Cape Town - Shale gas appears to be a greater greenhouse gas culprit than previously thought.
New research has revealed that there are high levels of the potent greenhouse gas methane emitted from fracking wells drilled in the US – in some case 100 to 1 000 times greater than measurements in the official inventories.
The high levels of methane were found in the air above fracking wells that were in the drilling stage, a pre-production stage not previously thought to have significant methane emissions. The research, published in Proceedings of the National Academy of Sciences this week, was undertaken by 13 scientists from several research institutions. Their work has shown that the industry measurements have significantly underestimated the amount of methane the wells emit.
Methane is a potent greenhouse gas, with greater heat-trapping qualities than carbon dioxide. According to the US Environmental Protection Agency the comparative impact of methane on climate change is more than 20 times greater than CO2 over a 100-year period.
The methane measurements from fracking wells were made by researchers using a specially equipped aircraft with an on-board laboratory. The plane flew above the Marcellus shales in Pennsylvania and identified plumes of methane gas from single fracking wells, from groups of wells and also did larger regional measurements.
One of the researchers, chemistry professor Paul Shepson of Purdue University, said their findings illustrated a weakness in the methods of making inventories of methane emissions from fracking. The flight measurements were an important additional method that could better define the impacts of shale gas development.
“It is particularly noteworthy that large emissions were measured for wells in the drilling phase, in some cases 100 to 1 000 times greater than inventory estimates. This indicates that there are emissions during the drilling process that are not captured in the inventory,” Shepson said.
Globally more than 60 percent of total methane emissions come from human activities, particularly industry, agriculture and waste management.
There has been a boom in the production in shale gas in the US, where it is described as an important “bridge fuel” to a lowering carbon emissions because burning natural gas produces less CO2 emissions than coal. If fracking gas wells “leak” potent climate-changing methane into the atmosphere before it is captured to be used as a fuel, the leakage of greenhouse gas negates some of the CO2 savings. - Cape Times