and up to 21% if the compost production system is increased according to the AMB’s waste management program goals. An LCA was performed to determine the impacts associated to supplying the total yearly NPK demand with mineral fertilizer only and by combining mineral with different compost production scenarios (current and future). Results indicate that a mineral fertilizer scenario has more impacts than when combining it with compost, with significant differences in Mineral Resource Scarcity (33%), Marine Eutrophication (46%), and Fossil Resource Scarcity (78%), when compared to the scenario where 21% of the nutrient need is met by compost. The avoided burdens associated with preventing landfilling and energy recovery from biogas resulted in environmental savings equal to 9% of the total net carbon footprint (Global Warming) of the MSW system in the AMB and 17 times less in Freshwater Eutrophication than what was generated in the mineral fertilizer only scenario, even when including the impacts associated to the compost production in the anaerobic digestion facilities. This study aims to inform policy makers about the benefits of circularity of nutrients by considering their entire life cycle in the city, from waste to crop, to systemically quantify the benefits beyond the waste management facilities and beyond urban agriculture.ISIE2
Gara Villalba presented the Integrated System Analysis of Urban Vegetation and Agriculture (URBAG): an interdisciplinary and participatory decision approach that is geographically explicit to evaluate the design and implementation of green infrastructures in urban environments. It is founded on multi-criteria decision analysis and compares the urban space with and without the GI by employing both exposure and sensitivity analyses. We illustrate the usefulness of URBAG in analyzing the spatial distribution of the impacts of green infrastructure and how it affects the environment and sensitive populations, transferring the scientific knowledge to urban policy and governance for successful GI implementation.
A decision approach to evaluate the design and implementation of green infrastructures in urban environments
Abstract: Cities are implementing green infrastructures (GI) to address societal challenges such as climate change mitigation, natural disaster adaptation, and food security. However, we lack the tools and understanding to systematically address the trade-offs and synergies that GIs can create in urban environments (e.g., a GI implemented for improving urban resilience can create or exacerbate inequalities). We propose the Integrated System Analysis of Urban Vegetation and Agriculture (URBAG): an interdisciplinary and participatory decision approach that is geographically explicit to evaluate the design and implementation of green infrastructures in urban environments. It is founded on multi-criteria decision analysis and compares the urban space with and without the GI by employing both exposure and sensitivity analyses. The framework has four phases: 1) Defining the aim, scope, and scale of the assessment (2) Selecting criteria and indicators that line up with the aim of the assessment for the GI, (3) calculating the indicators, and (4) analyzing and determining the impacts according to the weights selected by relevant stakeholders. To illustrate URBAG, we assess various scenarios of peri-urban agriculture in the Metropolitan Area of Barcelona with the overall aim to increase local crop production, restore abandoned lands, and reduce heat wave effects. For the assessment, four criteria were analyzed: (1) Heat Conditions and Exposure, (2) Spaces for cultural and recreational experiences, (3) Food self-sufficiency and (4) Environmental impacts of fertilizer use. The indicators were temporally and geographically determined based on atmospheric model simulations and life cycle assessment. Results showed that an increase in agricultural areas can reduce daytime temperature during heatwaves (up to 1.7ºC), and how these reductions where partially located in areas with large elderly populations, a vulnerable group to heat exposure. The accessibility to green spaces for recreational experiences was also improved by the increase of agricultural areas, but most of these new accessibilities were not located in sensitive areas with high population density. In the case of food self-sufficiency, the scenario with the greatest agricultural area is expected to meet up to 12.8% of the fresh produce demand of the city, while the crop production location does not match the areas with the highest demand of food within the city. Finally, freshwater eutrophication associated to increased fertilizer use due to more agriculture proved insignificant because of the very low value of P equivalent emitted due to short river segments, but the biodiversity indicator points out a significant exposure in already mid-low biodiversity river basins. This case study illustrates the usefulness of URBAG in analyzing the spatial distribution of the impacts of green infrastructure and how it affects the environment and sensitive populations, transferring the scientific knowledge to urban policy and governance for successful GI implementation.ISIE_Villalba2
Angelica Mendoza presented a poster entitled “Can circular strategies contribute to sustainable food production in cities? The case of nutrients circulation for urban agriculture in a metropolitan area”. This work focuses on nutrient circulation strategies for urban agriculture using prospective-regionalized Life Cycle Assessment. Angelica evaluates the direct and indirect impacts such as climate change and eutrophication of potential future expansion of urban agriculture.
Can circular strategies contribute to sustainable food production in cities? The case of nutrients circulation for urban agriculture in a metropolitan area
Abstract: Cities will require several transformations to become more resilient, sustainable and multifunctional systems, especially in terms of provision of food. In this study, we attempt to determine to what extent circular strategies can help in the sustainability of future food production of metropolitan areas. In particular we focus on nutrient circulation strategies and further assess theoretical transition scenarios for urban agriculture (UA) using prospective-regionalized LCA integrating knowledge from previous studies on urban land use, nutrients recovery from municipal sources, regionalized LCA of UA and prospective LCA. We apply this approach to the Metropolitan Area of Barcelona (AMB) to evaluate the direct and indirect impacts such as climate change and eutrophication of potential future expansion of urban agriculture as proposed by the urban master plan using the functional unit of yearly total crop production. The various nutrient circularity scenarios proposed include the use of struvite from waste water treatment plants and compost from domestic organic waste. Results show that in light of future resource restrictions, circular nutrient strategies will have an increasingly important role in cities to supply nutrients for urban crop production while reducing impacts associated to UA. However, they need to be considered in terms of their life cycle as alternatives to mineral sources of nutrients and as a reduction in waste management to see the environmental benefits of UA.Angelica_Poster_ISIE2023_Leiden