Abstract

Urban food waste in the U.S. is almost exclusively bound for landfills, with significant environmental and the economic consequences. Contrary to this linear flow, cities across the developed world are implementing organics collection programs (OCP) that transform waste into a resource. These systems convert excess food into inputs (e.g. biofuel or soil amendment) for other processes (i.e. food and energy production, water reclamation) thereby approximating naturally occurring closed-loop nutrient systems. However, efforts to address the flow of food waste into landfills have largely focused on technical solutions that alter the waste management systems of provision, largely ignoring the social aspects of food waste generation and source separation. Drawing on the Theory of Planned Behavior and concepts from social marketing research, results from longitudinal repeated-measures experiments indicate that providing supportive infrastructure is necessary for residents to act on their "intention" to divert food waste from landfills. The experiments are also the first to confirm that communicating the new community norms of separation in the context of a new OCP will increase separation behavior. In sum, closing the loop on urban food systems demands transformations of the systems of provision as well as the social aspects of waste systems. This research traces the evolution of organic waste policy on two continents using problem-framing as a lens through which to understand how different characterizations of food waste as a problem (i.e. as one of disposal efficiency, risk management or value recovery) result in different policy responses with varying degrees of linearity in urban food material flows. This dissertation contends that successfully closing the loop on urban food systems will demand new problem-framing that employs systems-thinking at the highest levels of policy-making, transformations of both the systems of provision and social practices, and an understanding of the relationship between social and natural systems (i.e. socio-ecological relationships).

Abstract

Integrated energy and urban mobility systems are key components for achieving cities’ sustainability. Several urban metabolism approaches are emerging as leading tools for quantifying energy consumption and use patterns of resources in urban environments. Examples are the mass balance accounting (or energy-materials flux approach) using several quantification methods such as material flow analysis and life cycle assessment and Odum’s emergy methods. In this research we adapt the extended metabolism model of a city developed by Newman (1999) and the material and energy flow accounting by Sheeri (2002) to assess the future role of electric vehicles, renewable energy use for mobility needs and energy efficiency increases for households living in the city of Aveiro, a medium-sized city of 78450 inhabitants in Portugal. The data used comprised an integrated set of energy, transport, socio-economic and solid waste production/treatment collected at the local and National level as part of the research project COST-TRENDS funded by the Portuguese Foundation for Science and Technology. The analysis of the potential energy mix (energy inputs from different sources) and households’ mobility needs refers to the horizon 2010-2020. Several energy sources were considered: hydric, wind, solar (thermic and photovoltaic) and solid waste (incineration and biogas). Potential accessibility indicators were developed to better convergence towards sustainable mobility objectives, measuring the potential for interaction and exchange of services and opportunities. Different household’s profiles were established to represent consumers’ behaviour. It was found that the above integrated energy system could provide a total of 2,61 MWh/household.year, which represents on average around 38,2% of the total energy needs for households’ daily mobility and 1,2 tonnes CO2/household.year avoided. On the other hand, the replacement of conventional internal combustion engine by battery electric vehicles could allow an energy reduction between 4,7 and 6,1 MWh/household.year until 2020 and a reduction of 1,6 tonnes CO2 /household.year. Fundação para a Ciência e Tecnologia, projeto COST-TRENDs 3 4 12 Em 28 de fevereiro de 2013 foram cedidos os direitos de publicação/copyright à WIT Press,para efeitos da sua inserção na publicação no livro/Book da WIT Press - "Sustainable Development and Planning 2013". DT/NPTS 2013 27 a 29 de maio