This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
That’s how Ed Davey, the United Kingdom’s Energy and Climate Minister, is describing the climate impacts of natural gas from shale formations:
This report shows that the continued use of gas is perfectly consistent with our carbon budgets over the next couple of decades. If shale gas production does reach significant levels we will need to make extra efforts in other areas. Because by on-shoring production we will be on-shoring the emissions as well. And, as this report recommends, we will still need to put in place a range of techniques to reduce emissions.
Mr. Davey is referring to results from a studied published this week by UK researchers Dr. David MacKay and Dr. Timothy J. Stone (PDF). The pair was asked in December 2012 to gather information on potential GHG emissions from shale and any impact on the UK’s climate targets.
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One of the main conclusions from the study is that the climate footprint of shale gas is comparable to conventional gas production, better than liquefied natural gas (LNG), and heaps better than coal:
The carbon footprint (emissions intensity) of shale gas extraction and use is likely to be in the range 200 – 253 g CO2e per kWh of chemical energy, which makes shale gas’s overall carbon footprint comparable to gas extracted from conventional sources (199 – 207 g CO2e/kWh(th)), and lower than the carbon footprint of Liquefied Natural Gas (233 - 270g CO2e/kWh(th)). When shale gas is used for electricity generation, its carbon footprint is likely to be in the range 423 – 535 g CO2e/kWh(e), which is significantly lower than the carbon footprint of coal, 837 – 1130 g CO2e/kWh(e).
These ranges represent a somewhat best case scenario as actual shale gas production results in methane emissions directly to the atmosphere, largely during the well completion stage. The authors recommend that stricter regulations and practices such as “reduced emissions completions” (RECs), or what’s commonly called “green completions”, be implemented. A “green completion” process would capture methane and inject it into a pipeline or be used to power on-site equipment.
However, global GHG emissions could continue to rise despite natural gas consumption if more intensive fuels like coal are displaced to other markets, which has been documented for the United States market. This “leakage” across political boundaries underscores the need for some larger, binding price on carbon or global emissions budget.
Besides the climate considerations, the UK is weighing how much it wants to rely on imports of LNG in the future. Domestic UK shale gas has the potential to offset declining North Sea gas production and avoid greater reliance on foreign gas imports. In 2011, imports exceeded production for the first time, with 47 percent of the imports supplied as LNG, primarily from Qatar. The UK is thought to contain 1,329 trillion cubic feet (tcf) of gas total. The amount that could be economically recovered is currently unknown.
