Newspaper article MinnPost.com

Is Shale Gas Driving Down CO2 Output? A New Analysis Says, Not So Much

Newspaper article MinnPost.com

Is Shale Gas Driving Down CO2 Output? A New Analysis Says, Not So Much

Article excerpt

You hear it said all the time: the shale-gas boom is not only driving down American energy bills and advancing our energy security, it's also driving down our greenhouse-gas emissions by displacing coal in our power plants.

The standard argument goes like this:

* Burning natural gas produces only about half the carbon- dioxide emissions as an equivalent quantity of coal.

* Natural gas produced nearly one-third of U.S. electric power last year, double its contribution in the year 2000; while coal's share fell from 50 percent to about 36 percent in the same period.

* Though electric-power generation remains the largest single source of carbon-dioxide emissions in the U.S., those emissions have been dropping even as the economy continues its recovery from recession.

* Therefore, natural gas must be the prime source of those reductions.

A fresh analysis challenges that reasoning, and uses the utilities' own data to show that natural gas is contributing only about one-quarter of the nation's most recent progress on CO2 -- with the rest attributable to falling demand, efficiency gains and mild weather.

The study was conducted by the CO2 Scorecard Group and looked at the year-to-year decline in U.S. emissions from 2011 to 2012.

Emissions dropping steadily

That drop was sizable - about 4 percent, representing 205 million metric tons - and brought these emissions to their lowest level since 1994, according the U.S. Energy Information Agency.

Emissions have fallen nationally in five of the last six years (2010 excepted), and EIA's summary spotlights natural gas's contribution without assigning it a precise share of the progress.

Researchers at CO2 Scorecard decided to dig deeper, delving into data from the eight regional coordinating councils that manage the North American power grid. Among their findings:

* While natural gas replaced coal in the generation of about 160 million megawatt-hours of electricity nationwide, it also displaced about 47 million Mwh of essentially CO2-free power from nuclear, hydroelectric, wind and solar sources.

* The displacement of noncoal sources by natural gas varied considerably from region to region; in the east-central and south- central U.S., increases in gas generation pretty much balanced declines in coal generation. But in the western U.S., gas displaced more nuclear and hydro power than coal.

* In the region covered by the Midwest Reliability Organization, which includes Minnesota, the picture was more mixed. Natural gas generation was up 5.5 million MWh while coal was down 8.9 million MWh. Wind was up 5.9 million MWh; nuclear and hydro were down 2.1 million MWh and 2.9 million MWh respectively.

Those of you who reflexively do the math as you read have no doubt noticed that the MRO numbers don't balance, and there's a good reason: Electric power demand also changed from year to year, leading to perhaps the most striking finding in the CO2 Scorecard analysis:

* 51 million MWh of coal-generated electricity was simply eliminated - people used less electricity in 2012. Energy efficiency, conservation and the mild January, February and March of 2012 are responsible for that reduction. [The MRO region's share of that 51 million MWh is listed at 3.4 million MWh. …

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