Greater focus needed on methane leakage from natural gas infrastructure

Abstract

Natural gas is seen by many as the future of American energy: a fuel that can provide energy independence and reduce greenhouse gas emissions in the process. However, there has also been confusion about the climate implications of increased use of natural gas for electric power and transportation. We propose and illustrate the use of technology warming potentials as a robust and transparent way to compare the cumulative radiative forcing created by alternative technologies fueled by natural gas and oil or coal by using the best available estimates of greenhouse gas emissions from each fuel cycle (i.e., production, transportation and use). We find that a shift to compressed natural gas vehicles from gasoline or diesel vehicles leads to greater radiative forcing of the climate for 80 or 280 yr, respectively, before beginning to produce benefits. Compressed natural gas vehicles could produce climate benefits on all time frames if the well-to-wheels CH 4 leakage were capped at a level 45-70% below current estimates. By contrast, using natural gas instead of coal for electric power plants can reduce radiative forcing immediately, and reducing CH 4 losses from the production and transportation of natural gas would produce even greater benefits. There is a need for the natural gas industry and science community to help obtain better emissions data and for increased efforts to reduce methane leakage in order to minimize the climate footprint of natural gas.W ith growing pressure to produce more domestic energy and to reduce greenhouse gas (GHG) emissions, natural gas is increasingly seen as the fossil fuel of choice for the United States as it transitions to renewable sources. Recent reports in the scientific literature and popular press have produced confusion about the climate implications of natural gas (1-5). On the one hand, a shift to natural gas is promoted as climate mitigation because it has lower carbon per unit energy than coal or oil (6). On the other hand, methane (CH 4 ), the prime constituent of natural gas, is itself a more potent GHG than carbon dioxide (CO 2 ); CH 4 leakage from the production, transportation and use of natural gas can offset benefits from fuel-switching.The climatic effect of replacing other fossil fuels with natural gas varies widely by sector (e.g., electricity generation or transportation) and by the fuel being replaced (e.g., coal, gasoline, or diesel fuel), distinctions that have been largely lacking in the policy debate. Estimates of the net climate implications of fuel-switching strategies should be based on complete fuel cycles (e.g., "wellto-wheels") and account for changes in emissions of relevant radiative forcing agents. Unfortunately, such analyses are weakened by the paucity of empirical data addressing CH 4 emissions through the natural gas supply network, hereafter referred to as CH 4 leakage.* The U.S. Environmental Protection Agency (EPA) recently doubled its previous estimate of CH 4 leakage from natural gas systems (6).In this paper, we illustrate the importance of...

Climate impacts of energy technologies depend on emissions timing

“…1a,b). Present approaches to technology evaluation use an equivalency metric to convert emissions to their CO 2 -equivalent value [1][2][3]9]. The most common metric is the global warming potential (GWP(τ )), which takes the ratio of the time-integrated radiative forcing of pulse non-CO 2 and CO 2 emissions over a fixed time horizon (τ ), typically 100 years.…”

Long-Path Quantum Cascade Laser–Based Sensor for Methane Measurements

“…The open-path-integrated sensing platform is especially advantageous for spatially heterogeneous and temporally variable CH 4 sources with large uncertainties, including agricultural emissions and petrochemical activities ranging from natural gas infrastructure leakage to hydraulic fracturing wells and waste facilities (Howarth et al 2011;Alvarez et al 2012;Peischl et al 2012;Péron et al 2012;Karion et al 2013;Miller et al 2013). Finally, open-path-integrated CH 4 measurements at long (kilometer) pathlengths can also be used to detect emissions for comparison with CH 4 model simulations and emission inventories on comparable spatial scales.…”

Sustainability lessons from shale development in the United States for Mexico and other emerging unconventional oil and gas developers

“…These emissions could possibly outweigh any carbon reduction benefits derived from using natural gas to replace other fossil fuels such as coal and oil for electricity generation [38]. Tables 1 and 2, provided by US Environmental Protection Agency (EPA), show estimates of total annual methane emissions from oil and gas production.…”

“…The net impact of greenhouse gas emissions from hydraulic fracturing activities is a subject of great debate that focuses on two main issues: the emissions of greenhouse gases derived from electricity production and the magnitude of methane leakage [38]. Methane emissions can come from direct releases during venting or from unintended leaks [31].…”