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Natural Gas, Efficiency Fuel U.S. Carbon Emissions Decline

U.S. carbon dioxide emissions related to energy consumption dropped to their lowest point since 1994 last year, according to a U.S. Energy Information Administration report released Monday afternoon.

The decline of coal as a power source in favor of natural gas in the U.S. is a big part of that decline, the EIA reported.

Natural gas power generation increased by 211.8 billion kilowatt hours in 2012 over 2011, while coal power declined by 215.2 billion kilowatt hours last year.

Fracking at a natural gas shale in Shreveport, La.
Credit: flickr/danielfoster437

The EIA reported that 2012 was the fifth year in a row that energy related carbon emissions declined after peaking in 2007, despite GDP growth. Emissions declined 3.8 percent in 2012 over 2011. 

“Although GDP increased by 2.8 percent in 2012, energy consumption fell by 2.4 percent in 2012,” according to the EIA report. “The emissions decline was the largest in a year with positive growth in per capita output and the only year to show a decline where per capita output increased 2 percent or more.”

The total carbon intensity of the U.S. economy declined in 2012 by 6.5 percent over the previous year — the largest drop since recordkeeping began in 1949 — mainly because the public has been eschewing coal for natural gas as a primary source of electricity.

The shift from coal to natural gas for electricity generation and slower economic growth were the main factors in reducing U.S. carbon emissions from 2007 to 2012 as compared to the previous 10 years said EIA analyst Perry Lindstrom. 

"Also, population has slowed a bit, which helps," he said. 

The EIA also attributed the carbon emission decline to several other factors, including a warm winter season in the first quarter of 2012, leading to a lower demand for energy to heat homes and businesses.

Credit: U.S. Energy Information Administration

Nationwide in 2012, the number of days that the EIA considers cold enough to require homes to be heated — called “heating degree days” — were 19 percent below the 10-year normal and 22 percent below 2011.

Residential electricity consumption declined by 3.4 percent from 2011, partly due to increased home energy efficiency.

U.S. residential carbon dioxide emissions from electricity and direct use of fuels totaled 760 million metric tons in 2012, down from 875 million metric tons in 2010 and 897 million metric tons in 2007.

The U.S. has seen a nearly 10 percent drop in energy intensity — the measure of British thermal units (Btu) per dollar of GDP — since 2007 largely because people having been driving fewer miles and heating their homes less than they’ve been cooling them.

More energy is needed to heat a home than to cool it, so a decrease in the number of days a home is heated while the number of days homes are cooled has increased has meant less energy has been consumed overall.

U.S. vehicle miles traveled have dropped 3.3 percent since 2007 while fleet vehicle efficiency improved 16 percent between 2007 and 2012.

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By Eric Peterson (Front Royal, VA 22630)
on October 22nd, 2013

The main factor is the market-driven rise in natural gas production.  Another part of the equation is the lackluster economy with mild deflation.  Gas prices have sunk and stayed low since 2008 despite the government (Federal Reserve) attempts to spur inflation.

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By katherine burns (tully, ny 13159)
on October 22nd, 2013

When carbon emissions are calculated, is only CO2 counted, or are methane emissions a part of the calculation?  Either way, how much methane has been emitted, and how does last year’s amount compare to previous years?  It seems very important that we know this, since methane is so much more powerful a greenhouse gas than CO2, especially in the first 20 years.

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By Dave (Basking Ridge, NJ 07920)
on October 23rd, 2013

Hi Katherine – That is an important point. I looked at the report and the emissions data reported there are only energy related CO2 emissions. The report does not address any changes in CO2 emissions related to other sources such as land use changes or cement production. It also does not address any other type of GHG from any source including methane from energy production, specifically natural gas production and use. The exact magnitude of net fugitive methane emissions from natural gas production, distribution and end use is unknown with low EPA and even lower industry estimates pitted against often somewhat higher independent estimates.

So to your point, since the data excludes fugitive methane emissions related to natural gas production and use, which is a major concern because methane is such a potent GHG, it is misleading and potentially wrong to interpret this report and these particular CO2 only data as proof of US GHG emission reductions. On a CO2 equivalent basis, energy related GHG emissions may have gone down, stayed the same or possibly even increased.

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By john harkness
on October 23rd, 2013

Good questions, kb.

The other crucial question is how our coal exports are counted. If we produced 0 carbon emissions but sent massive amounts of coal, gas and oil to other countries to be burned, should we feel great about that? Would our collective conscious be clean?

The flip side of that is, how much coal is being burned in China and other places to fuel our consumption of Walmart crap? Should we feel good that, since little is manufactured anymore here in the US, the smoke from factories and power plants is pouring out of stacks in other countries rather than from plants in our fair land?

For a harshly honest look at what probably needs to happen to get us anywhere near the already-too-high limit of 2 degrees C, please take the time to watch this from Kevin Anderson, Director of the Tyndall Centre for CC Research:

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By Debra (26435)
on October 24th, 2013

Methane went way up but I see that wasn’t mentioned.

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