Life-Cycle Inventory of Municipal Solid Waste and Yard Waste Windrow Composting in the United States

Abstract

This paper presents a life-cycle inventory (LCI) for solid waste composting. Three LCIs were developed for two typical municipal solid waste (MSW) composting facilities (MSWCFs) and one typical yard waste (YW) composting facility (YWCF). Municipal solid waste was assumed to comprise three organic components, food wastes, yard wastes, and mixed paper, as well as various inorganic components. Total costs, combined precombustion, and combustion energy requirements and 29 selected material flows—also referred to as LCI coefficients—were calculated by accounting for both the processes involved in originally producing, refining and transporting a material used in the facility as well as consumption during normal facility operation. Total costs ranged from $\$15/t$ to $\$50/t$ and energy requirements from $29\mathrm{kw}h/t$ to $167\mathrm{kw}h/t$ for a YWCF and a high quality MSW composting facility, respectively. More than 90% of the overall ${\mathrm{CO}}_2$ emissions in all facilities were due to the biological decomposition of the organic substrate, while the rest was due to fossil fuel combustion.