Recent Study on Methane Gas Emissions Generates Debate
A recently completed study prepared by researchers from Harvard University and seven other institutions reports that methane gas emissions are approximately 1.5 times greater than estimated by the US Environmental Protection Agency (EPA). The report was published in the Proceedings of the National Academy of Science. The potential for higher methane emissions could derail some of the enthusiasm of the Obama administration to promote natural gas as an alternative to coal in the battle over climate change.
Carbon dioxide and methane are considered to be among the most significant greenhouse gases contributing to global warming. Methane has a much shorter atmospheric life than carbon dioxide. Various studies have reported that methane gas may be 25 times to 34 times more powerful than carbon dioxide in trapping heat within the atmosphere. Additionally, methane facilitates the formation of ozone in urban areas. Carbon dioxide produced from natural gas at the generating facility is approximately 40 to 50% less than coal at the point of generation. An increase in earlier estimates of methane gas emissions could erode support to use natural gas as a bridge between the use of coal and greener technologies in the effort to reduce greenhouse gases.
The Harvard team gathered data for methane and other gases from airplanes and government sampling stations located throughout the United States. This data was integrated with meteorological information then was statistically modeled to predict the methane’s source. The EPA uses an entirely different approach in determining methane emissions; by counting the number of methane producing sources including agricultural operations, underground coal mines, oil refineries, landfills and gas wells, then estimating the emissions within different regions of the country.
The Harvard team evaluated the relationship between methane and other gases, such as propane, which is a byproduct of oil and gas production and oil refining. The data led researchers to conclude that the oil & gas production emissions were underestimated by the EPA. The data for the Harvard team was gathered from data collected during 2007 and 2008 and the report does not touch on the large expansion of oil and gas development that has occurred since that time.
An Environmental Defense Fund and energy industry sponsored study conducted by University of Texas researchers published in September 2013 indicates that fracing may emit less methane than estimated by the EPA. Findings also indicate that methane emissions are lower than EPA estimates at well sites that have been completed and are producing. This study was directed to the production of natural gas and other sources were not included. The University of Texas study used data that is more recent than the Harvard report, which may indicate improvements in the capture of fugitive emissions since the time the Harvard data was collected.
Legislative efforts to reduce methane emissions and best management practices at oil and gas well sites appear to be reducing fugitive emissions. Additionally, Colorado has proposed regulations that would reduce methane emissions during the production, storage and transportation of oil and gas.
The debate over the accuracy of the Harvard report appears to be generating interest in evaluating improved methods to calculate methane emissions. The report spurs debate that the reduction of fugitive methane emissions could result in additional revenue for the producers and would assist support for the continued expansion of markets for natural gas.