(495a) Techno-Economic and Environmental Analysis of the Conversion of Food Waste to Renewable Energy

Over 103 million tons of food waste are generated in the United States each year, making up over 24 percent of municipal solid waste (MSW) sent to landfills [1]. However, landfill costs are rising due to a lack of suitable landfill sites; furthermore, food waste often has the highest methane potential among MSW elements, accounting for a large portion of fugitive greenhouse gas (GHG) emissions from landfills [2]. Anaerobic digestion (AD) has the potential to be a more sustainable and value-added option for food waste treatment [3].

This study focuses on the techno-economic and environmental assessment of AD as a food waste solution. A city with a million population is assumed, and a percentage of food waste that would otherwise go to landfill may be collected by a stand-alone anaerobic digestion facility. As shown in Figure 1, four typical pathways are evaluated: flare, pipeline natural gas (PNG), onsite power generation including combined heat and power (CHP), and compressed natural gas (CNG). The current technology of different modules is discussed in this study. With reasonable assumptions, economic indicators such as simple payback period (PBP) and net present value (NPV) are calculated, and sensitivity analysis is performed.

The study finds that tipping fees play a significant economic role for the food waste treatment plant, with a general tipping price of more than $30 per ton required for a positive NPV. With conventional AD technology, the cost of biosolid treatment accounts for a substantial portion of the AD operation costs, but advanced AD technology such as thermal pretreatment (THP), solar drying, and thermal drying could potentially improve biosolid quality and lower disposal costs. CNG offers the greatest economic performance of the four pathways, yet market demand may constrain its use. With certain policy incentives on renewable natural gas (RNG) and electricity prices, PNG and onsite generation paths have a positive NPV, and advanced biosolid solutions potentially enable a positive NPV without policy support in the future. Food waste AD plants release significantly less GHG than landfills, according to environmental analysis, implying that they can play an important role in the environmental performance. This study suggests that AD will be a feasible and more sustainable food waste solution than landfill from an economic and environmental perspective.

References

[1] United States Environmental Protection Agency, “2018 Wasted Food Report,” no. November, p. 42, 2020, [Online]. Available: https://www.epa.gov/sites/production/files/2020-11/documents/2018_wasted....

[2] A. Badgett and A. Milbrandt, “Food waste disposal and utilization in the United States: A spatial cost benefit analysis,” J. Clean. Prod., vol. 314, no. August 2020, p. 128057, 2021, doi: 10.1016/j.jclepro.2021.128057.

[3] S. K. Pramanik, F. B. Suja, S. M. Zain, and B. K. Pramanik, “The anaerobic digestion process of biogas production from food waste: Prospects and constraints,” Bioresour. Technol. Reports, vol. 8, p. 100310, Dec. 2019, doi: 10.1016/J.BITEB.2019.100310.