Since 2007, the production of shale gas in large volumes has substantially reduced the wholesale price of natural gas in the US. This report examines the emissions savings in the US power sector, influenced by shale gas, and the concurrent trends in coal exports that may increase emissions in Europe and Asia. Electricity generated by the combustion of natural gas is generally considered to have a lower emissions intensity per unit electricity than that generated by burning coal. The relative lifecycle carbon footprint of gas produced by hydraulic fracturing is contested and at present there is a shortage of independent primary data. However, trends in the absolute quantities of CO2 emissions from combustion are less problematic and no less important when considering the implications of the US shale gas boom. US CO2 emissions from domestic energy have declined by 8.6% since a peak in 2005, the equivalent of 1.4% per year. Not all of this reduction has come in the power sector where shale gas has had most impact, and not all of the fuel switching has been due to the low price of gas. This report quantitatively explores the CO2 emissions consequences of fuel switching in the US power sector using two simple methodologies. The analysis presented is conditional upon its internal assumptions, but provides an indication of the scale of potential impacts. The calculations presented in this report suggest that more than half of the emissions avoided in the US power sector may have been exported as coal. In total, this export is equivalent to 340 MtCO2 emissions elsewhere in the world, i.e. 52% of the 650 MtCO2 of potential emissions avoided within the US. A similar conclusion holds for ‘peak to present’ trends. The estimated additional 75 million short tons of coal exported from the US in 2011 will release 150 MtCO2 to the atmosphere upon combustion. If added to the US CO2 output from fossil fuel combustion, the reduction from peak emissions in 2005 would be 360 MtCO2, i.e. a 6.0% change over this whole period or less than 1% per annum. This is far short of the rapid decarbonisation required to avoid dangerous climate change associated with a 2°C temperature rise.
|Place of Publication||Manchester|
|Number of pages||28|
|Publication status||Published - Oct 2012|
- shale gas
- US energy system
- power generation
- CO2 emissions