Urban areas often face versatile stressors (e.g., food security, congestion, energy shortage, water pollution, water scarcity, waste management, and storm and flooding), requiring better resilient and sustainable infrastructure systems. A system dynamics model (SDM), explored for the urban region of Orlando, Florida, acts as a multi-agent model for portraying material and energy flows across the food, energy, water, and waste (FEWW) sectors to account for urban sustainability transitions. The interlinkages between the FEWW sectors in the SDM are formulated with multiple layers of dependencies and interconnections of the available resources and their external climatic, environmental, and socioeconomic drivers through four case studies (scenarios). The vital components in the integrated FEWW infrastructure system include urban agriculture associated with the East End Market Urban Farm; energy from the fuel-diverse Curtis H. Stanton Energy Center; reclaimed wastewater treated by the Eastern Water Reclamation Facility, the Water Conserv II Water Reclamation Facility, and stormwater reuse; and solid waste management and biogas generation from the Orange County Landfill. The four scenarios evaluated climate change impacts, policy instruments, and land use teleconnection for waste management in the FEWW nexus, demonstrating regional synergies among these components. The use of multicriteria decision-making coupled with cost-benefit-risk tradeoff analysis supported the selection of case 4 as the most appropriate option as it provided greater renewable energy production and stormwater reuse. The SDM graphic user interface aids in the visualization of the dynamics of the FEWW nexus framework, demonstrating the specific role of renewable energy harvesting for sustainably transitioning Orlando into a circular economy.

The paper aims to understand the impacts of the spatial and temporal diffusion of Anaerobic Digestion (AD) on the Water Energy Food (WEF) nexus and to quantify the associated environmental, social and economic benefits. Contemporary tight carbon reduction targets urge the need to deploy renewable energy technologies however due to interdependencies across the WEF nexus, various technologies are beneficial for some but not all sectors. This paper quantifies the impacts of future possible AD technology diffusion choices on the environment, society and economy. This can aid decision makers to identify the potential consequences of various AD alternatives within the next three decades. The study considers an integrated WEF nexus approach and accounts for the interdependencies within the nexus. This was done by developing an Agent-Based Model (ABM) and simulating the relations between the main players within the nexus, thus examining the upscaling of AD diffusion and its consequences for water consumption, energy production, transportation, landfill use, food waste processing and digestate generation. Three future WEF nexus scenarios, that reflect potential alternatives of society and technology in Great Britain up to 2050, were utilised by the ABM implementation to test the sensitivity of AD diffusion choices. These scenarios describe possible changes to lifestyle, governance, technologies, climate, and social structures. Accounting for the uncertainty associated with such future simulations, the Monte Carlo method was employed to estimate the potential variations in scenario outputs. Results suggest that decentralisation results in the largest carbon reduction, but can incur more costs. Centralisation consumes 35% more water but produces 37% more energy (biogas). The paper has visualised the scenario outputs graphically to highlight the consequences of neglecting the inter-relationships between environmental, social and economic aspects of AD.