The Environmental Protection Agency recently released its draft inventory of annual U.S. greenhouse gas emissions. Reporting 2012 data, the inventory estimates methane emissions coming from natural gas and petroleum systems at around 7.6 million metric tons – that’s enough natural gas to provide energy to over 7 million homes annually. This new estimate when compared with last year’s report, which estimates emissions for the 2011 calendar year, shows overall methane emissions from natural gas and petroleum systems are 1.2 percent lower. Although this seems like good news, the new data is no cause for complacency, as it’s important to understand the cause of the changes which requires closer examination.
The draft inventory introduces some new methodological changes that reduce estimated emissions from previous years. The primary change was driven by the way EPA estimates emissions from gas well completions and workovers, the steps that follow hydraulic fracturing and clear liquids and sand from the well before production begins. Read More