Academic institutions present a unique opportunity for anaerobic digestion (AD) projects in that they have a concentrated population that generates waste, utilizes heat and electrical power, and often are motivated to implement sustainability initiatives. However, implementation of AD on college campuses in the U.S. is only beginning to emerge and data required to size and operate digesters are limited. This paper provides formulae to estimate food waste generated at college and university campuses base upon data collected at the Rochester Institute of Technology. Bottom-up and top-down estimates are presented and results are compared to an extensive review of publicly available data from other colleges and universities. The bottom-up methodology resulted in a lower estimate (18 kg food waste/enrolled student) than the top-down estimate (29 kg/enrolled student). Both were significantly lower than the estimate previously reported in the literature (64 kg/enrolled student). Bench-scale co-digestion experiments of the food waste with dairy manure resulted in a methane yield of 437 ml CH4/g VS. Applying this methodology to only 4-year colleges in New York State has the potential to generate 27 million GJ of energy from food waste.
Anaerobic digestion (AD) has gained popularity as an effective way to treat organic materials, produce clean energy, and reduce greenhouse gas emissions. There is a significant number of large-scale AD facilities operating world-wide, largely treating livestock wastes, and used primarily for electricity production in industrialized countries. At the same time, there are millions of small, household-scale ADs deployed in developing countries, mostly to provide biogas resources for heating and cooking. Decentralized low-volume AD systems could provide a local, renewable energy source (for electricity, heating, or both), reduce or eliminate waste disposal costs, and limit discharges of high strength wastes. The purpose of this study was to evaluate the feasibility of deploying low-volume anaerobic digestion (LVAD) systems at institutions generating significant food waste, using Rochester Institute of Technology (RIT) as a case study. Mass flows and energy balance, net present value (NPV), and discounted payback period (DPP) were used to assess the feasibility of implementing an anaerobic digestion system utilizing the campus organic waste resources. Our study showed that a positive NPV can be achieved if subsidies and incentives were applied to offset the initial capital investment. However, the economics can be improved by driving down equipment cost and accepting food waste from other establishments to generate revenue from tipping fees.
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