Cornell university campus metabolism and circular economy using a living laboratory approach to study major resource and material flows

Abstract

Urban metabolism (UM) resembles the metabolism of living organisms in a community context by consuming necessities and excreting waste. Exercising UM with a circular economy concept enhances sustainable practices by circulating energy and materials, minimizing and closing waste loops to push a system for a net-zero goal. This research tracks energy and material flows in the energy, food waste, and construction materials sectors of Cornell University, Ithaca, NY, serving as a case study for campus metabolism. These three sectors are the top emitters and are interconnected at the food-water-energy nexus in terms of emissions. In addition to the flow analysis, the study includes environmental and economic evaluations of the proposed digestate composting and estimation of embodied emissions for construction material building stocks. The results suggest that Cornell needs to transition from natural gas to geothermal for a rapid shift towards renewable energy and to increase circularity within the sector. Regarding food waste, the proposed digestate composting reduces emissions by 16–39 metric tons of CO2e with a financial gain of US$90 k to US$400 k per fiscal year compared to the traditional food waste composting practice. Lastly, the proportional evaluation between operational emissions from the energy sector and embodied emissions from stored building materials shows a decreasing trend in the contribution of operational emissions from 46.42% to 26.86% in 2008 and 2021, respectively. This result highlights the immediate need for Cornell's construction waste management to prevent future emissions of embodied carbon into the environment. The campus metabolism study advances our understanding of potential energy and material flows, along with emissions offsets, among the three sectors to achieve the goal of decarbonization. This study can unlock sustainability pathways and accelerate Cornell's progress toward carbon neutrality by 2035.