New EPA Data Show Continued Decline in Methane Emissions

This morning, EPA released its latest Greenhouse Gas Inventory, which shows that methane emissions from natural gas systems have declined significantly in recent years, thanks to new technologies and voluntary efforts by producers. Even more impressive is that these reductions have been made as natural gas production has ramped up significantly.

The downward trend that EPA identifies is arresting.  In last year’s Greenhouse Gas Inventory, EPA found that methane emissions from natural gas systems had fallen 10.2 percent since 1990, and emissions from field production had fallen 38 percent since 2006.  Those emission rates were already well below the threshold for natural gas to retain its clear environmental benefits.  In its latest report, EPA finds that methane emissions fell 16.9 percent since 1990, with field production emissions falling more than 40 percent since 2006.

From 2011 to 2012 (the most recent year for which data were available), methane emissions from natural gas systems declined by 12 percent.

Moreover, in last year’s inventory, EPA ranked natural gas systems as the number one source of methane emissions, followed by enteric fermentation (think cows…).  This year it has switched: enteric fermentation over took natural gas systems, due in large part to the significant decline in emissions from the latter. From the executive summary of the report:

“Natural gas systems were the second largest anthropogenic source category of CH4 emissions in the United States in 2012 with 127.1 Tg CO2 Eq. of CH4 emitted into the atmosphere. Those emissions have decreased by 25.8 Tg CO2 Eq. (16.9 percent) since 1990. The decrease in CH4 emissions is largely due to the observed decrease in emissions from production and distribution. The decrease in production emissions is due to increased voluntary reductions, from activities such as replacing high bleed pneumatic devices, regulatory reductions, and the increased use of plunger lifts for liquids unloading. The decrease in distribution emissions is due to a decrease in cast iron and unprotected steel pipelines. Emissions from field production accounted for 30.7 percent of CH4 emissions from natural gas systems in 2012. CH4 emissions from field production decreased by 25.6 percent from 1990 through 2012; however, the trend was not stable over the time series-emissions from this source increased by 24.9 percent from 1990 through 2006 due primarily to increases in hydraulically fractured well completions and workovers, and then declined by 40.4 percent from 2006 to 2012. Reasons for the 2006-2012 trend include an increase in plunger lift use for  liquids unloading, increased voluntary reductions over that time period (including those associated with pneumatic devices), and RECs use for well completions and workovers with hydraulic fracturing.” (ES-14)

These new data are a testament to the efforts that oil and natural gas producers have made to employ new technologies to reduce methane emissions, making development cleaner, safer and more efficient.  As the report reiterates, “Changes made to the methodology for completions with hydraulic fracturing and workovers with hydraulic fracturing (refracturing) resulted in a decrease in the estimate of CH4 emissions.” (3-68)

This downward trajectory is even more noteworthy when you consider how much natural gas production has increased over the years that were analyzed.  As we’ve noted before, since 2007, natural gas production increased by 26 percent. Over roughly the same amount of time, methane emissions from field production declined by 40.4 percent (from 2006 to 2012).

But the decline in methane emissions isn’t the only good news from the report.  There has also been a sustained decrease in CO2 emissions, thanks largely to our increased use of natural gas. From the report:

“In 2012, total U.S. greenhouse gas emissions were 6,501.5 Tg or million metric tons CO2 Eq. Total U.S. emissions have increased by 4.4 percent from 1990 to 2012, and emissions decreased from 2011 to 2012 by 3.3 percent (225.0 6 Tg CO2 Eq.). The decrease from 2011 to 2012 was due to a decrease in the carbon intensity of fuels consumed to generate electricity […] with increased natural gas consumption.” (2-1)

It’s also worth noting that this second consecutive GHG Inventory, in showing an even steeper decline in methane emissions, raises more questions about the “co-benefits” calculated for EPA’s New Source Performance Standards for hydraulically fractured wells, which we discussed last year.

EPA’s new data should be yet another nail in the coffin to the argument by anti-fracking activists that methane emissions from production are a climate “disaster,” or that shale represents a “gangplank” to global warming.  The actual data tell a very different story: Methane emissions are well below the threshold for natural gas to maintain its environmental benefits, and in fact those emissions are rapidly declining as production grows.  Carbon dioxide emissions are at their lowest level in twenty years thanks to the increased use of natural gas.   And all of this is happening in the midst of an energy boom that is creating thousands of jobs, enhancing our energy security, and reshaping our economy for the better.


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