Understanding Updates to the EPA Inventory of Greenhouse Gas Emissions from Natural Gas Systems Gina DeFrancesco Clean Energy Analyst | May 2019

The American Gas Association, founded in 1918, represents more than 200 local energy companies that deliver clean natural gas throughout the United States. There are more than 74 million residential, commercial and industrial natural gas customers in the U.S., of which 94 percent — more than 70 million customers — receive their gas from AGA members. Today, natural gas meets more than one-fourth of the United States' energy needs. www.aga.org

New Science, New Facts The Environmental Protection Agency (EPA) made substantial updates to its estimates of methane emissions in the Inventory of U.S. Greenhouse Gases and Sinks: 1990 – 2017 that it released in April 2019. The Inventory incorporates new data available from studies on emissions as well as its Greenhouse Gas Reporting Program (GHGRP).

Key Findings Annual methane emissions from natural gas distribution systems declined 73 percent from 1990 to 2017. The natural gas emissions rate of production from distribution systems remains less than 0.1 percent at 0.09 percent. The industry-wide natural gas emissions as a rate of production (the “leakage rate”) is 1.3 percent – a level still well below even the most stringent thresholds for immediate climate benefits from coal to gas switching. The EPA Inventory reveals once again that the natural gas distribution systems have a small emissions footprint shaped by a declining trend.

Key Findings continued Total methane emissions from all natural gas systems have declined 15 percent from 1990 to 2017. The ratio of methane emissions per unit of natural gas produced has declined continuously during the past two and a half decades, dropping 48 percent since 1990. Along with natural gas systems, methane emission sources include enteric fermentation and manure management (livestock), landfills, coal mining, petroleum systems, wastewater treatment, and others. Methane emissions from all economic sectors represent 10 percent of all greenhouse gas emissions in the U.S.; methane released from natural gas systems accounts for 2.6 percent of all U.S. greenhouse gas emissions. As companies and the country continue to modernize the natural gas infrastructure base and connect homes and businesses, there will be new opportunities to achieve low-cost carbon emissions reductions by leveraging this existing infrastructure and the nation’s natural gas resource.

U.S. Greenhouse Gas Emissions (Million Metric Tons CO2e) US GHG emissions are down 12 percent since 2005 with natural gas playing a key role in the decline U.S. Greenhouse Gas Emissions (Million Metric Tons CO2e) Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Sources of Methane Emissions 2017 Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Petroleum combustion accounts for most energy-related CO2 emissions, followed by natural gas Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Upstream natural gas systems Source: American Gas Association Playbook 2019

Downstream natural gas systems Source: American Gas Association Playbook 2019

Methane emissions from natural gas systems have declined 15 percent from 1990 levels Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Methane emissions have declined even as gross natural gas withdrawals climbed 53 percent Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Environmental Protection Agency Methane emissions per unit of natural gas produced have declined steadily since 1990 Down 48% since 1990 Includes methane emissions from petroleum production based on the natural gas fraction of total energy content produced from oil wells. Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017 Environmental Protection Agency

Natural gas distribution emissions dropped 73 percent since 1990 Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017 Energy Information Administration

Sources of distribution system emissions Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017, Annex Table 3.6-1 Environmental Protection Agency

Pipeline Replacement Lowers Emissions Miles of installed main has increased 50 percent since 1990. Even with this tremendous growth, estimated methane emissions from pipeline leaks declined 76 percent. A consequence of accelerated removal of unprotected steel and cast iron pipe replaced with plastic and protected steel. Activity Data and Emissions from EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Summary of Revisions to Natural Gas System Methane Estimates 2015 EPA explicitly defines emissions from exploration activities; this does not represent a methodologica l change, but a separate category for presentation Methane Emissions in 2016 Prior Inventory New Inventory Change Exploration 0.7 1.2 71% Production 106.8 108.4 1% Onshore Production 45.4 45.1 -1% Offshore Production 3.8 0% Gathering, Boosting 57.7 59.5 3% Processing 11.2 11.7 4% Transmission, Storage 32.8 32.4 Distribution 12.0 11.9 Natural Gas Total 163.5 165.7 Petroleum Field Operations 35.4 37.7 6% Oil and Gas Total 198.9 203.3 2% (MMT CO2e) Source: EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017

Gina DeFrancesco Clean Energy Analyst gdefrancesco@aga.org 202.824.7127

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