Emissions of carbon dioxide are less from natural gas than from coal and oil but methane emissions are far greater and methane is a much more potent potent greenhouse gas points out the author of a new paper.

Click to enlarge. From the paper. Comparison of the greenhouse gas footprint of shale gas, conventional natural gas, coal, and oil to generate a given quantity of heat. Two timescales for analyzing the relative warming of methane and carbon dioxide are considered: an integrated 20-year period (top) and an integrated 100-year period (bottom). For both shale gas and conventional natural gas, estimates are shown for the low and high-end methane emission estimates from Howarth et al. [8]. For coal, estimates are given for surface-mined and deep-mined coal, since methane emissions are greater for deeper mines. Blue bars show the direct emissions of carbon dioxide during combustion of the fuels; the small red bars show the indirect carbon dioxide emissions associated with developing and using the fuels; and the magenta bars show methane emissions converted to g C of carbon dioxide equivalents using period-appropriate global warming potentials. Courtesy: author and Wiley.

Higher methane emissions from natural gas means that using it to replace coal and oil will not reduce the overall greenhouse warming due to fossil fuel emissions, says study.

Both shale gas and conventional natural gas have a larger greenhouse gas footprint than do coal or oil, especially for the primary uses of residential and commercial heating.

Dr. Robert Howarth, a professor of ecology and environmental biology, came to this conclusion after assessing the best available data and analyzing greenhouse gas footprints for both methane (including shale gas and conventional gas) and carbon dioxide over a timescale of 20-years following emissions. The findings are published in Energy Science & Engineering.

“While emissions of carbon dioxide are less from natural gas than from coal and oil, methane emissions are far greater. Methane is such a potent greenhouse gas that these emissions make natural gas a dangerous fuel from the standpoint of global warming over the next several decades,” said Dr. Howarth. “Society should wean ourselves from all fossil fuels and not rely on the myth that natural gas is an acceptable bridge fuel to a sustainable future.”

Abstract

In April 2011, we published the first peer-reviewed analysis of the greenhouse gas footprint (GHG) of shale gas, concluding that the climate impact of shale gas may be worse than that of other fossil fuels such as coal and oil because of methane emissions. We noted the poor quality of publicly available data to support our analysis and called for further research. Our paper spurred a large increase in research and analysis, including several new studies that have better measured methane emissions from natural gas systems. Here, I review this new research in the context of our 2011 paper and the fifth assessment from the Intergovernmental Panel on Climate Change released in 2013. The best data available now indicate that our estimates of methane emission from both shale gas and conventional natural gas were relatively robust. Using these new, best available data and a 20-year time period for comparing the warming potential of methane to carbon dioxide, the conclusion stands that both shale gas and conventional natural gas have a larger GHG than do coal or oil, for any possible use of natural gas and particularly for the primary uses of residential and commercial heating. The 20-year time period is appropriate because of the urgent need to reduce methane emissions over the coming 15–35 years..

Citation

A bridge to nowhere: methane emissions and the

greenhouse gas footprint of natural gas by RobertW.Howarth published in Energy Science and Engineering 2014; 2(2): 47–60 doi:10.1002/ese3.35

Read the abstract and get the paper here.

Source

Wiley press release here.