11 Waste and wastewater
11.1 Introduction
In 2021, waste activities over the entire United States generated emissions of 169.2 MMTCO2e, or 2.7 percent of total U.S. greenhouse gas emissions (USEPA 2023). In the 11-county Twin Cities MSA region, municipal waste produced 1.813329 MMTCO2e, or 3.4% of the regional total.
Municipal waste can broadly be divided into biogenic wastewater emissions and solid waste emissions. Our inventory accounts for industrial waste emission point sources in the industrial sector and wastewater processing emissions such as electricity and transportation in their respective sectors. Note that the Metropolitan Council Climate Action Work Plan accounts for holistic operational inventory emissions from wastewater processing.
11.2 Results
11.2.1 Baseline emissions
Regional waste emissions have increased by 6.94% since 2005, likely tied to population growth despite successful measures to reduce emissions per capita.
11.2.2 Emissions by gas type
The majority of waste emissions by weight are CO2, but when accounting for the increased warming potential of methane, CO2e, methane contributes the most to global warming. CO2: 20% CH4: 69.7% N2O: 10.3%
11.2.3 Solid waste
2021 emissions
Solid waste generated 1.48 MMtCO2e of emissions in the Twin Cities MSA in 2021. Of that total, 59.7% of emissions came from landfill, 25.0% from waste to energy facilities, and the remaining 15.3% from organics and onsite.
Greenhouse gas emissions from solid waste are dominated by the landfill sector. In Hennepin, Ramsey, and Washington counties, municipal centers where a significant portion of waste is incinerated, waste-to-energy or incineration makes up a large fraction of emissions as well.
Historical emissions
The variation of solid waste emissions over the past 16 years is mainly due to variations in amount of waste collected. It does not take into account changes in methane capture and removal technology or adoption.