Estimation of Potential Nitrous Oxide Emissions from Landfills in the United States: 2010–2020

Nitrous oxide (N 2 O), a major greenhouse gas, has the potential to be emitted from waste landfills. Previous studies have demonstrated the propensity of landfilling facilities to emit significant quantities of N 2 O, a fact underscored by the IPCC Guidelines, which emphasize the importance of researching this phenomenon. However, due to the absence of established international guidelines for quantifying N 2 O emissions from landfills, many countries, including the United States, have excluded N 2 O from greenhouse gas inventories. Therefore, this study aims to estimate N 2 O emissions from landfills in the United States, a country with a significant landfill waste volume. In this study, N 2 O emissions from U.S. landfills over an 11-year period (2010–2020) are estimated by using the emission estimation formula provided in CDM AM0083 and emission factors from the 2006 IPCC Guidelines. Additionally, emissions were calculated spatially for each state and individual landfill facility. As a result, the impact of integrating N 2 O emissions from landfills into the national greenhouse gas inventory was assessed. The average annual landfill N 2 O emission in the United States over the 11-year period was estimated to be 3,214,693 ton-CO 2 -equivalent/year, with an overall decreasing trend. In 2020, Indiana, Michigan, and Oregon exhibited high landfill N 2 O emissions per capita, while the Virgin Islands, Connecticut, and Massachusetts demonstrated lower emissions. When incorporated into the U.S. greenhouse gas inventory, landfill N 2 O emissions represent 10.41% of the total sector N 2 O emissions. Although N 2 O emissions are declining alongside reduced waste landfilling in the United States, the quantity remains significant and should be factored into greenhouse gas inventory calculations and emission scenarios for the next CMIP6. Further research investigating N 2 O emission coefficients across different regions and waste types is necessary. Ultimately, this study aims to support the United Nations (UN)’s Sustainable Development Goals (SDGs), particularly SDG 11 (Sustainable Cities and Communities), 12 (Responsible Consumption and Production), and 13 (Climate Action), by enhancing the tools for accurate greenhouse gas inventory and promoting sustainable waste management.