Spring 2012

Is Shale Gas Good for Climate Change?

Daniel P. Schrag

Shale gas is a new energy resource that has shifted the dominant paradigm on U.S. hydrocarbon resources. Some have argued that shale gas will play an important role in reducing greenhouse gas emissions by displacing coal used for electricity, serving as a moderate-carbon “bridge fuel.” Others have questioned whether methane emissions from shale gas extraction lead to higher greenhouse gas emissions overall. I argue that the main impact of shale gas on climate change is neither the reduced emissions from fuel substitution nor the greenhouse gas footprint of natural gas itself, but rather the competition between abundant, low-cost gas and low-carbon technologies, including renewables and carbon capture and storage. This might be remedied if the gas industry joins forces with environmental groups, providing a counterbalance to the coal lobby, and ultimately eliminating the conventional use of coal in the United States.

DANIEL P. SCHRAG is the Sturgis Hooper Professor of Geology and Professor of Environmental Science and Engineering at Harvard University, where he is also Director of the Center for the Environment. He currently serves on President Obama's Council of Advisors on Science and Technology. He has authored more than one hundred articles on topics in geochemistry, geology, paleoclimatology, oceanography, energy technology, and energy policy.

Over the last ten years, technological innovation has transformed U.S. energy resources. Geologists have long known that organic-rich shales contain large quantities of natural gas, but the technology was not available to recover this gas at a reasonable cost. With the development of cheaper, more efficient horizontal drilling methods combined with improvements in hydraulic fracturing (“fracking”) techniques that greatly increase the permeability of the shale, vast reserves of natural gas are now available at relatively low cost. In just five years, shale gas has grown from 4 percent to more than 25 percent of the U.S. supply of natural gas. With the new shale gas reserves, the United States has decades of reserves of a critical energy resource for home heating, electricity generation, and a wide variety of industrial processes.

Environmental groups have had a mixed reaction to shale gas. National environmental organizations focused on climate change, as well as organizations concerned with air-quality issues, have cautiously embraced the new technologies in anticipation that greater availability of low-cost natural gas may displace coal in electricity generation, thereby reducing carbon dioxide emissions and substantially decreasing emission of other pollutants, particularly mercury and sulfur. Indeed, U.S. coal consumption fell 10 percent between 2007 and 2011, while natural gas production rose by 15 percent. On the other hand, many environmental groups have opposed the expansion of natural gas drilling, especially in places that historically have not seen extensive oil and gas activities. Some groups are concerned that the chemicals used in the fracking process will contaminate groundwater aquifers; others are concerned with natural gas leakage into aquifers and even residential houses; others are concerned with the overall footprint of natural gas extraction, including new roads, new pipelines, truck activity, and storage of toxic waste from produced water (a mixture of formation brines and chemicals from the fracking process).1

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  • 1For a good review of the environmental issues surrounding shale gas, see The Future of Natural Gas: An Interdisciplinary MIT Study (Cambridge, Mass.: Massachusetts Institute of Technology, 2011).
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