Natural gas power better than coal - despite the methane involved

Posted: 30 August 2011

Over its full cycle of production, distribution, and use, natural gas emits just over half as many greenhouse gas emissions as coal does for equivalent energy output, according to a new study.

The analysis from the Worldwatch Institute and the Deutsche Bank Climate Change Advisors, clarifies the role of methane releases in the calculation of comparative emissions between the two fossil fuels and explores how the growing share of natural gas production from shale formations could change that fuel's footprint.

Earlier this year, the US Environmental Protection Agency (EPA) updated its methodology for estimating methane emissions from natural gas systems, generating concern that the new, higher methane figures could minimize the greenhouse gas advantage that natural gas is seen widely to have over coal.

Energy emissions chart

Applying the EPA's new estimates, the life-cycle greenhouse gas footprint of natural gas-fired electricity increased roughly 11 per cent, according to the study. "Despite a substantial increase in the methane assumed to be emitted during natural gas production, we found that US natural gas-fired electricity generation still released 47 per ent fewer greenhouse gases than coal from source to use," said Saya Kitasei, a Worldwatch Institute Sustainable Energy Fellow and one of the contributing writers.

Win-win proposition

The authors stress that although methane emitted during natural gas production might not make natural gas-fired electricity dirtier than coal, it can and must be mitigated immediately.

"In addition to being a potent greenhouse gas, methane is a valuable energy source that natural gas producers should be capturing for sale," said Kitasei. "Because some of the same technologies that prevent methane from entering the atmosphere also reduce emissions of smog-forming compounds, tackling methane emissions is a win-win-win proposition."

The study points out that regulatory and technological tools to reduce methane emissions are being demonstrated in some US states and by some companies. Although reducing methane emissions has been largely voluntary to date in the United States, new EPA rules could require the natural gas industry to measure and report its greenhouse gas emissions and to use control technologies that will significantly reduce associated methane emissions as early as 2012.

Methane emissions during natural gas production, processing, transport, storage, and distribution can be mitigated now at moderately low cost, using existing technologies and best practices. Such capture potential presents a commercial and investment opportunity that would further improve the life-cycle greenhouse gas footprint of natural gas.

 

Worldwatch is an independent research organization based in Washington, D.C. that works on energy, resource, and environmental issues. The Institute's State of the World report is published annually in more than 20 languages. For more information, visit www.worldwatch.org
 

A new study seeks to shake up the assumption that use of coal, the most carbon-intensive fossil fuel, is bound to continue its inexorable rise. In fact, the authors predict that world coal production may reach its peak as early as this year, and then begin a permanent decline. The study, led by Tad Patzek, chairman of the Department of Petroleum and Geosystems Engineering at the University of Texas at Austin, and published in the August 2010 issue of Energy, predicts that by mid-century, the world's coal mining will supply only half as much energy as today.

Coal - peak graph