CES Spotlight Blog
Natural Gas: Still Cleaner Than Coal & Getting Better
Photo Credit: Joshua Doubek, Fracking the Bakken Formation in North Dakota
Depending on who you ask natural gas is either: (1) a clean bridge fuel that can be relied on until renewables (wind, solar and hydro) are ready for prime time, or (2) a ruinously cheap fossil fuel that is actually dirtier than coal. The University of Texas (UT) has teamed up with the Environmental Defense Fund (EDF) and nine petroleum companies to publish a study which seeks to shed light on the environmental impact of natural gas production. The study, is groundbreaking due to the fact that researchers used actual emissions from 190 onshore natural gas sites including nearly 500 wells, whereas previous studies done by Cornell University and the EPA relied only on estimated emissions.
Energy producers and some environmental organizations have championed natural gas as a cleaner alternative to coal and oil. Methane, the primary component of natural gas, emits on average half the carbon emissions of coal and a third of the carbon emissions of oil when burned. Other environmental groups, however, fear that the emission benefits gained from burning natural gas are negated by the release of methane during extraction. When methane is released into the atmosphere during the extraction and distribution process, instead of captured and burned, it becomes a potent greenhouse gas. A single molecule of fugitive methane that escapes prior to combustion causes as much warming as about 21 molecules of carbon dioxide.
In general, the UT study finds the overall methane emissions from natural gas production to be around 2.3 million metric tons per year, down from the EPA’s 2011 estimate of 2.5 million metric tons. Specifically, emissions from well completion (when the well is cleaned after the drilling and fracturing processes) were 600,000 tons less than predicted. The cause for this drastic emissions reduction has been the widespread adaptation of “green completion” technology by natural gas companies, which captures 99% of methane emitted during completion. The EPA’s New Source Performance Standards mandate companies to adopt green completion technology by January 2015, but the technology is already more widespread than expected. This reduction in methane emissions was partially offset by higher than expected emissions from chemical pumps, pneumatic controllers (used to regulate pressure and flow rate), and equipment leaks.
Some environmental groups questioned the objectivity of the report, noting that 90% of the funding for the report can from companies such as Shell, Anadarko Petroleum Corporation, Exxon Mobil, and Chevron. Representatives from the UT and the EDF are vigorously defending their neutrality, stating that the study was peer reviewed before being published, well sites were chosen by researchers instead of the companies, and that the high emissions from equipment leaks prove that companies did not modify sites beforehand.
The report’s implications are important for comparing the environmental impact of natural gas production against that of coal. The 2011 EPA report estimated that 0.47% of natural gas produced was lost at the well site, with losses increasing to 1.6% over the entire supply chain. The UT report focused solely on emissions lost at the well site and calculated a slightly lower number of 0.42%. Future studies carried out by UT with support from the EDF and partner companies will examine the rest of the natural gas supply chain. In order to keep its climate advantage over coal, methane emissions must be less than 3.2% of total gas produced.
Although not comprehensive, the UT report adds validity to the EPA estimate of 1.6% and suggests that natural gas is indeed a much cleaner source of energy than coal. The report also identifies areas of success and opportunity- mainly, that green completion technology is effective and that future regulation efforts should focus on monitoring the pneumatic controllers and equipment leaks. Tightening up the natural gas supply chain is a win-win for energy production companies and environmental organizations. Fewer methane emissions would result in more natural gas being available for sale and less impact on the environment.
Special thanks to CES Analyst Michael Lachance who researched and co-wrote this blog post.
Published article here: http://www.pnas.org/content/early/2013/09/10/1304880110.full.pdf+html