Shale-gas emissions during fracking only a quarter of potential amount1/4/2013
Actual greenhouse-gas emissions from hydraulic fracturing for shale-gas production are only a fraction of the potential emissions, claim researchers in the US.
Francis O'Sullivan and Sergey Paltsev from the Massachusetts Institute of Technology (MIT) estimate that in 2010 the total fugitive greenhouse-gas emissions from US shale-gas-related hydraulic fracturing amounted to 216 Gg of methane, compared with around 900 Gg of potential fugitive emissions of methane from the process.
"It has been suggested that the greenhouse-gas impact of shale gas might be greater than that of coal on a lifetime basis because of the calculated potential fugitive methane emissions," O'Sullivan told environmentalresearchweb. "But we have found that, taking actual field practice into account, the actual fugitive greenhouse-gas emission from shale-gas wells is only a quarter of potential emissions and represents 3.6% of the estimated 6,002 Gg of fugitive methane emissions from all natural-gas production-related sources in 2010."
As with all natural-gas production, greenhouse gases will escape into the atmosphere during shale-gas production in the time between drilling a well and having the pipeline ready to take the gas away. Previous research has assumed that all of this fugitive gas is vented into the atmosphere, but O'Sullivan and Paltsev surveyed current field practices and found that a large proportion of this fugitive gas is captured. They also found that performance and potential emissions vary dramatically between wells and so a broad statistical approach is essential when calculating emissions from shale-gas production.
"Our research shows that, when assessing the greenhouse-gas impact of gas production, it is important to have a good understanding of current gas-handling practices," said O'Sullivan. "There has been an over-emphasis on shale gas and its greenhouse-gas emissions. Shale-gas production is just one part of our overall gas-production system – a system that is massively leaky. We should not be focussing on one resource type but rather on reducing emissions wherever possible."
O'Sullivan welcomes new regulations from the US Environmental Protection Agency that aim to reduce greenhouse-gas emissions from natural-gas production.
O'Sullivan and Paltsev published their study in Environmental Research Letters (ERL).