Fugitive greenhouse gas emissions from coal seam gas production in Australia

Author:

Day, Stuart; Connell, Luke; Etheridge, David ; Norgate, Terry; Sherwood, Neil

Date of Publication:

2012-10-01

Publication Type:

Report

Pages:

29 p

Abstract:

Natural gas is widely viewed as a transitional fuel to a lower carbon economy because of its much lower greenhouse gas emissions per unit of electricity produced compared to coal. However, when comparing greenhouse emissions from different fuels it is important to include fugitive emissions released upstream of utilisation because even small losses of methane can have a significant impact due to its high global warming potential (GWP). Current estimates of these emissions are in many cases very uncertain, especially in relation to coal seam gas (CSG). Most of the methods used to estimate fugitive emissions from the gas industry are based on a comprehensive study of methane leakage from gas production, processing, transportation and distribution of conventional and unconventional natural gas in the United States during the early 1990s. The results of that study showed that fugitive emissions across the entire U.S. gas industry comprised about 1.4 % of total gas production during 1992. Since then the industry has changed significantly - the amount of gas produced is substantially higher and 'unconventional' sources (i.e. coal seam gas, shale gas, 'tight gas' and 'basin-centred' gas) now comprise a large proportion of total production. Recently, the U.S Environmental Protection Agency (USEPA) revised their estimate of fugitive emissions upwards to a level equivalent to approximately 2.2 % of production, despite an active methane mitigation programme throughout the U.S. gas industry. A recent report from researchers in the U.S. suggested that fugitive emissions from shale gas production may be much higher than previously estimated, and that any greenhouse advantage compared to coal would be severely reduced. Some of the assumptions made in this report have, however, been criticised as being unrepresentative of industry practices. Nevertheless, a subsequent study where emissions from tight gas (but not shale gas) production in Colorado were measured indicated that methane leakage may be higher than the recently revised USEPA estimate. In Australia, fugitive emissions from the CSG industry are not yet well defined. Initial estimates were about 0.1 % of total gas production, which is significantly lower than those reported from conventional gas production. More recently, emissions have been suggested at between 1.3 to 4.4 % of gas production, but these estimates are not based on measured emissions. Given that CSG is now a major and rapidly expanding industry in Australia it is important to understand the magnitude of fugitive emissions because the high global warming potential of methane can erode the benefit of switching from coal to gas. Knowledge of fugitive emissions from the industry will allow effective mitigation strategies to be adopted, if necessary. The recent emission estimates for unconventional gas production in the U.S. may not be a reliable indicator for emissions from the Australian CSG industry because of major differences in production and processing methods that could affect emissions. For example, in the U.S., hydraulic fracturing is used extensively in shale gas and tight gas production, whereas in Australia, far fewer CSG wells currently require this treatment. Measuring fugitive emissions is often complex, but methodologies have been developed that have been successfully applied to diffuse emission sources in various industries, including coal mining. These general methodologies are likely to be applicable, or could be adapted, to the problem of measuring fugitive emissions from the CSG industry. A programme of direct measurement and monitoring is required to more accurately account for fugitive emissions from CSG than is currently available.

Publisher:

CSIRO

Place of Publication:

Newcastle, New South Wales

Keywords:

coal seam gas; fugitive emissions

Field Of Research:

Climate Change Processes

Full Text Availability:

Published Version (pdf) (839KB)

DOI:

https://doi.org/10.4225/08/584d959a38c7d

Rights Notice:

This report has been placed on the CSIRO repository and may be made available to persons outside of CSIRO for non commercial purposes, in its entirety and without deletion of disclaimers and copyright information.

Identifier:

EP128173

Publication Sub Type:

Technical Report (Author)

Language:

English

Attribution Statement:

Day, Stuart; Connell, Luke; Etheridge, David; Norgate, Terry; Sherwood, Neil. Fugitive greenhouse gas emissions from coal seam gas production in Australia. Newcastle, New South Wales: CSIRO; 2012. csiro:EP128173. https://doi.org/10.4225/08/584d959a38c7d