Dear Council -
As I understand it, the data below (from the research journals cited) suggests residential methane emissions are a small part of total anthropogenic methane emissions (bovine gassing, tundra release, pipelines). Residential methane emissions are also a smaller part of CO2 equivalent emissions as a whole.
While methane is a significant heat-trapping gas, residential appliance methane appears to be a small fraction of the total, even given the potency of methane compared to CO2. The studies' estimates appear consistent with one another.
The findings are:
-- residential appliance natural gas ('NG') emissions account for 0.1% of total US anthropogenic methane emissions, which in turn account for ~10% of total US greenhouse gas emissions.
-- residential NG emissions are ~15% of California's NG methane emissions.
Those fractions suggest that residential emission reduction choices should well consider appliance replacement costs and cost-effective alternatives for city emissions reductions. Whether leaky pipelines serving residences are counted should be clarified for policy decisions.
John Kadvany / College Ave
"Annually, ∼30 [97.5% CI: 19-160] Gg of methane emissions can be attributed to U.S. residential NG appliances, corresponding to ∼830 [530-4500] Gg carbon dioxide equivalent (CO2e100). This accounts for ∼0.1% [0.08-0.7%] of U.S. anthropogenic methane emissions (which account for ∼10% of total U.S. greenhouse gas emissions)" [1]
"Together, emissions from residential NG are 35.7 (21.7-64.0) Gg CH4/yr, equivalent to ∼15% of California's NG CH4 emissions, suggesting leak repair, improvement of combustion appliances, and adoption of nonfossil energy heating sources can help California meet its 2050 climate goals." [2]
1. Unburned Methane Emissions from Residential Natural Gas Appliances
Zachary Merrin et al. Environmental Science & Technology. 2019.
2. An Estimate of Natural Gas Methane Emissions from California Homes
Marc L Fischer et al. Environmental Science & Technology. 2018.
