As politically divisive as hydraulic fracturing is, we still need much more data to determine its environmental effects before deciding if it can be major source of energy during our transition away from fossil fuels. Unfortunately, this lack of data apparently means that companies are able to begin large operations without knowing all the costs, due to a lack of regulations that should probably be there while more research is done.
This brings us to a new study published in PNAS that shows orders of magnitude larger methane emission from well pads at fracking sites that were not previously thought to be significant contributors to greenhouse gas emission.
Methane is a substantial greenhouse gas contributor.. It actually has about thirty times the global warming potential of carbon dioxide (CO2), but plays less of a role due to its smaller overall percentage in the atmosphere. But there has been a disturbing trend over the past decade of an increase in methane concentration in the atmosphere – thus the great importance in understanding when and where we are emitting it! In fact, if methane emissions are large enough, fracking may be on the same level as coal in terms of warming potential.
This study used an aircraft to fly over well pads and measure methane emissions from individual plumes coming from the pads. These flights occurred during June 2012 in southwestern PA, and they measured the flux of CH4 coming from each pad (measured in CH4/s, or CH4/s/km^2 if not integrated over a particular area).This figure basically says it all – the orange dotted line is the sampling region where the aircraft measured methane emissions. The red circles and green and blue lines are measures of parts per million (ppm) of CH4 measured. Across the sampling region, a regional flux of 2-13 g CH4 /s/ km^2 was measured. The authors then integrated over distance and averaged across all the wells in the sampling region, and found a flux of 34 g CH4 /s per well, orders of magnitude beyond previous estimates.
What’s more surprising is that these wells had not even become fully operational – the companies were still drilling down to depth. Thus, these emissions are basically leaks during preparation that have previously been unaccounted for. Just to have it hit home, here’s another figure showing methane emissions as a function of horizontal distance vs altitude for several pads near Tau (see first figure):
Although I’m not an expert on this area of study, the authors appeared to be diligent about controlling for other possible sources of methane emission (although the figure above shows it’s clearly emitting from a ground source!). It’s hard not to be biased about fracking after seeing results like this – clearly we are moving way too fast and expanding fracking sites before we know what harm we’re doing. We just don’t have a good enough picture of what the long-term consequences are.
Caulton, D., Shepson, P., Santoro, R., Sparks, J., Howarth, R., Ingraffea, A., Cambaliza, M., Sweeney, C., Karion, A., Davis, K., Stirm, B., Montzka, S., & Miller, B. (2014). Toward a better understanding and quantification of methane emissions from shale gas development Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1316546111