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| Fig. 1: A schematic depiction of the process of hydraulic fracturing for shale gas. (Source: Wikimedia Commons) |
In a time where the search for alternative energy is at an all time high, a process called hydraulic fracturing has risen in popularity due to advances in technology and its potential economic and environmental advantages. This mechanism, better known as fracking, "fractures" low permeability rocks by introducing high-pressure liquid to extract the natural gas that is stuck beneath them. [1] One of natural gas's biggest draws is its low emission of Carbon Dioxide (CO2), a main component of the human influence on the atmospheric greenhouse effect, compared to its counterparts coal and oil. With that being said, there is no shortage in controversy as many people see the resulting leakage of methane from shale-gas production as greatly outweighing the decreased emission of CO2.
Since 2006, the United States has reduced its carbon emission more than any other nation. [2] While many may believe this is due to increased investment in renewable green energy, the real impact can be found in the shale oil and natural gas uprising. This significant shift from coal to natural gas accounts for more than 60% of the CO2 emission declines in the US. [2] More specifically, electrical power generation is responsible for nearly 40 percent, 38.1% to be exact, of all U.S. carbon dioxide emissions. Breaking this down, we can see that coal is responsible for a bulk of the CO2 emissions followed by followed by natural gas and finally petroleum. Their respective percentages of carbon dioxide emissions within the electrical power generation is 29.2%, 8.1%, and 0.7%. [3] Therefore, wouldn't the best course of action for the health of Earth's atmosphere be to expand the practice of hydraulic fracturing unlocking immense amounts of the world's natural gas for public consumption?
Unfortunately, an almost inevitable result of fracking is methane leakage out of the natural gas wells. While a well is being hydraulically fractured, "methane escapes from flow-back return fluids - and during drill out following the fracturing." [4] When released into the atmosphere, Methane can be far more powerful than CO2 with regards to its role as a greenhouse gas in warming Earth's atmosphere. Global Warming Potential, better known as GWP, is the most common way of measuring the potency of greenhouse gases. "A direct interpretation is that the GWP is an index of the total energy added to the climate system by a component in question relative to that added by CO2." [5] Recent studies show that Methane has a GWP of around 72 over a 20 year period and about 25 on a 100 year period. [6] Given the impact methane emissions has in comparison to carbon dioxide, this methane leakage would need to be kept to a certain level in order for the decline in CO2 emissions to outweigh that of the methane emissions. A recent study done by the Proceedings of the National Academy of Sciences places a threshold at 3.2% of total methane leakage, "beyond which [natural] gas becomes worse for the climate than coal for at least some period of time." [7] Studies have been conducted throughout the United States looking for answers on what the normal methane leakage at fracking wells is and while the results have varied, many of reached a similar conclusion to that of natural gas fields in Utah where leakage rates hovered in the range of 6.2%-11.7%. [8] While this emission rate is not necessarily universal, from 2000-2010 the amount of wells in the US used for hydraulic fracturing nearly doubled exponentially increasing the potential for methane leakage into the atmosphere. [1]
In looking at the process of hydraulic fracturing and its main pros and cons, the question remains, is it accelerating or decelerating the process of global warming? While much of the research is far from concrete, early signs point to fracking's side affects being more harmful to the atmosphere than beneficial. The release of methane, which is nearly 100 times stronger than CO2 in its effect as a greenhouse gas over the course of a 20 year period, looks to outweigh the positive side affect that comes from burning natural gas, a decline in CO2 emissions as compared to coal and oil. With that being said, fracking still holds the potential to be an aid to the process of slowing global warming. Further research into solving or at least diminishing the methane leakage problem from natural gas wells appears to have the most potential in proving hydraulic fracturing's benefit to our earth and atmosphere's well being.
© Dean Poplawski. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] N. Oreskes, "The Centerpiece of Obama's Energy Policy Will Actually Make Climate Change Worse," The Nation, 28 Jul 14.
[2] S. Moore, "Fracking is the Answer to Global Warming," Washington Times, 26 Sep 14.
[3] "EPA Regulation of Greenhouse Gas Emissions From New Power Plants," Center for Climate and Energy Solutions, November 2013.
[4] R. Howarth, R. Santoro, and A. Ingraffea, "Methane and the Greenhouse-Gas Footprint of Natural Gas From Shale Formations," Climatic Change 106, 679 (2011).
[5] Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. by T. F. Stocker et al. (Cambridge University Press, 2014).
[6] R. Howarth, "A Bridge to Nowhere: Methane Emissions and the Greenhouse Gas Footprint of Natural Gas," Energy, Science, and Engineering 2, 47 (2014).
[7] R. Alvareza et al., "Greater Focus Needed on Methane Leakage From Natural Gas Infrastructure," Proc. Natl. Acad. Sci. (USA) 109, 6435 (2012).
[8] A. Karion et al., "Methane Emissions Estimate From Airborne Measurements Over a Western United States Natural Gas Field," Geophys. Res. Lett. 40, 4393 (2013).
