14 Aug 2012

Shale gas helping reduce carbon & overall emissions – but by how much?

Written by Jim Pierobon

The results are adding up. It’s hard to ignore how the surging deployment of natural gas for industrial uses and power generation is reducing the growth in U.S. carbon and other harmful emissions and possibly lowering overall emissions.

Two recent studies draw from different data sets so one should be careful not to jump to an overly optimistic conclusion. That said, the trends are encouraging for anyone aspiring to breathe cleaner air and displace burning coal.

The 2012 Benchmarking Air Emissions report by CERES is the eighth report in a series highlighting environmental performance and progress in the nation’s electric power sector. The report is based on 2010 generation and emissions data from the U.S. Energy Information Administration and the U.S. Environmental Protection Agency, and also includes analysis of preliminary 2011 emissions data.

Using preliminary sector-wide emissions data from 2011, the report reflects a continued downward trend in CO2 emissions, falling an additional five percent compared to 2010. Emissions of CO2 had increased by about five percent from 2009 to 2010 as demand for electricity increased with the recovering economy.

But CO2 emissions declined by a similar amount from 2010 to 2011 due to a shift away from coal-fired generation. Preliminary data also indicate that in 2011, sector-wide power plant SO2 and NOx emissions continued to fall, dropping 40 percent and 35 percent below 2008 levels, respectively. Emissions of these pollutants are expected to decline further as power plant owners install additional pollution controls and plan to retire roughly 12 percent of the nation’s coal-burning fleet.

Mindy Lubber, president of Ceres, which prepared the report with M.J. Bradley & Associates, NRDC, Entergy, Exelon, Tenaska and Bank of America, asserted: “This is an historic transition for the electric power industry. More and more power producers are shifting away from coal-fired generation in favor of lower-emitting natural gas-fired plants, renewable power and energy efficiency.”

In addition to the natural gas boom, industry adaptations to stronger Clean Air Act emissions standards and state-driven efficiency and renewable energy incentives are playing key roles.

The CO2 Scorecard, in its own report, found similar threads explaining declining emissions. The left-leaning research group was quick not to give shale natural gas too much credit over a longer time-frame.

The Scorecard concluded that “price driven displacement of coal by natural gas can account for just around 10% of the CO2 reductions during the period 2006-11.

“Nearly 90% of the cuts in CO2 emissions were caused by: (1) the decline in petroleum use in the transportation sector, (2) displacement of coal by mostly non-price factors, and (3) its replacement by wind, hydro and other renewables.

“Each ton of CO2 saved from price driven displacement of coal by gas in the electricity sector was offset by a ton or more of CO2 from its increased use in commercial, residential and industrial sectors.”

Only a ‘peripheral role’ for natural gas?

“We also show,” the CO2 Scorecard continued, “that both renewables and energy efficiency measures independently outperform the CO2 savings from coal-to-gas displacement, indicating that natural gas can at best play a peripheral role in cutting CO2 emissions, and it cannot substitute for authentic climate policies based on regulations, clean energy standards and carbon price.

“Natural gas deserves credit where it is due, but pro-gas advocacy has led to a significant overstatement of the true CO2 cutting credentials of shale gas. This is a mistake and it undercuts the effort to keep policy discussions accurate.”

Early this month, the Energy Information Administration reported that CO2 emissions resulting from energy use during the first quarter of 2012 were the lowest in two decades for any January-March period.

CREDIT: U.S. Energy Information Administration. This and other illustrations can be found here.

Normally, CO2 emissions during the year are highest in the first quarter because of strong demand for heat produced by fossil fuels. However, CO2 emissions during January-March 2012 were low due to a combination of three factors:

  • A mild winter that reduced household heating demand and therefore energy use
  • A decline in coal-fired electricity generation, due largely to historically low natural gas prices
  • Reduced gasoline demand

The most common thread among these and other reports point to how efficiency, renewables and natural gas — together — are pointing the U.S. toward a more sustainable economy.

Key findings of the CERES report include:

  • In 2010, sector-wide power plant emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx) were both 68 percent lower than they were in 1990, the report’s benchmark year.  From 2008 to 2010, SO2 emissions fell by 32 percent and NOx emissions fell by 31 percent as the sector shifted away from coal.
  • From 2008 to 2010, power plant carbon dioxide (CO2) emissions fell four percent; however, emissions were still 24 percent higher than they were in 1990, the report’s benchmark year. Further reductions are expected as utilities retire 12 percent of the nation’s coal-fired generation fleet.
  • Excluding large hydroelectric projects, renewable energy accounted for nearly five percent of U.S. electricity generation in 2011, and more than doubled from 2004 to 2011 to 195 million megawatt-hours.
  • Utility energy efficiency budgets increased 26 percent from 2010 to 2011, and record levels of efficiency resources are being purchased in the nation’s largest electricity markets.

Here’s how production of “dry” natural gas (excluding natural gas liquids, or NGLs) has gyrated since the 1973 Arab Oil Embargo. CREDIT: CO2 Scorecard


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