Introduction

This analytical review was originally prepared as a discussion note for the executive committee of IEAGHG in response to concern resulting from publication in the USA of an academic paper claiming that methane emissions arising from the production of shale gas could be sufficient to make unconventional natural gas from that source more greenhouse intensive than coal. Such a claim runs counter to the conventional wisdom that converting an application from coal to natural gas invariably results in a reduction in the greenhouse gas (GHG) emission consequences of the application, particularly so for power generation.

This review has identified that there is a dearth of representative public domain data on the natural gas industry in general and on the shale gas industry in particular, with conflicting claims of appropriate assumptions. To assist with understanding the issues, a model has been developed for carrying out Full Fuel Cycle (FFC) analyses and a methodology has been developed to accommodate uncertainty. This model has been populated with illustrative data. This review has been prepared for IEAGHG as a Technical Note to share with a wider readership with the intent of providing a framework for discussion of the impact on GHG emissions from Natural Gas production.

This issue is set against an on-going background of disagreement between environmentalists, academics and the shale gas industry, particularly in the USA. That disagreement is principally focused on incidents of adverse impacts on groundwater quality and community amenity attributed to hydraulic fracturing (fracking). There are some jurisdictions, in the USA and elsewhere, that have imposed a moratorium on the use of that enabling technology pending a better general understanding of the associated environmental issues.

Although fracking for shale gas production is the focus of this study, the wider issues involved in comparing the FFC emissions from coal and gas fired power generation apply also to conventional gas production. The recent upsurge in the global use of natural gas, particularly in the USA, has given rise to increases in Liquefied Natural Gas (LNG) transportation of gas, the application of carbon capture and storage (CCS) to gas fired power generation and concerns about the global warming potential of methane. These wider issues are considered in this report.