Wide Variation in Life Cycle Greenhouse Gas Emissions of U.S. Natural Gas Power Plants from Upstream Methane Leakage

Abstract:

Natural gas accounted for 38% of electricity generation in the U.S. in 2019, with recent growth attributed to its low cost and ability to complement increasing renewable generation. However, methane leakage associated with production, processing, and transportation of natural gas threaten to erode the benefits of natural gas over coal. Recent empirical measurements of methane emissions at upstream oil and gas sites demonstrate wide variation in leakage rates – from 1.1% in the Marcellus to over 6.3% in the Bakken. Therefore, the source of natural gas for power plants play a significant role in life-cycle emissions impacts. In this study we develop a tool to trace the origin and leakage rates of natural gas consumed at individual power plants to better understand the climate impacts of gas-fired power generation.

We develop a spatially-explicit model to track natural gas movements from shale-plays to power plants using publicly available data from the United States Energy Information Agency (EIA), geospatial data for the US pipeline network and shale-plays, and basin-specific methane leakage rates from peer-reviewed literature. Preliminary analysis of the model applied to the 138 power plants across 13 states receiving gas from the Transcontinental Gas Pipeline Company reveal contributions from two basins – Marcellus and Eagle Ford – with associated leakage ranging between 1.1% and 2.2%. Similarly, power plants in New Mexico and Arizona receiving gas from the El Paso Natural Gas Company pipeline from the Permian basin embody a 3.7% leakage rate, significantly higher than the national average. We discuss the implications of high life-cycle emissions from natural gas power plants on state-level emissions mitigation goals.